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Main
Date: 14 Sep 2007 19:21:49
From: jim beam
Subject: vacuum de-gas thread continued
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Peter Cole wrote:
> jim beam wrote:
>> Peter Cole wrote:
>>> jim beam wrote:
>>>> Peter Cole wrote: <snip for clarity>
>>>>>
>>>>>>> "One plant has been making over 1.2 million tons of
>>>>>>> degassed sheet steel to supply the automotive market"
>>>>>>> (annual).
>>>>>
>>>>> Given that the US annual vehicle production is around 15M,
>>>>> just that one plant would be contributing around 200lb of
>>>>> *sheet* to the average vehicle.
>>>>
>>>> and as i said earlier, for a 3,000lb vehicle, it's /clearly/
>>>> not being used for /all/ the material.
>>>>
>>>>
>>>>>
>>>>>
>>>>>> and even then, not every manufacturer would be interested.
>>>>>> it would be great for forged cranks for example, but the
>>>>>> majority of producers cast cranks because it's so much
>>>>>> cheaper - fatigue benefits of superior materials be hanged.
>>>>>>
>>>>>
>>>>> http://tinyurl.com/ywqhhy
>>>>
>>>> what part of "Racing Crankshaft" is hard to comprehend as being
>>>> atypical when we're talking about using cast iron for cheap
>>>> crap?
>>>>
>>>>
>>>>>
>>>>>
>>>>>> as for chronology, the benefits have been known for a long
>>>>>> time - since the 30's i believe, but knowing about it,
>>>>>> being able to produce it, and /paying/ for it are all
>>>>>> completely different things. i don't believe that an auto
>>>>>> industry that will save 6' of copper wire by using the same
>>>>>> bulb for brake lights and turn signals, or not using
>>>>>> washers/gaskets on spark plugs, has the /slightest/
>>>>>> interest in paying extra for vacuum degassed steels when
>>>>>> cheap cast iron crap will do.
>>>>>
>>>>> Well, you're entitled to your beliefs, but it seems you are
>>>>> wrong.
>>>>
>>>> eh? wrong like trying to bullshit about racing cranks being
>>>> used in everyday vehicles is wrong?
>>>
>>> Who said that? All I'm proving with that link is that a complete
>>> (65lb) crankshaft, forged with vacuum degassed steel is only
>>> $438, qty 1. How much do you think the vacuum degassing added to
>>> that price?
>>
>> er, the majority of domestic crankshafts are cast. /you/ cite one
>> that isn't in a context of being contrarian. as usual.
>
> No, just looking at the economics.
>
>>>>> As for vacuum degassing being somehow cost prohibitive for
>>>>> bicycle spokes, consider that even at an extra $100/ton, the
>>>>> change in raw material costs would be less than a dime for a
>>>>> bike's worth of spokes.
>>>>
>>>> er, you need to check out
>>>> http://www.steelonthenet.com/steel_cost_bof.html
>>>>
>>>> if i'm paying $261.50 per ton for steel, paying an extra 38% to
>>>> get it degassed is kind of significant.
>>>
>>> Not if you're making spokes, which is the whole point.
>>
>> yes if you're making spokes, which is the whole point. materials
>> costs are something and they need to be managed. processing is
>> another.
>
> OK, you're claiming that for a $438/65lb ($6.75/lb) crankshaft,
> vacuum degassed steel is economical,
eh? don't put those words in my mouth - never said anything /like/ that.
> but for a $.60/8g spoke
> ($165/lb) it isn't?
bullshit argument. see above.
>
>>> All of these examples prove that vacuum degassed steel has been
>>> in common use for a long time and doesn't cost much, contrary to
>>> your assertions. Since this is the crux of your argument about
>>> the need for stress relieving, you need to rethink the matter.
>>
>> it's been around since the 30's iirc, but it's not been widely used
>> - partly due to low tonnage, but mainly due to cost. it's not
>> /prohibitively/ expensive, but if it erodes a manufacturers profit,
>> and there's no benefit for that application, who is going to use
>> it?
>
> You are the one claiming the benefit (in spokes). It's been around
> and widely available since the mid 60's anyway -- used in bulk,
> cost-sensitive apps (auto sheet metal) since the 70's at least.
and bike spokes since the 70's.
>
> Let's review.
>
> You have claimed that stress relieving of spokes is not necessary
> since spoke failures are caused by surface defects, commonly
> inclusions.
no, you're paraphrasing and getting it wrong.
> The solution is to use quality spokes like Sapim, who,
> according to their website, use vacuum degassed steel. You back up
> this claim with a hand drawing of a spoke failing at an inclusion,
> which you assert is representative.
it is. /you/ go out and examine spoke failures and post photos that
contradict it if you can. my camera gear doesn't macro as small as my
loupe, hence the diagram.
>
> You claim that the use of vacuum degassed steels was unlikely until
> fairly recently because of cost and availability.
in automotive use. and i cited the cheaper alternative used. [whoops -
let's omit the inconvenient facts. forget i said that. or cited
anything even.]
> The record
> indicates that this was not true since at least the mid-60's.
eh? your own numbers contradict that!!!
>
> You claim that the use of vacuum degassed steel in spokes is still
> prohibitively expensive for some manufacturers.
no, you're paraphrasing and getting it wrong.
> It defies reason that
> a manufacturer could afford the alloying elements of stainless and
> not afford to degass the steel.
bullshit. see above.
>
> Let's suppose your claim that spokes only fail at inclusions is true,
> and that after using defect free material we don't need to stress
> relieve. This is because:
>
> 1) There aren't any residual stresses to relieve.
no, you're paraphrasing and getting it wrong.
>
> 2) They don't matter for fatigue life.
no, you're paraphrasing and getting it wrong.
>
> Item 1 is false. Metallurgists have agreed with Jobst's model on this
> forum (it's archived).
i'm a metallurgist, and i disagree. jobst doesn't take any of the real
world fatigue initiators into account in formulation of his theory.
/and/ he cites deformation of a strain aging material as part of his
explanation. two major fuck-ups, and you still want to claim jobst
knows what he's talking about? clearly /you/ don't know any better!
> I have observed the residual stress first hand
> by making a "slitting" experiment -- a technique that is used in
> industry.
and you have failed to observe fatigue initiate at a region of high
residual stress! just because it rains on thursdays doesn't mean that
beans don't make you fart.
>
> Item 2 is also false. If a spoke is nominally tensioned to 33% of
> yield, and the endurance limit is 40% of yield, even a small amount
> of residual stress can dramatically shorten the fatigue life.
in theory, yes. but FATIGUE IS NOT ***OBSERVED*** TO BE INITIATING AT A
REGION OF HIGH RESIDUAL STRESS!!! how many times does this need to be
repeated? just because this fact is inconvenient to the "theory"
doesn't mean it can be ignored.
> Since
> Jobst has reported spoke lifetimes of over 10^8 cycles, his technique
> must be reducing residual stresses to a very low level since he must
> be below the endurance limit.
i don't buy that "jobst has reported" bullshit. jobst first made
assertions to me in private correspondence that he had been riding the
same wheels for 300,000 miles. it has since emerged that not only has
he replaced rims and hubs, but spokes as well. what? suppress data
that doesn't suit the myth? say it can't be so!
either you're gullible and uneducated, or it suits you to bullshit too.
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Date: 17 Sep 2007 05:04:05
From: Chalo
Subject: Re: vacuum de-gas thread continued
|
On Sep 16, 10:51 pm, "Jambo" <-...@-.- > wrote:
> "Bill Sornson" <as...@ask.me> wrote in message
>
> news:46edf832$0$28827$4c368faf@roadrunner.com...
>
> > SEE HOW EASY IT IS TO TRIM EXCESS CRAP?!? YOU LEFT 11 KBs JUST TO ADD A
> > ONE-LINE TAG!!!
>
> > Shhhhhhhhhhhhhhhhhhhhhhhheeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeesssssssssssssssssssssssssssshhhhhhhhhhhhhhhhhh....................................................................................................................
>
> > Ah.
>
> Is it just imagination, or does Bill Sornson's contribution to this n.g.
> consist only of inane comments or rabid right-wing propaganda? Because I
> think he'll be better off in another newsgroup.
Cut him some slack-- the incredible cognitive dissonance associated
with his still being a Bush supporter is really taking its toll.
Homeboy could exercise his constitutionally protected right to eat his
own firearm any day now.
Chalo
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Date: 16 Sep 2007 22:30:37
From: Bill Sornson
Subject: Re: vacuum de-gas thread continued
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Chalo wrote:
> On Sep 16, 10:51 pm, "Jambo" <-...@-.-> wrote:
>> "Bill Sornson" <as...@ask.me> wrote in message
>>
>> news:46edf832$0$28827$4c368faf@roadrunner.com...
>>
>>> SEE HOW EASY IT IS TO TRIM EXCESS CRAP?!? YOU LEFT 11 KBs JUST TO
>>> ADD A ONE-LINE TAG!!!
>>
>>> Shhhhhhhhhhhhhhhhhhhhhhhheeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeesssssssssssssssssssssssssssshhhhhhhhhhhhhhhhhh....................................................................................................................
>>
>>> Ah.
>>
>> Is it just imagination, or does Bill Sornson's contribution to this
>> n.g. consist only of inane comments or rabid right-wing propaganda?
>> Because I think he'll be better off in another newsgroup.
Plonked you days ago, hate-bag. You're more than welcome to return the
favor.
> Cut him some slack-- the incredible cognitive dissonance associated
> with his still being a Bush supporter is really taking its toll.
> Homeboy could exercise his constitutionally protected right to eat his
> own firearm any day now.
Never owned a weapon of any sort, but it figures that you'd think in terms
of EATING ONE since you're a fat tub of gelatinous lard.
Go hose your pits, skank. I /know/ you can't find your groin area.
(Understandable since you have seen it in decades. LOL )
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Date: 15 Sep 2007 13:35:05
From:
Subject: Re: vacuum de-gas thread continued
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On Sep 15, 12:10 pm, Ben C <spams...@spam.eggs > wrote:
> On 2007-09-15, Peter Cole <peter_c...@comcast.net> wrote:
> I'm not old enough to remember what bikes were like in the 60's and
> 70's, but most older bikes I've seen of quite good quality (Reynolds 531
> frame sort of level) had galvanized spokes. Is it true that stainless
> steel has come down in price in the last 40 or 50 years and/or is more
> widespread in its use for spokes?
Dear Ben,
Stainless steel spokes are certainly more widespread.
Nowadays, galvanized spokes are considered cheap and inferior.
"Quality" spokes are stainless steel and cost more.
Galvanized spokes are actually a bit stronger than stainless steel
spokes, but the extra strength has no advantage, since typical spoke
tension is 100~150 kgf, well below the 225~250 kgf yield point that
Jobst measured for thinner stainless steel 1.8 mm spokes. (And
inflating the tire can reduce the spoke tension up to 15% on 700c
rims.)
In the 1981-1983 first edition of "The Bicycle Wheel," Jobst tested
six spokes, three galvanized and three stainless steel (S.S.)::
Union 14 gauge
DT 14 gauge
Robegel Sport 14 gauge
DT S.S. 14 gauge
DT S.S. 15 gauge
Robegel S.S. 15-16 gauge
The DT galvanized 14 gauge has a slightly higher and slightly sharper
stress-strain curve than the DT stainless steel 14 gauge--the
stainless steel was not quite as strong, but was more ductile.
A few years later, Jobst re-tested spokes for the second edition of
1988. He tested only DT and Wheelsmith and only stainless steel
spokes--galvanized had practically vanished.
Jobst noticed an impressive improvement in ductility:
"In contrast to tests performed for the first edition of this book,
these spokes withstood substantial elongation before failure. Some
butted spokes stretched more than six millimeters without breaking, at
which point the test was stopped."
--p. 132, "The Bicycle Wheel," 2nd edition, 1988
So the stainless steel spokes had not only replaced galvanized as the
material for quality spokes, but they had also improved in ductility
over early stainless steel spokes.
A few years after that, Jobst wrote in the third edition of 1993:
"It appears that the better spokes now available would have made the
discovery of many of the concepts of this book more difficult for lack
of failure data. I am grateful in retrospect for the poor durability
of earlier spokes. They operated so near their limits that durability
was significantly altered by the techniques that I have outlined."
--p. 124, "The Bicycle Wheel," 3rd Edition, 1993
In short, spokes apparently improved so much in a decade that the
failure rate plummeted. Jobst's observation is supported by the fact
that riders gradually stopped carrying spare spokes on long rides.
Cheers,
Carl Fogel
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Date: 15 Sep 2007 17:10:09
From: Ben C
Subject: Re: vacuum de-gas thread continued
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On 2007-09-15, carlfogel@comcast.net <carlfogel@comcast.net > wrote:
> On Sep 15, 12:10 pm, Ben C <spams...@spam.eggs> wrote:
>> On 2007-09-15, Peter Cole <peter_c...@comcast.net> wrote:
>
>> I'm not old enough to remember what bikes were like in the 60's and
>> 70's, but most older bikes I've seen of quite good quality (Reynolds 531
>> frame sort of level) had galvanized spokes. Is it true that stainless
>> steel has come down in price in the last 40 or 50 years and/or is more
>> widespread in its use for spokes?
>
> Dear Ben,
>
> Stainless steel spokes are certainly more widespread.
>
> Nowadays, galvanized spokes are considered cheap and inferior.
> "Quality" spokes are stainless steel and cost more.
>
> Galvanized spokes are actually a bit stronger than stainless steel
> spokes, but the extra strength has no advantage, since typical spoke
> tension is 100~150 kgf, well below the 225~250 kgf yield point that
> Jobst measured for thinner stainless steel 1.8 mm spokes. (And
> inflating the tire can reduce the spoke tension up to 15% on 700c
> rims.)
>
> In the 1981-1983 first edition of "The Bicycle Wheel," Jobst tested
> six spokes, three galvanized and three stainless steel (S.S.)::
>
> Union 14 gauge
> DT 14 gauge
> Robegel Sport 14 gauge
>
> DT S.S. 14 gauge
> DT S.S. 15 gauge
> Robegel S.S. 15-16 gauge
>
> The DT galvanized 14 gauge has a slightly higher and slightly sharper
> stress-strain curve than the DT stainless steel 14 gauge--the
> stainless steel was not quite as strong, but was more ductile.
>
> A few years later, Jobst re-tested spokes for the second edition of
> 1988. He tested only DT and Wheelsmith and only stainless steel
> spokes--galvanized had practically vanished.
>
> Jobst noticed an impressive improvement in ductility:
>
> "In contrast to tests performed for the first edition of this book,
> these spokes withstood substantial elongation before failure. Some
> butted spokes stretched more than six millimeters without breaking, at
> which point the test was stopped."
>
> --p. 132, "The Bicycle Wheel," 2nd edition, 1988
>
> So the stainless steel spokes had not only replaced galvanized as the
> material for quality spokes, but they had also improved in ductility
> over early stainless steel spokes.
Thanks for another excellent answer.
Does the extra ductility have any advantage _per se_ for spokes?
It might be a side-effect of some other improvement and therefore a clue
about the introduction of some new process like vacuum degassing.
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Date: 15 Sep 2007 19:45:32
From: Michael Press
Subject: Re: vacuum de-gas thread continued
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In article
<slrnfeom1n.5o4.spamspam@bowser.marioworld >,
Ben C <spamspam@spam.eggs > wrote:
> Does the extra ductility have any advantage _per se_ for spokes?
>
> It might be a side-effect of some other improvement and therefore a clue
> about the introduction of some new process like vacuum degassing.
It will extend the time interval between onset of
deterioration in a spoke and failure. A more ductile
metal spoke will yield more extension before fracture.
A compromised spoke will elongate. If the rider notices
the wheel is untrue or that the spoke is loose he will
tighten the spoke. Thus the spoke comes to notice. If
it needs tightening more than once, which is more
likely with a more ductile spoke metal, the rider is
alerted. Probably will wait until the spoke breaks, but
at least the rider knows there is some kind of problem;
and, heck, he may lose the wheel or spokes before the
more ductile spoke fractures.
--
Michael Press
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Date: 16 Sep 2007 08:05:09
From: jim beam
Subject: Re: vacuum de-gas thread continued
|
Michael Press wrote:
> In article
> <slrnfeom1n.5o4.spamspam@bowser.marioworld>,
> Ben C <spamspam@spam.eggs> wrote:
>
>> Does the extra ductility have any advantage _per se_ for spokes?
>>
>> It might be a side-effect of some other improvement and therefore a clue
>> about the introduction of some new process like vacuum degassing.
>
> It will extend the time interval between onset of
> deterioration in a spoke and failure. A more ductile
> metal spoke will yield more extension before fracture.
> A compromised spoke will elongate. If the rider notices
> the wheel is untrue or that the spoke is loose he will
> tighten the spoke. Thus the spoke comes to notice. If
> it needs tightening more than once, which is more
> likely with a more ductile spoke metal, the rider is
> alerted. Probably will wait until the spoke breaks, but
> at least the rider knows there is some kind of problem;
> and, heck, he may lose the wheel or spokes before the
> more ductile spoke fractures.
>
there is a rough correlation between ductility and fatigue resistance,
but it's very imprecise and not typically something you'd use as a
design factor.
since fatigue is the biggest concern for applications that approach
material limits, and at high stress, no material is immune from fatigue,
designers concentrate on delaying onset. this means attention to
design, surface finish, corrosion, stress concentrations, material
quality, etc. even residual stress! this is the approach of the
aerospace industry.
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Date: 16 Sep 2007 08:24:54
From: Peter Cole
Subject: Re: vacuum de-gas thread continued
|
Michael Press wrote:
> In article
> <slrnfeom1n.5o4.spamspam@bowser.marioworld>,
> Ben C <spamspam@spam.eggs> wrote:
>
>> Does the extra ductility have any advantage _per se_ for spokes?
>>
>> It might be a side-effect of some other improvement and therefore a clue
>> about the introduction of some new process like vacuum degassing.
>
> It will extend the time interval between onset of
> deterioration in a spoke and failure. A more ductile
> metal spoke will yield more extension before fracture.
> A compromised spoke will elongate. If the rider notices
> the wheel is untrue or that the spoke is loose he will
> tighten the spoke. Thus the spoke comes to notice. If
> it needs tightening more than once, which is more
> likely with a more ductile spoke metal, the rider is
> alerted. Probably will wait until the spoke breaks, but
> at least the rider knows there is some kind of problem;
> and, heck, he may lose the wheel or spokes before the
> more ductile spoke fractures.
>
Since the maximum stress seen by the spoke is when a wheel is unloaded,
and that is well below the point of bulk plastic deformation, I don't
see how ductility enters into the picture.
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Date: 16 Sep 2007 07:52:55
From: jim beam
Subject: Re: vacuum de-gas thread continued
|
Peter Cole wrote:
> Michael Press wrote:
>> In article <slrnfeom1n.5o4.spamspam@bowser.marioworld>,
>> Ben C <spamspam@spam.eggs> wrote:
>>
>>> Does the extra ductility have any advantage _per se_ for spokes?
>>>
>>> It might be a side-effect of some other improvement and therefore a clue
>>> about the introduction of some new process like vacuum degassing.
>>
>> It will extend the time interval between onset of
>> deterioration in a spoke and failure. A more ductile
>> metal spoke will yield more extension before fracture.
>> A compromised spoke will elongate. If the rider notices
>> the wheel is untrue or that the spoke is loose he will
>> tighten the spoke. Thus the spoke comes to notice. If
>> it needs tightening more than once, which is more
>> likely with a more ductile spoke metal, the rider is
>> alerted. Probably will wait until the spoke breaks, but
>> at least the rider knows there is some kind of problem;
>> and, heck, he may lose the wheel or spokes before the
>> more ductile spoke fractures.
>>
>
> Since the maximum stress seen by the spoke is when a wheel is unloaded,
er, no. maximum stress is on lateral loading.
> and that is well below the point of bulk plastic deformation, I don't
> see how ductility enters into the picture.
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Date: 16 Sep 2007 11:29:34
From: Peter Cole
Subject: Re: vacuum de-gas thread continued
|
jim beam wrote:
> Peter Cole wrote:
>> Michael Press wrote:
>>> In article <slrnfeom1n.5o4.spamspam@bowser.marioworld>,
>>> Ben C <spamspam@spam.eggs> wrote:
>>>
>>>> Does the extra ductility have any advantage _per se_ for spokes?
>>>>
>>>> It might be a side-effect of some other improvement and therefore a
>>>> clue
>>>> about the introduction of some new process like vacuum degassing.
>>>
>>> It will extend the time interval between onset of
>>> deterioration in a spoke and failure. A more ductile
>>> metal spoke will yield more extension before fracture.
>>> A compromised spoke will elongate. If the rider notices
>>> the wheel is untrue or that the spoke is loose he will
>>> tighten the spoke. Thus the spoke comes to notice. If
>>> it needs tightening more than once, which is more
>>> likely with a more ductile spoke metal, the rider is
>>> alerted. Probably will wait until the spoke breaks, but
>>> at least the rider knows there is some kind of problem;
>>> and, heck, he may lose the wheel or spokes before the
>>> more ductile spoke fractures.
>>>
>>
>> Since the maximum stress seen by the spoke is when a wheel is unloaded,
>
> er, no. maximum stress is on lateral loading.
Give me a call when you stretch a spoke.
>
>
>> and that is well below the point of bulk plastic deformation, I don't
>> see how ductility enters into the picture.
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Date: 16 Sep 2007 08:43:59
From: jim beam
Subject: Re: vacuum de-gas thread continued
|
Peter Cole wrote:
> jim beam wrote:
>> Peter Cole wrote:
>>> Michael Press wrote:
>>>> In article <slrnfeom1n.5o4.spamspam@bowser.marioworld>,
>>>> Ben C <spamspam@spam.eggs> wrote:
>>>>
>>>>> Does the extra ductility have any advantage _per se_ for spokes?
>>>>>
>>>>> It might be a side-effect of some other improvement and therefore a
>>>>> clue
>>>>> about the introduction of some new process like vacuum degassing.
>>>>
>>>> It will extend the time interval between onset of
>>>> deterioration in a spoke and failure. A more ductile
>>>> metal spoke will yield more extension before fracture.
>>>> A compromised spoke will elongate. If the rider notices
>>>> the wheel is untrue or that the spoke is loose he will
>>>> tighten the spoke. Thus the spoke comes to notice. If
>>>> it needs tightening more than once, which is more
>>>> likely with a more ductile spoke metal, the rider is
>>>> alerted. Probably will wait until the spoke breaks, but
>>>> at least the rider knows there is some kind of problem;
>>>> and, heck, he may lose the wheel or spokes before the
>>>> more ductile spoke fractures.
>>>>
>>>
>>> Since the maximum stress seen by the spoke is when a wheel is unloaded,
>>
>> er, no. maximum stress is on lateral loading.
>
> Give me a call when you stretch a spoke.
plastic or elastic? spokes are only loaded to 1/3 yield. that gives
you a /lot/ of latitude for stress increase with no permanent deformation.
>
>
>>
>>
>>> and that is well below the point of bulk plastic deformation, I don't
>>> see how ductility enters into the picture.
|
| | | | | | | | |
Date: 16 Sep 2007 16:07:26
From: Peter Cole
Subject: Re: vacuum de-gas thread continued
|
jim beam wrote:
> Peter Cole wrote:
>> jim beam wrote:
>>> Peter Cole wrote:
>>>> Michael Press wrote:
>>>>> In article <slrnfeom1n.5o4.spamspam@bowser.marioworld>,
>>>>> Ben C <spamspam@spam.eggs> wrote:
>>>>>
>>>>>> Does the extra ductility have any advantage _per se_ for spokes?
>>>>>>
>>>>>> It might be a side-effect of some other improvement and therefore
>>>>>> a clue
>>>>>> about the introduction of some new process like vacuum degassing.
>>>>>
>>>>> It will extend the time interval between onset of
>>>>> deterioration in a spoke and failure. A more ductile
>>>>> metal spoke will yield more extension before fracture.
>>>>> A compromised spoke will elongate. If the rider notices
>>>>> the wheel is untrue or that the spoke is loose he will
>>>>> tighten the spoke. Thus the spoke comes to notice. If
>>>>> it needs tightening more than once, which is more
>>>>> likely with a more ductile spoke metal, the rider is
>>>>> alerted. Probably will wait until the spoke breaks, but
>>>>> at least the rider knows there is some kind of problem;
>>>>> and, heck, he may lose the wheel or spokes before the
>>>>> more ductile spoke fractures.
>>>>>
>>>>
>>>> Since the maximum stress seen by the spoke is when a wheel is unloaded,
>>>
>>> er, no. maximum stress is on lateral loading.
>>
>> Give me a call when you stretch a spoke.
>
> plastic or elastic? spokes are only loaded to 1/3 yield. that gives
> you a /lot/ of latitude for stress increase with no permanent deformation.
The context is ductility, figure it out.
>
>
>>
>>
>>>
>>>
>>>> and that is well below the point of bulk plastic deformation, I
>>>> don't see how ductility enters into the picture.
|
| | | | | | | | | |
Date: 16 Sep 2007 13:32:44
From: jim beam
Subject: Re: vacuum de-gas thread continued
|
Peter Cole wrote:
> jim beam wrote:
>> Peter Cole wrote:
>>> jim beam wrote:
>>>> Peter Cole wrote:
>>>>> Michael Press wrote:
>>>>>> In article <slrnfeom1n.5o4.spamspam@bowser.marioworld>,
>>>>>> Ben C <spamspam@spam.eggs> wrote:
>>>>>>
>>>>>>> Does the extra ductility have any advantage _per se_ for spokes?
>>>>>>>
>>>>>>> It might be a side-effect of some other improvement and therefore
>>>>>>> a clue
>>>>>>> about the introduction of some new process like vacuum degassing.
>>>>>>
>>>>>> It will extend the time interval between onset of
>>>>>> deterioration in a spoke and failure. A more ductile
>>>>>> metal spoke will yield more extension before fracture.
>>>>>> A compromised spoke will elongate. If the rider notices
>>>>>> the wheel is untrue or that the spoke is loose he will
>>>>>> tighten the spoke. Thus the spoke comes to notice. If
>>>>>> it needs tightening more than once, which is more
>>>>>> likely with a more ductile spoke metal, the rider is
>>>>>> alerted. Probably will wait until the spoke breaks, but
>>>>>> at least the rider knows there is some kind of problem;
>>>>>> and, heck, he may lose the wheel or spokes before the
>>>>>> more ductile spoke fractures.
>>>>>>
>>>>>
>>>>> Since the maximum stress seen by the spoke is when a wheel is
>>>>> unloaded,
>>>>
>>>> er, no. maximum stress is on lateral loading.
>>>
>>> Give me a call when you stretch a spoke.
>>
>> plastic or elastic? spokes are only loaded to 1/3 yield. that gives
>> you a /lot/ of latitude for stress increase with no permanent
>> deformation.
>
>
> The context is ductility, figure it out.
but the territory is elasticity for the reasons given above. is this
still confusing?
>
>>
>>
>>>
>>>
>>>>
>>>>
>>>>> and that is well below the point of bulk plastic deformation, I
>>>>> don't see how ductility enters into the picture.
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Date: 16 Sep 2007 17:45:33
From: Peter Cole
Subject: Re: vacuum de-gas thread continued
|
jim beam wrote:
> Peter Cole wrote:
>> jim beam wrote:
>>> Peter Cole wrote:
>>>> jim beam wrote:
>>>>> Peter Cole wrote:
>>>>>> Michael Press wrote:
>>>>>>> In article <slrnfeom1n.5o4.spamspam@bowser.marioworld>,
>>>>>>> Ben C <spamspam@spam.eggs> wrote:
>>>>>>>
>>>>>>>> Does the extra ductility have any advantage _per se_ for spokes?
>>>>>>>>
>>>>>>>> It might be a side-effect of some other improvement and
>>>>>>>> therefore a clue
>>>>>>>> about the introduction of some new process like vacuum degassing.
>>>>>>>
>>>>>>> It will extend the time interval between onset of
>>>>>>> deterioration in a spoke and failure. A more ductile
>>>>>>> metal spoke will yield more extension before fracture.
>>>>>>> A compromised spoke will elongate. If the rider notices
>>>>>>> the wheel is untrue or that the spoke is loose he will
>>>>>>> tighten the spoke. Thus the spoke comes to notice. If
>>>>>>> it needs tightening more than once, which is more
>>>>>>> likely with a more ductile spoke metal, the rider is
>>>>>>> alerted. Probably will wait until the spoke breaks, but
>>>>>>> at least the rider knows there is some kind of problem;
>>>>>>> and, heck, he may lose the wheel or spokes before the
>>>>>>> more ductile spoke fractures.
>>>>>>>
>>>>>>
>>>>>> Since the maximum stress seen by the spoke is when a wheel is
>>>>>> unloaded,
>>>>>
>>>>> er, no. maximum stress is on lateral loading.
>>>>
>>>> Give me a call when you stretch a spoke.
>>>
>>> plastic or elastic? spokes are only loaded to 1/3 yield. that gives
>>> you a /lot/ of latitude for stress increase with no permanent
>>> deformation.
>>
>>
>> The context is ductility, figure it out.
>
> but the territory is elasticity for the reasons given above. is this
> still confusing?
It shouldn't be, but apparently is (to you), how else would you
interpret "A compromised spoke will elongate." (above)?
>>>>>> and that is well below the point of bulk plastic deformation, I
>>>>>> don't see how ductility enters into the picture.
You also didn't apparently get as far as this last part in your reading.
|
| | | | | | | | | | | |
Date: 16 Sep 2007 15:05:03
From: jim beam
Subject: Re: vacuum de-gas thread continued
|
Peter Cole wrote:
> jim beam wrote:
>> Peter Cole wrote:
>>> jim beam wrote:
>>>> Peter Cole wrote:
>>>>> jim beam wrote:
>>>>>> Peter Cole wrote:
>>>>>>> Michael Press wrote:
>>>>>>>> In article <slrnfeom1n.5o4.spamspam@bowser.marioworld>,
>>>>>>>> Ben C <spamspam@spam.eggs> wrote:
>>>>>>>>
>>>>>>>>> Does the extra ductility have any advantage _per se_ for spokes?
>>>>>>>>>
>>>>>>>>> It might be a side-effect of some other improvement and
>>>>>>>>> therefore a clue
>>>>>>>>> about the introduction of some new process like vacuum degassing.
>>>>>>>>
>>>>>>>> It will extend the time interval between onset of
>>>>>>>> deterioration in a spoke and failure. A more ductile
>>>>>>>> metal spoke will yield more extension before fracture.
>>>>>>>> A compromised spoke will elongate. If the rider notices
>>>>>>>> the wheel is untrue or that the spoke is loose he will
>>>>>>>> tighten the spoke. Thus the spoke comes to notice. If
>>>>>>>> it needs tightening more than once, which is more
>>>>>>>> likely with a more ductile spoke metal, the rider is
>>>>>>>> alerted. Probably will wait until the spoke breaks, but
>>>>>>>> at least the rider knows there is some kind of problem;
>>>>>>>> and, heck, he may lose the wheel or spokes before the
>>>>>>>> more ductile spoke fractures.
>>>>>>>>
>>>>>>>
>>>>>>> Since the maximum stress seen by the spoke is when a wheel is
>>>>>>> unloaded,
>>>>>>
>>>>>> er, no. maximum stress is on lateral loading.
>>>>>
>>>>> Give me a call when you stretch a spoke.
>>>>
>>>> plastic or elastic? spokes are only loaded to 1/3 yield. that
>>>> gives you a /lot/ of latitude for stress increase with no permanent
>>>> deformation.
>>>
>>>
>>> The context is ductility, figure it out.
>>
>> but the territory is elasticity for the reasons given above. is this
>> still confusing?
>
> It shouldn't be, but apparently is (to you), how else would you
> interpret "A compromised spoke will elongate." (above)?
shit dude, you could twist and distort the truth out of sunrise! it's
quite impressive - in a pervy kind of way.
elasticity is not plasticity. don't confuse them and use the word
"elongation" when you're not defining which is which.
>
>>>>>>> and that is well below the point of bulk plastic deformation, I
>>>>>>> don't see how ductility enters into the picture.
>
> You also didn't apparently get as far as this last part in your reading.
er, you want to talk ductility when you don't understand the difference
between elasticity and plasticity? let's see if we can get your
training wheels off first...
|
| | | | | | | | | | | | |
Date: 16 Sep 2007 20:05:29
From: Peter Cole
Subject: Re: vacuum de-gas thread continued
|
jim beam wrote:
> Peter Cole wrote:
>> jim beam wrote:
>>> Peter Cole wrote:
>>>> jim beam wrote:
>>>>> Peter Cole wrote:
>>>>>> jim beam wrote:
>>>>>>> Peter Cole wrote:
>>>>>>>> Michael Press wrote:
>>>>>>>>> In article <slrnfeom1n.5o4.spamspam@bowser.marioworld>,
>>>>>>>>> Ben C <spamspam@spam.eggs> wrote:
>>>>>>>>>
>>>>>>>>>> Does the extra ductility have any advantage _per se_ for spokes?
>>>>>>>>>>
>>>>>>>>>> It might be a side-effect of some other improvement and
>>>>>>>>>> therefore a clue
>>>>>>>>>> about the introduction of some new process like vacuum degassing.
>>>>>>>>>
>>>>>>>>> It will extend the time interval between onset of
>>>>>>>>> deterioration in a spoke and failure. A more ductile
>>>>>>>>> metal spoke will yield more extension before fracture.
>>>>>>>>> A compromised spoke will elongate. If the rider notices
>>>>>>>>> the wheel is untrue or that the spoke is loose he will
>>>>>>>>> tighten the spoke. Thus the spoke comes to notice. If
>>>>>>>>> it needs tightening more than once, which is more
>>>>>>>>> likely with a more ductile spoke metal, the rider is
>>>>>>>>> alerted. Probably will wait until the spoke breaks, but
>>>>>>>>> at least the rider knows there is some kind of problem;
>>>>>>>>> and, heck, he may lose the wheel or spokes before the
>>>>>>>>> more ductile spoke fractures.
>>>>>>>>>
>>>>>>>>
>>>>>>>> Since the maximum stress seen by the spoke is when a wheel is
>>>>>>>> unloaded,
>>>>>>>
>>>>>>> er, no. maximum stress is on lateral loading.
>>>>>>
>>>>>> Give me a call when you stretch a spoke.
>>>>>
>>>>> plastic or elastic? spokes are only loaded to 1/3 yield. that
>>>>> gives you a /lot/ of latitude for stress increase with no permanent
>>>>> deformation.
>>>>
>>>>
>>>> The context is ductility, figure it out.
>>>
>>> but the territory is elasticity for the reasons given above. is this
>>> still confusing?
>>
>> It shouldn't be, but apparently is (to you), how else would you
>> interpret "A compromised spoke will elongate." (above)?
>
> shit dude, you could twist and distort the truth out of sunrise! it's
> quite impressive - in a pervy kind of way.
>
> elasticity is not plasticity. don't confuse them and use the word
> "elongation" when you're not defining which is which.
>
OK, why would elastic elongation require the spoke to be "retightened"?
What does elastic have to do with ductility (above)?
You still can't read.
>
>>
>>>>>>>> and that is well below the point of bulk plastic deformation, I
>>>>>>>> don't see how ductility enters into the picture.
>>
>> You also didn't apparently get as far as this last part in your reading.
>
> er, you want to talk ductility when you don't understand the difference
> between elasticity and plasticity? let's see if we can get your
> training wheels off first...
You can't read.
|
| | | | | | | | | | | | | |
Date: 18 Sep 2007 21:35:28
From: jim beam
Subject: Re: vacuum de-gas thread continued
|
Peter Cole wrote:
> jim beam wrote:
>> Peter Cole wrote:
>>> jim beam wrote:
>>>> Peter Cole wrote:
>>>>> jim beam wrote:
>>>>>> Peter Cole wrote:
>>>>>>> jim beam wrote:
>>>>>>>> Peter Cole wrote:
>>>>>>>>> Michael Press wrote:
>>>>>>>>>> In article <slrnfeom1n.5o4.spamspam@bowser.marioworld>,
>>>>>>>>>> Ben C <spamspam@spam.eggs> wrote:
>>>>>>>>>>
>>>>>>>>>>> Does the extra ductility have any advantage _per se_ for spokes?
>>>>>>>>>>>
>>>>>>>>>>> It might be a side-effect of some other improvement and
>>>>>>>>>>> therefore a clue
>>>>>>>>>>> about the introduction of some new process like vacuum
>>>>>>>>>>> degassing.
>>>>>>>>>>
>>>>>>>>>> It will extend the time interval between onset of
>>>>>>>>>> deterioration in a spoke and failure. A more ductile
>>>>>>>>>> metal spoke will yield more extension before fracture.
>>>>>>>>>> A compromised spoke will elongate. If the rider notices
>>>>>>>>>> the wheel is untrue or that the spoke is loose he will
>>>>>>>>>> tighten the spoke. Thus the spoke comes to notice. If
>>>>>>>>>> it needs tightening more than once, which is more
>>>>>>>>>> likely with a more ductile spoke metal, the rider is
>>>>>>>>>> alerted. Probably will wait until the spoke breaks, but
>>>>>>>>>> at least the rider knows there is some kind of problem;
>>>>>>>>>> and, heck, he may lose the wheel or spokes before the
>>>>>>>>>> more ductile spoke fractures.
>>>>>>>>>>
>>>>>>>>>
>>>>>>>>> Since the maximum stress seen by the spoke is when a wheel is
>>>>>>>>> unloaded,
>>>>>>>>
>>>>>>>> er, no. maximum stress is on lateral loading.
>>>>>>>
>>>>>>> Give me a call when you stretch a spoke.
>>>>>>
>>>>>> plastic or elastic? spokes are only loaded to 1/3 yield. that
>>>>>> gives you a /lot/ of latitude for stress increase with no
>>>>>> permanent deformation.
>>>>>
>>>>>
>>>>> The context is ductility, figure it out.
>>>>
>>>> but the territory is elasticity for the reasons given above. is
>>>> this still confusing?
>>>
>>> It shouldn't be, but apparently is (to you), how else would you
>>> interpret "A compromised spoke will elongate." (above)?
>>
>> shit dude, you could twist and distort the truth out of sunrise! it's
>> quite impressive - in a pervy kind of way.
>>
>> elasticity is not plasticity. don't confuse them and use the word
>> "elongation" when you're not defining which is which.
>>
>
> OK, why would elastic elongation require the spoke to be "retightened"?
>
> What does elastic have to do with ductility (above)?
>
> You still can't read.
i can read you trying to avoid admitting that spoke tension can increase
under lateral load. and i can read you then trying to say that stress
increase always causes plastic deformation - it doesn't. and even if we
try making sense of the example you keep changing, it's trivially clear
that a spoke that needs tightening /still/ doesn't evidence plastic
deformation of a spoke - not when a soft aluminum hub hole can deform at
lower stress.
oh, and elasticity has nothing to do with ductility - don't put those
words in my mouth.
>
>>
>>>
>>>>>>>>> and that is well below the point of bulk plastic deformation, I
>>>>>>>>> don't see how ductility enters into the picture.
>>>
>>> You also didn't apparently get as far as this last part in your reading.
>>
>> er, you want to talk ductility when you don't understand the
>> difference between elasticity and plasticity? let's see if we can get
>> your training wheels off first...
>
> You can't read.
|
| | | | | | | | | | | | | | |
Date: 19 Sep 2007 08:44:37
From: Peter Cole
Subject: Re: vacuum de-gas thread continued
|
jim beam wrote:
> Peter Cole wrote:
>>>>>>>>>> Michael Press wrote:
>>>>>>>>>>> A more ductile
>>>>>>>>>>> metal spoke will yield more extension before fracture.
>>>>>>>>>>> A compromised spoke will elongate. If the rider notices
>>>>>>>>>>> the wheel is untrue or that the spoke is loose he will
>>>>>>>>>>> tighten the spoke. Thus the spoke comes to notice. If
>>>>>>>>>>> it needs tightening more than once, which is more
>>>>>>>>>>> likely with a more ductile spoke metal, the rider is
>>>>>>>>>>> alerted.
>> OK, why would elastic elongation require the spoke to be "retightened"?
>>
>> What does elastic have to do with ductility (above)?
>>
>> You still can't read.
> and i can read you then trying to say that stress
> increase always causes plastic deformation - it doesn't. and even if we
> try making sense of the example you keep changing, it's trivially clear
> that a spoke that needs tightening /still/ doesn't evidence plastic
> deformation of a spoke - not when a soft aluminum hub hole can deform at
> lower stress.
The context is above. It's speculation that ductile spokes can stretch
(plastically) in use. It's wrong. You're just raising straw men. Have fun.
|
| | | | | | | | | | | | | | | |
Date: 19 Sep 2007 20:30:34
From: jim beam
Subject: Re: vacuum de-gas thread continued
|
Peter Cole wrote:
> jim beam wrote:
>> Peter Cole wrote:
>>>>>>>>>>> Michael Press wrote:
>>>>>>>>>>>> A more ductile
>>>>>>>>>>>> metal spoke will yield more extension before fracture.
>>>>>>>>>>>> A compromised spoke will elongate. If the rider notices
>>>>>>>>>>>> the wheel is untrue or that the spoke is loose he will
>>>>>>>>>>>> tighten the spoke. Thus the spoke comes to notice. If
>>>>>>>>>>>> it needs tightening more than once, which is more
>>>>>>>>>>>> likely with a more ductile spoke metal, the rider is
>>>>>>>>>>>> alerted.
>
>>> OK, why would elastic elongation require the spoke to be "retightened"?
>>>
>>> What does elastic have to do with ductility (above)?
>>>
>>> You still can't read.
>
>> and i can read you then trying to say that stress
>> increase always causes plastic deformation - it doesn't. and even if we
>> try making sense of the example you keep changing, it's trivially clear
>> that a spoke that needs tightening /still/ doesn't evidence plastic
>> deformation of a spoke - not when a soft aluminum hub hole can deform at
>> lower stress.
>
> The context is above. It's speculation that ductile spokes can stretch
> (plastically) in use.
er, that was /your/ contention, not mine.
> It's wrong. You're just raising straw men. Have fun.
don't put bullshit false words in my mouth than criticize them peter.
because that makes you a prick.
|
| | | | | | | | | | | | | | | | |
Date: 20 Sep 2007 09:41:44
From: Peter Cole
Subject: Re: vacuum de-gas thread continued
|
jim beam wrote:
> Peter Cole wrote:
>> jim beam wrote:
>>> Peter Cole wrote:
>>>>>>>>>>>> Michael Press wrote:
>>>>>>>>>>>>> A more ductile
>>>>>>>>>>>>> metal spoke will yield more extension before fracture.
>>>>>>>>>>>>> A compromised spoke will elongate. If the rider notices
>>>>>>>>>>>>> the wheel is untrue or that the spoke is loose he will
>>>>>>>>>>>>> tighten the spoke. Thus the spoke comes to notice. If
>>>>>>>>>>>>> it needs tightening more than once, which is more
>>>>>>>>>>>>> likely with a more ductile spoke metal, the rider is
>>>>>>>>>>>>> alerted.
>>
>>>> OK, why would elastic elongation require the spoke to be "retightened"?
>>>>
>>>> What does elastic have to do with ductility (above)?
>>>>
>>>> You still can't read.
>>
>>> and i can read you then trying to say that stress
>>> increase always causes plastic deformation - it doesn't. and even if we
>>> try making sense of the example you keep changing, it's trivially clear
>>> that a spoke that needs tightening /still/ doesn't evidence plastic
>>> deformation of a spoke - not when a soft aluminum hub hole can deform at
>>> lower stress.
>>
>> The context is above. It's speculation that ductile spokes can stretch
>> (plastically) in use.
>
> er, that was /your/ contention, not mine.
No, it was the contention of Michael Press (as evidenced by the quote).
>
>> It's wrong. You're just raising straw men. Have fun.
>
> don't put bullshit false words in my mouth than criticize them peter.
> because that makes you a prick.
You put the "false words" in my mouth. I never said spokes stretched
elastically in use, MP did. I disagreed.
Why are you the only poster on this group who finds the need to be so
abusive? It serves no purpose. It only makes you sound like a nut.
|
| | | | | | | | | | | | | | | | | |
Date: 21 Sep 2007 00:18:25
From: Michael Press
Subject: Re: vacuum de-gas thread continued
|
In article
<4Mqdndlxi6QF5W_bnZ2dnUVZ_jCdnZ2d@comcast.com >,
Peter Cole <peter_cole@comcast.net > wrote:
> jim beam wrote:
> > Peter Cole wrote:
> >> jim beam wrote:
> >>> Peter Cole wrote:
> >>>>>>>>>>>> Michael Press wrote:
> >>>>>>>>>>>>> A more ductile
> >>>>>>>>>>>>> metal spoke will yield more extension before fracture.
> >>>>>>>>>>>>> A compromised spoke will elongate. If the rider notices
> >>>>>>>>>>>>> the wheel is untrue or that the spoke is loose he will
> >>>>>>>>>>>>> tighten the spoke. Thus the spoke comes to notice. If
> >>>>>>>>>>>>> it needs tightening more than once, which is more
> >>>>>>>>>>>>> likely with a more ductile spoke metal, the rider is
> >>>>>>>>>>>>> alerted.
> >>
> >>>> OK, why would elastic elongation require the spoke to be "retightened"?
> >>>>
> >>>> What does elastic have to do with ductility (above)?
> >>>>
> >>>> You still can't read.
> >>
> >>> and i can read you then trying to say that stress
> >>> increase always causes plastic deformation - it doesn't. and even if we
> >>> try making sense of the example you keep changing, it's trivially clear
> >>> that a spoke that needs tightening /still/ doesn't evidence plastic
> >>> deformation of a spoke - not when a soft aluminum hub hole can deform at
> >>> lower stress.
> >>
> >> The context is above. It's speculation that ductile spokes can stretch
> >> (plastically) in use.
> >
> > er, that was /your/ contention, not mine.
>
> No, it was the contention of Michael Press (as evidenced by the quote).
>
> >
> >> It's wrong. You're just raising straw men. Have fun.
> >
> > don't put bullshit false words in my mouth than criticize them peter.
> > because that makes you a prick.
>
> You put the "false words" in my mouth. I never said spokes stretched
> elastically in use, MP did. I disagreed.
I was not clear about stretching. I was speaking to Ben C's
"Does the extra ductility have any advantage _per se_ for spokes?"
I know perfectly well that spokes to not stretch in use,
_except_ when damaged from impact, corrosion, or fatigue cracking.
> Why are you the only poster on this group who finds the need to be so
> abusive? It serves no purpose. It only makes you sound like a nut.
--
Michael Press
|
| | | | | | | | | | | | | | | | | |
Date: 20 Sep 2007 20:33:02
From: jim beam
Subject: Re: vacuum de-gas thread continued
|
Peter Cole wrote:
> jim beam wrote:
>> Peter Cole wrote:
>>> jim beam wrote:
>>>> Peter Cole wrote:
>>>>>>>>>>>>> Michael Press wrote:
>>>>>>>>>>>>>> A more ductile
>>>>>>>>>>>>>> metal spoke will yield more extension before fracture.
>>>>>>>>>>>>>> A compromised spoke will elongate. If the rider notices
>>>>>>>>>>>>>> the wheel is untrue or that the spoke is loose he will
>>>>>>>>>>>>>> tighten the spoke. Thus the spoke comes to notice. If
>>>>>>>>>>>>>> it needs tightening more than once, which is more
>>>>>>>>>>>>>> likely with a more ductile spoke metal, the rider is
>>>>>>>>>>>>>> alerted.
>>>
>>>>> OK, why would elastic elongation require the spoke to be
>>>>> "retightened"?
>>>>>
>>>>> What does elastic have to do with ductility (above)?
>>>>>
>>>>> You still can't read.
>>>
>>>> and i can read you then trying to say that stress
>>>> increase always causes plastic deformation - it doesn't. and even
>>>> if we
>>>> try making sense of the example you keep changing, it's trivially clear
>>>> that a spoke that needs tightening /still/ doesn't evidence plastic
>>>> deformation of a spoke - not when a soft aluminum hub hole can
>>>> deform at
>>>> lower stress.
>>>
>>> The context is above. It's speculation that ductile spokes can
>>> stretch (plastically) in use.
>>
>> er, that was /your/ contention, not mine.
>
> No, it was the contention of Michael Press (as evidenced by the quote).
wriggle and squirm.
>
>>
>>> It's wrong. You're just raising straw men. Have fun.
>>
>> don't put bullshit false words in my mouth than criticize them peter.
>> because that makes you a prick.
>
> You put the "false words" in my mouth. I never said spokes stretched
> elastically in use, MP did. I disagreed.
ok, let's get this crystal clear: do spokes stretch elastically in use
or do they not? be unequivocal.
>
> Why are you the only poster on this group who finds the need to be so
> abusive? It serves no purpose. It only makes you sound like a nut.
wriggle and squirm.
|
| | | |
Date: 15 Sep 2007 17:19:04
From:
Subject: Re: vacuum de-gas thread continued
|
On Sat, 15 Sep 2007 17:10:09 -0500, Ben C <spamspam@spam.eggs > wrote:
>On 2007-09-15, carlfogel@comcast.net <carlfogel@comcast.net> wrote:
>> On Sep 15, 12:10 pm, Ben C <spams...@spam.eggs> wrote:
>>> On 2007-09-15, Peter Cole <peter_c...@comcast.net> wrote:
>>
>>> I'm not old enough to remember what bikes were like in the 60's and
>>> 70's, but most older bikes I've seen of quite good quality (Reynolds 531
>>> frame sort of level) had galvanized spokes. Is it true that stainless
>>> steel has come down in price in the last 40 or 50 years and/or is more
>>> widespread in its use for spokes?
>>
>> Dear Ben,
>>
>> Stainless steel spokes are certainly more widespread.
>>
>> Nowadays, galvanized spokes are considered cheap and inferior.
>> "Quality" spokes are stainless steel and cost more.
>>
>> Galvanized spokes are actually a bit stronger than stainless steel
>> spokes, but the extra strength has no advantage, since typical spoke
>> tension is 100~150 kgf, well below the 225~250 kgf yield point that
>> Jobst measured for thinner stainless steel 1.8 mm spokes. (And
>> inflating the tire can reduce the spoke tension up to 15% on 700c
>> rims.)
>>
>> In the 1981-1983 first edition of "The Bicycle Wheel," Jobst tested
>> six spokes, three galvanized and three stainless steel (S.S.)::
>>
>> Union 14 gauge
>> DT 14 gauge
>> Robegel Sport 14 gauge
>>
>> DT S.S. 14 gauge
>> DT S.S. 15 gauge
>> Robegel S.S. 15-16 gauge
>>
>> The DT galvanized 14 gauge has a slightly higher and slightly sharper
>> stress-strain curve than the DT stainless steel 14 gauge--the
>> stainless steel was not quite as strong, but was more ductile.
>>
>> A few years later, Jobst re-tested spokes for the second edition of
>> 1988. He tested only DT and Wheelsmith and only stainless steel
>> spokes--galvanized had practically vanished.
>>
>> Jobst noticed an impressive improvement in ductility:
>>
>> "In contrast to tests performed for the first edition of this book,
>> these spokes withstood substantial elongation before failure. Some
>> butted spokes stretched more than six millimeters without breaking, at
>> which point the test was stopped."
>>
>> --p. 132, "The Bicycle Wheel," 2nd edition, 1988
>>
>> So the stainless steel spokes had not only replaced galvanized as the
>> material for quality spokes, but they had also improved in ductility
>> over early stainless steel spokes.
>
>Thanks for another excellent answer.
>
>Does the extra ductility have any advantage _per se_ for spokes?
>
>It might be a side-effect of some other improvement and therefore a clue
>about the introduction of some new process like vacuum degassing.
Dear Ben,
I'm still wondering about that.
After considerable fuss and several trips to the local university, I
had hopes of the engineering department doing stress-strain tests on
some new Sapim 14 gauge stainless spokes to see how they stretched in
2007, compared to Jobst's last test in 1988.
Alas, I'm still waiting, months later, which reminds me why I don't
miss working at universities.
I don't know if more ductility means more durable spokes, but the two
do seem to have been noticed at the same time.
A curious point that I forgot is that carbon steel (galvanized) spokes
are actually more fatigue resistant than stainless steel spokes:
"The choice of carbon vs. stainless steel spokes hinges on which
facotr is considered more important: resistance to corrosion or
resistance to fatigue failure. . . . carbon steel has an advantage
over stainless steel in that it is more resistant to the other common
mode of spoke failure, fatigue."
--"Intro. to Engineering Materials: The Bicycle & the Walkman," p.13
Elsewhere, that 1993 textbook by two U. of Pennsylvania engineering
professors has a cycles-to-failure graph for the two steels, showing
that stainless steel spokes failed substantially _sooner_ in their
spoke fatigue testing than carbon steel.
However, that testing involved spinning a straight, unbent spoke
section and pushing it gently sideways as it whirled, which isn't the
same as a bent spoke elbow.
It's possible that more ductile stainless steel somehow produces much
lower residual stresses when bent to an elbow than the more fatigue
resistant carbon steel, which in turn could mean that the textbook
applied the right test to the wrong part of the spoke and got the
wrong answer.
Cheers,
Carl Fogel
|
| | | | |
Date: 16 Sep 2007 08:22:14
From: Peter Cole
Subject: Re: vacuum de-gas thread continued
|
carlfogel@comcast.net wrote:
> On Sat, 15 Sep 2007 17:10:09 -0500, Ben C <spamspam@spam.eggs> wrote:
>
>> On 2007-09-15, carlfogel@comcast.net <carlfogel@comcast.net> wrote:
>>> On Sep 15, 12:10 pm, Ben C <spams...@spam.eggs> wrote:
>>>> On 2007-09-15, Peter Cole <peter_c...@comcast.net> wrote:
>>>> I'm not old enough to remember what bikes were like in the 60's and
>>>> 70's, but most older bikes I've seen of quite good quality (Reynolds 531
>>>> frame sort of level) had galvanized spokes. Is it true that stainless
>>>> steel has come down in price in the last 40 or 50 years and/or is more
>>>> widespread in its use for spokes?
>>> Dear Ben,
>>>
>>> Stainless steel spokes are certainly more widespread.
>>>
>>> Nowadays, galvanized spokes are considered cheap and inferior.
>>> "Quality" spokes are stainless steel and cost more.
>>>
>>> Galvanized spokes are actually a bit stronger than stainless steel
>>> spokes, but the extra strength has no advantage, since typical spoke
>>> tension is 100~150 kgf, well below the 225~250 kgf yield point that
>>> Jobst measured for thinner stainless steel 1.8 mm spokes. (And
>>> inflating the tire can reduce the spoke tension up to 15% on 700c
>>> rims.)
>>>
>>> In the 1981-1983 first edition of "The Bicycle Wheel," Jobst tested
>>> six spokes, three galvanized and three stainless steel (S.S.)::
>>>
>>> Union 14 gauge
>>> DT 14 gauge
>>> Robegel Sport 14 gauge
>>>
>>> DT S.S. 14 gauge
>>> DT S.S. 15 gauge
>>> Robegel S.S. 15-16 gauge
>>>
>>> The DT galvanized 14 gauge has a slightly higher and slightly sharper
>>> stress-strain curve than the DT stainless steel 14 gauge--the
>>> stainless steel was not quite as strong, but was more ductile.
>>>
>>> A few years later, Jobst re-tested spokes for the second edition of
>>> 1988. He tested only DT and Wheelsmith and only stainless steel
>>> spokes--galvanized had practically vanished.
>>>
>>> Jobst noticed an impressive improvement in ductility:
>>>
>>> "In contrast to tests performed for the first edition of this book,
>>> these spokes withstood substantial elongation before failure. Some
>>> butted spokes stretched more than six millimeters without breaking, at
>>> which point the test was stopped."
>>>
>>> --p. 132, "The Bicycle Wheel," 2nd edition, 1988
>>>
>>> So the stainless steel spokes had not only replaced galvanized as the
>>> material for quality spokes, but they had also improved in ductility
>>> over early stainless steel spokes.
>> Thanks for another excellent answer.
>>
>> Does the extra ductility have any advantage _per se_ for spokes?
>>
>> It might be a side-effect of some other improvement and therefore a clue
>> about the introduction of some new process like vacuum degassing.
>
> Dear Ben,
>
> I'm still wondering about that.
>
> After considerable fuss and several trips to the local university, I
> had hopes of the engineering department doing stress-strain tests on
> some new Sapim 14 gauge stainless spokes to see how they stretched in
> 2007, compared to Jobst's last test in 1988.
>
> Alas, I'm still waiting, months later, which reminds me why I don't
> miss working at universities.
>
> I don't know if more ductility means more durable spokes, but the two
> do seem to have been noticed at the same time.
>
> A curious point that I forgot is that carbon steel (galvanized) spokes
> are actually more fatigue resistant than stainless steel spokes:
>
> "The choice of carbon vs. stainless steel spokes hinges on which
> facotr is considered more important: resistance to corrosion or
> resistance to fatigue failure. . . . carbon steel has an advantage
> over stainless steel in that it is more resistant to the other common
> mode of spoke failure, fatigue."
>
> --"Intro. to Engineering Materials: The Bicycle & the Walkman," p.13
>
> Elsewhere, that 1993 textbook by two U. of Pennsylvania engineering
> professors has a cycles-to-failure graph for the two steels, showing
> that stainless steel spokes failed substantially _sooner_ in their
> spoke fatigue testing than carbon steel.
>
> However, that testing involved spinning a straight, unbent spoke
> section and pushing it gently sideways as it whirled, which isn't the
> same as a bent spoke elbow.
>
> It's possible that more ductile stainless steel somehow produces much
> lower residual stresses when bent to an elbow than the more fatigue
> resistant carbon steel, which in turn could mean that the textbook
> applied the right test to the wrong part of the spoke and got the
> wrong answer.
>
> Cheers,
>
> Carl Fogel
The whole story on the material aspect of fatigue is given by the S-N
curve, also known as a Wöhler curve. (See
http://en.wikipedia.org/wiki/Fatigue_%28material%29#The_S-N_curve for an
example). These curves need to be adjusted for the case of spokes, since
they are typically for a (sinusoidal) stress cycle around zero, where
spokes have (significant) a non-zero bias.
It's common experience to have spokes survive 10^7 cycles, with some
(Jobst) reporting 10^8 or so.
S-N curves represent the ideal, with near perfect samples, and must be
derated for realities like defects and corrosion.
The higher fatigue resistance of carbon steel vs stainless, in practical
terms, means that it's theoretically possible to make crappier spokes
and have them last as long. The fact that old carbon spokes failed
earlier seems to only indicate that they were made (much) more poorly.
The S-N curves for those spokes must have departed significantly from
the ideal.
|
| | | | | |
Date: 16 Sep 2007 07:51:29
From: jim beam
Subject: Re: vacuum de-gas thread continued
|
Peter Cole wrote:
> carlfogel@comcast.net wrote:
>> On Sat, 15 Sep 2007 17:10:09 -0500, Ben C <spamspam@spam.eggs> wrote:
>>
>>> On 2007-09-15, carlfogel@comcast.net <carlfogel@comcast.net> wrote:
>>>> On Sep 15, 12:10 pm, Ben C <spams...@spam.eggs> wrote:
>>>>> On 2007-09-15, Peter Cole <peter_c...@comcast.net> wrote:
>>>>> I'm not old enough to remember what bikes were like in the 60's and
>>>>> 70's, but most older bikes I've seen of quite good quality
>>>>> (Reynolds 531
>>>>> frame sort of level) had galvanized spokes. Is it true that stainless
>>>>> steel has come down in price in the last 40 or 50 years and/or is more
>>>>> widespread in its use for spokes?
>>>> Dear Ben,
>>>>
>>>> Stainless steel spokes are certainly more widespread.
>>>>
>>>> Nowadays, galvanized spokes are considered cheap and inferior.
>>>> "Quality" spokes are stainless steel and cost more.
>>>>
>>>> Galvanized spokes are actually a bit stronger than stainless steel
>>>> spokes, but the extra strength has no advantage, since typical spoke
>>>> tension is 100~150 kgf, well below the 225~250 kgf yield point that
>>>> Jobst measured for thinner stainless steel 1.8 mm spokes. (And
>>>> inflating the tire can reduce the spoke tension up to 15% on 700c
>>>> rims.)
>>>>
>>>> In the 1981-1983 first edition of "The Bicycle Wheel," Jobst tested
>>>> six spokes, three galvanized and three stainless steel (S.S.)::
>>>>
>>>> Union 14 gauge
>>>> DT 14 gauge
>>>> Robegel Sport 14 gauge
>>>>
>>>> DT S.S. 14 gauge
>>>> DT S.S. 15 gauge
>>>> Robegel S.S. 15-16 gauge
>>>>
>>>> The DT galvanized 14 gauge has a slightly higher and slightly sharper
>>>> stress-strain curve than the DT stainless steel 14 gauge--the
>>>> stainless steel was not quite as strong, but was more ductile.
>>>>
>>>> A few years later, Jobst re-tested spokes for the second edition of
>>>> 1988. He tested only DT and Wheelsmith and only stainless steel
>>>> spokes--galvanized had practically vanished.
>>>>
>>>> Jobst noticed an impressive improvement in ductility:
>>>>
>>>> "In contrast to tests performed for the first edition of this book,
>>>> these spokes withstood substantial elongation before failure. Some
>>>> butted spokes stretched more than six millimeters without breaking, at
>>>> which point the test was stopped."
>>>>
>>>> --p. 132, "The Bicycle Wheel," 2nd edition, 1988
>>>>
>>>> So the stainless steel spokes had not only replaced galvanized as the
>>>> material for quality spokes, but they had also improved in ductility
>>>> over early stainless steel spokes.
>>> Thanks for another excellent answer.
>>>
>>> Does the extra ductility have any advantage _per se_ for spokes?
>>>
>>> It might be a side-effect of some other improvement and therefore a clue
>>> about the introduction of some new process like vacuum degassing.
>>
>> Dear Ben,
>>
>> I'm still wondering about that.
>>
>> After considerable fuss and several trips to the local university, I
>> had hopes of the engineering department doing stress-strain tests on
>> some new Sapim 14 gauge stainless spokes to see how they stretched in
>> 2007, compared to Jobst's last test in 1988.
>>
>> Alas, I'm still waiting, months later, which reminds me why I don't
>> miss working at universities.
>>
>> I don't know if more ductility means more durable spokes, but the two
>> do seem to have been noticed at the same time.
>>
>> A curious point that I forgot is that carbon steel (galvanized) spokes
>> are actually more fatigue resistant than stainless steel spokes:
>>
>> "The choice of carbon vs. stainless steel spokes hinges on which
>> facotr is considered more important: resistance to corrosion or
>> resistance to fatigue failure. . . . carbon steel has an advantage
>> over stainless steel in that it is more resistant to the other common
>> mode of spoke failure, fatigue."
>>
>> --"Intro. to Engineering Materials: The Bicycle & the Walkman," p.13
>>
>> Elsewhere, that 1993 textbook by two U. of Pennsylvania engineering
>> professors has a cycles-to-failure graph for the two steels, showing
>> that stainless steel spokes failed substantially _sooner_ in their
>> spoke fatigue testing than carbon steel.
>>
>> However, that testing involved spinning a straight, unbent spoke
>> section and pushing it gently sideways as it whirled, which isn't the
>> same as a bent spoke elbow.
>>
>> It's possible that more ductile stainless steel somehow produces much
>> lower residual stresses when bent to an elbow than the more fatigue
>> resistant carbon steel, which in turn could mean that the textbook
>> applied the right test to the wrong part of the spoke and got the
>> wrong answer.
>>
>> Cheers,
>>
>> Carl Fogel
>
> The whole story on the material aspect of fatigue is given by the S-N
> curve, also known as a W�hler curve. (See
> http://en.wikipedia.org/wiki/Fatigue_%28material%29#The_S-N_curve for an
> example). These curves need to be adjusted for the case of spokes, since
> they are typically for a (sinusoidal) stress cycle around zero, where
> spokes have (significant) a non-zero bias.
>
> It's common experience to have spokes survive 10^7 cycles, with some
> (Jobst) reporting 10^8 or so.
>
> S-N curves represent the ideal, with near perfect samples, and must be
> derated for realities like defects and corrosion.
>
> The higher fatigue resistance of carbon steel vs stainless, in practical
> terms, means that it's theoretically possible to make crappier spokes
> and have them last as long.
no, if it's a steel whose carbon content is low enough to retain the
dislocation locking mechanism we discussed before, those spokes would
last forever, if stress was below that of their endurance limit.
> The fact that old carbon spokes failed
> earlier seems to only indicate that they were made (much) more poorly.
no, they're made exactly the same way. the difference is the material
quality.
> The S-N curves for those spokes must have departed significantly from
> the ideal.
fudge.
|
| | | | | | |
Date: 16 Sep 2007 11:28:22
From: Peter Cole
Subject: Re: vacuum de-gas thread continued
|
jim beam wrote:
> Peter Cole wrote:
>> carlfogel@comcast.net wrote:
>>> On Sat, 15 Sep 2007 17:10:09 -0500, Ben C <spamspam@spam.eggs> wrote:
>>>
>>>> On 2007-09-15, carlfogel@comcast.net <carlfogel@comcast.net> wrote:
>>>>> On Sep 15, 12:10 pm, Ben C <spams...@spam.eggs> wrote:
>>>>>> On 2007-09-15, Peter Cole <peter_c...@comcast.net> wrote:
>>>>>> I'm not old enough to remember what bikes were like in the 60's and
>>>>>> 70's, but most older bikes I've seen of quite good quality
>>>>>> (Reynolds 531
>>>>>> frame sort of level) had galvanized spokes. Is it true that stainless
>>>>>> steel has come down in price in the last 40 or 50 years and/or is
>>>>>> more
>>>>>> widespread in its use for spokes?
>>>>> Dear Ben,
>>>>>
>>>>> Stainless steel spokes are certainly more widespread.
>>>>>
>>>>> Nowadays, galvanized spokes are considered cheap and inferior.
>>>>> "Quality" spokes are stainless steel and cost more.
>>>>>
>>>>> Galvanized spokes are actually a bit stronger than stainless steel
>>>>> spokes, but the extra strength has no advantage, since typical spoke
>>>>> tension is 100~150 kgf, well below the 225~250 kgf yield point that
>>>>> Jobst measured for thinner stainless steel 1.8 mm spokes. (And
>>>>> inflating the tire can reduce the spoke tension up to 15% on 700c
>>>>> rims.)
>>>>>
>>>>> In the 1981-1983 first edition of "The Bicycle Wheel," Jobst tested
>>>>> six spokes, three galvanized and three stainless steel (S.S.)::
>>>>>
>>>>> Union 14 gauge
>>>>> DT 14 gauge
>>>>> Robegel Sport 14 gauge
>>>>>
>>>>> DT S.S. 14 gauge
>>>>> DT S.S. 15 gauge
>>>>> Robegel S.S. 15-16 gauge
>>>>>
>>>>> The DT galvanized 14 gauge has a slightly higher and slightly sharper
>>>>> stress-strain curve than the DT stainless steel 14 gauge--the
>>>>> stainless steel was not quite as strong, but was more ductile.
>>>>>
>>>>> A few years later, Jobst re-tested spokes for the second edition of
>>>>> 1988. He tested only DT and Wheelsmith and only stainless steel
>>>>> spokes--galvanized had practically vanished.
>>>>>
>>>>> Jobst noticed an impressive improvement in ductility:
>>>>>
>>>>> "In contrast to tests performed for the first edition of this book,
>>>>> these spokes withstood substantial elongation before failure. Some
>>>>> butted spokes stretched more than six millimeters without breaking, at
>>>>> which point the test was stopped."
>>>>>
>>>>> --p. 132, "The Bicycle Wheel," 2nd edition, 1988
>>>>>
>>>>> So the stainless steel spokes had not only replaced galvanized as the
>>>>> material for quality spokes, but they had also improved in ductility
>>>>> over early stainless steel spokes.
>>>> Thanks for another excellent answer.
>>>>
>>>> Does the extra ductility have any advantage _per se_ for spokes?
>>>>
>>>> It might be a side-effect of some other improvement and therefore a
>>>> clue
>>>> about the introduction of some new process like vacuum degassing.
>>>
>>> Dear Ben,
>>>
>>> I'm still wondering about that.
>>>
>>> After considerable fuss and several trips to the local university, I
>>> had hopes of the engineering department doing stress-strain tests on
>>> some new Sapim 14 gauge stainless spokes to see how they stretched in
>>> 2007, compared to Jobst's last test in 1988.
>>>
>>> Alas, I'm still waiting, months later, which reminds me why I don't
>>> miss working at universities.
>>>
>>> I don't know if more ductility means more durable spokes, but the two
>>> do seem to have been noticed at the same time.
>>>
>>> A curious point that I forgot is that carbon steel (galvanized) spokes
>>> are actually more fatigue resistant than stainless steel spokes:
>>>
>>> "The choice of carbon vs. stainless steel spokes hinges on which
>>> facotr is considered more important: resistance to corrosion or
>>> resistance to fatigue failure. . . . carbon steel has an advantage
>>> over stainless steel in that it is more resistant to the other common
>>> mode of spoke failure, fatigue."
>>>
>>> --"Intro. to Engineering Materials: The Bicycle & the Walkman," p.13
>>>
>>> Elsewhere, that 1993 textbook by two U. of Pennsylvania engineering
>>> professors has a cycles-to-failure graph for the two steels, showing
>>> that stainless steel spokes failed substantially _sooner_ in their
>>> spoke fatigue testing than carbon steel.
>>>
>>> However, that testing involved spinning a straight, unbent spoke
>>> section and pushing it gently sideways as it whirled, which isn't the
>>> same as a bent spoke elbow.
>>>
>>> It's possible that more ductile stainless steel somehow produces much
>>> lower residual stresses when bent to an elbow than the more fatigue
>>> resistant carbon steel, which in turn could mean that the textbook
>>> applied the right test to the wrong part of the spoke and got the
>>> wrong answer.
>>>
>>> Cheers,
>>>
>>> Carl Fogel
>>
>> The whole story on the material aspect of fatigue is given by the S-N
>> curve, also known as a W�hler curve. (See
>> http://en.wikipedia.org/wiki/Fatigue_%28material%29#The_S-N_curve for
>> an example). These curves need to be adjusted for the case of spokes,
>> since they are typically for a (sinusoidal) stress cycle around zero,
>> where spokes have (significant) a non-zero bias.
>>
>> It's common experience to have spokes survive 10^7 cycles, with some
>> (Jobst) reporting 10^8 or so.
>>
>> S-N curves represent the ideal, with near perfect samples, and must be
>> derated for realities like defects and corrosion.
>>
>> The higher fatigue resistance of carbon steel vs stainless, in
>> practical terms, means that it's theoretically possible to make
>> crappier spokes and have them last as long.
>
> no, if it's a steel whose carbon content is low enough to retain the
> dislocation locking mechanism we discussed before,
> those spokes would
> last forever, if stress was below that of their endurance limit.
Ditto for stainless.
>
>> The fact that old carbon spokes failed earlier seems to only indicate
>> that they were made (much) more poorly.
>
> no, they're made exactly the same way. the difference is the material
> quality.
>
>> The S-N curves for those spokes must have departed significantly from
>> the ideal.
>
> fudge.
Whatever.
|
| | | | | | | |
Date: 16 Sep 2007 08:42:18
From: jim beam
Subject: Re: vacuum de-gas thread continued
|
Peter Cole wrote:
> jim beam wrote:
>> Peter Cole wrote:
>>> carlfogel@comcast.net wrote:
>>>> On Sat, 15 Sep 2007 17:10:09 -0500, Ben C <spamspam@spam.eggs> wrote:
>>>>
>>>>> On 2007-09-15, carlfogel@comcast.net <carlfogel@comcast.net> wrote:
>>>>>> On Sep 15, 12:10 pm, Ben C <spams...@spam.eggs> wrote:
>>>>>>> On 2007-09-15, Peter Cole <peter_c...@comcast.net> wrote:
>>>>>>> I'm not old enough to remember what bikes were like in the 60's and
>>>>>>> 70's, but most older bikes I've seen of quite good quality
>>>>>>> (Reynolds 531
>>>>>>> frame sort of level) had galvanized spokes. Is it true that
>>>>>>> stainless
>>>>>>> steel has come down in price in the last 40 or 50 years and/or is
>>>>>>> more
>>>>>>> widespread in its use for spokes?
>>>>>> Dear Ben,
>>>>>>
>>>>>> Stainless steel spokes are certainly more widespread.
>>>>>>
>>>>>> Nowadays, galvanized spokes are considered cheap and inferior.
>>>>>> "Quality" spokes are stainless steel and cost more.
>>>>>>
>>>>>> Galvanized spokes are actually a bit stronger than stainless steel
>>>>>> spokes, but the extra strength has no advantage, since typical spoke
>>>>>> tension is 100~150 kgf, well below the 225~250 kgf yield point that
>>>>>> Jobst measured for thinner stainless steel 1.8 mm spokes. (And
>>>>>> inflating the tire can reduce the spoke tension up to 15% on 700c
>>>>>> rims.)
>>>>>>
>>>>>> In the 1981-1983 first edition of "The Bicycle Wheel," Jobst tested
>>>>>> six spokes, three galvanized and three stainless steel (S.S.)::
>>>>>>
>>>>>> Union 14 gauge
>>>>>> DT 14 gauge
>>>>>> Robegel Sport 14 gauge
>>>>>>
>>>>>> DT S.S. 14 gauge
>>>>>> DT S.S. 15 gauge
>>>>>> Robegel S.S. 15-16 gauge
>>>>>>
>>>>>> The DT galvanized 14 gauge has a slightly higher and slightly sharper
>>>>>> stress-strain curve than the DT stainless steel 14 gauge--the
>>>>>> stainless steel was not quite as strong, but was more ductile.
>>>>>>
>>>>>> A few years later, Jobst re-tested spokes for the second edition of
>>>>>> 1988. He tested only DT and Wheelsmith and only stainless steel
>>>>>> spokes--galvanized had practically vanished.
>>>>>>
>>>>>> Jobst noticed an impressive improvement in ductility:
>>>>>>
>>>>>> "In contrast to tests performed for the first edition of this book,
>>>>>> these spokes withstood substantial elongation before failure. Some
>>>>>> butted spokes stretched more than six millimeters without
>>>>>> breaking, at
>>>>>> which point the test was stopped."
>>>>>>
>>>>>> --p. 132, "The Bicycle Wheel," 2nd edition, 1988
>>>>>>
>>>>>> So the stainless steel spokes had not only replaced galvanized as the
>>>>>> material for quality spokes, but they had also improved in ductility
>>>>>> over early stainless steel spokes.
>>>>> Thanks for another excellent answer.
>>>>>
>>>>> Does the extra ductility have any advantage _per se_ for spokes?
>>>>>
>>>>> It might be a side-effect of some other improvement and therefore a
>>>>> clue
>>>>> about the introduction of some new process like vacuum degassing.
>>>>
>>>> Dear Ben,
>>>>
>>>> I'm still wondering about that.
>>>>
>>>> After considerable fuss and several trips to the local university, I
>>>> had hopes of the engineering department doing stress-strain tests on
>>>> some new Sapim 14 gauge stainless spokes to see how they stretched in
>>>> 2007, compared to Jobst's last test in 1988.
>>>>
>>>> Alas, I'm still waiting, months later, which reminds me why I don't
>>>> miss working at universities.
>>>>
>>>> I don't know if more ductility means more durable spokes, but the two
>>>> do seem to have been noticed at the same time.
>>>>
>>>> A curious point that I forgot is that carbon steel (galvanized) spokes
>>>> are actually more fatigue resistant than stainless steel spokes:
>>>>
>>>> "The choice of carbon vs. stainless steel spokes hinges on which
>>>> facotr is considered more important: resistance to corrosion or
>>>> resistance to fatigue failure. . . . carbon steel has an advantage
>>>> over stainless steel in that it is more resistant to the other common
>>>> mode of spoke failure, fatigue."
>>>>
>>>> --"Intro. to Engineering Materials: The Bicycle & the Walkman," p.13
>>>>
>>>> Elsewhere, that 1993 textbook by two U. of Pennsylvania engineering
>>>> professors has a cycles-to-failure graph for the two steels, showing
>>>> that stainless steel spokes failed substantially _sooner_ in their
>>>> spoke fatigue testing than carbon steel.
>>>>
>>>> However, that testing involved spinning a straight, unbent spoke
>>>> section and pushing it gently sideways as it whirled, which isn't the
>>>> same as a bent spoke elbow.
>>>>
>>>> It's possible that more ductile stainless steel somehow produces much
>>>> lower residual stresses when bent to an elbow than the more fatigue
>>>> resistant carbon steel, which in turn could mean that the textbook
>>>> applied the right test to the wrong part of the spoke and got the
>>>> wrong answer.
>>>>
>>>> Cheers,
>>>>
>>>> Carl Fogel
>>>
>>> The whole story on the material aspect of fatigue is given by the S-N
>>> curve, also known as a W�hler curve. (See
>>> http://en.wikipedia.org/wiki/Fatigue_%28material%29#The_S-N_curve for
>>> an example). These curves need to be adjusted for the case of spokes,
>>> since they are typically for a (sinusoidal) stress cycle around zero,
>>> where spokes have (significant) a non-zero bias.
>>>
>>> It's common experience to have spokes survive 10^7 cycles, with some
>>> (Jobst) reporting 10^8 or so.
>>>
>>> S-N curves represent the ideal, with near perfect samples, and must
>>> be derated for realities like defects and corrosion.
>>>
>>> The higher fatigue resistance of carbon steel vs stainless, in
>>> practical terms, means that it's theoretically possible to make
>>> crappier spokes and have them last as long.
>>
>> no, if it's a steel whose carbon content is low enough to retain the
>> dislocation locking mechanism we discussed before,
>
>
>> those spokes would last forever, if stress was below that of their
>> endurance limit.
>
> Ditto for stainless.
but stainless doesn't have an endurance limit so that's incorrect! i've
explained why. what's your problem?
>
>>
>>> The fact that old carbon spokes failed earlier seems to only indicate
>>> that they were made (much) more poorly.
>>
>> no, they're made exactly the same way. the difference is the material
>> quality.
>>
>>> The S-N curves for those spokes must have departed significantly from
>>> the ideal.
>>
>> fudge.
>
> Whatever.
|
| | | | | | | | |
Date: 16 Sep 2007 17:16:02
From: Peter Cole
Subject: Re: vacuum de-gas thread continued
|
jim beam wrote:
> Peter Cole wrote:
>> jim beam wrote:
>>> Peter Cole wrote:
>>>> carlfogel@comcast.net wrote:
>>>>> On Sat, 15 Sep 2007 17:10:09 -0500, Ben C <spamspam@spam.eggs> wrote:
>>>>>
>>>>>> On 2007-09-15, carlfogel@comcast.net <carlfogel@comcast.net> wrote:
>>>>>>> On Sep 15, 12:10 pm, Ben C <spams...@spam.eggs> wrote:
>>>>>>>> On 2007-09-15, Peter Cole <peter_c...@comcast.net> wrote:
>>>>>>>> I'm not old enough to remember what bikes were like in the 60's and
>>>>>>>> 70's, but most older bikes I've seen of quite good quality
>>>>>>>> (Reynolds 531
>>>>>>>> frame sort of level) had galvanized spokes. Is it true that
>>>>>>>> stainless
>>>>>>>> steel has come down in price in the last 40 or 50 years and/or
>>>>>>>> is more
>>>>>>>> widespread in its use for spokes?
>>>>>>> Dear Ben,
>>>>>>>
>>>>>>> Stainless steel spokes are certainly more widespread.
>>>>>>>
>>>>>>> Nowadays, galvanized spokes are considered cheap and inferior.
>>>>>>> "Quality" spokes are stainless steel and cost more.
>>>>>>>
>>>>>>> Galvanized spokes are actually a bit stronger than stainless steel
>>>>>>> spokes, but the extra strength has no advantage, since typical spoke
>>>>>>> tension is 100~150 kgf, well below the 225~250 kgf yield point that
>>>>>>> Jobst measured for thinner stainless steel 1.8 mm spokes. (And
>>>>>>> inflating the tire can reduce the spoke tension up to 15% on 700c
>>>>>>> rims.)
>>>>>>>
>>>>>>> In the 1981-1983 first edition of "The Bicycle Wheel," Jobst tested
>>>>>>> six spokes, three galvanized and three stainless steel (S.S.)::
>>>>>>>
>>>>>>> Union 14 gauge
>>>>>>> DT 14 gauge
>>>>>>> Robegel Sport 14 gauge
>>>>>>>
>>>>>>> DT S.S. 14 gauge
>>>>>>> DT S.S. 15 gauge
>>>>>>> Robegel S.S. 15-16 gauge
>>>>>>>
>>>>>>> The DT galvanized 14 gauge has a slightly higher and slightly
>>>>>>> sharper
>>>>>>> stress-strain curve than the DT stainless steel 14 gauge--the
>>>>>>> stainless steel was not quite as strong, but was more ductile.
>>>>>>>
>>>>>>> A few years later, Jobst re-tested spokes for the second edition of
>>>>>>> 1988. He tested only DT and Wheelsmith and only stainless steel
>>>>>>> spokes--galvanized had practically vanished.
>>>>>>>
>>>>>>> Jobst noticed an impressive improvement in ductility:
>>>>>>>
>>>>>>> "In contrast to tests performed for the first edition of this book,
>>>>>>> these spokes withstood substantial elongation before failure. Some
>>>>>>> butted spokes stretched more than six millimeters without
>>>>>>> breaking, at
>>>>>>> which point the test was stopped."
>>>>>>>
>>>>>>> --p. 132, "The Bicycle Wheel," 2nd edition, 1988
>>>>>>>
>>>>>>> So the stainless steel spokes had not only replaced galvanized as
>>>>>>> the
>>>>>>> material for quality spokes, but they had also improved in ductility
>>>>>>> over early stainless steel spokes.
>>>>>> Thanks for another excellent answer.
>>>>>>
>>>>>> Does the extra ductility have any advantage _per se_ for spokes?
>>>>>>
>>>>>> It might be a side-effect of some other improvement and therefore
>>>>>> a clue
>>>>>> about the introduction of some new process like vacuum degassing.
>>>>>
>>>>> Dear Ben,
>>>>>
>>>>> I'm still wondering about that.
>>>>>
>>>>> After considerable fuss and several trips to the local university, I
>>>>> had hopes of the engineering department doing stress-strain tests on
>>>>> some new Sapim 14 gauge stainless spokes to see how they stretched in
>>>>> 2007, compared to Jobst's last test in 1988.
>>>>>
>>>>> Alas, I'm still waiting, months later, which reminds me why I don't
>>>>> miss working at universities.
>>>>>
>>>>> I don't know if more ductility means more durable spokes, but the two
>>>>> do seem to have been noticed at the same time.
>>>>>
>>>>> A curious point that I forgot is that carbon steel (galvanized) spokes
>>>>> are actually more fatigue resistant than stainless steel spokes:
>>>>>
>>>>> "The choice of carbon vs. stainless steel spokes hinges on which
>>>>> facotr is considered more important: resistance to corrosion or
>>>>> resistance to fatigue failure. . . . carbon steel has an advantage
>>>>> over stainless steel in that it is more resistant to the other common
>>>>> mode of spoke failure, fatigue."
>>>>>
>>>>> --"Intro. to Engineering Materials: The Bicycle & the Walkman," p.13
>>>>>
>>>>> Elsewhere, that 1993 textbook by two U. of Pennsylvania engineering
>>>>> professors has a cycles-to-failure graph for the two steels, showing
>>>>> that stainless steel spokes failed substantially _sooner_ in their
>>>>> spoke fatigue testing than carbon steel.
>>>>>
>>>>> However, that testing involved spinning a straight, unbent spoke
>>>>> section and pushing it gently sideways as it whirled, which isn't the
>>>>> same as a bent spoke elbow.
>>>>>
>>>>> It's possible that more ductile stainless steel somehow produces much
>>>>> lower residual stresses when bent to an elbow than the more fatigue
>>>>> resistant carbon steel, which in turn could mean that the textbook
>>>>> applied the right test to the wrong part of the spoke and got the
>>>>> wrong answer.
>>>>>
>>>>> Cheers,
>>>>>
>>>>> Carl Fogel
>>>>
>>>> The whole story on the material aspect of fatigue is given by the
>>>> S-N curve, also known as a W�hler curve. (See
>>>> http://en.wikipedia.org/wiki/Fatigue_%28material%29#The_S-N_curve
>>>> for an example). These curves need to be adjusted for the case of
>>>> spokes, since they are typically for a (sinusoidal) stress cycle
>>>> around zero, where spokes have (significant) a non-zero bias.
>>>>
>>>> It's common experience to have spokes survive 10^7 cycles, with some
>>>> (Jobst) reporting 10^8 or so.
>>>>
>>>> S-N curves represent the ideal, with near perfect samples, and must
>>>> be derated for realities like defects and corrosion.
>>>>
>>>> The higher fatigue resistance of carbon steel vs stainless, in
>>>> practical terms, means that it's theoretically possible to make
>>>> crappier spokes and have them last as long.
>>>
>>> no, if it's a steel whose carbon content is low enough to retain the
>>> dislocation locking mechanism we discussed before,
>>
>>
>>> those spokes would last forever, if stress was below that of their
>>> endurance limit.
>>
>> Ditto for stainless.
>
> but stainless doesn't have an endurance limit so that's incorrect! i've
> explained why. what's your problem?
You are entitled to your opinion, but it seems to be unique.
Manufacturers typically spec an "endurance limit" for stainless at 10^7
cycles. Why? Because it's pretty much the same at 10^8 and 10^9. The
knee, according to Sandvik is around 2*10^6.
Do the math. If spokes have a static load of ~33% UTS, and lots of
people (myself included) have experience of near 100% non-failure at
10^7 cycles (13,000 miles), it's perfectly believable that spokes can do
over 10^8 (as Jobst reports) or even 10^9. If 10^9 isn't infinite for
you (1.3 million miles) just say so. Common real world experience
demonstrates stainless has an effective endurance limit, just like the
makers say.
Fully hardened 302 has an endurance limit of 35-40% of UTS, as opposed
to plain steel's 45-50%. This, of course, is for ideal, polished
specimens. The fact that it's common to run spokes to 10^7 cycles at
~33% UTS without seeing anything like a 50% failure, even with the
non-ideal state of those spokes (defects, residual stress, corrosion),
indicates we're below the endurance limit. We can't be far below that
limit, so residual stress -- even at relatively low levels -- can cause
failures.
You can obsess about "fatigue limit" vs "endurance limit" all you want,
the distinction is in your head. If the 10^9 stress limit is 5% below
the 10^7 limit, it makes no real difference. Since 90% of the spoke
lifetime will be spent in crack initiation, it has no effect on spoke
strength, either.
You can call Jobst (or me) a liar, but Sandvik (a maker of spoke wire)
backs him up.
|
| | | | | | | | | |
Date: 16 Sep 2007 15:05:47
From: jim beam
Subject: Re: vacuum de-gas thread continued
|
Peter Cole wrote:
> jim beam wrote:
>> Peter Cole wrote:
>>> jim beam wrote:
>>>> Peter Cole wrote:
>>>>> carlfogel@comcast.net wrote:
>>>>>> On Sat, 15 Sep 2007 17:10:09 -0500, Ben C <spamspam@spam.eggs> wrote:
>>>>>>
>>>>>>> On 2007-09-15, carlfogel@comcast.net <carlfogel@comcast.net> wrote:
>>>>>>>> On Sep 15, 12:10 pm, Ben C <spams...@spam.eggs> wrote:
>>>>>>>>> On 2007-09-15, Peter Cole <peter_c...@comcast.net> wrote:
>>>>>>>>> I'm not old enough to remember what bikes were like in the 60's
>>>>>>>>> and
>>>>>>>>> 70's, but most older bikes I've seen of quite good quality
>>>>>>>>> (Reynolds 531
>>>>>>>>> frame sort of level) had galvanized spokes. Is it true that
>>>>>>>>> stainless
>>>>>>>>> steel has come down in price in the last 40 or 50 years and/or
>>>>>>>>> is more
>>>>>>>>> widespread in its use for spokes?
>>>>>>>> Dear Ben,
>>>>>>>>
>>>>>>>> Stainless steel spokes are certainly more widespread.
>>>>>>>>
>>>>>>>> Nowadays, galvanized spokes are considered cheap and inferior.
>>>>>>>> "Quality" spokes are stainless steel and cost more.
>>>>>>>>
>>>>>>>> Galvanized spokes are actually a bit stronger than stainless steel
>>>>>>>> spokes, but the extra strength has no advantage, since typical
>>>>>>>> spoke
>>>>>>>> tension is 100~150 kgf, well below the 225~250 kgf yield point that
>>>>>>>> Jobst measured for thinner stainless steel 1.8 mm spokes. (And
>>>>>>>> inflating the tire can reduce the spoke tension up to 15% on 700c
>>>>>>>> rims.)
>>>>>>>>
>>>>>>>> In the 1981-1983 first edition of "The Bicycle Wheel," Jobst tested
>>>>>>>> six spokes, three galvanized and three stainless steel (S.S.)::
>>>>>>>>
>>>>>>>> Union 14 gauge
>>>>>>>> DT 14 gauge
>>>>>>>> Robegel Sport 14 gauge
>>>>>>>>
>>>>>>>> DT S.S. 14 gauge
>>>>>>>> DT S.S. 15 gauge
>>>>>>>> Robegel S.S. 15-16 gauge
>>>>>>>>
>>>>>>>> The DT galvanized 14 gauge has a slightly higher and slightly
>>>>>>>> sharper
>>>>>>>> stress-strain curve than the DT stainless steel 14 gauge--the
>>>>>>>> stainless steel was not quite as strong, but was more ductile.
>>>>>>>>
>>>>>>>> A few years later, Jobst re-tested spokes for the second edition of
>>>>>>>> 1988. He tested only DT and Wheelsmith and only stainless steel
>>>>>>>> spokes--galvanized had practically vanished.
>>>>>>>>
>>>>>>>> Jobst noticed an impressive improvement in ductility:
>>>>>>>>
>>>>>>>> "In contrast to tests performed for the first edition of this book,
>>>>>>>> these spokes withstood substantial elongation before failure. Some
>>>>>>>> butted spokes stretched more than six millimeters without
>>>>>>>> breaking, at
>>>>>>>> which point the test was stopped."
>>>>>>>>
>>>>>>>> --p. 132, "The Bicycle Wheel," 2nd edition, 1988
>>>>>>>>
>>>>>>>> So the stainless steel spokes had not only replaced galvanized
>>>>>>>> as the
>>>>>>>> material for quality spokes, but they had also improved in
>>>>>>>> ductility
>>>>>>>> over early stainless steel spokes.
>>>>>>> Thanks for another excellent answer.
>>>>>>>
>>>>>>> Does the extra ductility have any advantage _per se_ for spokes?
>>>>>>>
>>>>>>> It might be a side-effect of some other improvement and therefore
>>>>>>> a clue
>>>>>>> about the introduction of some new process like vacuum degassing.
>>>>>>
>>>>>> Dear Ben,
>>>>>>
>>>>>> I'm still wondering about that.
>>>>>>
>>>>>> After considerable fuss and several trips to the local university, I
>>>>>> had hopes of the engineering department doing stress-strain tests on
>>>>>> some new Sapim 14 gauge stainless spokes to see how they stretched in
>>>>>> 2007, compared to Jobst's last test in 1988.
>>>>>>
>>>>>> Alas, I'm still waiting, months later, which reminds me why I don't
>>>>>> miss working at universities.
>>>>>>
>>>>>> I don't know if more ductility means more durable spokes, but the two
>>>>>> do seem to have been noticed at the same time.
>>>>>>
>>>>>> A curious point that I forgot is that carbon steel (galvanized)
>>>>>> spokes
>>>>>> are actually more fatigue resistant than stainless steel spokes:
>>>>>>
>>>>>> "The choice of carbon vs. stainless steel spokes hinges on which
>>>>>> facotr is considered more important: resistance to corrosion or
>>>>>> resistance to fatigue failure. . . . carbon steel has an advantage
>>>>>> over stainless steel in that it is more resistant to the other common
>>>>>> mode of spoke failure, fatigue."
>>>>>>
>>>>>> --"Intro. to Engineering Materials: The Bicycle & the Walkman," p.13
>>>>>>
>>>>>> Elsewhere, that 1993 textbook by two U. of Pennsylvania engineering
>>>>>> professors has a cycles-to-failure graph for the two steels, showing
>>>>>> that stainless steel spokes failed substantially _sooner_ in their
>>>>>> spoke fatigue testing than carbon steel.
>>>>>>
>>>>>> However, that testing involved spinning a straight, unbent spoke
>>>>>> section and pushing it gently sideways as it whirled, which isn't the
>>>>>> same as a bent spoke elbow.
>>>>>>
>>>>>> It's possible that more ductile stainless steel somehow produces much
>>>>>> lower residual stresses when bent to an elbow than the more fatigue
>>>>>> resistant carbon steel, which in turn could mean that the textbook
>>>>>> applied the right test to the wrong part of the spoke and got the
>>>>>> wrong answer.
>>>>>>
>>>>>> Cheers,
>>>>>>
>>>>>> Carl Fogel
>>>>>
>>>>> The whole story on the material aspect of fatigue is given by the
>>>>> S-N curve, also known as a W�hler curve. (See
>>>>> http://en.wikipedia.org/wiki/Fatigue_%28material%29#The_S-N_curve
>>>>> for an example). These curves need to be adjusted for the case of
>>>>> spokes, since they are typically for a (sinusoidal) stress cycle
>>>>> around zero, where spokes have (significant) a non-zero bias.
>>>>>
>>>>> It's common experience to have spokes survive 10^7 cycles, with
>>>>> some (Jobst) reporting 10^8 or so.
>>>>>
>>>>> S-N curves represent the ideal, with near perfect samples, and must
>>>>> be derated for realities like defects and corrosion.
>>>>>
>>>>> The higher fatigue resistance of carbon steel vs stainless, in
>>>>> practical terms, means that it's theoretically possible to make
>>>>> crappier spokes and have them last as long.
>>>>
>>>> no, if it's a steel whose carbon content is low enough to retain the
>>>> dislocation locking mechanism we discussed before,
>>>
>>>
>>>> those spokes would last forever, if stress was below that of their
>>>> endurance limit.
>>>
>>> Ditto for stainless.
>>
>> but stainless doesn't have an endurance limit so that's incorrect!
>> i've explained why. what's your problem?
>
> You are entitled to your opinion, but it seems to be unique.
>
> Manufacturers typically spec an "endurance limit" for stainless at 10^7
> cycles. Why? Because it's pretty much the same at 10^8 and 10^9. The
> knee, according to Sandvik is around 2*10^6.
>
> Do the math. If spokes have a static load of ~33% UTS, and lots of
> people (myself included) have experience of near 100% non-failure at
> 10^7 cycles (13,000 miles), it's perfectly believable that spokes can do
> over 10^8 (as Jobst reports) or even 10^9. If 10^9 isn't infinite for
> you (1.3 million miles) just say so. Common real world experience
> demonstrates stainless has an effective endurance limit, just like the
> makers say.
>
> Fully hardened 302 has an endurance limit of 35-40% of UTS, as opposed
> to plain steel's 45-50%. This, of course, is for ideal, polished
> specimens. The fact that it's common to run spokes to 10^7 cycles at
> ~33% UTS without seeing anything like a 50% failure, even with the
> non-ideal state of those spokes (defects, residual stress, corrosion),
> indicates we're below the endurance limit. We can't be far below that
> limit, so residual stress -- even at relatively low levels -- can cause
> failures.
>
> You can obsess about "fatigue limit" vs "endurance limit" all you want,
> the distinction is in your head. If the 10^9 stress limit is 5% below
> the 10^7 limit, it makes no real difference. Since 90% of the spoke
> lifetime will be spent in crack initiation, it has no effect on spoke
> strength, either.
>
> You can call Jobst (or me) a liar, but Sandvik (a maker of spoke wire)
> backs him up.
sandvik are faced with the problem of selling materials to "engineers"
who demand something they can't have. and if engineers can't be
bothered to understand the science, what next? present information in a
way that kinda sorta fudges it for their dumb asses so they can
misinterpret what they want. because that's reality.
fact: there is no dislocation locking mechanism. there is no endurance
limit. end of story.
|
| | | | | | | | | | |
Date: 16 Sep 2007 20:06:41
From: Peter Cole
Subject: Re: vacuum de-gas thread continued
|
jim beam wrote:
> Peter Cole wrote:
>> jim beam wrote:
>>> Peter Cole wrote:
>>>> jim beam wrote:
>>>>> Peter Cole wrote:
>>>>>> carlfogel@comcast.net wrote:
>>>>>>> On Sat, 15 Sep 2007 17:10:09 -0500, Ben C <spamspam@spam.eggs>
>>>>>>> wrote:
>>>>>>>
>>>>>>>> On 2007-09-15, carlfogel@comcast.net <carlfogel@comcast.net> wrote:
>>>>>>>>> On Sep 15, 12:10 pm, Ben C <spams...@spam.eggs> wrote:
>>>>>>>>>> On 2007-09-15, Peter Cole <peter_c...@comcast.net> wrote:
>>>>>>>>>> I'm not old enough to remember what bikes were like in the
>>>>>>>>>> 60's and
>>>>>>>>>> 70's, but most older bikes I've seen of quite good quality
>>>>>>>>>> (Reynolds 531
>>>>>>>>>> frame sort of level) had galvanized spokes. Is it true that
>>>>>>>>>> stainless
>>>>>>>>>> steel has come down in price in the last 40 or 50 years and/or
>>>>>>>>>> is more
>>>>>>>>>> widespread in its use for spokes?
>>>>>>>>> Dear Ben,
>>>>>>>>>
>>>>>>>>> Stainless steel spokes are certainly more widespread.
>>>>>>>>>
>>>>>>>>> Nowadays, galvanized spokes are considered cheap and inferior.
>>>>>>>>> "Quality" spokes are stainless steel and cost more.
>>>>>>>>>
>>>>>>>>> Galvanized spokes are actually a bit stronger than stainless steel
>>>>>>>>> spokes, but the extra strength has no advantage, since typical
>>>>>>>>> spoke
>>>>>>>>> tension is 100~150 kgf, well below the 225~250 kgf yield point
>>>>>>>>> that
>>>>>>>>> Jobst measured for thinner stainless steel 1.8 mm spokes. (And
>>>>>>>>> inflating the tire can reduce the spoke tension up to 15% on 700c
>>>>>>>>> rims.)
>>>>>>>>>
>>>>>>>>> In the 1981-1983 first edition of "The Bicycle Wheel," Jobst
>>>>>>>>> tested
>>>>>>>>> six spokes, three galvanized and three stainless steel (S.S.)::
>>>>>>>>>
>>>>>>>>> Union 14 gauge
>>>>>>>>> DT 14 gauge
>>>>>>>>> Robegel Sport 14 gauge
>>>>>>>>>
>>>>>>>>> DT S.S. 14 gauge
>>>>>>>>> DT S.S. 15 gauge
>>>>>>>>> Robegel S.S. 15-16 gauge
>>>>>>>>>
>>>>>>>>> The DT galvanized 14 gauge has a slightly higher and slightly
>>>>>>>>> sharper
>>>>>>>>> stress-strain curve than the DT stainless steel 14 gauge--the
>>>>>>>>> stainless steel was not quite as strong, but was more ductile.
>>>>>>>>>
>>>>>>>>> A few years later, Jobst re-tested spokes for the second
>>>>>>>>> edition of
>>>>>>>>> 1988. He tested only DT and Wheelsmith and only stainless steel
>>>>>>>>> spokes--galvanized had practically vanished.
>>>>>>>>>
>>>>>>>>> Jobst noticed an impressive improvement in ductility:
>>>>>>>>>
>>>>>>>>> "In contrast to tests performed for the first edition of this
>>>>>>>>> book,
>>>>>>>>> these spokes withstood substantial elongation before failure. Some
>>>>>>>>> butted spokes stretched more than six millimeters without
>>>>>>>>> breaking, at
>>>>>>>>> which point the test was stopped."
>>>>>>>>>
>>>>>>>>> --p. 132, "The Bicycle Wheel," 2nd edition, 1988
>>>>>>>>>
>>>>>>>>> So the stainless steel spokes had not only replaced galvanized
>>>>>>>>> as the
>>>>>>>>> material for quality spokes, but they had also improved in
>>>>>>>>> ductility
>>>>>>>>> over early stainless steel spokes.
>>>>>>>> Thanks for another excellent answer.
>>>>>>>>
>>>>>>>> Does the extra ductility have any advantage _per se_ for spokes?
>>>>>>>>
>>>>>>>> It might be a side-effect of some other improvement and
>>>>>>>> therefore a clue
>>>>>>>> about the introduction of some new process like vacuum degassing.
>>>>>>>
>>>>>>> Dear Ben,
>>>>>>>
>>>>>>> I'm still wondering about that.
>>>>>>>
>>>>>>> After considerable fuss and several trips to the local university, I
>>>>>>> had hopes of the engineering department doing stress-strain tests on
>>>>>>> some new Sapim 14 gauge stainless spokes to see how they
>>>>>>> stretched in
>>>>>>> 2007, compared to Jobst's last test in 1988.
>>>>>>>
>>>>>>> Alas, I'm still waiting, months later, which reminds me why I don't
>>>>>>> miss working at universities.
>>>>>>>
>>>>>>> I don't know if more ductility means more durable spokes, but the
>>>>>>> two
>>>>>>> do seem to have been noticed at the same time.
>>>>>>>
>>>>>>> A curious point that I forgot is that carbon steel (galvanized)
>>>>>>> spokes
>>>>>>> are actually more fatigue resistant than stainless steel spokes:
>>>>>>>
>>>>>>> "The choice of carbon vs. stainless steel spokes hinges on which
>>>>>>> facotr is considered more important: resistance to corrosion or
>>>>>>> resistance to fatigue failure. . . . carbon steel has an advantage
>>>>>>> over stainless steel in that it is more resistant to the other
>>>>>>> common
>>>>>>> mode of spoke failure, fatigue."
>>>>>>>
>>>>>>> --"Intro. to Engineering Materials: The Bicycle & the Walkman," p.13
>>>>>>>
>>>>>>> Elsewhere, that 1993 textbook by two U. of Pennsylvania engineering
>>>>>>> professors has a cycles-to-failure graph for the two steels, showing
>>>>>>> that stainless steel spokes failed substantially _sooner_ in their
>>>>>>> spoke fatigue testing than carbon steel.
>>>>>>>
>>>>>>> However, that testing involved spinning a straight, unbent spoke
>>>>>>> section and pushing it gently sideways as it whirled, which isn't
>>>>>>> the
>>>>>>> same as a bent spoke elbow.
>>>>>>>
>>>>>>> It's possible that more ductile stainless steel somehow produces
>>>>>>> much
>>>>>>> lower residual stresses when bent to an elbow than the more fatigue
>>>>>>> resistant carbon steel, which in turn could mean that the textbook
>>>>>>> applied the right test to the wrong part of the spoke and got the
>>>>>>> wrong answer.
>>>>>>>
>>>>>>> Cheers,
>>>>>>>
>>>>>>> Carl Fogel
>>>>>>
>>>>>> The whole story on the material aspect of fatigue is given by the
>>>>>> S-N curve, also known as a W�hler curve. (See
>>>>>> http://en.wikipedia.org/wiki/Fatigue_%28material%29#The_S-N_curve
>>>>>> for an example). These curves need to be adjusted for the case of
>>>>>> spokes, since they are typically for a (sinusoidal) stress cycle
>>>>>> around zero, where spokes have (significant) a non-zero bias.
>>>>>>
>>>>>> It's common experience to have spokes survive 10^7 cycles, with
>>>>>> some (Jobst) reporting 10^8 or so.
>>>>>>
>>>>>> S-N curves represent the ideal, with near perfect samples, and
>>>>>> must be derated for realities like defects and corrosion.
>>>>>>
>>>>>> The higher fatigue resistance of carbon steel vs stainless, in
>>>>>> practical terms, means that it's theoretically possible to make
>>>>>> crappier spokes and have them last as long.
>>>>>
>>>>> no, if it's a steel whose carbon content is low enough to retain
>>>>> the dislocation locking mechanism we discussed before,
>>>>
>>>>
>>>>> those spokes would last forever, if stress was below that of their
>>>>> endurance limit.
>>>>
>>>> Ditto for stainless.
>>>
>>> but stainless doesn't have an endurance limit so that's incorrect!
>>> i've explained why. what's your problem?
>>
>> You are entitled to your opinion, but it seems to be unique.
>>
>> Manufacturers typically spec an "endurance limit" for stainless at
>> 10^7 cycles. Why? Because it's pretty much the same at 10^8 and 10^9.
>> The knee, according to Sandvik is around 2*10^6.
>>
>> Do the math. If spokes have a static load of ~33% UTS, and lots of
>> people (myself included) have experience of near 100% non-failure at
>> 10^7 cycles (13,000 miles), it's perfectly believable that spokes can
>> do over 10^8 (as Jobst reports) or even 10^9. If 10^9 isn't infinite
>> for you (1.3 million miles) just say so. Common real world experience
>> demonstrates stainless has an effective endurance limit, just like the
>> makers say.
>>
>> Fully hardened 302 has an endurance limit of 35-40% of UTS, as opposed
>> to plain steel's 45-50%. This, of course, is for ideal, polished
>> specimens. The fact that it's common to run spokes to 10^7 cycles at
>> ~33% UTS without seeing anything like a 50% failure, even with the
>> non-ideal state of those spokes (defects, residual stress, corrosion),
>> indicates we're below the endurance limit. We can't be far below that
>> limit, so residual stress -- even at relatively low levels -- can
>> cause failures.
>>
>> You can obsess about "fatigue limit" vs "endurance limit" all you
>> want, the distinction is in your head. If the 10^9 stress limit is 5%
>> below the 10^7 limit, it makes no real difference. Since 90% of the
>> spoke lifetime will be spent in crack initiation, it has no effect on
>> spoke strength, either.
>>
>> You can call Jobst (or me) a liar, but Sandvik (a maker of spoke wire)
>> backs him up.
>
> sandvik are faced with the problem of selling materials to "engineers"
> who demand something they can't have. and if engineers can't be
> bothered to understand the science, what next? present information in a
> way that kinda sorta fudges it for their dumb asses so they can
> misinterpret what they want. because that's reality.
>
> fact: there is no dislocation locking mechanism. there is no endurance
> limit. end of story.
OK Sandvik is lying, too. Right. Keep drinking your own Kool-Aid.
|
| | | | | | | | | | | |
Date: 18 Sep 2007 21:34:47
From: jim beam
Subject: Re: vacuum de-gas thread continued
|
Peter Cole wrote:
> jim beam wrote:
>> Peter Cole wrote:
>>> jim beam wrote:
>>>> Peter Cole wrote:
>>>>> jim beam wrote:
>>>>>> Peter Cole wrote:
>>>>>>> carlfogel@comcast.net wrote:
>>>>>>>> On Sat, 15 Sep 2007 17:10:09 -0500, Ben C <spamspam@spam.eggs>
>>>>>>>> wrote:
>>>>>>>>
>>>>>>>>> On 2007-09-15, carlfogel@comcast.net <carlfogel@comcast.net>
>>>>>>>>> wrote:
>>>>>>>>>> On Sep 15, 12:10 pm, Ben C <spams...@spam.eggs> wrote:
>>>>>>>>>>> On 2007-09-15, Peter Cole <peter_c...@comcast.net> wrote:
>>>>>>>>>>> I'm not old enough to remember what bikes were like in the
>>>>>>>>>>> 60's and
>>>>>>>>>>> 70's, but most older bikes I've seen of quite good quality
>>>>>>>>>>> (Reynolds 531
>>>>>>>>>>> frame sort of level) had galvanized spokes. Is it true that
>>>>>>>>>>> stainless
>>>>>>>>>>> steel has come down in price in the last 40 or 50 years
>>>>>>>>>>> and/or is more
>>>>>>>>>>> widespread in its use for spokes?
>>>>>>>>>> Dear Ben,
>>>>>>>>>>
>>>>>>>>>> Stainless steel spokes are certainly more widespread.
>>>>>>>>>>
>>>>>>>>>> Nowadays, galvanized spokes are considered cheap and inferior.
>>>>>>>>>> "Quality" spokes are stainless steel and cost more.
>>>>>>>>>>
>>>>>>>>>> Galvanized spokes are actually a bit stronger than stainless
>>>>>>>>>> steel
>>>>>>>>>> spokes, but the extra strength has no advantage, since typical
>>>>>>>>>> spoke
>>>>>>>>>> tension is 100~150 kgf, well below the 225~250 kgf yield point
>>>>>>>>>> that
>>>>>>>>>> Jobst measured for thinner stainless steel 1.8 mm spokes. (And
>>>>>>>>>> inflating the tire can reduce the spoke tension up to 15% on 700c
>>>>>>>>>> rims.)
>>>>>>>>>>
>>>>>>>>>> In the 1981-1983 first edition of "The Bicycle Wheel," Jobst
>>>>>>>>>> tested
>>>>>>>>>> six spokes, three galvanized and three stainless steel (S.S.)::
>>>>>>>>>>
>>>>>>>>>> Union 14 gauge
>>>>>>>>>> DT 14 gauge
>>>>>>>>>> Robegel Sport 14 gauge
>>>>>>>>>>
>>>>>>>>>> DT S.S. 14 gauge
>>>>>>>>>> DT S.S. 15 gauge
>>>>>>>>>> Robegel S.S. 15-16 gauge
>>>>>>>>>>
>>>>>>>>>> The DT galvanized 14 gauge has a slightly higher and slightly
>>>>>>>>>> sharper
>>>>>>>>>> stress-strain curve than the DT stainless steel 14 gauge--the
>>>>>>>>>> stainless steel was not quite as strong, but was more ductile.
>>>>>>>>>>
>>>>>>>>>> A few years later, Jobst re-tested spokes for the second
>>>>>>>>>> edition of
>>>>>>>>>> 1988. He tested only DT and Wheelsmith and only stainless steel
>>>>>>>>>> spokes--galvanized had practically vanished.
>>>>>>>>>>
>>>>>>>>>> Jobst noticed an impressive improvement in ductility:
>>>>>>>>>>
>>>>>>>>>> "In contrast to tests performed for the first edition of this
>>>>>>>>>> book,
>>>>>>>>>> these spokes withstood substantial elongation before failure.
>>>>>>>>>> Some
>>>>>>>>>> butted spokes stretched more than six millimeters without
>>>>>>>>>> breaking, at
>>>>>>>>>> which point the test was stopped."
>>>>>>>>>>
>>>>>>>>>> --p. 132, "The Bicycle Wheel," 2nd edition, 1988
>>>>>>>>>>
>>>>>>>>>> So the stainless steel spokes had not only replaced galvanized
>>>>>>>>>> as the
>>>>>>>>>> material for quality spokes, but they had also improved in
>>>>>>>>>> ductility
>>>>>>>>>> over early stainless steel spokes.
>>>>>>>>> Thanks for another excellent answer.
>>>>>>>>>
>>>>>>>>> Does the extra ductility have any advantage _per se_ for spokes?
>>>>>>>>>
>>>>>>>>> It might be a side-effect of some other improvement and
>>>>>>>>> therefore a clue
>>>>>>>>> about the introduction of some new process like vacuum degassing.
>>>>>>>>
>>>>>>>> Dear Ben,
>>>>>>>>
>>>>>>>> I'm still wondering about that.
>>>>>>>>
>>>>>>>> After considerable fuss and several trips to the local
>>>>>>>> university, I
>>>>>>>> had hopes of the engineering department doing stress-strain
>>>>>>>> tests on
>>>>>>>> some new Sapim 14 gauge stainless spokes to see how they
>>>>>>>> stretched in
>>>>>>>> 2007, compared to Jobst's last test in 1988.
>>>>>>>>
>>>>>>>> Alas, I'm still waiting, months later, which reminds me why I don't
>>>>>>>> miss working at universities.
>>>>>>>>
>>>>>>>> I don't know if more ductility means more durable spokes, but
>>>>>>>> the two
>>>>>>>> do seem to have been noticed at the same time.
>>>>>>>>
>>>>>>>> A curious point that I forgot is that carbon steel (galvanized)
>>>>>>>> spokes
>>>>>>>> are actually more fatigue resistant than stainless steel spokes:
>>>>>>>>
>>>>>>>> "The choice of carbon vs. stainless steel spokes hinges on which
>>>>>>>> facotr is considered more important: resistance to corrosion or
>>>>>>>> resistance to fatigue failure. . . . carbon steel has an advantage
>>>>>>>> over stainless steel in that it is more resistant to the other
>>>>>>>> common
>>>>>>>> mode of spoke failure, fatigue."
>>>>>>>>
>>>>>>>> --"Intro. to Engineering Materials: The Bicycle & the Walkman,"
>>>>>>>> p.13
>>>>>>>>
>>>>>>>> Elsewhere, that 1993 textbook by two U. of Pennsylvania engineering
>>>>>>>> professors has a cycles-to-failure graph for the two steels,
>>>>>>>> showing
>>>>>>>> that stainless steel spokes failed substantially _sooner_ in their
>>>>>>>> spoke fatigue testing than carbon steel.
>>>>>>>>
>>>>>>>> However, that testing involved spinning a straight, unbent spoke
>>>>>>>> section and pushing it gently sideways as it whirled, which
>>>>>>>> isn't the
>>>>>>>> same as a bent spoke elbow.
>>>>>>>>
>>>>>>>> It's possible that more ductile stainless steel somehow produces
>>>>>>>> much
>>>>>>>> lower residual stresses when bent to an elbow than the more fatigue
>>>>>>>> resistant carbon steel, which in turn could mean that the textbook
>>>>>>>> applied the right test to the wrong part of the spoke and got the
>>>>>>>> wrong answer.
>>>>>>>>
>>>>>>>> Cheers,
>>>>>>>>
>>>>>>>> Carl Fogel
>>>>>>>
>>>>>>> The whole story on the material aspect of fatigue is given by the
>>>>>>> S-N curve, also known as a W�hler curve. (See
>>>>>>> http://en.wikipedia.org/wiki/Fatigue_%28material%29#The_S-N_curve
>>>>>>> for an example). These curves need to be adjusted for the case of
>>>>>>> spokes, since they are typically for a (sinusoidal) stress cycle
>>>>>>> around zero, where spokes have (significant) a non-zero bias.
>>>>>>>
>>>>>>> It's common experience to have spokes survive 10^7 cycles, with
>>>>>>> some (Jobst) reporting 10^8 or so.
>>>>>>>
>>>>>>> S-N curves represent the ideal, with near perfect samples, and
>>>>>>> must be derated for realities like defects and corrosion.
>>>>>>>
>>>>>>> The higher fatigue resistance of carbon steel vs stainless, in
>>>>>>> practical terms, means that it's theoretically possible to make
>>>>>>> crappier spokes and have them last as long.
>>>>>>
>>>>>> no, if it's a steel whose carbon content is low enough to retain
>>>>>> the dislocation locking mechanism we discussed before,
>>>>>
>>>>>
>>>>>> those spokes would last forever, if stress was below that of their
>>>>>> endurance limit.
>>>>>
>>>>> Ditto for stainless.
>>>>
>>>> but stainless doesn't have an endurance limit so that's incorrect!
>>>> i've explained why. what's your problem?
>>>
>>> You are entitled to your opinion, but it seems to be unique.
>>>
>>> Manufacturers typically spec an "endurance limit" for stainless at
>>> 10^7 cycles. Why? Because it's pretty much the same at 10^8 and 10^9.
>>> The knee, according to Sandvik is around 2*10^6.
>>>
>>> Do the math. If spokes have a static load of ~33% UTS, and lots of
>>> people (myself included) have experience of near 100% non-failure at
>>> 10^7 cycles (13,000 miles), it's perfectly believable that spokes can
>>> do over 10^8 (as Jobst reports) or even 10^9. If 10^9 isn't infinite
>>> for you (1.3 million miles) just say so. Common real world experience
>>> demonstrates stainless has an effective endurance limit, just like
>>> the makers say.
>>>
>>> Fully hardened 302 has an endurance limit of 35-40% of UTS, as
>>> opposed to plain steel's 45-50%. This, of course, is for ideal,
>>> polished specimens. The fact that it's common to run spokes to 10^7
>>> cycles at ~33% UTS without seeing anything like a 50% failure, even
>>> with the non-ideal state of those spokes (defects, residual stress,
>>> corrosion), indicates we're below the endurance limit. We can't be
>>> far below that limit, so residual stress -- even at relatively low
>>> levels -- can cause failures.
>>>
>>> You can obsess about "fatigue limit" vs "endurance limit" all you
>>> want, the distinction is in your head. If the 10^9 stress limit is 5%
>>> below the 10^7 limit, it makes no real difference. Since 90% of the
>>> spoke lifetime will be spent in crack initiation, it has no effect on
>>> spoke strength, either.
>>>
>>> You can call Jobst (or me) a liar, but Sandvik (a maker of spoke
>>> wire) backs him up.
>>
>> sandvik are faced with the problem of selling materials to "engineers"
>> who demand something they can't have. and if engineers can't be
>> bothered to understand the science, what next? present information in
>> a way that kinda sorta fudges it for their dumb asses so they can
>> misinterpret what they want. because that's reality.
>>
>> fact: there is no dislocation locking mechanism. there is no
>> endurance limit. end of story.
>
> OK Sandvik is lying, too.
no they're not - they're simply trying to publish data engineers can use!
> Right. Keep drinking your own Kool-Aid.
|
| | | | | | | | | | | | |
Date: 19 Sep 2007 08:47:55
From: Peter Cole
Subject: Re: vacuum de-gas thread continued
|
jim beam wrote:
> Peter Cole wrote:
>> jim beam wrote:
>>> sandvik are faced with the problem of selling materials to
>>> "engineers" who demand something they can't have. and if engineers
>>> can't be bothered to understand the science, what next? present
>>> information in a way that kinda sorta fudges it for their dumb asses
>>> so they can misinterpret what they want. because that's reality.
>>>
>>> fact: there is no dislocation locking mechanism. there is no
>>> endurance limit. end of story.
>>
>> OK Sandvik is lying, too.
>
> no they're not - they're simply trying to publish data engineers can use!
>
>
>> Right. Keep drinking your own Kool-Aid.
Every time you are presented with proof your claims are wrong you accuse
others of lying. Here you state that Sandvik must lie because all
engineers are stupid. Do you gave any idea how crazy that sounds?
>
|
| | | | | | | | | | | | | |
Date: 19 Sep 2007 20:29:06
From: jim beam
Subject: Re: vacuum de-gas thread continued
|
Peter Cole wrote:
> jim beam wrote:
>> Peter Cole wrote:
>>> jim beam wrote:
>
>>>> sandvik are faced with the problem of selling materials to
>>>> "engineers" who demand something they can't have. and if engineers
>>>> can't be bothered to understand the science, what next? present
>>>> information in a way that kinda sorta fudges it for their dumb asses
>>>> so they can misinterpret what they want. because that's reality.
>>>>
>>>> fact: there is no dislocation locking mechanism. there is no
>>>> endurance limit. end of story.
>>>
>>> OK Sandvik is lying, too.
>>
>> no they're not - they're simply trying to publish data engineers can use!
>>
>>
>>> Right. Keep drinking your own Kool-Aid.
>
> Every time you are presented with proof your claims are wrong you accuse
> others of lying. Here you state that Sandvik must lie because all
> engineers are stupid. Do you gave any idea how crazy that sounds?
>
do you know how crazy bullshit in the face of contradictory fact sounds?
from a guy that's been bullshitting about elasticity and plasticity
and getting it wrong, your bullshit about endurance limits in a material
that doesn't have one, and for which mechanism you had no idea, sounds
pretty fucking weak.
|
| | | | | | | | | | | | | | |
Date: 20 Sep 2007 09:35:08
From: Peter Cole
Subject: Re: vacuum de-gas thread continued
|
jim beam wrote:
> Peter Cole wrote:
>> jim beam wrote:
>>> Peter Cole wrote:
>>>> jim beam wrote:
>>
>>>>> sandvik are faced with the problem of selling materials to
>>>>> "engineers" who demand something they can't have. and if engineers
>>>>> can't be bothered to understand the science, what next? present
>>>>> information in a way that kinda sorta fudges it for their dumb
>>>>> asses so they can misinterpret what they want. because that's
>>>>> reality.
>>>>>
>>>>> fact: there is no dislocation locking mechanism. there is no
>>>>> endurance limit. end of story.
>>>>
>>>> OK Sandvik is lying, too.
>>>
>>> no they're not - they're simply trying to publish data engineers can
>>> use!
>>>
>>>
>>>> Right. Keep drinking your own Kool-Aid.
>>
>> Every time you are presented with proof your claims are wrong you
>> accuse others of lying. Here you state that Sandvik must lie because
>> all engineers are stupid. Do you gave any idea how crazy that sounds?
>>
>
> do you know how crazy bullshit in the face of contradictory fact sounds?
Where's the "contradictory fact", near as I can tell it's only in your
mind -- which doesn't make it a fact.
> from a guy that's been bullshitting about elasticity and plasticity and
> getting it wrong, your bullshit about endurance limits in a material
> that doesn't have one, and for which mechanism you had no idea, sounds
> pretty fucking weak.
Oh, back to that. That's a misquote, which I proved by citing the
archives. I don't have to go back over that again, do I? Not that it
would do any good... you'll just keep repeating it. Arguing with you is
pointless (and abusive), you just make stuff up.
|
| | | | | | | | | | | | | | | |
Date: 20 Sep 2007 20:33:43
From: jim beam
Subject: Re: vacuum de-gas thread continued
|
Peter Cole wrote:
> jim beam wrote:
>> Peter Cole wrote:
>>> jim beam wrote:
>>>> Peter Cole wrote:
>>>>> jim beam wrote:
>>>
>>>>>> sandvik are faced with the problem of selling materials to
>>>>>> "engineers" who demand something they can't have. and if
>>>>>> engineers can't be bothered to understand the science, what next?
>>>>>> present information in a way that kinda sorta fudges it for their
>>>>>> dumb asses so they can misinterpret what they want. because
>>>>>> that's reality.
>>>>>>
>>>>>> fact: there is no dislocation locking mechanism. there is no
>>>>>> endurance limit. end of story.
>>>>>
>>>>> OK Sandvik is lying, too.
>>>>
>>>> no they're not - they're simply trying to publish data engineers can
>>>> use!
>>>>
>>>>
>>>>> Right. Keep drinking your own Kool-Aid.
>>>
>>> Every time you are presented with proof your claims are wrong you
>>> accuse others of lying. Here you state that Sandvik must lie because
>>> all engineers are stupid. Do you gave any idea how crazy that sounds?
>>>
>>
>> do you know how crazy bullshit in the face of contradictory fact sounds?
>
> Where's the "contradictory fact", near as I can tell it's only in your
> mind -- which doesn't make it a fact.
>
>> from a guy that's been bullshitting about elasticity and plasticity
>> and getting it wrong, your bullshit about endurance limits in a
>> material that doesn't have one, and for which mechanism you had no
>> idea, sounds pretty fucking weak.
>
> Oh, back to that. That's a misquote, which I proved by citing the
> archives.
eh? you compared plastic elongation with elastic elongation as if they
are the same thing. they're not. do you still not understand that?
> I don't have to go back over that again, do I? Not that it
> would do any good... you'll just keep repeating it. Arguing with you is
> pointless (and abusive), you just make stuff up.
wriggle and squirm.
|
| | | | | | | | | | | |
Date: 16 Sep 2007 20:44:44
From: Bill Sornson
Subject: Re: vacuum de-gas thread continued
|
Peter Cole wrote:
> jim beam wrote:
>> Peter Cole wrote:
>>> You can call Jobst (or me) a liar, but Sandvik (a maker of spoke
>>> wire) backs him up.
>> sandvik are faced with the problem of selling materials to
>> "engineers" who demand something they can't have. and if engineers
>> can't be bothered to understand the science, what next? present
>> information in a way that kinda sorta fudges it for their dumb asses
>> so they can misinterpret what they want. because that's reality.
>> fact: there is no dislocation locking mechanism. there is no
>> endurance limit. end of story.
> OK Sandvik is lying, too. Right. Keep drinking your own Kool-Aid.
SEE HOW EASY IT IS TO TRIM EXCESS CRAP?!? YOU LEFT 11 KBs JUST TO ADD A
ONE-LINE TAG!!!
Shhhhhhhhhhhhhhhhhhhhhhhheeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeesssssssssssssssssssssssssssshhhhhhhhhhhhhhhhhh....................................................................................................................
Ah.
|
| | | | | | | | | | | | |
Date: 16 Sep 2007 23:51:30
From: Jambo
Subject: Re: vacuum de-gas thread continued
|
"Bill Sornson" <askme@ask.me > wrote in message
news:46edf832$0$28827$4c368faf@roadrunner.com...
> SEE HOW EASY IT IS TO TRIM EXCESS CRAP?!? YOU LEFT 11 KBs JUST TO ADD A
> ONE-LINE TAG!!!
>
> Shhhhhhhhhhhhhhhhhhhhhhhheeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeesssssssssssssssssssssssssssshhhhhhhhhhhhhhhhhh....................................................................................................................
>
> Ah.
Is it just imagination, or does Bill Sornson's contribution to this n.g.
consist only of inane comments or rabid right-wing propaganda? Because I
think he'll be better off in another newsgroup.
|
| | | | |
Date: 15 Sep 2007 21:37:43
From:
Subject: Re: vacuum de-gas thread continued
|
On Sat, 15 Sep 2007 17:19:04 -0600, carlfogel@comcast.net wrote:
>On Sat, 15 Sep 2007 17:10:09 -0500, Ben C <spamspam@spam.eggs> wrote:
>
>>On 2007-09-15, carlfogel@comcast.net <carlfogel@comcast.net> wrote:
>>> On Sep 15, 12:10 pm, Ben C <spams...@spam.eggs> wrote:
>>>> On 2007-09-15, Peter Cole <peter_c...@comcast.net> wrote:
>>>
>>>> I'm not old enough to remember what bikes were like in the 60's and
>>>> 70's, but most older bikes I've seen of quite good quality (Reynolds 531
>>>> frame sort of level) had galvanized spokes. Is it true that stainless
>>>> steel has come down in price in the last 40 or 50 years and/or is more
>>>> widespread in its use for spokes?
>>>
>>> Dear Ben,
>>>
>>> Stainless steel spokes are certainly more widespread.
>>>
>>> Nowadays, galvanized spokes are considered cheap and inferior.
>>> "Quality" spokes are stainless steel and cost more.
>>>
>>> Galvanized spokes are actually a bit stronger than stainless steel
>>> spokes, but the extra strength has no advantage, since typical spoke
>>> tension is 100~150 kgf, well below the 225~250 kgf yield point that
>>> Jobst measured for thinner stainless steel 1.8 mm spokes. (And
>>> inflating the tire can reduce the spoke tension up to 15% on 700c
>>> rims.)
>>>
>>> In the 1981-1983 first edition of "The Bicycle Wheel," Jobst tested
>>> six spokes, three galvanized and three stainless steel (S.S.)::
>>>
>>> Union 14 gauge
>>> DT 14 gauge
>>> Robegel Sport 14 gauge
>>>
>>> DT S.S. 14 gauge
>>> DT S.S. 15 gauge
>>> Robegel S.S. 15-16 gauge
>>>
>>> The DT galvanized 14 gauge has a slightly higher and slightly sharper
>>> stress-strain curve than the DT stainless steel 14 gauge--the
>>> stainless steel was not quite as strong, but was more ductile.
>>>
>>> A few years later, Jobst re-tested spokes for the second edition of
>>> 1988. He tested only DT and Wheelsmith and only stainless steel
>>> spokes--galvanized had practically vanished.
>>>
>>> Jobst noticed an impressive improvement in ductility:
>>>
>>> "In contrast to tests performed for the first edition of this book,
>>> these spokes withstood substantial elongation before failure. Some
>>> butted spokes stretched more than six millimeters without breaking, at
>>> which point the test was stopped."
>>>
>>> --p. 132, "The Bicycle Wheel," 2nd edition, 1988
>>>
>>> So the stainless steel spokes had not only replaced galvanized as the
>>> material for quality spokes, but they had also improved in ductility
>>> over early stainless steel spokes.
>>
>>Thanks for another excellent answer.
>>
>>Does the extra ductility have any advantage _per se_ for spokes?
>>
>>It might be a side-effect of some other improvement and therefore a clue
>>about the introduction of some new process like vacuum degassing.
>
>Dear Ben,
>
>I'm still wondering about that.
>
>After considerable fuss and several trips to the local university, I
>had hopes of the engineering department doing stress-strain tests on
>some new Sapim 14 gauge stainless spokes to see how they stretched in
>2007, compared to Jobst's last test in 1988.
>
>Alas, I'm still waiting, months later, which reminds me why I don't
>miss working at universities.
>
>I don't know if more ductility means more durable spokes, but the two
>do seem to have been noticed at the same time.
>
>A curious point that I forgot is that carbon steel (galvanized) spokes
>are actually more fatigue resistant than stainless steel spokes:
>
>"The choice of carbon vs. stainless steel spokes hinges on which
>facotr is considered more important: resistance to corrosion or
>resistance to fatigue failure. . . . carbon steel has an advantage
>over stainless steel in that it is more resistant to the other common
>mode of spoke failure, fatigue."
>
>--"Intro. to Engineering Materials: The Bicycle & the Walkman," p.13
>
>Elsewhere, that 1993 textbook by two U. of Pennsylvania engineering
>professors has a cycles-to-failure graph for the two steels, showing
>that stainless steel spokes failed substantially _sooner_ in their
>spoke fatigue testing than carbon steel.
>
>However, that testing involved spinning a straight, unbent spoke
>section and pushing it gently sideways as it whirled, which isn't the
>same as a bent spoke elbow.
>
>It's possible that more ductile stainless steel somehow produces much
>lower residual stresses when bent to an elbow than the more fatigue
>resistant carbon steel, which in turn could mean that the textbook
>applied the right test to the wrong part of the spoke and got the
>wrong answer.
>
>Cheers,
>
>Carl Fogel
A straight section of stainless steel spoke with no residual stresses
will fatigue sooner than a less ductile section of carbon steel spoke.
But it seems to me, as a layman, that the more ductile stainless steel
spoke will be likely to have less residual stress after bending, since
it bends more easily in the first place.
If so, an unstressed straight section of stainless steel spoke will
fatigue sooner than a less ductile carbon steel spoke, as "The Bicycle
& the Walkman" shows, but the case may be reversed at spoke bends,
with the stainless steel spoke having less residual stress--and the
elbow is where most failures occur.
However, that's just a naive expectation, thrown out to see what the
people who study materials say.
Cheers,
Carl Fogel
|
| | | | | |
Date: 16 Sep 2007 02:52:49
From: Ben C
Subject: Re: vacuum de-gas thread continued
|
On 2007-09-16, carlfogel@comcast.net <carlfogel@comcast.net > wrote:
[...]
> A straight section of stainless steel spoke with no residual stresses
> will fatigue sooner than a less ductile section of carbon steel spoke.
>
> But it seems to me, as a layman, that the more ductile stainless steel
> spoke will be likely to have less residual stress after bending, since
> it bends more easily in the first place.
That sounds logical enough. But on the other hand, all steel is supposed
to have about the same modulus of elasticity, so in that sense it's just
as difficult to bend. Ductile means you can bend it further without it
breaking, not necessarily that it's any easier to bend. If the stiffness
is the same, one might think the residual stresses would also be the
same.
Literally ductile means "able to be drawn out [into a wire]". Which
gives me an idea why it might be desirable for spoke materials-- they
are wire. So it might be easier and cheaper to make huge reels of wire
out of the more ductile material.
> If so, an unstressed straight section of stainless steel spoke will
> fatigue sooner than a less ductile carbon steel spoke, as "The Bicycle
> & the Walkman" shows, but the case may be reversed at spoke bends,
> with the stainless steel spoke having less residual stress--and the
> elbow is where most failures occur.
>
> However, that's just a naive expectation, thrown out to see what the
> people who study materials say.
My guess is that another factor is corrosion. Galvanizing resists
corrosion but I would think less effectively than stainless steel.
|
| | | | | | |
Date: 16 Sep 2007 12:32:20
From: _
Subject: Re: vacuum de-gas thread continued
|
On Sun, 16 Sep 2007 02:52:49 -0500, Ben C wrote:
> On 2007-09-16, carlfogel@comcast.net <carlfogel@comcast.net> wrote:
> [...]
>> A straight section of stainless steel spoke with no residual stresses
>> will fatigue sooner than a less ductile section of carbon steel spoke.
>>
>> But it seems to me, as a layman, that the more ductile stainless steel
>> spoke will be likely to have less residual stress after bending, since
>> it bends more easily in the first place.
>
> That sounds logical enough. But on the other hand, all steel is supposed
> to have about the same modulus of elasticity, so in that sense it's just
> as difficult to bend. Ductile means you can bend it further without it
> breaking, not necessarily that it's any easier to bend. If the stiffness
> is the same, one might think the residual stresses would also be the
> same.
>
You may be running afoul of nomenclature and definition here (much like
"jim beam" and his confusion over fatigue and endurance limit(s)). The
modulus of elasticity describes how hard it is to made a thing bend below
the point where it will not return. Ductility describes how much it will
stretch (for bending, one side stretches) after that point, and before the
point where it breaks. The force required to produce a certain amount
ductile stretching is not linearly related - if at all- to the force
requried to produce a certain amount of elastic bending.
|
| | | | | | | |
Date: 16 Sep 2007 11:46:29
From: Ben C
Subject: Re: vacuum de-gas thread continued
|
On 2007-09-16, _ <jtayNOSPAMlor@hfDONTSENDMESPAMx.andara.com > wrote:
> On Sun, 16 Sep 2007 02:52:49 -0500, Ben C wrote:
>
>> On 2007-09-16, carlfogel@comcast.net <carlfogel@comcast.net> wrote:
>> [...]
>>> A straight section of stainless steel spoke with no residual stresses
>>> will fatigue sooner than a less ductile section of carbon steel spoke.
>>>
>>> But it seems to me, as a layman, that the more ductile stainless steel
>>> spoke will be likely to have less residual stress after bending, since
>>> it bends more easily in the first place.
>>
>> That sounds logical enough. But on the other hand, all steel is supposed
>> to have about the same modulus of elasticity, so in that sense it's just
>> as difficult to bend. Ductile means you can bend it further without it
>> breaking, not necessarily that it's any easier to bend. If the stiffness
>> is the same, one might think the residual stresses would also be the
>> same.
>>
>
> You may be running afoul of nomenclature and definition here (much like
> "jim beam" and his confusion over fatigue and endurance limit(s)).
He explained something about carbon diffusion, but was quite brief,
although it sounded interesting. If you know more about it don't be shy.
> The modulus of elasticity describes how hard it is to made a thing
> bend below the point where it will not return.
Modulus of elasticity is stress/strain-- how much stress you need for a
given strain. But how much stress you need to reach the point below (or
"above" I probably would have said) which it won't return is called the
yield stress. Two materials could have the same modulus but different
yield stresses.
> Ductility describes how much it will stretch (for bending, one side
> stretches) after that point, and before the point where it breaks.
> The force required to produce a certain amount ductile stretching is
> not linearly related - if at all- to the force requried to produce a
> certain amount of elastic bending.
I think the stress/strain graph goes pretty flat at the point where it
starts yielding even if the material is ductile. In other words you can
probably carry on pulling with a roughly constant force and it will go
on yielding and just stretch out.
I would expect the force you need to make wire to depend on the yield
stress (as opposed to its modulus) of the material, and on the thickness
of the wire, but not on its length.
|
| | | | | | | | |
Date: 16 Sep 2007 18:56:44
From: _
Subject: Re: vacuum de-gas thread continued
|
On Sun, 16 Sep 2007 11:46:29 -0500, Ben C wrote:
>
>> The modulus of elasticity describes how hard it is to made a thing
>> bend below the point where it will not return.
>
> Modulus of elasticity is stress/strain-- how much stress you need for a
> given strain. But how much stress you need to reach the point below (or
> "above" I probably would have said) which it won't return is called the
> yield stress. Two materials could have the same modulus but different
> yield stresses.
I know that. You (and many others here) know that. But not everyone may,
and I was using the simplest words possible. If you read it again, you'll
see that I was referring to points below , not *at* yield.
|
| | | | | | | | | |
Date: 16 Sep 2007 16:00:52
From: Ben C
Subject: Re: vacuum de-gas thread continued
|
On 2007-09-16, _ <jtayNOSPAMlor@hfDONTSENDMESPAMx.andara.com > wrote:
> On Sun, 16 Sep 2007 11:46:29 -0500, Ben C wrote:
>
>>
>>> The modulus of elasticity describes how hard it is to made a thing
>>> bend below the point where it will not return.
>>
>> Modulus of elasticity is stress/strain-- how much stress you need for a
>> given strain. But how much stress you need to reach the point below (or
>> "above" I probably would have said) which it won't return is called the
>> yield stress. Two materials could have the same modulus but different
>> yield stresses.
>
>
> I know that. You (and many others here) know that. But not everyone may,
> and I was using the simplest words possible. If you read it again, you'll
> see that I was referring to points below , not *at* yield.
Ah, now I see what you mean. Yes, I'm sorry, I did misread what you
wrote. Hence my confusion over the choice of the word "below", but I was
being a bit stupid.
|
| | | | | | | | |
Date: 16 Sep 2007 09:54:47
From: jim beam
Subject: Re: vacuum de-gas thread continued
|
Ben C wrote:
> On 2007-09-16, _ <jtayNOSPAMlor@hfDONTSENDMESPAMx.andara.com> wrote:
>> On Sun, 16 Sep 2007 02:52:49 -0500, Ben C wrote:
>>
>>> On 2007-09-16, carlfogel@comcast.net <carlfogel@comcast.net> wrote:
>>> [...]
>>>> A straight section of stainless steel spoke with no residual stresses
>>>> will fatigue sooner than a less ductile section of carbon steel spoke.
>>>>
>>>> But it seems to me, as a layman, that the more ductile stainless steel
>>>> spoke will be likely to have less residual stress after bending, since
>>>> it bends more easily in the first place.
>>> That sounds logical enough. But on the other hand, all steel is supposed
>>> to have about the same modulus of elasticity, so in that sense it's just
>>> as difficult to bend. Ductile means you can bend it further without it
>>> breaking, not necessarily that it's any easier to bend. If the stiffness
>>> is the same, one might think the residual stresses would also be the
>>> same.
>>>
>> You may be running afoul of nomenclature and definition here (much like
>> "jim beam" and his confusion over fatigue and endurance limit(s)).
>
> He explained something about carbon diffusion, but was quite brief,
> although it sounded interesting. If you know more about it don't be shy.
>
>> The modulus of elasticity describes how hard it is to made a thing
>> bend below the point where it will not return.
>
> Modulus of elasticity is stress/strain-- how much stress you need for a
> given strain. But how much stress you need to reach the point below (or
> "above" I probably would have said) which it won't return is called the
> yield stress. Two materials could have the same modulus but different
> yield stresses.
>
>> Ductility describes how much it will stretch (for bending, one side
>> stretches) after that point, and before the point where it breaks.
>> The force required to produce a certain amount ductile stretching is
>> not linearly related - if at all- to the force requried to produce a
>> certain amount of elastic bending.
>
> I think the stress/strain graph goes pretty flat at the point where it
> starts yielding even if the material is ductile. In other words you can
> probably carry on pulling with a roughly constant force and it will go
> on yielding and just stretch out.
only strain aging material - like mild steel.
http://www.flickr.com/photos/38636024@N00/327752060/
item 2.
>
> I would expect the force you need to make wire to depend on the yield
> stress (as opposed to its modulus) of the material, and on the thickness
> of the wire, but not on its length.
|
| | | | | | | |
Date: 16 Sep 2007 07:45:59
From: jim beam
Subject: Re: vacuum de-gas thread continued
|
_ wrote:
> On Sun, 16 Sep 2007 02:52:49 -0500, Ben C wrote:
>
>> On 2007-09-16, carlfogel@comcast.net <carlfogel@comcast.net> wrote:
>> [...]
>>> A straight section of stainless steel spoke with no residual stresses
>>> will fatigue sooner than a less ductile section of carbon steel spoke.
>>>
>>> But it seems to me, as a layman, that the more ductile stainless steel
>>> spoke will be likely to have less residual stress after bending, since
>>> it bends more easily in the first place.
>> That sounds logical enough. But on the other hand, all steel is supposed
>> to have about the same modulus of elasticity, so in that sense it's just
>> as difficult to bend. Ductile means you can bend it further without it
>> breaking, not necessarily that it's any easier to bend. If the stiffness
>> is the same, one might think the residual stresses would also be the
>> same.
>>
>
> You may be running afoul of nomenclature and definition here (much like
> "jim beam" and his confusion over fatigue and endurance limit(s)). The
> modulus of elasticity describes how hard it is to made a thing bend below
> the point where it will not return. Ductility describes how much it will
> stretch (for bending, one side stretches) after that point, and before the
> point where it breaks. The force required to produce a certain amount
> ductile stretching is not linearly related - if at all- to the force
> requried to produce a certain amount of elastic bending.
you're both right. mostly. to put it another way, if an alloy reaches
failure at 15% elongation and plasticity commences at 0.5% elongation,
14.5% is a measure of ductility.
|
| |
Date: 15 Sep 2007 11:36:05
From: Peter Cole
Subject: Re: vacuum de-gas thread continued
|
jim beam wrote:
> Peter Cole wrote:
>> jim beam wrote:
>>>>> if i'm paying $261.50 per ton for steel, paying an extra 38% to
>>>>> get it degassed is kind of significant.
>>>>
>>>> Not if you're making spokes, which is the whole point.
>>>
>>> yes if you're making spokes, which is the whole point. materials
>>> costs are something and they need to be managed. processing is
>>> another.
>>
>> OK, you're claiming that for a $438/65lb ($6.75/lb) crankshaft,
>> vacuum degassed steel is economical,
>
> eh? don't put those words in my mouth - never said anything /like/ that.
>
>
>> but for a $.60/8g spoke
>> ($165/lb) it isn't?
>
> bullshit argument. see above.
Hey, at a nickel a pound extra, either degassing is an economical factor
or not in spoke making. Stop accusing me of "bullshit" and just address
the issue. Do you think a nickel a pound has any real effect on material
choice for spokes or not?
>> You are the one claiming the benefit (in spokes). It's been around
>> and widely available since the mid 60's anyway -- used in bulk,
>> cost-sensitive apps (auto sheet metal) since the 70's at least.
>
> and bike spokes since the 70's.
How do you know this?
>> Let's review.
>>
>> You have claimed that stress relieving of spokes is not necessary
>> since spoke failures are caused by surface defects, commonly
>> inclusions.
>
> no, you're paraphrasing and getting it wrong.
>
>
>> The solution is to use quality spokes like Sapim, who,
>> according to their website, use vacuum degassed steel. You back up
>> this claim with a hand drawing of a spoke failing at an inclusion,
>> which you assert is representative.
>
> it is. /you/ go out and examine spoke failures and post photos that
> contradict it if you can. my camera gear doesn't macro as small as my
> loupe, hence the diagram.
So the inclusions you have seen have been large enough to identify with
a loupe?
>> You claim that the use of vacuum degassed steels was unlikely until
>> fairly recently because of cost and availability.
>
> in automotive use. and i cited the cheaper alternative used. [whoops -
> let's omit the inconvenient facts. forget i said that. or cited
> anything even.]
I'm sorry, I don't recall, what was the alternative? According to the
source I cited, vacuum degassed steel was used by the Japanese in auto
sheet steel in the 70's. What does all this have to do with spokes?
Vacuum degassing was certainly doable in the 60's for a cost insensitive
application like spokes.
>> The record
>> indicates that this was not true since at least the mid-60's.
>
> eh? your own numbers contradict that!!!
For the second time -- what numbers?
>> You claim that the use of vacuum degassed steel in spokes is still
>> prohibitively expensive for some manufacturers.
>
> no, you're paraphrasing and getting it wrong.
>
>
>> It defies reason that
>> a manufacturer could afford the alloying elements of stainless and
>> not afford to degass the steel.
>
> bullshit. see above.
Instead of simply saying "wrong" & "bullshit", correct me if you can.
>> Let's suppose your claim that spokes only fail at inclusions is true,
>> and that after using defect free material we don't need to stress
>> relieve. This is because:
>>
>> 1) There aren't any residual stresses to relieve.
>
> no, you're paraphrasing and getting it wrong.
>
>>
>> 2) They don't matter for fatigue life.
>
> no, you're paraphrasing and getting it wrong.
>
>
>>
>> Item 1 is false. Metallurgists have agreed with Jobst's model on this
>> forum (it's archived).
>
> i'm a metallurgist, and i disagree.
> jobst doesn't take any of the real
> world fatigue initiators into account in formulation of his theory.
I don't think he has to. Adding the fact that fatigue cracks start at
surface defects overwhelmingly, whether those defects are inclusions,
slip bands or nicks from use/fabrication, doesn't change the model.
He states explicitly that surface finish is very important to fatigue
life. That in no way contradicts the residual stress model.
> /and/ he cites deformation of a strain aging material as part of his
> explanation.
No, he doesn't. Your repetition of this ad nauseam is only based on his
inclusion of one graph in his book in the section called "Metals and
Stress". The graph is not referenced in the text as applying to spokes
specifically or any type of spoke in particular - as a matter of fact,
the graph is not referenced at all. The next section "Spoke Failure"
does explicitly reference other graphs of actual spoke stress-strain
data. This quibble of yours is basically without any merit at all, which
you might appreciate if you ever read the book.
> two major fuck-ups, and you still want to claim jobst
> knows what he's talking about? clearly /you/ don't know any better!
I think we can leave that question to the reader. Your claims have no
support or supporters from what I can see.
>> I have observed the residual stress first hand
>> by making a "slitting" experiment -- a technique that is used in
>> industry.
>
> and you have failed to observe fatigue initiate at a region of high
> residual stress! just because it rains on thursdays doesn't mean that
> beans don't make you fart.
Your claim that residual stress is higher in interior sections together
with your belief than inclusions are a major factor contradicts your own
observation that fatigue typically initiates surface cracks, since
inclusions should be uniformly distributed -- ergo would predict
cracking initiation in interior sections.
The reference I cited (slitting example) showed a stress profile where
surface residual stress was only slightly lower than peak residual
stress. Granted, that was for a specimen with small deformation and
larger cross section to length geometry, but the issue remains that
residual stresses are significant enough at the skin to promote fatigue.
They might not be peak, but they are there, as my experiment demonstrated.
>> Item 2 is also false. If a spoke is nominally tensioned to 33% of
>> yield, and the endurance limit is 40% of yield, even a small amount
>> of residual stress can dramatically shorten the fatigue life.
>
> in theory, yes. but FATIGUE IS NOT ***OBSERVED*** TO BE INITIATING AT A
> REGION OF HIGH RESIDUAL STRESS!!! how many times does this need to be
> repeated? just because this fact is inconvenient to the "theory"
> doesn't mean it can be ignored.
I think you need to rephrase. Your "HIGH", needs to be replaced with
"HIGHEST". It seems that the skin residual stress is high enough, even
if it may not be the highest residual. "HIGH" in this context meaning
high enough, with or without additional stress concentrators (defects),
to dominate failure mode.
The residual surface stress needs only to be high enough that, when
combined with local concentrators and static load, exceeds the endurance
threshold by enough that the momentary overload causes local yield. The
outcome may or may not be enough to lower local skin stress to below the
endurance limit, practical experience indicates that it likely does.
>> Since
>> Jobst has reported spoke lifetimes of over 10^8 cycles, his technique
>> must be reducing residual stresses to a very low level since he must
>> be below the endurance limit.
>
> i don't buy that "jobst has reported" bullshit. jobst first made
> assertions to me in private correspondence that he had been riding the
> same wheels for 300,000 miles. it has since emerged that not only has
> he replaced rims and hubs, but spokes as well. what? suppress data
> that doesn't suit the myth? say it can't be so!
He has explained that he replaced only a few spokes that were chain
nicked. The replacement of rims and hubs has no effect on spoke
lifetime. The only effect of replacing damages spokes was to reduce the
sample size slightly. It doesn't invalidate the result.
|
| | |
Date: 15 Sep 2007 13:10:17
From: Ben C
Subject: Re: vacuum de-gas thread continued
|
On 2007-09-15, Peter Cole <peter_cole@comcast.net > wrote:
[...]
> Vacuum degassing was certainly doable in the 60's for a cost insensitive
> application like spokes.
I'm not old enough to remember what bikes were like in the 60's and
70's, but most older bikes I've seen of quite good quality (Reynolds 531
frame sort of level) had galvanized spokes. Is it true that stainless
steel has come down in price in the last 40 or 50 years and/or is more
widespread in its use for spokes?
|
| | | |
Date: 15 Sep 2007 22:29:36
From:
Subject: Re: vacuum de-gas thread continued
|
Ben C? writes:
>> Vacuum degassing was certainly doable in the 60's for a cost
>> insensitive application like spokes.
> I'm not old enough to remember what bikes were like in the 60's and
> 70's, but most older bikes I've seen of quite good quality (Reynolds
> 531 frame sort of level) had galvanized spokes. Is it true that
> stainless steel has come down in price in the last 40 or 50 years
> and/or is more widespread in its use for spokes?
You were riding among the wrong crowd. Stainless spokes were common
on better bicycles in the 1950's when I bought my first Cinelli.
Jobst Brandt
|
| | | | |
Date: 15 Sep 2007 17:50:12
From: Ben C
Subject: Re: vacuum de-gas thread continued
|
On 2007-09-15, jobst.brandt@stanfordalumni.org <jobst.brandt@stanfordalumni.org > wrote:
> Ben C? writes:
>
>>> Vacuum degassing was certainly doable in the 60's for a cost
>>> insensitive application like spokes.
>
>> I'm not old enough to remember what bikes were like in the 60's and
>> 70's, but most older bikes I've seen of quite good quality (Reynolds
>> 531 frame sort of level) had galvanized spokes. Is it true that
>> stainless steel has come down in price in the last 40 or 50 years
>> and/or is more widespread in its use for spokes?
>
> You were riding among the wrong crowd. Stainless spokes were common
> on better bicycles in the 1950's when I bought my first Cinelli.
Bah, you coffee-shop posers with your fancy Italian bikes and shiny
spokes.
|
| | | |
Date: 15 Sep 2007 12:34:27
From: jim beam
Subject: Re: vacuum de-gas thread continued
|
Ben C wrote:
> On 2007-09-15, Peter Cole <peter_cole@comcast.net> wrote:
> [...]
>> Vacuum degassing was certainly doable in the 60's for a cost insensitive
>> application like spokes.
>
> I'm not old enough to remember what bikes were like in the 60's and
> 70's, but most older bikes I've seen of quite good quality (Reynolds 531
> frame sort of level) had galvanized spokes. Is it true that stainless
> steel has come down in price in the last 40 or 50 years and/or is more
> widespread in its use for spokes?
do you /have/ to ask practical questions like that? you'll make him
feel uncomfortable.
|
| | | | |
Date: 15 Sep 2007 17:25:40
From: Peter Cole
Subject: Re: vacuum de-gas thread continued
|
jim beam wrote:
> Ben C wrote:
>> On 2007-09-15, Peter Cole <peter_cole@comcast.net> wrote:
>> [...]
>>> Vacuum degassing was certainly doable in the 60's for a cost
>>> insensitive application like spokes.
>>
>> I'm not old enough to remember what bikes were like in the 60's and
>> 70's, but most older bikes I've seen of quite good quality (Reynolds 531
>> frame sort of level) had galvanized spokes. Is it true that stainless
>> steel has come down in price in the last 40 or 50 years and/or is more
>> widespread in its use for spokes?
>
> do you /have/ to ask practical questions like that? you'll make him
> feel uncomfortable.
Asking me? I don't care. I just like them because they're prettier.
I'm here for the engineering, not the history.
And the warmth.
|
| | |
Date: 15 Sep 2007 09:36:03
From: jim beam
Subject: Re: vacuum de-gas thread continued
|
Peter Cole wrote:
> jim beam wrote:
>> Peter Cole wrote:
>>> jim beam wrote:
>
>>>>>> if i'm paying $261.50 per ton for steel, paying an extra 38% to
>>>>>> get it degassed is kind of significant.
>>>>>
>>>>> Not if you're making spokes, which is the whole point.
>>>>
>>>> yes if you're making spokes, which is the whole point. materials
>>>> costs are something and they need to be managed. processing is
>>>> another.
>>>
>>> OK, you're claiming that for a $438/65lb ($6.75/lb) crankshaft,
>>> vacuum degassed steel is economical,
>>
>> eh? don't put those words in my mouth - never said anything /like/ that.
>>
>>
>>> but for a $.60/8g spoke
>>> ($165/lb) it isn't?
>>
>> bullshit argument. see above.
>
> Hey, at a nickel a pound extra, either degassing is an economical factor
> or not in spoke making. Stop accusing me of "bullshit" and just address
> the issue. Do you think a nickel a pound has any real effect on material
> choice for spokes or not?
i think that increasing my raw material costs by 34% is significant.
and to keep trying to avoid that important point is bullshit.
manufacturers pay the freight on vacuum degassed steel simply because of
superior mechanical properties, not because they don't know how to
manage their costs.
>
>
>>> You are the one claiming the benefit (in spokes). It's been around
>>> and widely available since the mid 60's anyway -- used in bulk,
>>> cost-sensitive apps (auto sheet metal) since the 70's at least.
>>
>> and bike spokes since the 70's.
>
> How do you know this?
er, i went to materials school, remember? they teach that stuff there.
>
>
>>> Let's review.
>>>
>>> You have claimed that stress relieving of spokes is not necessary
>>> since spoke failures are caused by surface defects, commonly
>>> inclusions.
>>
>> no, you're paraphrasing and getting it wrong.
>>
>>
>>> The solution is to use quality spokes like Sapim, who,
>>> according to their website, use vacuum degassed steel. You back up
>>> this claim with a hand drawing of a spoke failing at an inclusion,
>>> which you assert is representative.
>>
>> it is. /you/ go out and examine spoke failures and post photos that
>> contradict it if you can. my camera gear doesn't macro as small as my
>> loupe, hence the diagram.
>
> So the inclusions you have seen have been large enough to identify with
> a loupe?
absolutely not. what part of "electron microscopy" could possibly lead
you to conclude otherwise? unless you want to put words in my mouth
with intent to deceive of course.
>
>
>>> You claim that the use of vacuum degassed steels was unlikely until
>>> fairly recently because of cost and availability.
>>
>> in automotive use. and i cited the cheaper alternative used. [whoops
>> - let's omit the inconvenient facts. forget i said that. or cited
>> anything even.]
>
> I'm sorry, I don't recall, what was the alternative?
pah-leeeeze. you can't remember??? how convenient!!!
> According to the
> source I cited, vacuum degassed steel was used by the Japanese in auto
> sheet steel in the 70's. What does all this have to do with spokes?
> Vacuum degassing was certainly doable in the 60's for a cost insensitive
> application like spokes.
but it wasn't used. you could buy chrome plated spokes in the 70's, and
that /causes/ fatigue.
>
>
>>> The record
>>> indicates that this was not true since at least the mid-60's.
>>
>> eh? your own numbers contradict that!!!
>
> For the second time -- what numbers?
your flexible dates!
>
>>> You claim that the use of vacuum degassed steel in spokes is still
>>> prohibitively expensive for some manufacturers.
>>
>> no, you're paraphrasing and getting it wrong.
>>
>>
>>> It defies reason that
>>> a manufacturer could afford the alloying elements of stainless and
>>> not afford to degass the steel.
>>
>> bullshit. see above.
>
> Instead of simply saying "wrong" & "bullshit", correct me if you can.
read your on freakin' words.
>
>
>>> Let's suppose your claim that spokes only fail at inclusions is true,
>>> and that after using defect free material we don't need to stress
>>> relieve. This is because:
>>>
>>> 1) There aren't any residual stresses to relieve.
>>
>> no, you're paraphrasing and getting it wrong.
>>
>>>
>>> 2) They don't matter for fatigue life.
>>
>> no, you're paraphrasing and getting it wrong.
>>
>>
>>>
>>> Item 1 is false. Metallurgists have agreed with Jobst's model on this
>>> forum (it's archived).
>>
>> i'm a metallurgist, and i disagree.
>
>
>> jobst doesn't take any of the real world fatigue initiators into
>> account in formulation of his theory.
>
> I don't think he has to. Adding the fact that fatigue cracks start at
> surface defects overwhelmingly, whether those defects are inclusions,
> slip bands or nicks from use/fabrication, doesn't change the model.
>
> He states explicitly that surface finish is very important to fatigue
> life.
he throws in one line and marches straight onto what he's preconceived
as being responsible, because /he/ wants to claim solution!!!
> That in no way contradicts the residual stress model.
yes it does. jobst thinks he's seeing spoke failure cause by residual
stress. he hasn't analyzed failure at all, simply tried to force
selected information to support his preconception. if he's bothered to
actually examine failures, [and understood the subject properly] he's
have seen where the fatigue was initiating and considered what people
that get paid to do this stuff would have considered - surface finish
and material. he could also have considered residual stress and
concluded that if fatigue starts in a region of compressive residual
stress, then residual stress is /not/ causing that fatigue!!!
>
>> /and/ he cites deformation of a strain aging material as part of his
>> explanation.
>
> No, he doesn't. Your repetition of this ad nauseam is only based on his
> inclusion of one graph in his book in the section called "Metals and
> Stress". The graph is not referenced in the text as applying to spokes
> specifically or any type of spoke in particular - as a matter of fact,
> the graph is not referenced at all. The next section "Spoke Failure"
> does explicitly reference other graphs of actual spoke stress-strain
> data. This quibble of yours is basically without any merit at all, which
> you might appreciate if you ever read the book.
er, citing the wrong material stress/strain graph illustrates a
fundamental misconception. jobst writes elsewhere that that spokes are
not work hardened as "stress relief" deformation occurs, and if this
were a strain aging material, this might be true. but for stainless
spoke wire, it's not, and saying so reinforces the misconception that
surrounds citing the wrong stress/strain graph!
>
>> two major fuck-ups, and you still want to claim jobst knows what he's
>> talking about? clearly /you/ don't know any better!
>
> I think we can leave that question to the reader. Your claims have no
> support or supporters from what I can see.
i don't see gaining your "support" as a benefit.
>
>>> I have observed the residual stress first hand
>>> by making a "slitting" experiment -- a technique that is used in
>>> industry.
>>
>> and you have failed to observe fatigue initiate at a region of high
>> residual stress! just because it rains on thursdays doesn't mean that
>> beans don't make you fart.
>
> Your claim that residual stress is higher in interior sections together
> with your belief than inclusions are a major factor contradicts your own
> observation that fatigue typically initiates surface cracks, since
> inclusions should be uniformly distributed -- ergo would predict
> cracking initiation in interior sections.
you goofed off materials lectures kiddo. no, inclusions are typically
not evenly distributed.
but let's not get distracted by your education and stick to the facts as
you seek to misconstrue them - that inclusions are a major factor in
fatigue is a matter of the literature. there are libraries full of this
stuff. even in engineering schools - go read. and you're conveniently
ignoring the distribution of residual stresses. yet again, if fatigue
is observed to be initiating in a region of low or even compressive
residual stress, it's not the cause. period.
>
> The reference I cited (slitting example) showed a stress profile where
> surface residual stress was only slightly lower than peak residual
> stress.
no it doesn't! it shows that equilibrium is disturbed and distortion is
required to accommodate it!!!
> Granted, that was for a specimen with small deformation and
> larger cross section to length geometry, but the issue remains that
> residual stresses are significant enough at the skin to promote fatigue.
but the residual stress profiles don't support that!
> They might not be peak, but they are there, as my experiment demonstrated.
you misunderstand what you're looking at.
>
>>> Item 2 is also false. If a spoke is nominally tensioned to 33% of
>>> yield, and the endurance limit is 40% of yield, even a small amount
>>> of residual stress can dramatically shorten the fatigue life.
>>
>> in theory, yes. but FATIGUE IS NOT ***OBSERVED*** TO BE INITIATING AT
>> A REGION OF HIGH RESIDUAL STRESS!!! how many times does this need to
>> be repeated? just because this fact is inconvenient to the "theory"
>> doesn't mean it can be ignored.
>
> I think you need to rephrase. Your "HIGH", needs to be replaced with
> "HIGHEST". It seems that the skin residual stress is high enough, even
> if it may not be the highest residual. "HIGH" in this context meaning
> high enough, with or without additional stress concentrators (defects),
> to dominate failure mode.
er, so how do you account for fatigue initiation in a region of
COMPRESSIVE residual stress? the fatigue fairy?
>
> The residual surface stress needs only to be high enough that, when
> combined with local concentrators and static load, exceeds the endurance
> threshold by enough that the momentary overload causes local yield. The
> outcome may or may not be enough to lower local skin stress to below the
> endurance limit, practical experience indicates that it likely does.
see above. you need to do some real life fatigue observation.
>
>
>>> Since
>>> Jobst has reported spoke lifetimes of over 10^8 cycles, his technique
>>> must be reducing residual stresses to a very low level since he must
>>> be below the endurance limit.
>>
>> i don't buy that "jobst has reported" bullshit. jobst first made
>> assertions to me in private correspondence that he had been riding the
>> same wheels for 300,000 miles. it has since emerged that not only has
>> he replaced rims and hubs, but spokes as well. what? suppress data
>> that doesn't suit the myth? say it can't be so!
>
> He has explained that he replaced only a few spokes that were chain
> nicked.
how convenient. given that he's shown to, er, "forget" vital data when
telling stories, you want to assume his memory is suddenly
"non-forgetful" when it doesn't suit? i don't think so.
> The replacement of rims and hubs has no effect on spoke
> lifetime. The only effect of replacing damages spokes was to reduce the
> sample size slightly. It doesn't invalidate the result.
it's not a result, it's a claim. see above.
|
| | | |
Date: 15 Sep 2007 15:58:13
From: Peter Cole
Subject: Re: vacuum de-gas thread continued
|
jim beam wrote:
> Peter Cole wrote:
>> Hey, at a nickel a pound extra, either degassing is an economical
>> factor or not in spoke making. Stop accusing me of "bullshit" and just
>> address the issue. Do you think a nickel a pound has any real effect
>> on material choice for spokes or not?
>
> i think that increasing my raw material costs by 34% is significant. and
> to keep trying to avoid that important point is bullshit.
It's important for rebar, but not for spokes.
> manufacturers pay the freight on vacuum degassed steel simply because of
> superior mechanical properties, not because they don't know how to
> manage their costs.
Who said that? That doesn't even make sense.
>>>> You are the one claiming the benefit (in spokes). It's been around
>>>> and widely available since the mid 60's anyway -- used in bulk,
>>>> cost-sensitive apps (auto sheet metal) since the 70's at least.
>>>
>>> and bike spokes since the 70's.
>>
>> How do you know this?
>
> er, i went to materials school, remember? they teach that stuff there.
They taught bicycle spokes at "materials school"? What's "materials
school" anyway. I take it it's not a university?
>>> it is. /you/ go out and examine spoke failures and post photos that
>>> contradict it if you can. my camera gear doesn't macro as small as
>>> my loupe, hence the diagram.
>>
>> So the inclusions you have seen have been large enough to identify
>> with a loupe?
>
> absolutely not. what part of "electron microscopy" could possibly lead
> you to conclude otherwise? unless you want to put words in my mouth
> with intent to deceive of course.
No, just trying to understand the point of your "diagram".
>>>> You claim that the use of vacuum degassed steels was unlikely until
>>>> fairly recently because of cost and availability.
>>>
>>> in automotive use. and i cited the cheaper alternative used.
>>> [whoops - let's omit the inconvenient facts. forget i said that. or
>>> cited anything even.]
>>
>> I'm sorry, I don't recall, what was the alternative?
>
> pah-leeeeze. you can't remember??? how convenient!!!
No, the only technique I recall you mention was oxygen injection. That
couldn't be what you're referring to, since that's been 100% standard
since the 60's.
That's my last guess. So what was it?
>> According to the source I cited, vacuum degassed steel was used by the
>> Japanese in auto sheet steel in the 70's. What does all this have to
>> do with spokes? Vacuum degassing was certainly doable in the 60's for
>> a cost insensitive application like spokes.
>
> but it wasn't used.
Not that it really matters, but if you have nothing to back that claim
up with there's little to conclude but you're -- you know what...
> you could buy chrome plated spokes in the 70's, and
> that /causes/ fatigue.
Who cares?
>>>> The record
>>>> indicates that this was not true since at least the mid-60's.
>>>
>>> eh? your own numbers contradict that!!!
>>
>> For the second time -- what numbers?
>
> your flexible dates!
Third time?
>>>> It defies reason that
>>>> a manufacturer could afford the alloying elements of stainless and
>>>> not afford to degass the steel.
>>>
>>> bullshit. see above.
>>
>> Instead of simply saying "wrong" & "bullshit", correct me if you can.
>
> read your on freakin' words.
Good rebuttal!
>>>> Let's suppose your claim that spokes only fail at inclusions is true,
>>>> and that after using defect free material we don't need to stress
>>>> relieve. This is because:
>>>>
>>>> 1) There aren't any residual stresses to relieve.
>>>
>>> no, you're paraphrasing and getting it wrong.
>>>
>>>>
>>>> 2) They don't matter for fatigue life.
>>>
>>> no, you're paraphrasing and getting it wrong.
>>>
>>>
>>>>
>>>> Item 1 is false. Metallurgists have agreed with Jobst's model on this
>>>> forum (it's archived).
>>>
>>> i'm a metallurgist, and i disagree.
So you say.
>>> jobst doesn't take any of the real world fatigue initiators into
>>> account in formulation of his theory.
>>
>> I don't think he has to. Adding the fact that fatigue cracks start at
>> surface defects overwhelmingly, whether those defects are inclusions,
>> slip bands or nicks from use/fabrication, doesn't change the model.
>>
>> He states explicitly that surface finish is very important to fatigue
>> life.
>
> he throws in one line and marches straight onto what he's preconceived
> as being responsible, because /he/ wants to claim solution!!!
You'll have to do better than that. What else should he have said about
surface finish?
>> That in no way contradicts the residual stress model.
>
> yes it does. jobst thinks he's seeing spoke failure cause by residual
> stress. he hasn't analyzed failure at all, simply tried to force
> selected information to support his preconception. if he's bothered to
> actually examine failures, [and understood the subject properly] he's
> have seen where the fatigue was initiating and considered what people
> that get paid to do this stuff would have considered - surface finish
> and material.
Those things are important to fatigue, as he said, but so is stress.
You're inventing an argument.
> he could also have considered residual stress and
> concluded that if fatigue starts in a region of compressive residual
> stress, then residual stress is /not/ causing that fatigue!!!
I guess this is a cryptic reference to spokes failing on elbow outsides,
something only you seem to have seen in quantity (4:1). It's been
patiently explained to you that's because you don't correct your spoke
line. As soon as you tension, you'll get a huge bending stress, enough
to bulk yield under working load, causing the loose spokes you also
complain about.
>>> /and/ he cites deformation of a strain aging material as part of his
>>> explanation.
>>
>> No, he doesn't. Your repetition of this ad nauseam is only based on his
>> inclusion of one graph in his book in the section called "Metals and
>> Stress". The graph is not referenced in the text as applying to spokes
>> specifically or any type of spoke in particular - as a matter of fact,
>> the graph is not referenced at all. The next section "Spoke Failure"
>> does explicitly reference other graphs of actual spoke stress-strain
>> data. This quibble of yours is basically without any merit at all,
>> which you might appreciate if you ever read the book.
>
> er, citing the wrong material stress/strain graph illustrates a
> fundamental misconception.
He didn't "cite" it. It's just in the beginning of the chapter showing a
typical stress/strain. The fact that it has a little blip in it that SS
doesn't is immaterial to the content.
> jobst writes elsewhere that that spokes are
> not work hardened as "stress relief" deformation occurs, and if this
> were a strain aging material, this might be true. but for stainless
> spoke wire, it's not,
It's essentially true if you don't bulk yield, which is the whole point
of stress relief.
>>>> I have observed the residual stress first hand
>>>> by making a "slitting" experiment -- a technique that is used in
>>>> industry.
>>>
>>> and you have failed to observe fatigue initiate at a region of high
>>> residual stress! just because it rains on thursdays doesn't mean
>>> that beans don't make you fart.
>>
>> Your claim that residual stress is higher in interior sections
>> together with your belief than inclusions are a major factor
>> contradicts your own observation that fatigue typically initiates
>> surface cracks, since inclusions should be uniformly distributed --
>> ergo would predict cracking initiation in interior sections.
>
> you goofed off materials lectures kiddo. no, inclusions are typically
> not evenly distributed.
How's that? After rolling and drawing? We are talking about *modern*
steel aren't we? (Your views on oxygen injection and degassing as new
and exotic makes me wonder). What about isotropic effects of inclusions?
(while we're on the subject).
> but let's not get distracted by your education and stick to the facts as
> you seek to misconstrue them - that inclusions are a major factor in
> fatigue is a matter of the literature.
Sure, what about relative to surface defects in an application like
spokes with relatively clean steel?
> and you're conveniently
> ignoring the distribution of residual stresses.
No, I've described them, the stress profile is well known, both in
theory and actual measurement. It's been beaten to death on this forum
in the past. Simple bend, simple stress profile.
> yet again, if fatigue
> is observed to be initiating in a region of low or even compressive
> residual stress, it's not the cause. period.
Your failures, on your wheels, caused by your bad builds. Keep rejecting
it and keep breaking spokes.
>> The reference I cited (slitting example) showed a stress profile where
>> surface residual stress was only slightly lower than peak residual
>> stress.
>
> no it doesn't! it shows that equilibrium is disturbed and distortion is
> required to accommodate it!!!
Of course. The technique is to measure the distortion(strain)
after/while slitting (drilling a hole is another common approach), then
calculate what the stresses must have been to generate the measured
distortion(strain).
Your statement indicates a basic misunderstanding of how the technique
works. Perhaps you should reread.
>> Granted, that was for a specimen with small deformation and larger
>> cross section to length geometry, but the issue remains that residual
>> stresses are significant enough at the skin to promote fatigue.
>
> but the residual stress profiles don't support that!
Which ones? Those in the article (bar) or in a typical spoke? If the
former, reread, there are 2 graphs, you're confused. If the latter, this
has been beaten to death years ago on this NG, why do you keep bringing
it up? The residual stress profile supports it exactly.
>> They might not be peak, but they are there, as my experiment
>> demonstrated.
>
> you misunderstand what you're looking at.
I think it should be obvious by now that you're the one with the
misunderstanding.
>>>> Item 2 is also false. If a spoke is nominally tensioned to 33% of
>>>> yield, and the endurance limit is 40% of yield, even a small amount
>>>> of residual stress can dramatically shorten the fatigue life.
>>>
>>> in theory, yes. but FATIGUE IS NOT ***OBSERVED*** TO BE INITIATING
>>> AT A REGION OF HIGH RESIDUAL STRESS!!! how many times does this need
>>> to be repeated? just because this fact is inconvenient to the
>>> "theory" doesn't mean it can be ignored.
>>
>> I think you need to rephrase. Your "HIGH", needs to be replaced with
>> "HIGHEST". It seems that the skin residual stress is high enough, even
>> if it may not be the highest residual. "HIGH" in this context meaning
>> high enough, with or without additional stress concentrators
>> (defects), to dominate failure mode.
>
> er, so how do you account for fatigue initiation in a region of
> COMPRESSIVE residual stress? the fatigue fairy?
Bad build. Stubborn builder.
>> The residual surface stress needs only to be high enough that, when
>> combined with local concentrators and static load, exceeds the
>> endurance threshold by enough that the momentary overload causes local
>> yield. The outcome may or may not be enough to lower local skin stress
>> to below the endurance limit, practical experience indicates that it
>> likely does.
>
> see above. you need to do some real life fatigue observation.
My wheels work OK.
>>>> Since
>>>> Jobst has reported spoke lifetimes of over 10^8 cycles, his technique
>>>> must be reducing residual stresses to a very low level since he must
>>>> be below the endurance limit.
>>>
>>> i don't buy that "jobst has reported" bullshit. jobst first made
>>> assertions to me in private correspondence that he had been riding
>>> the same wheels for 300,000 miles. it has since emerged that not
>>> only has he replaced rims and hubs, but spokes as well. what?
>>> suppress data that doesn't suit the myth? say it can't be so!
>>
>> He has explained that he replaced only a few spokes that were chain
>> nicked.
>
> how convenient. given that he's shown to, er, "forget" vital data when
> telling stories, you want to assume his memory is suddenly
> "non-forgetful" when it doesn't suit? i don't think so.
Hopeless exaggeration. How do you expect anyone to take you seriously?
|
| |
Date: 14 Sep 2007 19:41:35
From: jim beam
Subject: Re: vacuum de-gas thread continued
|
jim beam wrote:
> peter cole wrote:
<snip for clarity >
>> The solution is to use quality spokes like Sapim, who,
>> according to their website, use vacuum degassed steel. You back up
>> this claim with a hand drawing of a spoke failing at an inclusion,
>> which you assert is representative.
>
> it is. /you/ go out and examine spoke failures and post photos that
> contradict it if you can. my camera gear doesn't macro as small as my
> loupe, hence the diagram.
>
correction: the diagram is not illustrating failure at an inclusion -
[peter cole misrepresentation - you'd need electron microscopy to
confirm that]. but the diagram /is/ that of observed spoke fatigue.
|
| | |
Date: 15 Sep 2007 12:09:36
From: Peter Cole
Subject: Re: vacuum de-gas thread continued
|
jim beam wrote:
> jim beam wrote:
>> peter cole wrote:
>
> <snip for clarity>
>
>>> The solution is to use quality spokes like Sapim, who,
>>> according to their website, use vacuum degassed steel. You back up
>>> this claim with a hand drawing of a spoke failing at an inclusion,
>>> which you assert is representative.
>>
>> it is. /you/ go out and examine spoke failures and post photos that
>> contradict it if you can. my camera gear doesn't macro as small as my
>> loupe, hence the diagram.
>>
>
> correction: the diagram is not illustrating failure at an inclusion -
> [peter cole misrepresentation - you'd need electron microscopy to
> confirm that]. but the diagram /is/ that of observed spoke fatigue.
OK. The drawing says "nucleation" (fancy word for "start of crack"). Now
you say inclusions aren't the (likely) source of nucleation? Pardon me
for making that assumption given all your emphasis on vacuum degassing.
What does this diagram represent? Your belief that fatigue cracks
initiate at the surface? That's hardly news to anyone.
Here's a (partial) list of the things you've got wrong:
-spokes do come from the factory with residual stress, including
significant skin stress.
-you must adjust the factory spoke angle or get flex failures/spoke
slackening (which you have reported)
-adjusting the spoke angle will cause large residual skin stresses
-adjusted spokes don't have a significant bending moment, either from
elbow support or lacing
-any defect - inclusion, tool mark, slip band, will cause elevated local
stress
-fatigue cracks almost always initiate at the surface
-stainless steel does have an endurance limit
Buy the book, follow the instructions, and your spoke problems will be
over. Mine are.
|
| | | |
Date: 15 Sep 2007 13:31:33
From: Ben C
Subject: Re: vacuum de-gas thread continued
|
On 2007-09-15, Peter Cole <peter_cole@comcast.net > wrote:
[...]
>[1]. -you must adjust the factory spoke angle or get flex failures/spoke
> slackening (which you have reported)
>[2] -adjusting the spoke angle will cause large residual skin stresses
>[3] -adjusted spokes don't have a significant bending moment, either from
> elbow support or lacing
Something I still want to clear up.
In your view, after [1], does the elbow spring back at all?
If yes, then the stresses in [2] are the applied stresses of holding a
piece of bent wire in the bent position without letting it spring back
(tensile on the exterior, outside of bend, outbound spoke).
If no, then they are residual stresses (and in this case would be
compressive on the exterior, outside of bend, outbound spoke).
If yes, I don't object to the term "residual stress" in the sense of the
residual stress of a structure. I know jim beam does. But let's lay that
one to rest for now.
If yes, then how can [3] be true?
|
| | | | |
Date: 15 Sep 2007 22:43:16
From:
Subject: Re: vacuum de-gas thread continued
|
Ben C? writes:
>> [1] -you must adjust the factory spoke angle or get flex
>> failures/spoke slackening (which you have reported)
>> [2] -adjusting the spoke angle will cause large residual skin
>> stresses
>> [3] -adjusted spokes don't have a significant bending moment,
>> either from elbow support or lacing
> Something I still want to clear up.
> In your view, after [1], does the elbow spring back at all?
> If yes, then the stresses in [2] are the applied stresses of holding
> a piece of bent wire in the bent position without letting it spring
> back (tensile on the exterior, outside of bend, outbound spoke).
> If no, then they are residual stresses (and in this case would be
> compressive on the exterior, outside of bend, outbound spoke).
> If yes, I don't object to the term "residual stress" in the sense of
> the residual stress of a structure. I know jim beam does. But let's
> lay that one to rest for now.
> If yes, then how can [3] be true?
Two kinds of residual stress (in contrast to load induced stress)
affect spoke life and together with cyclic loading cause failures.
One kind is manufacture induced stress that is both compression and
tension, the other is wheel build stress caused by lacing spokes.
These occur at both ends, the threads having residual stress from cold
forming and subsequently being bent as the spoke bends on exiting the
spoke nipple from non radial spoking and flange width.
They also occur at the elbow from cold forming and are in the free
state, tension on the inside and compression on the outside of the
elbow. The bend outbound spokes receive when laced into a wheel put
the outside of the elbow into tension. Additional stress can occur if
the elbow is unsupported because the flange is too thin or the spoke
is not lying reasonably flush against the outside of the flange.
For these reasons, a wheel build should include improving the spoke
line from hub to spoke nipple and stress relieving by momentary
overload of individual spokes.
As to spring-back, all steel does that when cold formed and not always
so it is measurable.
Jobst Brandt
|
| | | | | |
Date: 16 Sep 2007 08:24:18
From: jim beam
Subject: Re: vacuum de-gas thread continued
|
jobst.brandt@stanfordalumni.org wrote:
> Ben C? writes:
>
>>> [1] -you must adjust the factory spoke angle or get flex
>>> failures/spoke slackening (which you have reported)
>>> [2] -adjusting the spoke angle will cause large residual skin
>>> stresses
>>> [3] -adjusted spokes don't have a significant bending moment,
>>> either from elbow support or lacing
>
>> Something I still want to clear up.
>
>> In your view, after [1], does the elbow spring back at all?
>
>> If yes, then the stresses in [2] are the applied stresses of holding
>> a piece of bent wire in the bent position without letting it spring
>> back (tensile on the exterior, outside of bend, outbound spoke).
>
>> If no, then they are residual stresses (and in this case would be
>> compressive on the exterior, outside of bend, outbound spoke).
>
>> If yes, I don't object to the term "residual stress" in the sense of
>> the residual stress of a structure. I know jim beam does. But let's
>> lay that one to rest for now.
>
>> If yes, then how can [3] be true?
>
> Two kinds of residual stress (in contrast to load induced stress)
> affect spoke life and together with cyclic loading cause failures.
> One kind is manufacture induced stress that is both compression and
> tension, the other is wheel build stress caused by lacing spokes.
no, there's only one kind of residual stress.
>
> These occur at both ends, the threads having residual stress from cold
> forming and subsequently being bent as the spoke bends on exiting the
> spoke nipple from non radial spoking and flange width.
there's only one kind of residual stress. timetable [beyond a few
minutes] and location mean nothing.
>
> They also occur at the elbow from cold forming and are in the free
> state, tension on the inside and compression on the outside of the
> elbow. The bend outbound spokes receive when laced into a wheel put
> the outside of the elbow into tension. Additional stress can occur if
> the elbow is unsupported because the flange is too thin or the spoke
> is not lying reasonably flush against the outside of the flange.
>
> For these reasons, a wheel build should include improving the spoke
> line from hub to spoke nipple and stress relieving by momentary
> overload of individual spokes.
>
> As to spring-back, all steel does that when cold formed and not always
> so it is measurable.
ah, the jobstian ethereal allusion to things that don't exist, but which
sound like an excuse to peons that wouldn't understand!!!
bottom line reality - observation contradicts your residual stress
"theory". you need to get over that and reformulate accordingly.
bluster about "different kinds of residual stress" and unobservable
elasticity are so much bullshit from a guy that doesn't know a damned
thing about deformation, fracture mechanics, fatigue, or even dislocations.
go to the library jobst, learn about fatigue. then put in some
microscope time with some fatigued spokes. when you're done, get back
to us and we'll see whether you've made any progress.
|
| | | | |
Date: 15 Sep 2007 16:24:10
From: Peter Cole
Subject: Re: vacuum de-gas thread continued
|
Ben C wrote:
> On 2007-09-15, Peter Cole <peter_cole@comcast.net> wrote:
> [...]
>> [1]. -you must adjust the factory spoke angle or get flex failures/spoke
>> slackening (which you have reported)
>> [2] -adjusting the spoke angle will cause large residual skin stresses
>> [3] -adjusted spokes don't have a significant bending moment, either from
>> elbow support or lacing
>
> Something I still want to clear up.
>
> In your view, after [1], does the elbow spring back at all?
>
> If yes, then the stresses in [2] are the applied stresses of holding a
> piece of bent wire in the bent position without letting it spring back
> (tensile on the exterior, outside of bend, outbound spoke).
>
> If no, then they are residual stresses (and in this case would be
> compressive on the exterior, outside of bend, outbound spoke).
I think you've got it backwards. You should really get the book. I feel
like I'm paraphrasing it in installments.
It's the outbound spokes that usually need correction, the angle needs
to be reduced to get rid of the bow.
This is done after tensioning.
They will spring back. If you don't over-correct, you'll be left with
residual tension on the inside. If you over-correct, you'll be left with
bending and residual tension on the inside. If you under-correct or not
correct at all, you may be left with bending causing net tension on the
outside.
> If yes, I don't object to the term "residual stress" in the sense of the
> residual stress of a structure.
Good to know.
> If yes, then how can [3] be true?
If you have a perfect spoke line from hub hole to nipple after spring back.
|
| | | | | |
Date: 15 Sep 2007 16:57:30
From: Ben C
Subject: Re: vacuum de-gas thread continued
|
On 2007-09-15, Peter Cole <peter_cole@comcast.net > wrote:
> Ben C wrote:
>> On 2007-09-15, Peter Cole <peter_cole@comcast.net> wrote:
>> [...]
>>> [1]. -you must adjust the factory spoke angle or get flex failures/spoke
>>> slackening (which you have reported)
>>> [2] -adjusting the spoke angle will cause large residual skin stresses
>>> [3] -adjusted spokes don't have a significant bending moment, either from
>>> elbow support or lacing
>>
>> Something I still want to clear up.
>>
>> In your view, after [1], does the elbow spring back at all?
>>
>> If yes, then the stresses in [2] are the applied stresses of holding a
>> piece of bent wire in the bent position without letting it spring back
>> (tensile on the exterior, outside of bend, outbound spoke).
>>
>> If no, then they are residual stresses (and in this case would be
>> compressive on the exterior, outside of bend, outbound spoke).
>
> I think you've got it backwards. You should really get the book. I feel
> like I'm paraphrasing it in installments.
>
> It's the outbound spokes that usually need correction, the angle needs
> to be reduced to get rid of the bow.
>
> This is done after tensioning.
>
> They will spring back. If you don't over-correct, you'll be left with
> residual tension on the inside. If you over-correct, you'll be left with
> bending and residual tension on the inside. If you under-correct or not
> correct at all, you may be left with bending causing net tension on the
> outside.
>
>
>> If yes, I don't object to the term "residual stress" in the sense of the
>> residual stress of a structure.
>
> Good to know.
>
>> If yes, then how can [3] be true?
>
> If you have a perfect spoke line from hub hole to nipple after spring back.
If there was spring-back, then "if yes" is false. But I think I know
what you mean.
I think I agree: it probably can spring back, although I know Jobst says
it can't. The problem, he says, is that the flange is in the way making
it impossible to overbend. That makes sense, but I kind of think that if
you put the bend in while the spoke is still fairly loose it has quite a
bit of freedom and there could be room for it to spring back somehow.
|
| | | | | | |
Date: 16 Sep 2007 09:27:48
From: jim beam
Subject: Re: vacuum de-gas thread continued
|
Ben C wrote:
> On 2007-09-15, Peter Cole <peter_cole@comcast.net> wrote:
>> Ben C wrote:
>>> On 2007-09-15, Peter Cole <peter_cole@comcast.net> wrote:
>>> [...]
>>>> [1]. -you must adjust the factory spoke angle or get flex failures/spoke
>>>> slackening (which you have reported)
>>>> [2] -adjusting the spoke angle will cause large residual skin stresses
>>>> [3] -adjusted spokes don't have a significant bending moment, either from
>>>> elbow support or lacing
>>> Something I still want to clear up.
>>>
>>> In your view, after [1], does the elbow spring back at all?
>>>
>>> If yes, then the stresses in [2] are the applied stresses of holding a
>>> piece of bent wire in the bent position without letting it spring back
>>> (tensile on the exterior, outside of bend, outbound spoke).
>>>
>>> If no, then they are residual stresses (and in this case would be
>>> compressive on the exterior, outside of bend, outbound spoke).
>> I think you've got it backwards. You should really get the book. I feel
>> like I'm paraphrasing it in installments.
>>
>> It's the outbound spokes that usually need correction, the angle needs
>> to be reduced to get rid of the bow.
>>
>> This is done after tensioning.
>>
>> They will spring back. If you don't over-correct, you'll be left with
>> residual tension on the inside. If you over-correct, you'll be left with
>> bending and residual tension on the inside. If you under-correct or not
>> correct at all, you may be left with bending causing net tension on the
>> outside.
>>
>>
>>> If yes, I don't object to the term "residual stress" in the sense of the
>>> residual stress of a structure.
>> Good to know.
>>
>>> If yes, then how can [3] be true?
>> If you have a perfect spoke line from hub hole to nipple after spring back.
>
> If there was spring-back, then "if yes" is false. But I think I know
> what you mean.
>
> I think I agree: it probably can spring back, although I know Jobst says
> it can't. The problem, he says, is that the flange is in the way making
> it impossible to overbend. That makes sense, but I kind of think that if
> you put the bend in while the spoke is still fairly loose it has quite a
> bit of freedom and there could be room for it to spring back somehow.
if you're bending against a flange, it can never fully conform - you
can't eliminate the elasticity part of the stress/strain graph.
http://www.flickr.com/photos/38636024@N00/327752060/
see items 3 & 4.
|
| | | | |
Date: 15 Sep 2007 12:35:21
From: jim beam
Subject: Re: vacuum de-gas thread continued
|
Ben C wrote:
> On 2007-09-15, Peter Cole <peter_cole@comcast.net> wrote:
> [...]
>> [1]. -you must adjust the factory spoke angle or get flex failures/spoke
>> slackening (which you have reported)
>> [2] -adjusting the spoke angle will cause large residual skin stresses
>> [3] -adjusted spokes don't have a significant bending moment, either from
>> elbow support or lacing
>
> Something I still want to clear up.
>
> In your view, after [1], does the elbow spring back at all?
>
> If yes, then the stresses in [2] are the applied stresses of holding a
> piece of bent wire in the bent position without letting it spring back
> (tensile on the exterior, outside of bend, outbound spoke).
>
> If no, then they are residual stresses (and in this case would be
> compressive on the exterior, outside of bend, outbound spoke).
you have grasped the concept. 10 points.
>
> If yes, I don't object to the term "residual stress" in the sense of the
> residual stress of a structure. I know jim beam does. But let's lay that
> one to rest for now.
>
> If yes, then how can [3] be true?
|
| | | |
Date: 15 Sep 2007 10:02:08
From: jim beam
Subject: Re: vacuum de-gas thread continued
|
Peter Cole wrote:
> jim beam wrote:
>> jim beam wrote:
>>> peter cole wrote:
>>
>> <snip for clarity>
>>
>>>> The solution is to use quality spokes like Sapim, who,
>>>> according to their website, use vacuum degassed steel. You back up
>>>> this claim with a hand drawing of a spoke failing at an inclusion,
>>>> which you assert is representative.
>>>
>>> it is. /you/ go out and examine spoke failures and post photos that
>>> contradict it if you can. my camera gear doesn't macro as small as
>>> my loupe, hence the diagram.
>>>
>>
>> correction: the diagram is not illustrating failure at an inclusion -
>> [peter cole misrepresentation - you'd need electron microscopy to
>> confirm that]. but the diagram /is/ that of observed spoke fatigue.
>
> OK. The drawing says "nucleation" (fancy word for "start of crack").
er, "nucleation" is the term people in /my/ field use...
> Now
> you say inclusions aren't the (likely) source of nucleation?
no, i say that it's not observable optically.
> Pardon me
> for making that assumption given all your emphasis on vacuum degassing.
you're a bullshitter.
> What does this diagram represent? Your belief that fatigue cracks
> initiate at the surface? That's hardly news to anyone.
er, well it's apparently news to those that think spoke initiates in
regions of high residual stress - in that case, fatigue would be
initiating near the neutral plane. and it doesn't. bullshitter.
>
> Here's a (partial) list of the things you've got wrong:
>
> -spokes do come from the factory with residual stress, including
> significant skin stress.
"significant" my ass. and i've said that right from day one. /prove/
it's a factor in this fatigue. observation says not. [i'm sorry, is
that inconvenient?]
> -you must adjust the factory spoke angle or get flex failures/spoke
> slackening (which you have reported)
manufacturers don't think so. and calculating spoke exit angle doesn't
support that either.
> -adjusting the spoke angle will cause large residual skin stresses
not residual skin stress. don't put those words in my mouth. it can
increase internally though - as i've said before. but we're not worried
about that since fatigue is not observed to be a factor starting there.
> -adjusted spokes don't have a significant bending moment, either from
> elbow support or lacing
not my words. don't bullshit.
> -any defect - inclusion, tool mark, slip band, will cause elevated local
> stress
indeed. why do you have a problem with that? it's observed fact.
> -fatigue cracks almost always initiate at the surface
indeed. why do you have a problem with that? it's observed fact.
> -stainless steel does have an endurance limit
not at normal temperatures it doesn't. see other post.
>
>
> Buy the book, follow the instructions, and your spoke problems will be
> over. Mine are.
the book will indeed allow you to lace a wheel and bed the spokes in.
but the theory is bullshit. and is all the crap about anodizing,
"swaging", increasing strength as spoke tension increases, etc., is
ridiculous.
|
| | | | |
Date: 15 Sep 2007 16:39:33
From: Peter Cole
Subject: Re: vacuum de-gas thread continued
|
jim beam wrote:
> Peter Cole wrote:
>
>>
>> OK. The drawing says "nucleation" (fancy word for "start of crack").
>
> er, "nucleation" is the term people in /my/ field use...
Put it in your next paper.
>> Now you say inclusions aren't the (likely) source of nucleation?
>
> no, i say that it's not observable optically.
>
>> Pardon me for making that assumption given all your emphasis on vacuum
>> degassing.
>
> you're a bullshitter.
Whatever.
>> What does this diagram represent? Your belief that fatigue cracks
>> initiate at the surface? That's hardly news to anyone.
>
> er, well it's apparently news to those that think spoke initiates in
> regions of high residual stress -
No, it isn't.
> in that case, fatigue would be
> initiating near the neutral plane. and it doesn't.
You still haven't (in all these tedious posts) explained how you come to
the misconception that high residual stresses don't occur at the surface.
> bullshitter.
Whatever.
>> Here's a (partial) list of the things you've got wrong:
>>
>> -spokes do come from the factory with residual stress, including
>> significant skin stress.
>
> "significant" my ass. and i've said that right from day one. /prove/
> it's a factor in this fatigue. observation says not. [i'm sorry, is
> that inconvenient?]
I observed the stress. You're welcome to repeat the experiment.
>> -you must adjust the factory spoke angle or get flex failures/spoke
>> slackening (which you have reported)
>
> manufacturers don't think so. and calculating spoke exit angle doesn't
> support that either.
Yes, but your spoke slacking/breaking does.
Simple geometry shows inbound and outbound spokes can't have the same angle.
>> -adjusting the spoke angle will cause large residual skin stresses
>
> not residual skin stress. don't put those words in my mouth.
I'm not. They're coming from my (virtual) mouth and the mouths of
everyone else but you.
> it can
> increase internally though - as i've said before. but we're not worried
> about that since fatigue is not observed to be a factor starting there.
You claim. No proof.
>> -adjusted spokes don't have a significant bending moment, either from
>> elbow support or lacing
>
> not my words.
Sure, in the "loose spokes breaking" thread.
> don't bullshit.
Whatever.
>> -any defect - inclusion, tool mark, slip band, will cause elevated
>> local stress
>
> indeed. why do you have a problem with that? it's observed fact.
I don't. You're the one obsessed with inclusions.
>> -fatigue cracks almost always initiate at the surface
>
> indeed. why do you have a problem with that? it's observed fact.
So drawing a picture adds nothing.
>> -stainless steel does have an endurance limit
>
> not at normal temperatures it doesn't. see other post.
Effectively it does, at least according to Sandvik. Go set them
straight, they make spokes.
>> Buy the book, follow the instructions, and your spoke problems will be
>> over. Mine are.
>
> the book will indeed allow you to lace a wheel and bed the spokes in.
> but the theory is bullshit.
Whatever.
> and is all the crap about anodizing,
> "swaging", increasing strength as spoke tension increases, etc., is
> ridiculous.
Put it in a sig.
|
| | | | | |
Date: 16 Sep 2007 07:41:41
From: jim beam
Subject: Re: vacuum de-gas thread continued
|
Peter Cole wrote:
<snip usual crap >
ok, let's get to the bottom of this - materials are just a side show.
what do you think i could possibly gain by bullshitting you?
more importantly, what could you possibly lose by learning what you
don't know?
|
| | | | | | |
Date: 16 Sep 2007 11:27:26
From: Peter Cole
Subject: Re: vacuum de-gas thread continued
|
jim beam wrote:
> Peter Cole wrote:
> <snip usual crap>
>
> ok, let's get to the bottom of this - materials are just a side show.
If you say so.
>
> what do you think i could possibly gain by bullshitting you?
Who cares?
>
> more importantly, what could you possibly lose by learning what you
> don't know?
As opposed to learning what I already know? You make no sense.
|
| | | | | | | |
Date: 16 Sep 2007 08:39:42
From: jim beam
Subject: Re: vacuum de-gas thread continued
|
Peter Cole wrote:
> jim beam wrote:
>> Peter Cole wrote:
>> <snip usual crap>
>>
>> ok, let's get to the bottom of this - materials are just a side show.
>
> If you say so.
>
>>
>> what do you think i could possibly gain by bullshitting you?
>
> Who cares?
>
>
>>
>> more importantly, what could you possibly lose by learning what you
>> don't know?
>
> As opposed to learning what I already know? You make no sense.
but what you say you know is deficient in certain key areas... you
insist on proving that repeatedly as if you're resisting some demon.
why? what is the loss? what is the gain?
|
| | | | | | | | |
Date: 16 Sep 2007 15:48:48
From: Peter Cole
Subject: Re: vacuum de-gas thread continued
|
jim beam wrote:
> Peter Cole wrote:
>> jim beam wrote:
>>> Peter Cole wrote:
>>> <snip usual crap>
>>>
>>> ok, let's get to the bottom of this - materials are just a side show.
>>
>> If you say so.
>>
>>>
>>> what do you think i could possibly gain by bullshitting you?
>>
>> Who cares?
>>
>>
>>>
>>> more importantly, what could you possibly lose by learning what you
>>> don't know?
>>
>> As opposed to learning what I already know? You make no sense.
>
> but what you say you know is deficient in certain key areas...
So you say.
> you insist on proving that repeatedly as if you're resisting some demon.
Prove what? I'm just citing reputable sources.
> why? what is the loss? what is the gain?
I have no idea what you are talking about.
|
| | | | | | | | | |
Date: 16 Sep 2007 13:31:11
From: jim beam
Subject: Re: vacuum de-gas thread continued
|
Peter Cole wrote:
> jim beam wrote:
>> Peter Cole wrote:
>>> jim beam wrote:
>>>> Peter Cole wrote:
>>>> <snip usual crap>
>>>>
>>>> ok, let's get to the bottom of this - materials are just a side show.
>>>
>>> If you say so.
>>>
>>>>
>>>> what do you think i could possibly gain by bullshitting you?
>>>
>>> Who cares?
>>>
>>>
>>>>
>>>> more importantly, what could you possibly lose by learning what you
>>>> don't know?
>>>
>>> As opposed to learning what I already know? You make no sense.
>>
>> but what you say you know is deficient in certain key areas...
>
> So you say.
>
>> you insist on proving that repeatedly as if you're resisting some demon.
>
> Prove what? I'm just citing reputable sources.
citing a manufacturer web site as if to say stainless steel has fatigue
endurance, when it doesn't actually say that, is not "citation of a
reputable source"!!!
>
>> why? what is the loss? what is the gain?
>
> I have no idea what you are talking about.
dude, if i post a [necessarily truncated] description of something,
which covers say 95% of a topic, you're pretty damned expert at not only
figuring out the 5% not covered, but twisting it into some vast
construction of perverse gainsay. if you genuinely had "no idea", you
wouldn't be able to do that.
|
| | | | | | | | | | |
Date: 16 Sep 2007 17:48:25
From: Peter Cole
Subject: Re: vacuum de-gas thread continued
|
jim beam wrote:
> Peter Cole wrote:
>> jim beam wrote:
>>> Peter Cole wrote:
>>>> jim beam wrote:
>>>>> Peter Cole wrote:
>>>>> <snip usual crap>
>>>>>
>>>>> ok, let's get to the bottom of this - materials are just a side show.
>>>>
>>>> If you say so.
>>>>
>>>>>
>>>>> what do you think i could possibly gain by bullshitting you?
>>>>
>>>> Who cares?
>>>>
>>>>
>>>>>
>>>>> more importantly, what could you possibly lose by learning what you
>>>>> don't know?
>>>>
>>>> As opposed to learning what I already know? You make no sense.
>>>
>>> but what you say you know is deficient in certain key areas...
>>
>> So you say.
>>
>>> you insist on proving that repeatedly as if you're resisting some demon.
>>
>> Prove what? I'm just citing reputable sources.
>
> citing a manufacturer web site as if to say stainless steel has fatigue
> endurance, when it doesn't actually say that, is not "citation of a
> reputable source"!!!
No, the term is "endurance limit", and they did say that.
>>> why? what is the loss? what is the gain?
>>
>> I have no idea what you are talking about.
>
> dude, if i post a [necessarily truncated] description of something,
> which covers say 95% of a topic, you're pretty damned expert at not only
> figuring out the 5% not covered, but twisting it into some vast
> construction of perverse gainsay. if you genuinely had "no idea", you
> wouldn't be able to do that.
You lost me at "vast construction of perverse gainsay", if not before. I
honestly have absolutely no idea of what you're talking about.
|
| | | | | | | | | | | |
Date: 16 Sep 2007 15:08:40
From: jim beam
Subject: Re: vacuum de-gas thread continued
|
Peter Cole wrote:
> jim beam wrote:
>> Peter Cole wrote:
>>> jim beam wrote:
>>>> Peter Cole wrote:
>>>>> jim beam wrote:
>>>>>> Peter Cole wrote:
>>>>>> <snip usual crap>
>>>>>>
>>>>>> ok, let's get to the bottom of this - materials are just a side show.
>>>>>
>>>>> If you say so.
>>>>>
>>>>>>
>>>>>> what do you think i could possibly gain by bullshitting you?
>>>>>
>>>>> Who cares?
>>>>>
>>>>>
>>>>>>
>>>>>> more importantly, what could you possibly lose by learning what
>>>>>> you don't know?
>>>>>
>>>>> As opposed to learning what I already know? You make no sense.
>>>>
>>>> but what you say you know is deficient in certain key areas...
>>>
>>> So you say.
>>>
>>>> you insist on proving that repeatedly as if you're resisting some
>>>> demon.
>>>
>>> Prove what? I'm just citing reputable sources.
>>
>> citing a manufacturer web site as if to say stainless steel has
>> fatigue endurance, when it doesn't actually say that, is not "citation
>> of a reputable source"!!!
>
> No, the term is "endurance limit", and they did say that.
there's no "knee" in the graph...
>
>>>> why? what is the loss? what is the gain?
>>>
>>> I have no idea what you are talking about.
>>
>> dude, if i post a [necessarily truncated] description of something,
>> which covers say 95% of a topic, you're pretty damned expert at not
>> only figuring out the 5% not covered, but twisting it into some vast
>> construction of perverse gainsay. if you genuinely had "no idea", you
>> wouldn't be able to do that.
>
> You lost me at "vast construction of perverse gainsay", if not before. I
> honestly have absolutely no idea of what you're talking about.
>
how convenient!
|
| | | | | | | | | | | | |
Date: 16 Sep 2007 20:08:28
From: Peter Cole
Subject: Re: vacuum de-gas thread continued
|
jim beam wrote:
> Peter Cole wrote:
>> jim beam wrote:
>>> Peter Cole wrote:
>>>> jim beam wrote:
>>>>> Peter Cole wrote:
>>>>>> jim beam wrote:
>>>>>>> Peter Cole wrote:
>>>>>>> <snip usual crap>
>>>>>>>
>>>>>>> ok, let's get to the bottom of this - materials are just a side
>>>>>>> show.
>>>>>>
>>>>>> If you say so.
>>>>>>
>>>>>>>
>>>>>>> what do you think i could possibly gain by bullshitting you?
>>>>>>
>>>>>> Who cares?
>>>>>>
>>>>>>
>>>>>>>
>>>>>>> more importantly, what could you possibly lose by learning what
>>>>>>> you don't know?
>>>>>>
>>>>>> As opposed to learning what I already know? You make no sense.
>>>>>
>>>>> but what you say you know is deficient in certain key areas...
>>>>
>>>> So you say.
>>>>
>>>>> you insist on proving that repeatedly as if you're resisting some
>>>>> demon.
>>>>
>>>> Prove what? I'm just citing reputable sources.
>>>
>>> citing a manufacturer web site as if to say stainless steel has
>>> fatigue endurance, when it doesn't actually say that, is not
>>> "citation of a reputable source"!!!
>>
>> No, the term is "endurance limit", and they did say that.
>
> there's no "knee" in the graph...
No, of course not, there's no knee on the graph on the Sandvik site. Oh,
but they're liars anyway. You're a riot.
>
>
>>
>>>>> why? what is the loss? what is the gain?
>>>>
>>>> I have no idea what you are talking about.
>>>
>>> dude, if i post a [necessarily truncated] description of something,
>>> which covers say 95% of a topic, you're pretty damned expert at not
>>> only figuring out the 5% not covered, but twisting it into some vast
>>> construction of perverse gainsay. if you genuinely had "no idea",
>>> you wouldn't be able to do that.
>>
>> You lost me at "vast construction of perverse gainsay", if not before.
>> I honestly have absolutely no idea of what you're talking about.
>>
>
> how convenient!
No, just incoherent.
|
| | | | | | | | | | | | | |
Date: 18 Sep 2007 21:34:31
From: jim beam
Subject: Re: vacuum de-gas thread continued
|
Peter Cole wrote:
> jim beam wrote:
>> Peter Cole wrote:
>>> jim beam wrote:
>>>> Peter Cole wrote:
>>>>> jim beam wrote:
>>>>>> Peter Cole wrote:
>>>>>>> jim beam wrote:
>>>>>>>> Peter Cole wrote:
>>>>>>>> <snip usual crap>
>>>>>>>>
>>>>>>>> ok, let's get to the bottom of this - materials are just a side
>>>>>>>> show.
>>>>>>>
>>>>>>> If you say so.
>>>>>>>
>>>>>>>>
>>>>>>>> what do you think i could possibly gain by bullshitting you?
>>>>>>>
>>>>>>> Who cares?
>>>>>>>
>>>>>>>
>>>>>>>>
>>>>>>>> more importantly, what could you possibly lose by learning what
>>>>>>>> you don't know?
>>>>>>>
>>>>>>> As opposed to learning what I already know? You make no sense.
>>>>>>
>>>>>> but what you say you know is deficient in certain key areas...
>>>>>
>>>>> So you say.
>>>>>
>>>>>> you insist on proving that repeatedly as if you're resisting some
>>>>>> demon.
>>>>>
>>>>> Prove what? I'm just citing reputable sources.
>>>>
>>>> citing a manufacturer web site as if to say stainless steel has
>>>> fatigue endurance, when it doesn't actually say that, is not
>>>> "citation of a reputable source"!!!
>>>
>>> No, the term is "endurance limit", and they did say that.
>>
>> there's no "knee" in the graph...
>
> No, of course not, there's no knee on the graph on the Sandvik site. Oh,
> but they're liars anyway. You're a riot.
the knee is what evidences a true endurance limit. i'm sorry that
doesn't suit your argument, but it's the truth nevertheless.
>
>
>>
>>
>>>
>>>>>> why? what is the loss? what is the gain?
>>>>>
>>>>> I have no idea what you are talking about.
>>>>
>>>> dude, if i post a [necessarily truncated] description of something,
>>>> which covers say 95% of a topic, you're pretty damned expert at not
>>>> only figuring out the 5% not covered, but twisting it into some vast
>>>> construction of perverse gainsay. if you genuinely had "no idea",
>>>> you wouldn't be able to do that.
>>>
>>> You lost me at "vast construction of perverse gainsay", if not
>>> before. I honestly have absolutely no idea of what you're talking about.
>>>
>>
>> how convenient!
>
> No, just incoherent.
|
| | | | | | | | | | | | | | |
Date: 19 Sep 2007 08:52:34
From: Peter Cole
Subject: Re: vacuum de-gas thread continued
|
jim beam wrote:
> Peter Cole wrote:
>> jim beam wrote:
>>> Peter Cole wrote:
>>>> jim beam wrote:
>>>>> citing a manufacturer web site as if to say stainless steel has
>>>>> fatigue endurance, when it doesn't actually say that, is not
>>>>> "citation of a reputable source"!!!
>>>>
>>>> No, the term is "endurance limit", and they did say that.
>>>
>>> there's no "knee" in the graph...
>>
>> No, of course not, there's no knee on the graph on the Sandvik site.
>> Oh, but they're liars anyway. You're a riot.
>
> the knee is what evidences a true endurance limit. i'm sorry that
> doesn't suit your argument, but it's the truth nevertheless.
Of course a knee shows endurance limit, there is a knee in the graph on
the Sandvik (makers of spoke wire) site, plus a description of the knee
in the accompanying text. Stop twisting, calling everyone "liars" and
"stupid" and admit you are wrong.
|
| | | | | | | | | | | | | | | |
Date: 19 Sep 2007 20:26:03
From: jim beam
Subject: Re: vacuum de-gas thread continued
|
Peter Cole wrote:
> jim beam wrote:
>> Peter Cole wrote:
>>> jim beam wrote:
>>>> Peter Cole wrote:
>>>>> jim beam wrote:
>
>>>>>> citing a manufacturer web site as if to say stainless steel has
>>>>>> fatigue endurance, when it doesn't actually say that, is not
>>>>>> "citation of a reputable source"!!!
>>>>>
>>>>> No, the term is "endurance limit", and they did say that.
>>>>
>>>> there's no "knee" in the graph...
>>>
>>> No, of course not, there's no knee on the graph on the Sandvik site.
>>> Oh, but they're liars anyway. You're a riot.
>>
>> the knee is what evidences a true endurance limit. i'm sorry that
>> doesn't suit your argument, but it's the truth nevertheless.
>
> Of course a knee shows endurance limit, there is a knee in the graph on
> the Sandvik (makers of spoke wire) site, plus a description of the knee
> in the accompanying text. Stop twisting, calling everyone "liars" and
> "stupid" and admit you are wrong.
for stainless, the graph is simply bent. unless you're looking at
something i haven't seen and you're [conveniently] not citing. what,
peter cole bullshit? never!
|
| | | | | | | | | | | | | | | | |
Date: 20 Sep 2007 09:27:20
From: Peter Cole
Subject: Re: vacuum de-gas thread continued
|
jim beam wrote:
> Peter Cole wrote:
>> jim beam wrote:
>>> Peter Cole wrote:
>>>> jim beam wrote:
>>>>> Peter Cole wrote:
>>>>>> jim beam wrote:
>>
>>>>>>> citing a manufacturer web site as if to say stainless steel has
>>>>>>> fatigue endurance, when it doesn't actually say that, is not
>>>>>>> "citation of a reputable source"!!!
>>>>>>
>>>>>> No, the term is "endurance limit", and they did say that.
>>>>>
>>>>> there's no "knee" in the graph...
>>>>
>>>> No, of course not, there's no knee on the graph on the Sandvik site.
>>>> Oh, but they're liars anyway. You're a riot.
>>>
>>> the knee is what evidences a true endurance limit. i'm sorry that
>>> doesn't suit your argument, but it's the truth nevertheless.
>>
>> Of course a knee shows endurance limit, there is a knee in the graph
>> on the Sandvik (makers of spoke wire) site, plus a description of the
>> knee in the accompanying text. Stop twisting, calling everyone "liars"
>> and "stupid" and admit you are wrong.
>
> for stainless, the graph is simply bent. unless you're looking at
> something i haven't seen and you're [conveniently] not citing. what,
> peter cole bullshit? never!
As I said (immediately above), the graph and description of the graph is
on the Sandvik site. Your rebuttal is that they are liars. This is your
standard reply when sources disagree with your beliefs.
|
| | | | | | | | | | | | | | | | | |
Date: 20 Sep 2007 20:34:07
From: jim beam
Subject: Re: vacuum de-gas thread continued
|
Peter Cole wrote:
> jim beam wrote:
>> Peter Cole wrote:
>>> jim beam wrote:
>>>> Peter Cole wrote:
>>>>> jim beam wrote:
>>>>>> Peter Cole wrote:
>>>>>>> jim beam wrote:
>>>
>>>>>>>> citing a manufacturer web site as if to say stainless steel has
>>>>>>>> fatigue endurance, when it doesn't actually say that, is not
>>>>>>>> "citation of a reputable source"!!!
>>>>>>>
>>>>>>> No, the term is "endurance limit", and they did say that.
>>>>>>
>>>>>> there's no "knee" in the graph...
>>>>>
>>>>> No, of course not, there's no knee on the graph on the Sandvik
>>>>> site. Oh, but they're liars anyway. You're a riot.
>>>>
>>>> the knee is what evidences a true endurance limit. i'm sorry that
>>>> doesn't suit your argument, but it's the truth nevertheless.
>>>
>>> Of course a knee shows endurance limit, there is a knee in the graph
>>> on the Sandvik (makers of spoke wire) site, plus a description of the
>>> knee in the accompanying text. Stop twisting, calling everyone
>>> "liars" and "stupid" and admit you are wrong.
>>
>> for stainless, the graph is simply bent. unless you're looking at
>> something i haven't seen and you're [conveniently] not citing. what,
>> peter cole bullshit? never!
>
> As I said (immediately above), the graph and description of the graph is
> on the Sandvik site.
it's bent - that's not a "knee".
> Your rebuttal is that they are liars.
no, my rebuttal was that they're simplifying to terminology "engineers"
understand. [and evidently failing in this case.]
> This is your
> standard reply when sources disagree with your beliefs.
why do you always twist and misinterpret? i've explained the graphical
difference between a true endurance limit and the commonly cited
"fatigue limit". i've even explained the mechanism as to why these two
different phenomena are observed. but here you are reverting to
deliberate misconstruction. what is your problem? what do you have to
lose by learning?
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