Spoke tension meter

[41]

jim beam wrote:
> 41 wrote:

> >>google "strain ageing": 207,000 hits.
> >>
> >>http://www.steeluniversity.org/content/html/eng/default.asp?catid=139&pageid=2081271364
> >>
> >>idiot.
> >
> >
> > BZZZT.
> > I figured the long delay for you to produce anything even resembling an
> > answer w as because you had to run over to your mother's basement for
> > your undergraduate notes, or to remember the term needed for a Google
> > search. As typical for you, you throw around fancy terms and web pages,
> > but without taking the time to read them or to understand the ideas.
>
> point is, why don't /you/ do a google search? presumably because you're
> not interested in the tech, just being a troll.
>
> >
> > To take only the most obvious point. Do you really think any reasonably
> > high qual ity stainless steel spoke has been manufactured so poorly so
> > as to be subject to any important strain ageing? Tip: in your own
> > reference, which you obviously didn't read, check out ways to eliminate
> > strain ageing- which is essentially what the whole section was about.
> > Spokes are high quality, ductile, and do not go stale.
>
> hmm. what is "high quality stainless steel" exactly? as for equating
> ageing with the word "stale", that's trollspeak. i'll talk tech with
> you, but it doesn't seem you want that.


http://tinyurl.com/c75ws
http://tinyurl.com/dp8y5
http://tinyurl.com/7ofdp


> > ============================ ============================================
> > Fresh spokes and an ever growing pile of ********- from JIM BEAM... and
> > company!
> >
> > CALL and inquire about our Usenet stalking specials. Psychopathic
> > creepiness assured.
> > ================== =======================================================
> >s

 

[[email protected]]

On Sun, 26 Jun 2005 20:23:33 -0700, Benjamin Lewis
<[email protected]> wrote:

>jobst brandt wrote:
>
>> Benjamin Lewis writes:
>>

>>>> dvt writes:
^^^^^^^^^^^^^^^^
>>>> It's still possible, however, that the process of building a wheel
>>>> produces residual stress in the spoke. In that case, stress relief
>>>> would be helpful.
>>
>>> Possible? I increased the tension in a spoke in my wheel and it
>>> yielded. What more do you want?
>>
>> I think we have defined residual stress as that stress not related to
>> spoke tension but to forming the spoke in manufacture and wheel
>> lacing. Even elbow angle modification from tensioning is not tensile
>> stress derived from spoke cross section and tensio,n but rather a
>> forming process. That is what residual stress is in this context.
>
>Yes, but apparently a new disagreement on semantics has now started,
>despite the fact that it has no bearing one what's going on. I think we're
>back to another "wheel-doesn't-stand-on-spokes-I-don't-get-superposition"
>thing.

Dear Benjamin, Jobst, and David,

I'm not arguing, just hoping to clarify things.

First, I stuck a line in above to show that dvt wrote the
first paragraph.

It's clear that Benjamin disagreed with him.

But I'm not sure if Jobst was agreeing or disagreeing with
Benjamin.

I think that Benjamin is arguing elsewhere (it isn't in the
quotes above) that he put spokes into a wheel, tensioned
them without any spoke-line correcting or bending, squeezed
a pair of spoke together as Jobst recommends, removed them,
and saw a change in the elbow bend. (Sorry if I've got any
details wrong.)

I think that dvt was wondering whether the change in the
elbow was due to a stress being relieved by extra tension
without bending, or due to increased tension straightening
the elbow. (Again, sorry if this isn't what was intended.)

Benjamin replied that he increased tension and the spoke
yielded. (That was darned clear.)

I think (but I'm not sure) that Jobst replied to Benjamin
that no, changes in the elbow angle are a forming process,
not a matter of residual stress relief.

Is that roughly what the three of you are saying?

Carl Fogel

 

[Luns Tee]

In article <[email protected]>,
<[email protected]> wrote:
>First, the higher the spoke tension, the more effective the
>technique would be. Again, the figures are just examples,
>not real data, but assume that there are some 200 pound
>residual stress bands in the elbow. Squeeze a pair of spokes
>in the same way and nothing happens--the 200 pound spoke
>tension, plus the 200 pound residual tensile stress, plus
>the 100 pounds of squeeze-induced extra tension add up to
>only 500 pounds of tension, well short of the 600 pounds
>needed to yield things.

Carl,
I think you're getting things a little clouded up in that
residual stresses being relieved are only across some of the spoke's
area, while these forces of 200 and 600 pounds refer to the aggregates
across the entire spoke.

But perhaps it might help for you to re-frame the situation for
you to think of it in another manner. Imagine the spoke is made of 600
filaments of very fine wire, each with a yield strength of 1 pound.
Somehow bind the ends of all these wires together in some manner (weld
them together if you like) that you can apply a tension to the whole
lot. Sounds simple so far, right? Just divide the applied force by 600
and that's the tension you apply to each strand.

There's a catch though. Imagine some filaments of the wire are
longer than the others, but the ends are bound to the very ends of the
filaments rather than to a fixed length worth of filament. When you pull
on the whole lot, the shorter filaments get tension first, while the
longer ones are slack to begin with. Pull further, and as the short
filaments stretch, the slack ones can start taking up tension too.
In an actual spoke, these filaments are bound throughout their length,
so the 'long' ones can actually support compression instead of flopping
around loose, but let's not delve into that right now.

So, let's say we apply 200 pounds of tension. A simplified
scenario might be that 200 of the filaments are short and 0.9lb each,
while the other 400 are (ever so slightly) longer and support 0.05lb
each. Arrange these filaments in whatever order you like, and you can
mix it up with a continuum of values in between while you're at it,
but let's stick with these numbers for convenience for this discussion.

Add another pound of tension, and all the filaments increase
by 1/600 lb, the filaments' spring constant not being a function of
the tension already present. When you've brought the tension up to 260
pounds, the short filaments hit their yield ceiling, carrying 1lb each,
while the other filaments now carry 0.15lb each. All the filaments are
ever so slightly longer than they were before, but this is an elastic
stretching, and they'll return to their original lengths when the
extra tension is removed.

But, we're literally on the brink of stress relief now. Add
another 40 pounds of tension and what happens? The long filaments
stretch a bit more, but the short ones run into their yield limit. The
short ones deform plastically, becoming longer, but not taking up any
more tension than they were supporting before. The extra tension is
supported only by the long filaments.
Now, you have 200 filaments carrying 1lb each, and 400 carrying
0.25lb each, for the total of 300 lbs.

Now, relax the tension by 100 lbs to get back to the 200 lbs
installed tension. All the filaments relax by 1/6 lb, the relaxing
being an elastic deformation. 200 filaments are now carrying 5/6 lb or
0.83lbs, and the rest, 0.083lbs each.

Note that this 0.83lb tension is less than the 0.9 we started
with - the short filaments being now that much farther away from
yield. Also note that the overall tension only had to increase by 30%
before things started to change - far from a 3x increase.

-Luns

 

[dvt]

Benjamin Lewis wrote:
> dvt wrote:

>>Benjamin Lewis wrote:

>>>dvt wrote:

>>>>It's still possible, however, that the process of building a wheel
>>>>produces residual stress in the spoke. In that case, stress relief
>>>>would be helpful.

>>>Possible? I increased the tension in a spoke in my wheel and it
>>>yielded. What more do you want?

>>I haven't been convinced that yielding a spoke at the elbow is evidence
>>of residual stress. Another plausible explanation is that the geometry
>>of the spoke/hub interface caused a stress concentration at the elbow,

> That's residual stress.

If it's simply a stress concentration due to geometry, then it would
disappear if I let the tension off the spoke. I wouldn't have thought to
call that residual stress.

--
Dave
dvt at psu dot edu

 

[dvt]

Benjamin Lewis wrote:
> Yes, but apparently a new disagreement on semantics has now started,
> despite the fact that it has no bearing one what's going on. I think we're
> back to another "wheel-doesn't-stand-on-spokes-I-don't-get-superposition"
> thing.

Benjamin, I don't think it's a new disagreement. It might be only me
that misunderstood your concept of residual stress. And yes, it has
direct bearing on what's going on. Spoke squeezing is said to relieve
residual stress. If I don't understand what you mean by residual stress,
then I can't understand the rest of it.

I take umbrage at the insinuation that I'm starting another wheel
standing on or hanging from spokes thread.

--
Dave
dvt at psu dot edu

 

[[email protected]]

Carl Fogel writes:

> It's clear that Benjamin disagreed with him.

> But I'm not sure if Jobst was agreeing or disagreeing with Benjamin.

> I think (but I'm not sure) that Jobst replied to Benjamin that no,
> changes in the elbow angle are a forming process, not a matter of
> residual stress relief.

> Is that roughly what the three of you are saying?

What I said should be clear all by itself, regardless of previous
comments or who made them. It relates solely to identifying what I
mean by residual stress, the stress that I propose can be reduced by
stretching spokes above their normal tensile load in a wheel:

>>> I think we have defined residual stress as that stress not related
>>> to spoke tension but to forming the spoke in manufacture and wheel
>>> lacing. Even elbow angle modification from tensioning is not
>>> tensile stress derived from spoke cross section and tension but
>>> rather a forming process. That is what residual stress is in this
>>> context.

[email protected]

 

[Peter Cole]

jim beam wrote:
> Peter Cole wrote:
>> A different alloy might have intrinsically better fatigue life.
>> Manufacturing (wire and/or spoke) may have improved. Who cares? The
>> question is academic (since most of us are not using any old spokes)
>> and neither the alloys of the old and new nor the manufacturing
>> processes are known, so how could this question ever be answered?
>
>
> differences between old & new /are/ well known. modern fatigue
> resistant steels are frequently vacuum degassed, and this process is
> used for modern spoke wire. it results in much lower inclusion counts
> which consequently means fewer fatigue initiation points. whether this
> is convenient to "stress relief" theory or not, vacuum degassing is well
> documented to improve fatigue life [unlike "stress relief" in highly
> cold worked tensile wire] and electron microscopy has proven fatigue
> initiation on micro-inclusions that were not visible with optical
> microscopy. why else would a manufacturer go to the [considerable]
> expense of specifying this kind of material if ordinary stainless would do?

I'm no expert, but according to what I've read, vacuum degassing is an
extremely common and low cost steel manufacturing technique and had been
widely used for at least 20 years.

"Vacuum oxygen carburization" seems to be quite common in stainless
steel refining. I think this is just the way steel has been made for
some time now.

<http://www.steel.org/learning/glossary/v.htm>

 

[Benjamin Lewis]

dvt wrote:

> Benjamin Lewis wrote:
>> dvt wrote:
>
>>> Benjamin Lewis wrote:
>
>>>> dvt wrote:
>
>>>>> It's still possible, however, that the process of building a wheel
>>>>> produces residual stress in the spoke. In that case, stress relief
>>>>> would be helpful.
>
>>>> Possible? I increased the tension in a spoke in my wheel and it
>>>> yielded. What more do you want?
>
>>> I haven't been convinced that yielding a spoke at the elbow is evidence
>>> of residual stress. Another plausible explanation is that the geometry
>>> of the spoke/hub interface caused a stress concentration at the elbow,
>
>> That's residual stress.
>
> If it's simply a stress concentration due to geometry, then it would
> disappear if I let the tension off the spoke. I wouldn't have thought to
> call that residual stress.

In the context of a laced and tensioned wheel, it's residual stress. It's
not conceptually any different from residual stresses in an untensioned
spoke.

--
Benjamin Lewis

"Love is a snowmobile racing across the tundra and then suddenly it flips
over, pinning you underneath. At night, the ice weasels come."
--Matt Groening

 

[dvt]

Benjamin Lewis wrote:
> dvt wrote:
>>If it's simply a stress concentration due to geometry, then it would
>>disappear if I let the tension off the spoke. I wouldn't have thought to
>>call that residual stress.

> In the context of a laced and tensioned wheel, it's residual stress. It's
> not conceptually any different from residual stresses in an untensioned
> spoke.

You're right in that stress is stress, by any other name. As I said, I
wouldn't have called it residual, since it doesn't disappear when
tension is let off. But let's not argue about that -- I think we agree
on the result, no matter what we call it. The difference in terms is a
big part of the reason that I didn't follow much of your logic earlier
in this discussion. I suspect I'm not alone.

I think both of the JB's are actually in agreement in this matter. One
JB calls it residual stress that is relieved, the other calls it bedding
in. Either way, it looks to me like they're simply differing on terms.
Sounds like a semantic argument to me.

And I didn't turn it into a semantic argument, I'm just pointing it out.

--
Dave
dvt at psu dot edu

 

[Benjamin Lewis]

dvt wrote:

> Benjamin Lewis wrote:
>> dvt wrote:
>>> If it's simply a stress concentration due to geometry, then it would
>>> disappear if I let the tension off the spoke. I wouldn't have thought
>>> to call that residual stress.
>
>> In the context of a laced and tensioned wheel, it's residual stress.
>> It's not conceptually any different from residual stresses in an
>> untensioned spoke.
>
> You're right in that stress is stress, by any other name. As I said, I
> wouldn't have called it residual, since it doesn't disappear when
> tension is let off. But let's not argue about that -- I think we agree
> on the result, no matter what we call it. The difference in terms is a
> big part of the reason that I didn't follow much of your logic earlier
> in this discussion. I suspect I'm not alone.
>
> I think both of the JB's are actually in agreement in this matter. One
> JB calls it residual stress that is relieved, the other calls it bedding
> in.

I don't believe so. Bedding in implies plastic deformation of the hub, not
of the spoke. Furthermore, I think you'll find "jim beam" will claim that
residual stress caused by spoke manufacture can't be relieved by spoke
squeezing.

--
Benjamin Lewis

"Love is a snowmobile racing across the tundra and then suddenly it flips
over, pinning you underneath. At night, the ice weasels come."
--Matt Groening

 

[[email protected]]

On Mon, 27 Jun 2005 06:22:35 -0400, dvt <[email protected]>
wrote:

[snip]

>I take umbrage at the insinuation that I'm starting another wheel
>standing on or hanging from spokes thread.

Dear dvt,

Umbrage . . .

A word with rather an umbrageous etymology . . .

Umbrella . . .

Rec.umbrellas.tech . . .

Does an umbrella hang from its spokes? The Mary Poppins
school debates this with the Bertie Wooster crowd.

Are there any umbrella-spoking patterns other than radial?

Are sew-on umbrella covers superior to those clinched in
place?

Do umbrella-makers stress-relieve their spokes?

Are umbrella quick-releases forbidden in track competition?

Do serious bumbershooters patch torn umbrellas or carry
spare covers?

Is there Park Tool parasol-checker that tells when the cover
has stretched enough (say half an inch of slack material in
a 3-foot umbrella) that it should be replaced?

Are traditional 36-spoke umbrellas deemed more durable than
flashy low-count models?

Do brolly enthusiasts have the equivalent of tandems, large
enough to shelter two?

Carl Fogel

 

[[email protected]]

On Mon, 27 Jun 2005 08:09:06 +0000 (UTC),
[email protected] (Luns Tee) wrote:

>In article <[email protected]>,
> <[email protected]> wrote:
>>First, the higher the spoke tension, the more effective the
>>technique would be. Again, the figures are just examples,
>>not real data, but assume that there are some 200 pound
>>residual stress bands in the elbow. Squeeze a pair of spokes
>>in the same way and nothing happens--the 200 pound spoke
>>tension, plus the 200 pound residual tensile stress, plus
>>the 100 pounds of squeeze-induced extra tension add up to
>>only 500 pounds of tension, well short of the 600 pounds
>>needed to yield things.
>
>Carl,
> I think you're getting things a little clouded up in that
>residual stresses being relieved are only across some of the spoke's
>area, while these forces of 200 and 600 pounds refer to the aggregates
>across the entire spoke.
>
> But perhaps it might help for you to re-frame the situation for
>you to think of it in another manner. Imagine the spoke is made of 600
>filaments of very fine wire, each with a yield strength of 1 pound.
>Somehow bind the ends of all these wires together in some manner (weld
>them together if you like) that you can apply a tension to the whole
>lot. Sounds simple so far, right? Just divide the applied force by 600
>and that's the tension you apply to each strand.
>
> There's a catch though. Imagine some filaments of the wire are
>longer than the others, but the ends are bound to the very ends of the
>filaments rather than to a fixed length worth of filament. When you pull
>on the whole lot, the shorter filaments get tension first, while the
>longer ones are slack to begin with. Pull further, and as the short
>filaments stretch, the slack ones can start taking up tension too.
>In an actual spoke, these filaments are bound throughout their length,
>so the 'long' ones can actually support compression instead of flopping
>around loose, but let's not delve into that right now.
>
> So, let's say we apply 200 pounds of tension. A simplified
>scenario might be that 200 of the filaments are short and 0.9lb each,
>while the other 400 are (ever so slightly) longer and support 0.05lb
>each. Arrange these filaments in whatever order you like, and you can
>mix it up with a continuum of values in between while you're at it,
>but let's stick with these numbers for convenience for this discussion.
>
> Add another pound of tension, and all the filaments increase
>by 1/600 lb, the filaments' spring constant not being a function of
>the tension already present. When you've brought the tension up to 260
>pounds, the short filaments hit their yield ceiling, carrying 1lb each,
>while the other filaments now carry 0.15lb each. All the filaments are
>ever so slightly longer than they were before, but this is an elastic
>stretching, and they'll return to their original lengths when the
>extra tension is removed.
>
> But, we're literally on the brink of stress relief now. Add
>another 40 pounds of tension and what happens? The long filaments
>stretch a bit more, but the short ones run into their yield limit. The
>short ones deform plastically, becoming longer, but not taking up any
>more tension than they were supporting before. The extra tension is
>supported only by the long filaments.
> Now, you have 200 filaments carrying 1lb each, and 400 carrying
>0.25lb each, for the total of 300 lbs.
>
> Now, relax the tension by 100 lbs to get back to the 200 lbs
>installed tension. All the filaments relax by 1/6 lb, the relaxing
>being an elastic deformation. 200 filaments are now carrying 5/6 lb or
>0.83lbs, and the rest, 0.083lbs each.
>
> Note that this 0.83lb tension is less than the 0.9 we started
>with - the short filaments being now that much farther away from
>yield. Also note that the overall tension only had to increase by 30%
>before things started to change - far from a 3x increase.
>
>-Luns

Dear Luns,

One problem (my fault) is that the example may well not
reflect how much the tension actually increases, what the
yield point is, or what any residual stresses are.

Joe Riel is working on calculating the tension increase. I
think that the increase in tension on a spoke already
tensioned to 200 pounds will be considerable with a 100
pound sideways force, which is roughly what's recommended
for squeezing pairs of spokes together.

Jobst's tensile tests in the back of the 2nd and 3rd edition
sorta-kinda look like around 600 lbs for the yield point,
and "The Bicycle Wheel and the Walkman" has a whole section
that calculated the yield point to 600 lbs.

If I'm following you, your idea is that the residual
stresses are groups of microscopic individual sections at
very low tensions and compressions, rather than the larger
unified bands suggested by the neutron diffraction pictures?

But I'm still a little puzzled. You're using the idea of 600
strands instead of a few bands, and getting much lower
stresses. Is the 600 strands and the 1-pound yield for each
strand just illustrative and meant to scale up (or maybe
down) if we go to six billion strands at the molecular
level?

I'm not arguing with the numbers, which we're picking just
to make illustrating the ideas possible, but trying to make
sure that I'm right that your approach is intended to scale
out to wherever the real stresses end up--six zillion
strands, each with a 1/zillion pound yield point, right?

Carl Fogel

 

[Joe Riel]

[email protected] writes:

> Joe Riel is working on calculating the tension increase. I
> think that the increase in tension on a spoke already
> tensioned to 200 pounds will be considerable with a 100
> pound sideways force, which is roughly what's recommended
> for squeezing pairs of spokes together.

I've got it worked out, however, I'm writing it up as a real document
(pdf), so I can refer to it later. Anyway, got sidetracked updating a
metapost drafting package (don't ask) which I use to create some
figures in the document. Maybe I'll have it ready by tonight.

Joe

 

[dvt]

Benjamin Lewis wrote:
> dvt wrote:
>>I think both of the JB's are actually in agreement in this matter. One
>>JB calls it residual stress that is relieved, the other calls it bedding
>>in.

> I don't believe so. Bedding in implies plastic deformation of the hub, not
> of the spoke. Furthermore, I think you'll find "jim beam" will claim that
> residual stress caused by spoke manufacture can't be relieved by spoke
> squeezing.

I guess we'll have to let them weigh in on this, although I'm pretty
sure there's too much animosity for either of them to admit agreement on
anything. Shame, that.

You say: "Bedding in implies plastic deformation of the hub, not of the
spoke." I think bedding in implies plastic deformation of the spoke/hub
interface. Both the hub and the spoke can give a little in that
relationship.

--
Dave
dvt at psu dot edu

 

[Benjamin Lewis]

dvt wrote:

> You say: "Bedding in implies plastic deformation of the hub, not of the
> spoke." I think bedding in implies plastic deformation of the spoke/hub
> interface. Both the hub and the spoke can give a little in that
> relationship.

They can, but I'm not sure I agree that that is a particularly good
definition, given that you can have bedding in without spoke deformation,
and you can have spoke deformation without bedding in. At least, I don't
*think* anyone would call it "bedding in" without any hub deformation.

If I slept on a flat rock, I wouldn't say there was any "bedding in" to the
rock occurring, even though my body partially conformed to the rock

--
Benjamin Lewis

"Love is a snowmobile racing across the tundra and then suddenly it flips
over, pinning you underneath. At night, the ice weasels come."
--Matt Groening

 

[Luns Tee]

In article <[email protected]>,
<[email protected]> wrote:
>But I'm still a little puzzled. You're using the idea of 600
>strands instead of a few bands, and getting much lower
>stresses.

They're not lower stresses, they're lower tensions. Stress is
tension divided by area, which with thinner strands still remains at the
same magnitude since both tension and area scale down together as you
keep subdividing things.

> Is the 600 strands and the 1-pound yield for each
>strand just illustrative and meant to scale up (or maybe
>down) if we go to six billion strands at the molecular
>level?

I think you've got the idea. Keep going, and you'd be looking
at an infinite number of strands with infinitessimal tensions each (but
with stresses that don't vanish as you keep going).
The spoke has a continuum of stresses across its section. You
can divide the section into regions of tension and compression (e.g. the
four bands in a bend). You can divide each tension region into high
medium and low tension, and the same for compression. When you stress
relieve, it's not the entire tension regions that are affected, only
those with the highest tensile stress - the highest concentration of
tension.

This is actually why I'd suggested (I think not in this thread
but in a parallel one) thinking of the tension in the spoke in
terms of a graph of stress - each point in the spoke's section has a
magnitude associated with it. Using these graphs lets you follow the
effects of bending to yield, springback, and stress relieving.

-Luns

 

[[email protected]]

Dave vt? writes:

>>> I think both of the JB's are actually in agreement in this
>>> matter. One JB calls it residual stress that is relieved, the
>>> other calls it bedding in.

>> I don't believe so. Bedding in implies plastic deformation of the
>> hub, not of the spoke. Furthermore, I think you'll find "jim beam"
>> will claim that residual stress caused by spoke manufacture can't
>> be relieved by spoke squeezing.

> You say: "Bedding in implies plastic deformation of the hub, not of
> the spoke." I think bedding in implies plastic deformation of the
> spoke/hub interface. Both the hub and the spoke can give a little in
> that relationship.

"Bedding in" requires yielding. The spoke cross section will not
yield from bearing against aluminum. You can bend the wire but that
is not "bedding in", that's bending and forming line of the wire, also
known for producing residual stress. Bedding is in this context has
been used solely to describe the plastic deformation of the flange
where the spoke bears on aluminum. Hence the term does not apply in
the sense that you seem to propose.

[email protected]

 

[Jasper Janssen]

On Thu, 16 Jun 2005 15:27:32 -0700, "Jay Beattie"
<[email protected]> wrote:

>Boston snob! Get the giant Wurlitzer with the monkey stop -- you
>know, where the little monky bangs the cymbals. That's a crowd
>pleaser and a must-have for any bicycle shop. You can even get
>the optional tire inflater stop. -- E. Power Beattie.

The organ in a local church here has a stop (among a few dozen) that makes
the Star Of Bethlehem turn circles, normally used only on Christmases.

Jasper

 

[Jasper Janssen]

On Wed, 15 Jun 2005 22:36:40 +0000 (UTC), [email protected]
(Luns Tee) wrote:

> While we're at it.. please explain how insufficient spoke
>tension causes spoke breakage. Inadequate tension produces an inferior
>wheel, certainly, but the failure of low spoke tension is that spokes
>go slack under load, allowing spoke nipples to rattle loose and the
>wheel to then go out of true. Spoke breakage is not part of this, even
>if it was more common at the time. But so were bell bottom pants.

I don't know *how* it works, but it's clear that it *does* work.

Jasper