I fixed a broken spoke!

dvt said:

jim beam said:

dvt wrote:

Quoted message said:

is this the 'unanswered' question?
'I've been watching this thread, hoping that I wasn't the only one with
this question. How do you "cant and drill" a hole in the hub flange so
that both inbound *and* outbound spokes are "optimized?"'

I snipped the last bit, leaving the specific question.

Quoted message said:

if you don't believe the hub holes are perpendicular to the flange, do
this experiment yourself.

I never doubted that hub flanges were canted. I *don't* understand why
you consider that cant optimal when there are so many different ways to
lace a wheel.

i already answered this question. 12/05.

Sheldon Brown said:

Peter Cole said:

I can't see what's so controversial about carefully taking the bow out
of a tensioned wheel if one exists.

I don't see it as controversial, but is much _easier_ to do it on an
un-tensioned wheel.

but doing it when the hub hole is not yet conformed to the spoke means
that it's being bent too much.

Quoted message said:

When you try to bend any piece of metal to a particular shape, you must
bend it past the desired position, allowing the elasticity of the metal
to bring it back to the desired shape once the force is removed.

Since you need to bend the spoke temporarily beyond "straight" you will
be fighting the spoke tension if you try to do this on a fully
tensioned wheel. Maybe your thumbs are strong enough for this, but
mine aren't.

Also, when the spoke are un-tensioned, it is easier to see when the
alignment has been optimized.

Sheldon "Sequence" Brown
+---------------------------------------------------+
| If you oppose making marriage legally available |
| to all adults, you are promoting promiscuity. |
+---------------------------------------------------+
Harris Cyclery, West Newton, Massachusetts
Phone 617-244-9772 FAX 617-244-1041
http://harriscyclery.com
Hard-to-find parts shipped Worldwide
http://captainbike.com http://sheldonbrown.com

Tom Sherman said:

Quoted message said:

... I agree and in addition, a spoke elbow that is, perhaps, 85°
and needs to be 95° cannot be opened to that angle once in
place...

Quoted message said:

Work hardening, "fulcrum" in the wrong place, or a combination of
the two?

No fulcrum about which to change the bend. Try it sometime. That is
why the spoke lone must be improved manually, because tension alone
will not change the shape of the elbow.

Spokes do not further work harden in use because that would require
substantial form change while yielding.

Jobst

Quoted message said:

Tom Sherman said:

Quoted message said:

... I agree and in addition, a spoke elbow that is, perhaps, 85°
and needs to be 95° cannot be opened to that angle once in
place...

Quoted message said:

Work hardening, "fulcrum" in the wrong place, or a combination of
the two?

No fulcrum about which to change the bend. Try it sometime. That is
why the spoke lone must be improved manually, because tension alone
will not change the shape of the elbow.

Spokes do not further work harden in use because that would require
substantial form change while yielding.

Jobst

Dear Jobst,

"The spoke lone" puzzled me for a moment, so others may wonder, too,
but the explanation is right next to the "o" on the keyboard.

"That is why the spoke line must be improved manually . . ."

It would be nice if someone else would take pity on my moment of
bafflement and confess to drawing a blank, even if only for an
instant.

Cheers,

Carl Fogel

Quoted message said:

Tom Sherman said:

Quoted message said:

... I agree and in addition, a spoke elbow that is, perhaps, 85°
and needs to be 95° cannot be opened to that angle once in
place...

Quoted message said:

Work hardening, "fulcrum" in the wrong place, or a combination of
the two?

No fulcrum about which to change the bend. Try it sometime.

if there's no fulcrum, what is this "flange" thing about which spokes
are being bent to "correct the spoke line"?

Quoted message said:

That is
why the spoke lone must be improved manually, because tension alone
will not change the shape of the elbow.

is that not because of hub hole conformance to the spoke???

Quoted message said:

Spokes do not further work harden in use because that would require
substantial form change while yielding.

but it's not "substantial". since stainless spoke steels do not strain
age, as demonstrated by the testing in your own book, they most
definitely /do/ work harden from from the slightest deformation while
the spoke line is being "corrected".

In article
<[email hidden]>,

Quoted message said:

"That is why the spoke line must be improved manually . . ."

It would be nice if someone else would take pity on my moment of
bafflement and confess to drawing a blank, even if only for an
instant.

More than an instant. Almost all Jobst's typographical
errors are a real word. Spell checkers are not what
they used to be. Used to bring me coffee and sit in my
lap.

--
Michael Press

Jobst Brandt said:

Tom Sherman said:

Quoted message said:

... I agree and in addition, a spoke elbow that is, perhaps, 85°
and needs to be 95° cannot be opened to that angle once in
place...

Quoted message said:

Work hardening, "fulcrum" in the wrong place, or a combination of
the two?

No fulcrum about which to change the bend. Try it sometime. That is
why the spoke lone must be improved manually, because tension alone
will not change the shape of the elbow.

Spokes do not further work harden in use because that would require
substantial form change while yielding.

Previous discussions on rec.bicycles.tech have established that most
higher quality spokes (e.g. DT, Sapim, and Wheelsmith) are made from
304 stainless steel.

It is my understanding that the austenitic (FCC) crystalline structure
of 304 is changed to a martensitic crystalline structure that is either
HCP or BCC when cold worked, and that (as expected) the martensite is
harder and less ductile (i.e. work hardened) than the parent austenite.

Is the amount of deformation when installing a new 304 spoke in a wheel
insufficient to significantly work harden the elbow?

--
Tom Sherman - Post Free or Die!

Johnny Sunset said:

Jobst Brandt said:

Tom Sherman said:

> ... I agree and in addition, a spoke elbow that is, perhaps, 85�
> and needs to be 95� cannot be opened to that angle once in
> place...
Work hardening, "fulcrum" in the wrong place, or a combination of
the two?

No fulcrum about which to change the bend. Try it sometime. That is
why the spoke lone must be improved manually, because tension alone
will not change the shape of the elbow.

Spokes do not further work harden in use because that would require
substantial form change while yielding.

Previous discussions on rec.bicycles.tech have established that most
higher quality spokes (e.g. DT, Sapim, and Wheelsmith) are made from
304 stainless steel.

i think that too much of an assumption. sapim describe their material
as "18/8", a broad but common designation which can be included in 304,
but neither d.t. nor wheelsmith say what they use iirc. whatever the
details, a simple magnet test reveals all 3 brands to be different.
sapim is strongly magnetic, wheelsmith very weakly and d.t. in between.

Quoted message said:

It is my understanding that the austenitic (FCC) crystalline structure
of 304 is changed to a martensitic crystalline structure that is either
HCP or BCC when cold worked, and that (as expected) the martensite is
harder and less ductile (i.e. work hardened) than the parent austenite.

there can indeed be work-induced martensitic transformations, but again,
i'm not comfortable saying that is definitely the case here. 304 is not
commonly designated as a martensitic grade.
http://www.msm.cam.ac.uk/phase-trans/2005/Stainless_steels/stainless.html

Quoted message said:

Is the amount of deformation when installing a new 304 spoke in a wheel
insufficient to significantly work harden the elbow?

unless it exhibits strain aging, /any/ deformation creates work
hardening. that's why the stress/strain graph *rises* above the yield
point rather than goes sideways.

Quoted message said:

Tom Sherman said:

Quoted message said:

... I agree and in addition, a spoke elbow that is, perhaps, 85°
and needs to be 95° cannot be opened to that angle once in
place...

Quoted message said:

Work hardening, "fulcrum" in the wrong place, or a combination of
the two?

No fulcrum about which to change the bend. Try it sometime. That is
why the spoke lone must be improved manually, because tension alone
will not change the shape of the elbow.

I'm not sure I understand this. Couldn't you slide a big flat-head
screwdriver between the spoke and the flange and bend it back out?

Pat

Pat Lamb said:

Quoted message said:

Quoted message said:

> ... I agree and in addition, a spoke elbow that is, perhaps, 85°
> and needs to be 95° cannot be opened to that angle once in
> place...

Quoted message said:

Quoted message said:

Quoted message said:

Work hardening, "fulcrum" in the wrong place, or a combination of
the two?

Quoted message said:

Quoted message said:

No fulcrum about which to change the bend. Try it sometime. That
is why the spoke line must be improved manually, because tension
alone will not change the shape of the elbow.

Quoted message said:

I'm not sure I understand this. Couldn't you slide a big flat-head
screwdriver between the spoke and the flange and bend it back out?

That doesn't work because the elbow would only rock in its aluminum
bore and change little if any. Besides, there is no gap to insert a
screwdriver. Something thin enough to enter there would be too weak
to bend a spoke.

Jobst Brandt

jim beam said:

dvt wrote:

Quoted message said:

Quoted message said:

I never doubted that hub flanges were canted. I *don't* understand why
you consider that cant optimal when there are so many different ways
to lace a wheel.

Quoted message said:

i already answered this question. 12/05.

jim beam said:

the hub holes deform during the build. "correcting the spoke line"
before this process has occurred is premature and will leave the
spoke elbow with the wrong resultant angle. the spoke elbow comes
pre-formed with the best resultant angle and the hub flange is canted
and drilled also to give the best resultant angle. it may look odd
when first laced, but when fully tensioned, the net result is
optimized. i therefore say leave the spoke elbow angle alone - do
/not/ bend.

jim beam said:

Quoted message said:

How are the hub flanges canted optimally for all the variations of
wheels?

Quoted message said:

they're not. they're optimized for the commonest configuration
32/36, 3x. road hubs for road rims, mtb hubs for 26" rims, etc.
roughly 3° for drive, 6° for non-drive.

When building a small wheel, or a wheel that's not 3x, or some other
combination that does not meet your specs, should the user "improve the
spoke line?"

What crossing pattern should be used with <32 spoke hubs?

--
Dave
dvt at psu dot edu

Everyone confesses that exertion which brings out all the powers of body
and mind is the best thing for us; but most people do all they can to
get rid of it, and as a general rule nobody does much more than
circumstances drive them to do. -Harriet Beecher Stowe, abolitionist and
novelist (1811-1896)

jim beam said:

Johnny Sunset said:

Jobst Brandt said:

Tom Sherman writes:

>> ... I agree and in addition, a spoke elbow that is, perhaps, 85?
>> and needs to be 95? cannot be opened to that angle once in
>> place...
> Work hardening, "fulcrum" in the wrong place, or a combination of
> the two?
No fulcrum about which to change the bend. Try it sometime. That is
why the spoke lone must be improved manually, because tension alone
will not change the shape of the elbow.

Spokes do not further work harden in use because that would require
substantial form change while yielding.

Previous discussions on rec.bicycles.tech have established that most
higher quality spokes (e.g. DT, Sapim, and Wheelsmith) are made from
304 stainless steel.

i think that too much of an assumption. sapim describe their material
as "18/8", a broad but common designation which can be included in 304,
but neither d.t. nor wheelsmith say what they use iirc. whatever the
details, a simple magnet test reveals all 3 brands to be different.
sapim is strongly magnetic, wheelsmith very weakly and d.t. in between.

Quoted message said:

From the Wheelsmith website [1]: "All Wheelsmith spokes are produced

from a specially drawn 304 stainless steel using a variety of cold
forging techniques, some proprietary."

Quoted message said:

Quoted message said:

It is my understanding that the austenitic (FCC) crystalline structure
of 304 is changed to a martensitic crystalline structure that is either
HCP or BCC when cold worked, and that (as expected) the martensite is
harder and less ductile (i.e. work hardened) than the parent austenite.

there can indeed be work-induced martensitic transformations, but again,
i'm not comfortable saying that is definitely the case here. 304 is not
commonly designated as a martensitic grade.
http://www.msm.cam.ac.uk/phase-trans/2005/Stainless_steels/stainless.html

This is a claim that austenitic 304 will form martensite when
plastically deformed at cold temperatures [2]. Are you differing on
degree of martensitic transformation or suggesting some other mechanism
for work hardening?

Quoted message said:

Quoted message said:

Is the amount of deformation when installing a new 304 spoke in a wheel
insufficient to significantly work harden the elbow?

unless it exhibits strain aging, /any/ deformation creates work
hardening. that's why the stress/strain graph *rises* above the yield
point rather than goes sideways.

I am aware of the strain hardening of 304 steel (having run tension
tests on said material to failure), which is why I used the qualifier
"significantly". Would the degree of work hardening of bending the
elbow of a 304 steel spoke to 85° make it impractical to bend back to
95°?

[1] <http://www.wheelsmith.com/index_files/wsspokes.htm>.
[2]
<http://doc.tms.org/ezMerchant/prodtms.nsf/ProductLookupItemID/MMTA-0606-1875/$FILE/MMTA-0606-1875F.pdf?OpenElement>.

--
Tom Sherman - Post Free or Die!

dvt said:

jim beam said:

dvt wrote:

Quoted message said:

Quoted message said:

I never doubted that hub flanges were canted. I *don't* understand
why you consider that cant optimal when there are so many different
ways to lace a wheel.

Quoted message said:

i already answered this question. 12/05.

jim beam said:

the hub holes deform during the build. "correcting the spoke line"
before this process has occurred is premature and will leave the
spoke elbow with the wrong resultant angle. the spoke elbow comes
pre-formed with the best resultant angle and the hub flange is canted
and drilled also to give the best resultant angle. it may look odd
when first laced, but when fully tensioned, the net result is
optimized. i therefore say leave the spoke elbow angle alone - do
/not/ bend.

jim beam said:

Quoted message said:

How are the hub flanges canted optimally for all the variations of
wheels?

Quoted message said:

they're not. they're optimized for the commonest configuration
32/36, 3x. road hubs for road rims, mtb hubs for 26" rims, etc.
roughly 3° for drive, 6° for non-drive.

When building a small wheel, or a wheel that's not 3x, or some other
combination that does not meet your specs, should the user "improve the
spoke line?"

in extreme circumstances, probably, yes. but otoh, i'd never use a
hub/rim combo that were that deviant. whatever the situation, if it
were my wheel, i'd do the "mavic method" of stress relief first [which
does not require full spoke tension] to be sure the hub holes were fully
conformed before any consideration of bending.

Quoted message said:

What crossing pattern should be used with <32 spoke hubs?

that's a "how long is a piece of string" question - it depends on the
hub size, rim size, etc. personally, i use 3x on 28 spoke, low flange,
road rim. and i never bend spoke elbows.

Johnny Sunset said:

jim beam said:

Johnny Sunset said:

Jobst Brandt wrote:
> Tom Sherman writes:
>
>>> ... I agree and in addition, a spoke elbow that is, perhaps, 85?
>>> and needs to be 95? cannot be opened to that angle once in
>>> place...
>> Work hardening, "fulcrum" in the wrong place, or a combination of
>> the two?
> No fulcrum about which to change the bend. Try it sometime. That is
> why the spoke lone must be improved manually, because tension alone
> will not change the shape of the elbow.
>
> Spokes do not further work harden in use because that would require
> substantial form change while yielding.
Previous discussions on rec.bicycles.tech have established that most
higher quality spokes (e.g. DT, Sapim, and Wheelsmith) are made from
304 stainless steel.

i think that too much of an assumption. sapim describe their material
as "18/8", a broad but common designation which can be included in 304,
but neither d.t. nor wheelsmith say what they use iirc. whatever the
details, a simple magnet test reveals all 3 brands to be different.
sapim is strongly magnetic, wheelsmith very weakly and d.t. in between.

Quoted message said:

From the Wheelsmith website [1]: "All Wheelsmith spokes are produced

from a specially drawn 304 stainless steel using a variety of cold
forging techniques, some proprietary."

Quoted message said:

Quoted message said:

It is my understanding that the austenitic (FCC) crystalline structure
of 304 is changed to a martensitic crystalline structure that is either
HCP or BCC when cold worked, and that (as expected) the martensite is
harder and less ductile (i.e. work hardened) than the parent austenite.

there can indeed be work-induced martensitic transformations, but again,
i'm not comfortable saying that is definitely the case here. 304 is not
commonly designated as a martensitic grade.
http://www.msm.cam.ac.uk/phase-trans/2005/Stainless_steels/stainless.html

This is a claim that austenitic 304 will form martensite when
plastically deformed at cold temperatures [2]. Are you differing on
degree of martensitic transformation or suggesting some other mechanism
for work hardening?

ok, 2 things:

1. yes, i would want to be sure of degree of transformation rather than
making extreme broad-brush claims. the second paper you cite does
indeed discuss transformation at low temperatures [-50 centigrade] which
accords with my understanding that transformation at more normal
temperatures is much more limited.
2. work hardening occurs regardless of any martensitic transformation.
as cited, extent and type of transformation will affect the degree of
hardening - obviously, but straight, stable austenitic stainless steels
significantly work harden as a function of deformation [increasing
dislocation density], as do most simple ductile metals.

Quoted message said:

Quoted message said:

Quoted message said:

Is the amount of deformation when installing a new 304 spoke in a wheel
insufficient to significantly work harden the elbow?

unless it exhibits strain aging, /any/ deformation creates work
hardening. that's why the stress/strain graph *rises* above the yield
point rather than goes sideways.

I am aware of the strain hardening of 304 steel (having run tension
tests on said material to failure), which is why I used the qualifier
"significantly". Would the degree of work hardening of bending the
elbow of a 304 steel spoke to 85� make it impractical to bend back to
95�?

if it remains austenitic, it's less likely to be an issue, but
regardless, it depends on the degree of cold work already performed. if
you're dealing with cold drawn wire, the majority of its strength
derives from cold work. it it's near its ductile limit [full hard],
then yes, additional bending could be a problem, but it's unlikely the
wire would be offered in this condition for general manufacture. and
"304" is a /real/ wide spec. since wheelsmith seem to regard the simple
grinding process they use to butt their spokes as "proprietary", i'd not
want to rely too heavily on accuracy of their disclosure of alloy used.

Quoted message said:

[1] <http://www.wheelsmith.com/index_files/wsspokes.htm>.
[2]
<http://doc.tms.org/ezMerchant/prodtms.nsf/ProductLookupItemID/MMTA-0606-1875/$FILE/MMTA-0606-1875F.pdf?OpenElement>.

that second paper is a good cite.

jim beam said:

dvt said:

When building a small wheel, or a wheel that's not 3x, or some other
combination that does not meet your specs, should the user "improve
the spoke line?"

in extreme circumstances, probably, yes. but otoh, i'd never use a
hub/rim combo that were that deviant. whatever the situation, if it
were my wheel, i'd do the "mavic method" of stress relief first [which
does not require full spoke tension] to be sure the hub holes were fully
conformed before any consideration of bending.

So in some cases, the benefits of "improving the spoke line" outweigh
what you you see as the detriments of that method. I'd like to know
where to draw that line.

--
Dave
dvt at psu dot edu

jim beam said:

Johnny Sunset said:

jim beam said:

Johnny Sunset wrote:
> Jobst Brandt wrote:
>> Tom Sherman writes:
>>
>>>> ... I agree and in addition, a spoke elbow that is, perhaps, 85?
>>>> and needs to be 95? cannot be opened to that angle once in
>>>> place...
>>> Work hardening, "fulcrum" in the wrong place, or a combination of
>>> the two?
>> No fulcrum about which to change the bend. Try it sometime. That
>> is why the spoke lone must be improved manually, because tension
>> alone will not change the shape of the elbow.
>>
>> Spokes do not further work harden in use because that would require
>> substantial form change while yielding.
> Previous discussions on rec.bicycles.tech have established that most
> higher quality spokes (e.g. DT, Sapim, and Wheelsmith) are made from
> 304 stainless steel.
i think that too much of an assumption. sapim describe their material
as "18/8", a broad but common designation which can be included in
304, but neither d.t. nor wheelsmith say what they use iirc. whatever
the details, a simple magnet test reveals all 3 brands to be
different. sapim is strongly magnetic, wheelsmith very weakly and d.t.
in between.

Quoted message said:

From the Wheelsmith website [1]: "All Wheelsmith spokes are produced

from a specially drawn 304 stainless steel using a variety of cold
forging techniques, some proprietary."

Quoted message said:

> It is my understanding that the austenitic (FCC) crystalline
> structure of 304 is changed to a martensitic crystalline structure
> that is either HCP or BCC when cold worked, and that (as expected)
> the martensite is harder and less ductile (i.e. work hardened) than
> the parent austenite.
there can indeed be work-induced martensitic transformations, but
again, i'm not comfortable saying that is definitely the case here.
304 is not commonly designated as a martensitic grade.
http://www.msm.cam.ac.uk/phase-trans/2005/Stainless_steels/stainless.html

This is a claim that austenitic 304 will form martensite when
plastically deformed at cold temperatures [2]. Are you differing on
degree of martensitic transformation or suggesting some other mechanism
for work hardening?

ok, 2 things:

1. yes, i would want to be sure of degree of transformation rather than
making extreme broad-brush claims. the second paper you cite does
indeed discuss transformation at low temperatures [-50 centigrade] which
accords with my understanding that transformation at more normal
temperatures is much more limited.
2. work hardening occurs regardless of any martensitic transformation.
as cited, extent and type of transformation will affect the degree of
hardening - obviously, but straight, stable austenitic stainless steels
significantly work harden as a function of deformation [increasing
dislocation density], as do most simple ductile metals.

Quoted message said:

Quoted message said:

> Is the amount of deformation when installing a new 304 spoke in a
> wheel insufficient to significantly work harden the elbow?
>
unless it exhibits strain aging, /any/ deformation creates work
hardening. that's why the stress/strain graph *rises* above the yield
point rather than goes sideways.

I am aware of the strain hardening of 304 steel (having run tension
tests on said material to failure), which is why I used the qualifier
"significantly". Would the degree of work hardening of bending the
elbow of a 304 steel spoke to 85� make it impractical to bend back to
95�?

if it remains austenitic, it's less likely to be an issue, but
regardless, it depends on the degree of cold work already performed. if
you're dealing with cold drawn wire, the majority of its strength
derives from cold work. it it's near its ductile limit [full hard],
then yes, additional bending could be a problem, but it's unlikely the
wire would be offered in this condition for general manufacture. and
"304" is a /real/ wide spec. since wheelsmith seem to regard the simple
grinding process they use to butt their spokes as "proprietary", i'd not
want to rely too heavily on accuracy of their disclosure of alloy used.

According to Wheelsmith, their butted spokes have "center sections [that]
are forged rather than cut, ground or drawn ...."

http://www.wheelsmith.com/index_files/spoketech.htm

Quoted message said:

Quoted message said:

[1] <http://www.wheelsmith.com/index_files/wsspokes.htm>. [2]
<http://doc.tms.org/ezMerchant/prodtms.nsf/ProductLookupItemID/MMTA-0606-1875/$FILE/MMTA-0606-1875F.pdf?OpenElement>.

that second paper is a good cite.

On Wed, 06 Dec 2006 20:41:56 -0800, jim beam <[email hidden]>

Quoted message said:

[email hidden] wrote:

Quoted message said:

Quoted message said:

I agree and in addition, a spoke elbow that is, perhaps, 85° and needs
to be 95° cannot be opened to that angle once in place. That is the
reason for not reusing spokes that have been taken out of a wheel.
The inbound and outbound spokes being difficult to recognize and the
ones with acute angles may not fit the new wheel.

eh? so which side of the fence do you sit here jobst? if the inbound
and outbound spokes can't be told apart after they've been used, there's
no necessity to "correct the spoke line", right?

How good are you at telling 95 from 85 degrees, visually, on something the
radius of a spoke head bend? In an often dark-ish workshop, of course.

Jasper

On Thu, 07 Dec 2006 21:12:34 -0800, jim beam <[email hidden]>

Quoted message said:

[email hidden] wrote:

Quoted message said:

Quoted message said:

No fulcrum about which to change the bend. Try it sometime.

if there's no fulcrum, what is this "flange" thing about which spokes
are being bent to "correct the spoke line"?

There's a fulcrum for bending it further, but not back, or at least not
without getting the nipple end *way* out of the wheel plane, ie, loosened.
And even then it's damn hard, because the geometry means that the force
you apply tends to rotate the spoke head instead of bending it, whereas
with bending further the head tends to lock in place.

This is incredibly obvious if you actually try it.

Jasper

On Thu, 07 Dec 2006 20:10:27 -0800, jim beam <[email hidden]>

Quoted message said:

Sheldon Brown said:

Peter Cole said:

I can't see what's so controversial about carefully taking the bow out
of a tensioned wheel if one exists.

I don't see it as controversial, but is much _easier_ to do it on an
un-tensioned wheel.

but doing it when the hub hole is not yet conformed to the spoke means
that it's being bent too much.

Does it matter if the hub flange is alu (and what kind) or chromed steel
as in classic and (still) ultracheap hubs?

Jasper

Gary Young said:

jim beam said:

Johnny Sunset said:

jim beam wrote:
> Johnny Sunset wrote:
>> Jobst Brandt wrote:
>>> Tom Sherman writes:
>>>
>>>>> ... I agree and in addition, a spoke elbow that is, perhaps, 85?
>>>>> and needs to be 95? cannot be opened to that angle once in
>>>>> place...
>>>> Work hardening, "fulcrum" in the wrong place, or a combination of
>>>> the two?
>>> No fulcrum about which to change the bend. Try it sometime. That
>>> is why the spoke lone must be improved manually, because tension
>>> alone will not change the shape of the elbow.
>>>
>>> Spokes do not further work harden in use because that would require
>>> substantial form change while yielding.
>> Previous discussions on rec.bicycles.tech have established that most
>> higher quality spokes (e.g. DT, Sapim, and Wheelsmith) are made from
>> 304 stainless steel.
> i think that too much of an assumption. sapim describe their material
> as "18/8", a broad but common designation which can be included in
> 304, but neither d.t. nor wheelsmith say what they use iirc. whatever
> the details, a simple magnet test reveals all 3 brands to be
> different. sapim is strongly magnetic, wheelsmith very weakly and d.t.
> in between.
>From the Wheelsmith website [1]: "All Wheelsmith spokes are produced
from a specially drawn 304 stainless steel using a variety of cold
forging techniques, some proprietary."

>> It is my understanding that the austenitic (FCC) crystalline
>> structure of 304 is changed to a martensitic crystalline structure
>> that is either HCP or BCC when cold worked, and that (as expected)
>> the martensite is harder and less ductile (i.e. work hardened) than
>> the parent austenite.
> there can indeed be work-induced martensitic transformations, but
> again, i'm not comfortable saying that is definitely the case here.
> 304 is not commonly designated as a martensitic grade.
> http://www.msm.cam.ac.uk/phase-trans/2005/Stainless_steels/stainless.html
This is a claim that austenitic 304 will form martensite when
plastically deformed at cold temperatures [2]. Are you differing on
degree of martensitic transformation or suggesting some other mechanism
for work hardening?

ok, 2 things:

1. yes, i would want to be sure of degree of transformation rather than
making extreme broad-brush claims. the second paper you cite does
indeed discuss transformation at low temperatures [-50 centigrade] which
accords with my understanding that transformation at more normal
temperatures is much more limited.
2. work hardening occurs regardless of any martensitic transformation.
as cited, extent and type of transformation will affect the degree of
hardening - obviously, but straight, stable austenitic stainless steels
significantly work harden as a function of deformation [increasing
dislocation density], as do most simple ductile metals.

Quoted message said:

>> Is the amount of deformation when installing a new 304 spoke in a
>> wheel insufficient to significantly work harden the elbow?
>>
> unless it exhibits strain aging, /any/ deformation creates work
> hardening. that's why the stress/strain graph *rises* above the yield
> point rather than goes sideways.
I am aware of the strain hardening of 304 steel (having run tension
tests on said material to failure), which is why I used the qualifier
"significantly". Would the degree of work hardening of bending the
elbow of a 304 steel spoke to 85� make it impractical to bend back to
95�?

if it remains austenitic, it's less likely to be an issue, but
regardless, it depends on the degree of cold work already performed. if
you're dealing with cold drawn wire, the majority of its strength
derives from cold work. it it's near its ductile limit [full hard],
then yes, additional bending could be a problem, but it's unlikely the
wire would be offered in this condition for general manufacture. and
"304" is a /real/ wide spec. since wheelsmith seem to regard the simple
grinding process they use to butt their spokes as "proprietary", i'd not
want to rely too heavily on accuracy of their disclosure of alloy used.

According to Wheelsmith, their butted spokes have "center sections [that]
are forged rather than cut, ground or drawn ...."

http://www.wheelsmith.com/index_files/spoketech.htm

yeah, i saw that too. the appearance of the spoke does not accord with
that statement though - it appears to have been ground and polished.
and i believe that the japanese factory from which wheelsmith spokes
originated uses this process also, producing both polished and
unpolished ground spokes, depending on price point. the only way to
know for sure is metallography. perhaps chas can oblige?

Quoted message said:

Quoted message said:

Quoted message said:

[1] <http://www.wheelsmith.com/index_files/wsspokes.htm>. [2]
<http://doc.tms.org/ezMerchant/prodtms.nsf/ProductLookupItemID/MMTA-0606-1875/$FILE/MMTA-0606-1875F.pdf?OpenElement>.

that second paper is a good cite.