What happens to brass spoke nipples during stainless-steel spoke-squeezing?



What happens to brass spoke nipples during the
stainless-steel spoke-squeezing?

Both are often recommended on rec.bicycles.tech.

For starters, here are some values . . .

36-spoke aluminum rim, aluminum hub
(easy squeezing, used in book and internet models)

295 mm double-butted stainless-steel spoke
(gotta pick some length and model)

1.8 mm mid-section (2.5447 mm^2 cross-section)
(recommended over 2.0 straight spokes)

brass nipples, ???
"Nominal Thread Size 2.2mm x 56 tpi Common 2mm spoke
threading"
http://www.parktool.com/repair_help/thread.shtml

"For the standard 14g (2.0mm) spoke, the thread is 0.080"
diameter, 56 tpi, 60 degree included angle."
http://www.trials-forum.co.uk/forum/index.php?showtopic=30462

100 Kgf (220 pounds) spoke tension
(round number, ballpark value for several manufacturers,
see end of http://www.parktool.com/repair_help/tm_1.shtml,
front averages 80-112 Kgf, r-rear averages 96-132 Kgf)

50 Kgf squeeze (110 pounds)
(a fairly strong single-hand squeeze)

Material Modulus of Modulus of
Elasticity, E Rigidity, G Poisson's
Mpsi GPa Mpsi GPa Ratio
---------------- ---- ----- ----- ----- ---------
Aluminum alloys 10.3 71.0 3.8 26.2 0.334
Brass 15.4 106.0 5.82 40.1 0.324
Stainless steel 27.6 190.0 10.6 73.1 0.305
http://ourworld.cs.com/MJVanVoorhis/techdata/t000.htm
(ballpark figures)

Obviously, all the values above may be high or low. I'm just
wondering what happens to the brass nipples in the aluminum
rim when a stainless steel spoke connecting them to the hub
is squeezed.

Curiously,

Carl Fogel
 
B

Bill Sornson

Guest
[email protected] wrote:
> What happens to brass spoke nipples during the
> stainless-steel spoke-squeezing?
>
> Both are often recommended on rec.bicycles.tech.
>
> For starters, here are some values . . .
>
> 36-spoke aluminum rim, aluminum hub
> (easy squeezing, used in book and internet models)
>
> 295 mm double-butted stainless-steel spoke
> (gotta pick some length and model)
>
> 1.8 mm mid-section (2.5447 mm^2 cross-section)
> (recommended over 2.0 straight spokes)
>
> brass nipples, ???
> "Nominal Thread Size 2.2mm x 56 tpi Common 2mm spoke
> threading"
> http://www.parktool.com/repair_help/thread.shtml
>
> "For the standard 14g (2.0mm) spoke, the thread is 0.080"
> diameter, 56 tpi, 60 degree included angle."
> http://www.trials-forum.co.uk/forum/index.php?showtopic=30462
>
> 100 Kgf (220 pounds) spoke tension
> (round number, ballpark value for several manufacturers,
> see end of http://www.parktool.com/repair_help/tm_1.shtml,
> front averages 80-112 Kgf, r-rear averages 96-132 Kgf)
>
> 50 Kgf squeeze (110 pounds)
> (a fairly strong single-hand squeeze)
>
> Material Modulus of Modulus of
> Elasticity, E Rigidity, G Poisson's
> Mpsi GPa Mpsi GPa Ratio
> ---------------- ---- ----- ----- ----- ---------
> Aluminum alloys 10.3 71.0 3.8 26.2 0.334
> Brass 15.4 106.0 5.82 40.1 0.324
> Stainless steel 27.6 190.0 10.6 73.1 0.305
> http://ourworld.cs.com/MJVanVoorhis/techdata/t000.htm
> (ballpark figures)
>
> Obviously, all the values above may be high or low. I'm just
> wondering what happens to the brass nipples in the aluminum
> rim when a stainless steel spoke connecting them to the hub
> is squeezed.


Dear Carl,

They perk up a little.

HTH, Bill S.
 
Carl Fogel writes:

> What happens to brass spoke nipples during the stainless-steel
> spoke-squeezing?


By insisting on this terminology you convey an incorrect picture of
what is occurring with spokes. This is actually stretching spokes
rather than squeezing them although the method by which they are most
easily stretched is by squeezing parallel pairs together.

So how about calling it spoke stretching than spoke squeezing?

> Both are often recommended on rec.bicycles.tech.


> For starters, here are some values...


> ...


> Obviously, all the values above may be high or low. I'm just
> wondering what happens to the brass nipples in the aluminum
> rim when a stainless steel spoke connecting them to the hub
> is squeezed.


The parameter of interest is yield stress rather than elastic modulus
of spoke nipples. That they don't rupture during stretching indicates
that their stress remains below yield. However, that should be
obvious because stress strain curves shown in "the Bicycle Wheel" are
from tensile tests that ruptured spokes, held at one end by a brass
spoke nipple and the other by a simulated aluminum flange.

[email protected]
 
J

Jay Beattie

Guest
<[email protected]> wrote in message
news:[email protected]
> What happens to brass spoke nipples during the
> stainless-steel spoke-squeezing?
>
> Both are often recommended on rec.bicycles.tech.
>
> For starters, here are some values . . .
>
> 36-spoke aluminum rim, aluminum hub
> (easy squeezing, used in book and internet models)
>
> 295 mm double-butted stainless-steel spoke
> (gotta pick some length and model)
>
> 1.8 mm mid-section (2.5447 mm^2 cross-section)
> (recommended over 2.0 straight spokes)
>
> brass nipples, ???
> "Nominal Thread Size 2.2mm x 56 tpi Common 2mm spoke
> threading"
> http://www.parktool.com/repair_help/thread.shtml
>
> "For the standard 14g (2.0mm) spoke, the thread is 0.080"
> diameter, 56 tpi, 60 degree included angle."
> http://www.trials-forum.co.uk/forum/index.php?showtopic=30462
>
> 100 Kgf (220 pounds) spoke tension
> (round number, ballpark value for several manufacturers,
> see end of http://www.parktool.com/repair_help/tm_1.shtml,
> front averages 80-112 Kgf, r-rear averages 96-132 Kgf)
>
> 50 Kgf squeeze (110 pounds)
> (a fairly strong single-hand squeeze)
>
> Material Modulus of Modulus of
> Elasticity, E Rigidity, G Poisson's
> Mpsi GPa Mpsi GPa Ratio
> ---------------- ---- ----- ----- ----- ---------
> Aluminum alloys 10.3 71.0 3.8 26.2 0.334
> Brass 15.4 106.0 5.82 40.1 0.324
> Stainless steel 27.6 190.0 10.6 73.1 0.305
> http://ourworld.cs.com/MJVanVoorhis/techdata/t000.htm
> (ballpark figures)
>
> Obviously, all the values above may be high or low. I'm just
> wondering what happens to the brass nipples in the aluminum
> rim when a stainless steel spoke connecting them to the hub
> is squeezed.


Dear Dr. Barnhart, The effect is negligible in the overall
equation, and it works well enough to get me from one planet to
another. -- Klaatu.
 
J

jim beam

Guest
[email protected] wrote:
> What happens to brass spoke nipples during the
> stainless-steel spoke-squeezing?
>
> Both are often recommended on rec.bicycles.tech.
>
> For starters, here are some values . . .
>
> 36-spoke aluminum rim, aluminum hub
> (easy squeezing, used in book and internet models)
>
> 295 mm double-butted stainless-steel spoke
> (gotta pick some length and model)
>
> 1.8 mm mid-section (2.5447 mm^2 cross-section)
> (recommended over 2.0 straight spokes)
>
> brass nipples, ???
> "Nominal Thread Size 2.2mm x 56 tpi Common 2mm spoke
> threading"
> http://www.parktool.com/repair_help/thread.shtml
>
> "For the standard 14g (2.0mm) spoke, the thread is 0.080"
> diameter, 56 tpi, 60 degree included angle."
> http://www.trials-forum.co.uk/forum/index.php?showtopic=30462
>
> 100 Kgf (220 pounds) spoke tension
> (round number, ballpark value for several manufacturers,
> see end of http://www.parktool.com/repair_help/tm_1.shtml,
> front averages 80-112 Kgf, r-rear averages 96-132 Kgf)
>
> 50 Kgf squeeze (110 pounds)
> (a fairly strong single-hand squeeze)
>
> Material Modulus of Modulus of
> Elasticity, E Rigidity, G Poisson's
> Mpsi GPa Mpsi GPa Ratio
> ---------------- ---- ----- ----- ----- ---------
> Aluminum alloys 10.3 71.0 3.8 26.2 0.334
> Brass 15.4 106.0 5.82 40.1 0.324
> Stainless steel 27.6 190.0 10.6 73.1 0.305
> http://ourworld.cs.com/MJVanVoorhis/techdata/t000.htm
> (ballpark figures)
>
> Obviously, all the values above may be high or low. I'm just
> wondering what happens to the brass nipples in the aluminum
> rim when a stainless steel spoke connecting them to the hub
> is squeezed.


what happens is small localized plastic deformation at the contact
points, otherwise known as bedding in.

>
> Curiously,
>
> Carl Fogel
 
J

jim beam

Guest
[email protected] wrote:
> Carl Fogel writes:
>
>
>>What happens to brass spoke nipples during the stainless-steel
>>spoke-squeezing?

>
>
> By insisting on this terminology you convey an incorrect picture of
> what is occurring with spokes. This is actually stretching spokes
> rather than squeezing them although the method by which they are most
> easily stretched is by squeezing parallel pairs together.
>
> So how about calling it spoke stretching than spoke squeezing?
>
>
>>Both are often recommended on rec.bicycles.tech.

>
>
>>For starters, here are some values...

>
>
>>...

>
>
>>Obviously, all the values above may be high or low. I'm just
>>wondering what happens to the brass nipples in the aluminum
>>rim when a stainless steel spoke connecting them to the hub
>>is squeezed.

>
>
> The parameter of interest is yield stress rather than elastic modulus
> of spoke nipples. That they don't rupture during stretching indicates
> that their stress remains below yield.


eh? let's repeat that for the sheer incredulity of it: "That they don't
rupture during stretching indicates that their stress remains below yield."

wow, what a peach. so what happened to plastic deformation? you know,
the part of the stress/strain graph above the hookes law region? the
vital part of the graph where work hardening manifests itself? you
/did/ once own some books covering deformation of materials, didn't you
jobst? [it was once thought to be a subject vital to mechanical
engineers you know.] and just in case you can't be bothered to do /any/
research, the only materials that progress immediately from elastic to
rupture are brittle materials with no dislocation mechanism like
glasses. you /do/ know about dislocations, don't you jobst? i mean,
your research into the mitigation of fatigue included dislocation theory
didn't it?

> However, that should be
> obvious because stress strain curves shown in "the Bicycle Wheel" are
> from tensile tests that ruptured spokes, held at one end by a brass
> spoke nipple and the other by a simulated aluminum flange.


so how come you have such difficulty understanding what those graphs
mean? they directly contradict your statement above, you know that,
right? and while we're digging around in your book, how come you've
never explained the [substantial] distinction between the strain aging
material graph you use to explain "stress relief" and the actual spoke
tests you perform that /don't/ exhibit that phenomenon? could it be
that you're just making stuff up again? come on jobst, if you want to
claim you're an engineer, you need to raise the bar.

>
> [email protected]
 
D

dvt

Guest
[email protected] wrote:
> What happens to brass spoke nipples during the
> stainless-steel spoke-squeezing?


If anything in the system yields, the tension should be lower after the
spoke-squeezing. I don't think there's any argument about that... the
argument is about *what* yields.

Jobstian physics says that the steel spoke, in general, does not yield
under the spoke squeezing. But specific regions of the spoke (those with
remanent stress from the spoke forming process) do yield.

Other parts of the system may also yield: nipple, flange, rim bed, ....
So you can perform an experiment to show that yielding occurs, but it's
tough to isolate any one of the components. It can be done, but it
requires fixtures, effort, and time. Putting these three together "on
the cheap" is pretty rare.

--
Dave
dvt at psu dot edu
 
P

Paul Kopit

Guest
On Mon, 23 May 2005 13:06:43 -0400, dvt <[email protected]> wrote:

>If anything in the system yields, the tension should be lower after the
>spoke-squeezing. I don't think there's any argument about that... the
>argument is about *what* yields.


I built a set of wheels today and got the tension high before the
first squeezing. The tension did indeed go down after the first
squeezing.