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butted spokes (?)



 
 
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  #21  
Old September 5th 05, 02:37 AM
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Default butted spokes (?)

Southern Comfort writes:

jobst calls them all "swaged" but that's because he's seemingly
unaware of the fact that different spokes are made by different
methods. some are indeed swaged, but some others are drawn and yet
others are ground & polished. the generic term for /all/ reduced
diameter spokes is therefore "butted". don't let anyone who knows
nothing about these different production methods tell you otherwise.


"Butted" comes from the upsetting of the end of a rod to make a
thicker feature such as a spoke head or to thicken the end on which
threads are to be cut. However, spokes are not thickened but thinned
by swaging, a metal forming process that can be done by hammering on
an anvil as was done in the days of yore, or by drawing through a
split die clamped onto the spoke mid-section.

DT chose to use the split die while hammering it in rotation around
the spoke. This not only reduces the cross section but work hardens
it. Just drawing the spoke through a split die (with helical seam)
may be faster but usually leaves drawing marks that must be polished
out. Toward the end of their days in business, Stella spokes had
terrible draw marks on their swaged spokes. The process can be
simulated by other means such as metal removal, something that does
not make as strong a spoke as swaging.

Jobst Brandt
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  #22  
Old September 5th 05, 02:44 AM
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Default butted spokes (?)

Jasper Janssen writes:

Disc brake torque is no greater spoke load than peak pedaling
torque and it is distributed to both sides of the wheel, which
pedaling torque is not.


Why is it distributed? Disc brake torque is applied in pretty much
the same place on the wheel as torque through a freewheel, so
wouldn't it be mostly on the brake-side spokes, like pedaling torque
is on drive side? In both cases you essentially add torque at one
hub flange.


Hubs made for disc brakes generally have a large diameter spool
between flanges. If they don't don't buy them. This is especially
true for rear hubs. The good disc brake front hubs I have seen have
such a spool, so braking spoke load is fairly equal on both sides of
the wheel.

Jobst Brandt
  #24  
Old September 5th 05, 02:58 AM
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Default butted spokes (?)

On 4 Sep 2005 18:04:24 -0700, "Ron Ruff"
wrote:


jim beam wrote:
Ron Ruff wrote:

If I calculated correctly their "fatigue test" results seem a little
odd. 1,000,000 wheel revolutions is only 1,340 miles
(27*pi/12/5280*1,000,000). Even the CX-rays with 3,500,000 revolutions
only get 4,690 miles.

I would be nice to know more about that testing...

all i've discovered is that it was done by cycling from 90kgf to zero.
that's much higher than most wheels see in service. being as fatigue
life is usually regarded as having a logarithmic relation to stress, you
can see that your mileage will quickly increase with decreasing stress
cycle.


So, they stressed the spokes in an unusual way to get them to break
sooner... fairly standard, I guess. Still, it seems odd that they would
have presented it as "wheel revolutions" when it really isn't... and it
makes their spokes look bad.

Also, that 200lb cycle is roughly only 20% of the tensile strength that
they list elsewhere... a huge difference between fatigue and static
strength.

Do you know of any other (hopefully better) online data regarding spoke
fatique and strength?


Dear Ron,

If you haven't seen it, here's a paper on a variety of spoke
details:

http://www.duke.edu/~hpgavin/papers/...heel-Paper.pdf

It mentions the Wheelsmith-Stanford testing of spokes to
destruction from some years ago.

Professor Gavin was kind enough to send me the details of
the Wheelsmith tests, but while they were on their way, one
of our more obnoxious anonymous nitwits became so
unspeakable that I apologized to Professor Gavin for
dragging him into our cesspool and promised not to even open
the envelope when it arrived.

[Carl stares longingly at an unopened manila envelope with a
$3.85 02-22-2005 postmark. Feels like more than 30 pages,
much too thick to read by holding the envelope up to the
light. Probably full of really fascinating stuff. Cursed
ethics! Back to the shelf. Maybe someone else will find a
copy.]

Carl Fogel
  #26  
Old September 5th 05, 03:11 AM
jim beam
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Default butted spokes (?)

wrote:
Southern Comfort writes:


jobst calls them all "swaged" but that's because he's seemingly
unaware of the fact that different spokes are made by different
methods. some are indeed swaged, but some others are drawn and yet
others are ground & polished. the generic term for /all/ reduced
diameter spokes is therefore "butted". don't let anyone who knows
nothing about these different production methods tell you otherwise.



"Butted" comes from the upsetting of the end of a rod to make a
thicker feature such as a spoke head or to thicken the end on which
threads are to be cut.


that is /so/ wrong. the head is upset. but that's not butting. and
you can't "thicken" a 1" length of 2mm wire just by striking one end.
where do you get this stuff????

However, spokes are not thickened but thinned
by swaging, a metal forming process that can be done by hammering on
an anvil as was done in the days of yore, or by drawing through a
split die clamped onto the spoke mid-section.


the hammering is called swaging, the drawing is called, er, drawing.
both create butted spokes. there are so many references to this in
production engineering texts, it's just shameful you can't be bothered
to look one up. you should check out the manufacture of butted tube
some time too.


DT chose to use the split die while hammering it in rotation around
the spoke.


it's not a die. it's a pair of hammers. bit like a diesel rotary
injector pump.

This not only reduces the cross section but work hardens
it.


as does drawing. grinding doesn't.

Just drawing the spoke through a split die (with helical seam)
may be faster but usually leaves drawing marks that must be polished
out.


no, drawn spokes never have die marks polished out - there's no point
because the surface defects are not oriented to have any negative impact
on fatigue. unlike ground spokes which get polished to remove
negatively oriented stress risers.

Toward the end of their days in business, Stella spokes had
terrible draw marks on their swaged spokes.


didn't matter except for appearances. and that contradicts your
statement about drawn spokes getting polished.

The process can be
simulated by other means such as metal removal,


grinding

something that does
not make as strong a spoke as swaging.


depends whether the spoke gets heat treated or not, but by & large,
swaging or drawing is the way to go.


Jobst Brandt


  #27  
Old September 5th 05, 03:20 AM
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Default butted spokes (?)

Jasper Janssen writes:

Hubs made for disc brakes generally have a large diameter spool
between flanges.


So do non-disc mountain hubs, including rears.


If they don't don't buy them. This is especially
true for rear hubs. The good disc brake front hubs I have seen have
such a spool, so braking spoke load is fairly equal on both sides of
the wheel.


A smaller or larger hubshell that transmits more or less load from
one side to the other can only mitigate the effect, it can't
actually make it go away, can it?


Make what go away? There is no problem with that such torque loading
when you consider that many rear wheels survive with little torque
reaching the left side spokes due to slender hub spools.

Oh, and a related but non argumentative question for you: In frame
tubing, over-sized, thin walled tubing can be lighter, stiffer, and
nearly as strong. How does that work for hubshells? Wouldn't the
ones with thick hubshells -- particularly in high-end, lightweight
ranges like XTR -- have bigger axle holes inside to conserve weight?
What is/would be the effect on rotational stiffness of thin wall,
oversize hubshell tubing?


Torsion load increase as the fourth power of diameter so you must
compute the polar moment of inertia of the OD of the cross section of
interest and subtract that of the ID. So you see it depends on both
diameter and wall thickness. This stuff is in "the Bicycle Wheel".

Jobst Brandt
  #28  
Old September 5th 05, 04:27 AM
Sheldon Brown
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Default butted spokes (?)

Southern Comfort wrote:

jobst calls them all "swaged" but that's because he's seemingly
unaware of the fact that different spokes are made by different
methods. some are indeed swaged, but some others are drawn and yet
others are ground & polished. the generic term for /all/ reduced
diameter spokes is therefore "butted". don't let anyone who knows
nothing about these different production methods tell you otherwise.


Jobst Brandt replied:

"Butted" comes from the upsetting of the end of a rod to make a
thicker feature such as a spoke head or to thicken the end on which
threads are to be cut.


No, "butted" is a term descriptive of the _shape_, not the process.
When something is thicker on the ends it is "butted."

We've been over this before, and I gave an O.E.D. reference to this in a
previous posting, but I don't feel like dragging my O.E.D. and the
magnifying glasss again.

Butted tubing is not made by thickening the walls at the ends of the
tubes either, but by thinning the walls in the middle.

The butt of a rifle is also not made by thickening, but rather by
removing wood.

I generally prefer not to use the term "swaged" to describe spokes,
because all spokes are swaged...that's how the head is made. Jobst
prefers the term "upset" for this operation, which is also correct.

Sheldon "But.." Brown
Newtonville, Massachusetts
+-----------------------------------------+
| Man invented language to satisfy his |
| deep need to complain. -- Lily Tomlin |
+-----------------------------------------+
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

  #29  
Old September 5th 05, 04:35 AM
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Default butted spokes (?)

On Sun, 04 Sep 2005 23:27:24 -0400, Sheldon Brown
wrote:

Southern Comfort wrote:

jobst calls them all "swaged" but that's because he's seemingly
unaware of the fact that different spokes are made by different
methods. some are indeed swaged, but some others are drawn and yet
others are ground & polished. the generic term for /all/ reduced
diameter spokes is therefore "butted". don't let anyone who knows
nothing about these different production methods tell you otherwise.


Jobst Brandt replied:

"Butted" comes from the upsetting of the end of a rod to make a
thicker feature such as a spoke head or to thicken the end on which
threads are to be cut.


No, "butted" is a term descriptive of the _shape_, not the process.
When something is thicker on the ends it is "butted."

We've been over this before, and I gave an O.E.D. reference to this in a
previous posting, but I don't feel like dragging my O.E.D. and the
magnifying glasss again.

Butted tubing is not made by thickening the walls at the ends of the
tubes either, but by thinning the walls in the middle.

The butt of a rifle is also not made by thickening, but rather by
removing wood.

I generally prefer not to use the term "swaged" to describe spokes,
because all spokes are swaged...that's how the head is made. Jobst
prefers the term "upset" for this operation, which is also correct.

Sheldon "But.." Brown
Newtonville, Massachusetts
+-----------------------------------------+
| Man invented language to satisfy his |
| deep need to complain. -- Lily Tomlin |
+-----------------------------------------+
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


Dear Sheldon,

It's always nice to meet someone else who dislikes that
rectangular magnifier and the tiny print.

And it's nice to see that you're not upset or making a
S.W.A.G. about the butt of a joke.

Carl Fogel
  #30  
Old September 5th 05, 05:09 AM
Sock Puppet
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Default butted spokes (?)


On 4-Sep-2005, wrote:

It's always nice to meet someone else who dislikes that
rectangular magnifier and the tiny print.


You can subscribe online for ONLY $295/year.
http://www.oed.com/subscribe/individuals-amer.html

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