two odd wheel-building techniques

wrote in message ...

Well that's bogus. Spoke will not work harden in use although they
may fail from fatigue. I think it's old mechanics jargon and myth and
lore from the days when fatigue failures were routinely attributed to
"look the axle crystallized and broke here" when in fact a fatigue
failure always exposes the crystal structure because it is inter-grain
boundaries that fail most easily in a metal.

The use of the two words 'work harden' are a perfectly acceptable way in
which to describe what happens to a spoke which has been bent back and forth
a few million times so it is brittle. Then it snaps. The dislocations can
be seen with 20x magnification most usually on the outside of the fracture
but sometimes upon the inside also, dependent on setting, which show that
bending moments existed before fracture.

To describe everything which you may feel could undermine your theory as
myth and lore is most immature. It is not necessary to complicate an issue
where two words adequately describe the condition unless thou wishes to
confuse the less knowledgeable.

Trevor

daveornee wrote in message ...

Wrote:
While snuffling around the internet, I found this page,
which has links to two pictures that show what seem like
unusual wheel-building details:

http://tinyurl.com/4tx6h

or

http://tinyurl.com/4tx6h

Click on the blue words in :

The builder adjusts spoke line and may add washers between
the spoke head and hub flange to limit movement within the
hub hole."

Then click on the blue words in:

The more stable the elbow within the hub hole the less
likely it will "work harden" and break, a common cause of
spoke failure. Using a special punch, the builder sets the
spoke head in the hub hole to assure it is well seated and
won't move when the wheel is tensioned . . .

Are the washers and the punch common wheel-building
techniques, snake-oil, or what?

Carl Fogel
"Why do spokes break?

Spokes always break as the result of an irregularity in the wheel
spider.

Cause 1

Play between the hub and the spoke. Each spoke is subjected to one load
cycle (loading/unloading) during each complete rotation of the wheel.

Each spoke in a bicycle wheel that has been ridden over 2000 km, for
example, has experienced one million load changes.

If there is even the slightest play between the spoke and the hub
flange, a broken spoke is just a question of time. The spoke
continually jerks back and forth in the flange, which subjects the
spoke elbow to massive stress. This causes the material to become
brittle, the spoke can no longer bear the load and breaks at the elbow.


Remedy

Place washers underneath the head of any spoke where play is felt at
the hub flange. "

Above quoted from the FAQ section of DT Swiss

"Hub hole suitability Hold the hub flange horizontally. Put the spoke,
with the head inside, a little higher. While centring, you should push
on the hub lightly; the spokes will easily adjust themselves.
(Attention: do not push so hard that the spokes bend!).
Using oversized hub holes is an easy solution. However, this will cause
a lot of play and is not recommended.

Consider the use of spoke washers

Too much tension on the spoke head will also cause problems.
Ideal hub hole Ø equals spoke thread Ø + 0.1 mm (eg. spoke thread on
14G/2 mm measures thread 2.25 mm + 0.1 = 2.35 mm: max. hole Ø 2.50
mm)."

Above quoted from the "checklist" section of Sapim's site.

The thickness (from 2.0 to 4.0 mm on samples I have measured) of the
flange and spoke hole size help in determining the use of spoke head
washers. Also, there are at least 3 different spoke head to elbow
dimension on DT spokes varying at least .85 mm from shortest to
longest. Since, there are these differences and differences in hub
flange thicknesses and spoke hole diameters as well as spoke diameters
at the hub end; you must make some accomodation for these differences.
I will disagree with Jobst's statement that once a spoke is tensioned
it's elbow doesn't move.
I move them by laterally,torsionally, and radially loading the wheel.
I minimize the movement by spoke alignment and proper tensioning.
I also use spoke head washers and setting techniques to minimize the
movement.
And to Mark's comment on " The punch is snake oil, and can actually
damage the flange if over done."
... yes you could do damage to the flange if it is ovedone, but I
don't think we are talking about holding the hub in a vise or on an
anvil while hitting the puch with a metal hammer. I give the spoke
heads a solid strike with a properly aligned puch fron the blow of a
plastic headed hammer.

I have yet to find a hub with too small a hole to fit the roll threaded
end (2.25 mm) of a 14 g spoke through.
I have yet to find a hub where the flange is too thick.... even the 4.0
mm ones from Phil Wood.

I still don't think there is snake oil or even linseed oil involved
here.

I have not found it necessary to use setting tools other than my fingers,
bending the outbond spokes back against the hub. Your other remarks I agree
with.

Trevor

Trevor Jeffrey wrote:
Mark McMaster wrote in message ...

The idea that spokes "work harden and break" in use is a
common misconception by those who do not understand metal
fatigue. It is unfortunately common that the mechanisms of
wheel failure are not understood by wheelbuilding "experts".
Take for example this other nugget of wisdom in the web page:


Please explain how a spoke subjected to a rocking motion eventually fails
due to fatigue, preferably in ten words.

What rocking motion are you referring to? Spokes in a properly
tensioned wheel do not rock. Another straw man.

I suppose this goes back to the example you raised of
bending a paper clip until it breaks. Although that example
is often used it is not applicable to bicycle spokes. The
paper clip example involves repeated bending the spoke
plastically, well beyond its yield point (low cycle post
yield fatigue). That does not happen to spokes in a wheel,
which maintain an average stress well below their yield.

So, I guess we can add metal fatigue to the ever growing
list of mechanical concepts you don't understand. You
really should quit while you're behind.

Mark McMaster

carl- Are the washers and the punch common wheel-building
techniques, snake-oil, or what? BRBR

Not at all. Washers are an important tool when the hub flange holes are BIG,
like in first gen Powertap. And any wheelbuilder worth their salt ensures the
spoke head is flush, using a small punch.

Peter Chisholm
Vecchio's Bicicletteria
1833 Pearl St.
Boulder, CO, 80302
(303)440-3535
http://www.vecchios.com
"Ruote convenzionali costruite eccezionalmente bene"

On Sat, 21 Aug 2004 18:31:29 -0600,
wrote:

On Sat, 21 Aug 2004 19:21:33 -0400, John Dacey
wrote:

On Sat, 21 Aug 2004 16:02:08 -0600, wrote:

The more stable the elbow within the hub hole the less
likely it will "work harden" and break, a common cause of
spoke failure. Using a special punch, the builder sets the
spoke head in the hub hole to assure it is well seated and
won't move when the wheel is tensioned . . .

Are the washers and the punch common wheel-building
techniques, snake-oil, or what?

Unless there is a gross mis-match in the diameters of the holes in the
hubshell and the spokes inserted therein, such measures are described
by

"To gild refined gold, to paint the lily,
To throw a perfume on the violet,
To smooth the ice, or add another hue
Unto the rainbow, or with taper-light
To seek the beauteous eye of heaven to garnish,
Is wasteful and ridiculous excess."

King John. Act iv. Sc. 2.
Edward de Vere


-------------------------------
John Dacey

Dear Eddie,

Nonsense--anyone can see that you're actually Izaak Walton.

George B. Shaw

[This private email reply ensued . . .]

Sorry, you have me confused with the fella that wrote the
seventeenth century treatise on pedalling techniques, "The
Compleat Ankler".

Oxford

[. . . so I replied as follows . . .]

Dear John,

If you don't post this pun, I will.

Threateningly,

Carl Fogel

[ . . . and received this defiant anfwer . . .]

Do your worft, fir.

-------------------------------
John Dacey
Bufiness Cycles, Miami, Florida
http://www.businesscycles.com
Since 1983
Our catalog of track equipment: online since 1996
-------------------------------

On 22 Aug 2004 13:41:12 GMT, (Qui si parla
Campagnolo ) wrote:

carl- Are the washers and the punch common wheel-building
techniques, snake-oil, or what? BRBR

Not at all. Washers are an important tool when the hub flange holes are BIG,
like in first gen Powertap. And any wheelbuilder worth their salt ensures the
spoke head is flush, using a small punch.


Can you say more about this punch thing? It's new to me. First, what
exactly is being done? Is the spoke head reshaped? Are you seating the
bottom (flange) side of the spoke as the limit, or is the spoke head
sitting flush the limit? Maybe they are one and the same- flush outer
head and seated back side of head? Does this whole operation depend on
the hub being used- it's spoke hole size and shaping?

Second, what is accomplished by this punching in terms of spoke life
or wheel strength, life, whatever?

I don't mean to set off another engineering discussion on the
newsgroup, although it may happen. I ask because I know that you have
built lots of wheels and have a good reputation for actual wheel
building. And as I said, this punching thing is new to me.

Then again given some of the recent wheel discussions here, you are
joking about using a punch and I missed the reference....

Dan Daniel wrote:
Can you say more about this punch thing? It's new to me. First, what
exactly is being done?

Some wheel builders use this tool to get the spoke head flush with the
hub flange. Being an armature wheel builder I've never seen the need of
using one, but since reading this thread I think I will.

http://www.mcmaster.com/catalog/110/...e/3420ac1l.gif

Kenny Lee

On Sun, 22 Aug 2004 13:58:34 -0700, Dan Daniel
wrote:

Can you say more about this punch thing? It's new to me. First, what
exactly is being done?

To clarify- I do know what a punch is, and I know how to use one. What
I mean is that the use of a punch in wheelbuilding is new to me....

On Mon, 23 Aug 2004 10:44:48 +0800, Kenny Lee wrote:

Dan Daniel wrote:
Can you say more about this punch thing? It's new to me. First, what
exactly is being done?

Some wheel builders use this tool to get the spoke head flush with the
hub flange. Being an armature wheel builder I've never seen the need of
using one, but since reading this thread I think I will.


What in this thread has convinced you?

http://www.mcmaster.com/catalog/110/...e/3420ac1l.gif


Ok, thanks.... I do know what a punch is and how they are used in
general

Trevor Jeffrey wrote:

wrote in message ...


Well that's bogus. Spoke will not work harden in use although they
may fail from fatigue. I think it's old mechanics jargon and myth and
lore from the days when fatigue failures were routinely attributed to
"look the axle crystallized and broke here" when in fact a fatigue
failure always exposes the crystal structure because it is inter-grain
boundaries that fail most easily in a metal.

The use of the two words 'work harden' are a perfectly acceptable way in
which to describe what happens to a spoke which has been bent back and forth
a few million times so it is brittle. Then it snaps. The dislocations can
be seen with 20x magnification most usually on the outside of the fracture
but sometimes upon the inside also, dependent on setting, which show that
bending moments existed before fracture.

Work hardening: An increase in hardness and yield strength that is due
to plastic deformation.

Spokes do not get "bent back and forth" beyond yield during the normal
use of a wheel, and if they did they would typically fail somewhere
between 10 and 100 cycles, not a few million cycles.

Using the term "work hardening" as a synonym for "fatigue" is not
acceptable usage, and does not help your credibility.
--
Tom Sherman