correction for jobst

Howdy Mr beam!

jim beam said:

while reluctant to start an epic journey i have no intention of trying
to finish [that of correcting the whole jobstian catalog of errors] the
following is commentary on a topic recently debated, but which remains
uncorrected in the "faq's" and which continues to mislead casual readers.

I don't think this explanation of Brandt's why the stress relieving
process works is useful, but your criticism is quite acute. I suppose
the article criticized is intended to explain why the stress relieving
procedure works, but would not be much surprised to learn otherwise. I
think the process of stress relieving is well enough explained in Mr
Brandt's book and elsewhere, relating to the construction of bicycle
wheels.

Quoted message said:

from:
http://sheldonbrown.com/brandt/stress-relieving.html

Quoted message said:

From: Jobst Brandt Date: November 29, 1999

It appears that the process of stress relieving is obscure to many if
not most people, because after seeming to have made it clear,
comments like the above surface. Spokes are cold formed from wire
that is (at least DT) as hard and work hardened as it can become.

What comment?

Quoted message said:

not true. spoke wire, when fully hardened, is in the range 1,500Nmm^-2.
spoke wire when actually used in spokes is in the range 900/1,000Nmm^-2
in 2mm sections, and 1,100/1,300Nmm^-2 in the butted sections.

Are you saying that it's commercially feasible to produce harder
spokes, or that the wire softens a bit as it is processed? If the
latter, it's mox nix. If the former, that's interesting, could you
provide information on sources and prices?

Why does stress relieving work? Surfaces, including metal, are
irregular unless a crystal surface. Metals are crystalline, composed
of many tiny crystals. So they are irregular. The metal forming
process smoothes out to a large extent these irregularities, the layman
calls them smooth; but closer observation with a microscope reveals
irregularities, holes and projections. Particularlly near the elbow
bend, it's very difficult to polish these irregularities out. And the
holes in the hub and rim are going to be fun to remove irregularities
from.

So, as the wheel is brought near final tension and true, in some cases
these irregularities on the spoke and rim or hub catch each other, and
instead of the nipple rotating another eighth of a turn around the
spoke, the spoke twists. While this may to some extent produce the
desired shortening of the distance from hub to rim, it will shortly be
undone by the next sharp increase/decrease of tension upon that
particular spoke. The stress relieving procedure provides the tension
spike, the spoke returns to the untwisted state, a trifle longer, and
the wheel goes out of true. Another round of truing and stress
relieving seems indicated, and another, until satisfied.

Don't be evil. Eschew obfuscation.

Dale Benjamin

jim beam said:

while reluctant to start an epic journey i have no intention of trying
to finish [that of correcting the whole jobstian catalog of errors] the
following is commentary on a topic recently debated, but which remains
uncorrected in the "faq's" and which continues to mislead casual readers.

from:
http://sheldonbrown.com/brandt/stress-relieving.html

Quoted message said:

From: Jobst Brandt Date: November 29, 1999

It appears that the process of stress relieving is obscure to many if
not most people, because after seeming to have made it clear,
comments like the above surface. Spokes are cold formed from wire
that is (at least DT) as hard and work hardened as it can become.

not true. spoke wire, when fully hardened, is in the range 1,500Nmm^-2.
spoke wire when actually used in spokes is in the range 900/1,000Nmm^-2
in 2mm sections, and 1,100/1,300Nmm^-2 in the butted sections.

Quoted message said:

Tensioning does not further harden spokes, there being no plastic
deformation. Besides, wire ductility is important in both forming
spokes and in use.

that is true, but note that plastic deformation is required by
definition if there is to be "stress relief".

Quoted message said:

The coiled wire from which spokes are made is straightened by running
it first between rollers staggered in X and then in Y, the wire
moving in the Z direction.

true. it straightens the wire.

Quoted message said:

Reverse bending acts as a degausser,

"like", not "as". [something of a red herring.]

Quoted message said:

having ever diminishing excursions that affect ever shallower depths
of the wire. This stress relieves the wire while removing the curl of
being shipped in a coil.

can't say that. it straightens it for sure. whether any residual
stress is relieved is not shown.

Quoted message said:

If it had no curl, releasing its free end on
the spool would allow it to uncoil explosively into a huge birds
nest.

true, but irrelevant.

Quoted message said:

Wire is cut into suitable lengths, the first operation being to cold
form a spoke head onto one end with one axial blow of a die, after
which the spoke is cut to a specific length before rolling the thread
and bending a 100 degree elbow.

well, 95 degree, but let's not quibble.

Quoted message said:

Threads, head, and elbow, contain metal that was plastically deformed
(beyond yield) as well as metal that was elastically deformed, each
having elastic memory.

no, there is no "memory". there is elastic deformation and plastic
deformation.

Quoted message said:

In these transitions, parts that yielded and
ones that did not conflict, each wanting to return to or stay in a
different shape.

that's elasticity, not memory.

Quoted message said:

This is why a spoke bent by hand springs back only
partially when released.

that's because it was only partially deformed. the springback is due to
elasticity.

Quoted message said:

On lacing spokes into a wheel, elbows are often additionally bent
(brought to yield),

on the recommendation of that author...

Quoted message said:

thus remaining at or exceeding yield stress
during tensioning.

which is something spoke manufacturers recommend against.

Quoted message said:

Threads also have internal tensile stress besides
local compressive stress at the threads.

that would be residual stress from cold rolling the threads.

Quoted message said:

The thread core is already
in tension from the lengthening effect of thread rolling

thread rolling doesn't lengthen. if it did, threads would not "rise" to
greater diameter than the feed wire - which is precisely what happens.

Quoted message said:

and its
stress only increases with tensioning.

to some extent, but which is benign in practice. no statistically
significant number of fatigue cracks /ever/ initiate internally, so
increasing internal tension has no bearing on fatigue.

Quoted message said:

Therefore, spokes in a newly built wheel have locations where stress
is near yield, some more so than others.

if there's residual stress. but that is not shown, only presumed.

Quoted message said:

Because fatigue endurance of
a metal at or near the yield stress is short, cyclic loads in such
spokes will cause failures at high stress points.

in a simplistic level, that's true. however, fatigue cracks only
initiate at surface features like blemishes, "orange peel" and tiny
inclusions. regions where there maybe high residual stress are not the
regions of the spoke where fatigue initiates, therefore this simplistic
assumption does not hold.

Quoted message said:

In normal use, a
wheel only unloads spokes,

if you include "normal use" to mean *never* getting out of the saddle on
a hill. /that/ action means lateral loading on wheels which can
significantly /increase/ spoke tension, not just decrease it.

Quoted message said:

but with spokes near yield, even these
stress cycles readily cause fatigue failures.

true that higher stress cycling increases fatigue.

Quoted message said:

Only the lightest
riders on smooth roads might be spared failures with a wheel whose
spokes have not been stress relieved.

translation: "here be dragons." truth is, use of a name brand high
quality spoke will do more for fatigue life than any form of weight loss
program.

Quoted message said:

Stress relieving to relax these high stress points is accomplished by
over-stressing them in order to erase their memory.

there is no "memory". if there is residual stress, it's a local elastic
strain field. that is not a memory effect.

Quoted message said:

It is not done to
bed the spokes into the hub, as is often stated.

except that if it's not done, spokes continue to bed into the hub while
the wheel is first being ridden and the wheel quickly goes significantly
out of true.

Quoted message said:

Bedding-in occurs
sufficiently from tension.

incorrect. tension in spokes increases as well as decreases. it is
essential therefore to ensure that during the build, spokes are bedded
in at tension at or above that seen in service to prevent further
bedding in sending the wheel out of true.

Quoted message said:

However, stretching spoke pairs with a
strong grasp at midspan, can momentarily increased tension by 50% to
100%.

untrue due to rim distortion. actual measurements [carl fogel] show
spoke tension increase to be of the same magnitude as the force of
squeeze. a 110N [50lb] squeeze on a spoke tensioned to 1,000N will
increase tension in the order of 10%, not 100%.

[this is because the rim is not perfectly rigid. tension increase
causes the rim to distort thus bringing the two ends of the wire closer
together and so reducing the theoretical tension increase that could be
achieved.]

Quoted message said:

Because spokes are usually tensioned no higher than 1/3 their
yield stress, this operation has no effect on the spoke as a whole,
affecting only the small high stress zones where spokes are near
yield. By stretching them, these zones relax below yield by as much
as the overload.

incorrect. plastic deformation is only that which occurs above the
hookes law region of the stress/strain graph. a material fundamentally
cannot relax below yield from yield alone - only relaxation of the
applied stress can achieve that.

Quoted message said:

Stress relieving with a light grasp of spoke pairs is worthless,

which may be true, but it's unproven, as is squeezing with a stronger grasp!

Quoted message said:

as
is bouncing the wheel or bending it in a partially opened drawer.
Pressing axially on the hub, while supporting the rim, requires a
force larger than is manually possible but is effective for spoking
machines (except the left side rear spokes that would collapse the
rim).

this operation does /not/ collapse the rim. [this touches on the
misconception that wheels collapse when spokes go slack - they don't,
only when local loading in the rim goes above yield. spoke slackness
alone can't achieve that.]

Quoted message said:

Another not recommend method, is laying the wheel on the floor
and walking on it with tennis shoes, carefully stepping on each pair
of crossed spokes. The method works but bends the rim and is
difficult to control.

it only bends the rim if excess force is used, or the rim is close to
buckling due to spoke tension being too high.

the best method is to press the axle of the hub against a block of wood
while grasping two opposite sides of the rim, rotating a little, then
repeating until all spokes have been seated. repeat as necessary as the
wheel is progressively tensioned to manufacturer spec and trued.

Quoted message said:

It is STRESS RELIEVING! Even though people insist on calling it
pre-stressing or seating-in.

the only demonstrated effect is seating in - it's visible on wheel
disassembly. testing to prove any assertion about residual stress or
its relief has not been performed. indeed, recent testing [carl fogel]
indicates that any residual stress in a spoke is relieved at tension
levels significantly below that of the initial wheel build. the process
called "stress relief" therefore /cannot/ be achieving anything more
than spoke seating.

Quoted message said:

The wheel is already prestressed when
tensioned.

yes, but that's a red herring - it's applied stress, not residual stress.

Hey, Bro-

Do you realize, with every new message, how closely you associate
yourself with Jobst?

If you have something independent to say, go write yourself a book.

Nicholas

Nicholas Grieco said:

jim beam said:

while reluctant to start an epic journey i have no intention of trying
to finish [that of correcting the whole jobstian catalog of errors] the
following is commentary on a topic recently debated, but which remains
uncorrected in the "faq's" and which continues to mislead casual readers.

from:
http://sheldonbrown.com/brandt/stress-relieving.html

Quoted message said:

From: Jobst Brandt Date: November 29, 1999

It appears that the process of stress relieving is obscure to many if
not most people, because after seeming to have made it clear,
comments like the above surface. Spokes are cold formed from wire
that is (at least DT) as hard and work hardened as it can become.

not true. spoke wire, when fully hardened, is in the range 1,500Nmm^-2.
spoke wire when actually used in spokes is in the range 900/1,000Nmm^-2
in 2mm sections, and 1,100/1,300Nmm^-2 in the butted sections.

Quoted message said:

Tensioning does not further harden spokes, there being no plastic
deformation. Besides, wire ductility is important in both forming
spokes and in use.

that is true, but note that plastic deformation is required by
definition if there is to be "stress relief".

Quoted message said:

The coiled wire from which spokes are made is straightened by running
it first between rollers staggered in X and then in Y, the wire
moving in the Z direction.

true. it straightens the wire.

Quoted message said:

Reverse bending acts as a degausser,

"like", not "as". [something of a red herring.]

Quoted message said:

having ever diminishing excursions that affect ever shallower depths
of the wire. This stress relieves the wire while removing the curl of
being shipped in a coil.

can't say that. it straightens it for sure. whether any residual
stress is relieved is not shown.

Quoted message said:

If it had no curl, releasing its free end on
the spool would allow it to uncoil explosively into a huge birds
nest.

true, but irrelevant.

Quoted message said:

Wire is cut into suitable lengths, the first operation being to cold
form a spoke head onto one end with one axial blow of a die, after
which the spoke is cut to a specific length before rolling the thread
and bending a 100 degree elbow.

well, 95 degree, but let's not quibble.

Quoted message said:

Threads, head, and elbow, contain metal that was plastically deformed
(beyond yield) as well as metal that was elastically deformed, each
having elastic memory.

no, there is no "memory". there is elastic deformation and plastic
deformation.

Quoted message said:

In these transitions, parts that yielded and
ones that did not conflict, each wanting to return to or stay in a
different shape.

that's elasticity, not memory.

Quoted message said:

This is why a spoke bent by hand springs back only
partially when released.

that's because it was only partially deformed. the springback is due to
elasticity.

Quoted message said:

On lacing spokes into a wheel, elbows are often additionally bent
(brought to yield),

on the recommendation of that author...

Quoted message said:

thus remaining at or exceeding yield stress
during tensioning.

which is something spoke manufacturers recommend against.

Quoted message said:

Threads also have internal tensile stress besides
local compressive stress at the threads.

that would be residual stress from cold rolling the threads.

Quoted message said:

The thread core is already
in tension from the lengthening effect of thread rolling

thread rolling doesn't lengthen. if it did, threads would not "rise" to
greater diameter than the feed wire - which is precisely what happens.

Quoted message said:

and its
stress only increases with tensioning.

to some extent, but which is benign in practice. no statistically
significant number of fatigue cracks /ever/ initiate internally, so
increasing internal tension has no bearing on fatigue.

Quoted message said:

Therefore, spokes in a newly built wheel have locations where stress
is near yield, some more so than others.

if there's residual stress. but that is not shown, only presumed.

Quoted message said:

Because fatigue endurance of
a metal at or near the yield stress is short, cyclic loads in such
spokes will cause failures at high stress points.

in a simplistic level, that's true. however, fatigue cracks only
initiate at surface features like blemishes, "orange peel" and tiny
inclusions. regions where there maybe high residual stress are not the
regions of the spoke where fatigue initiates, therefore this simplistic
assumption does not hold.

Quoted message said:

In normal use, a
wheel only unloads spokes,

if you include "normal use" to mean *never* getting out of the saddle on
a hill. /that/ action means lateral loading on wheels which can
significantly /increase/ spoke tension, not just decrease it.

Quoted message said:

but with spokes near yield, even these
stress cycles readily cause fatigue failures.

true that higher stress cycling increases fatigue.

Quoted message said:

Only the lightest
riders on smooth roads might be spared failures with a wheel whose
spokes have not been stress relieved.

translation: "here be dragons." truth is, use of a name brand high
quality spoke will do more for fatigue life than any form of weight loss
program.

Quoted message said:

Stress relieving to relax these high stress points is accomplished by
over-stressing them in order to erase their memory.

there is no "memory". if there is residual stress, it's a local elastic
strain field. that is not a memory effect.

Quoted message said:

It is not done to
bed the spokes into the hub, as is often stated.

except that if it's not done, spokes continue to bed into the hub while
the wheel is first being ridden and the wheel quickly goes significantly
out of true.

Quoted message said:

Bedding-in occurs
sufficiently from tension.

incorrect. tension in spokes increases as well as decreases. it is
essential therefore to ensure that during the build, spokes are bedded
in at tension at or above that seen in service to prevent further
bedding in sending the wheel out of true.

Quoted message said:

However, stretching spoke pairs with a
strong grasp at midspan, can momentarily increased tension by 50% to
100%.

untrue due to rim distortion. actual measurements [carl fogel] show
spoke tension increase to be of the same magnitude as the force of
squeeze. a 110N [50lb] squeeze on a spoke tensioned to 1,000N will
increase tension in the order of 10%, not 100%.

[this is because the rim is not perfectly rigid. tension increase
causes the rim to distort thus bringing the two ends of the wire closer
together and so reducing the theoretical tension increase that could be
achieved.]

Quoted message said:

Because spokes are usually tensioned no higher than 1/3 their
yield stress, this operation has no effect on the spoke as a whole,
affecting only the small high stress zones where spokes are near
yield. By stretching them, these zones relax below yield by as much
as the overload.

incorrect. plastic deformation is only that which occurs above the
hookes law region of the stress/strain graph. a material fundamentally
cannot relax below yield from yield alone - only relaxation of the
applied stress can achieve that.

Quoted message said:

Stress relieving with a light grasp of spoke pairs is worthless,

which may be true, but it's unproven, as is squeezing with a stronger grasp!

Quoted message said:

as
is bouncing the wheel or bending it in a partially opened drawer.
Pressing axially on the hub, while supporting the rim, requires a
force larger than is manually possible but is effective for spoking
machines (except the left side rear spokes that would collapse the
rim).

this operation does /not/ collapse the rim. [this touches on the
misconception that wheels collapse when spokes go slack - they don't,
only when local loading in the rim goes above yield. spoke slackness
alone can't achieve that.]

Quoted message said:

Another not recommend method, is laying the wheel on the floor
and walking on it with tennis shoes, carefully stepping on each pair
of crossed spokes. The method works but bends the rim and is
difficult to control.

it only bends the rim if excess force is used, or the rim is close to
buckling due to spoke tension being too high.

the best method is to press the axle of the hub against a block of wood
while grasping two opposite sides of the rim, rotating a little, then
repeating until all spokes have been seated. repeat as necessary as the
wheel is progressively tensioned to manufacturer spec and trued.

Quoted message said:

It is STRESS RELIEVING! Even though people insist on calling it
pre-stressing or seating-in.

the only demonstrated effect is seating in - it's visible on wheel
disassembly. testing to prove any assertion about residual stress or
its relief has not been performed. indeed, recent testing [carl fogel]
indicates that any residual stress in a spoke is relieved at tension
levels significantly below that of the initial wheel build. the process
called "stress relief" therefore /cannot/ be achieving anything more
than spoke seating.

Quoted message said:

The wheel is already prestressed when
tensioned.

yes, but that's a red herring - it's applied stress, not residual stress.

Hey, Bro-

Do you realize, with every new message, how closely you associate
yourself with Jobst?

If you have something independent to say, go write yourself a book.

Nicholas

Why should he write a book? He's relying on well-established
principles that any anonymous engineer with a broken shift key can
understand.

-Vee

dalebenjamin said:

Howdy Mr beam!

jim beam said:

while reluctant to start an epic journey i have no intention of trying
to finish [that of correcting the whole jobstian catalog of errors] the
following is commentary on a topic recently debated, but which remains
uncorrected in the "faq's" and which continues to mislead casual readers.

I don't think this explanation of Brandt's why the stress relieving
process works is useful, but your criticism is quite acute. I suppose
the article criticized is intended to explain why the stress relieving
procedure works, but would not be much surprised to learn otherwise. I
think the process of stress relieving is well enough explained in Mr
Brandt's book and elsewhere, relating to the construction of bicycle
wheels.

the physical procedure is described, but the theory proposed is based on
a number of gross misconceptions.

Quoted message said:

Quoted message said:

from:
http://sheldonbrown.com/brandt/stress-relieving.html

Quoted message said:

From: Jobst Brandt Date: November 29, 1999

It appears that the process of stress relieving is obscure to many if
not most people, because after seeming to have made it clear,
comments like the above surface. Spokes are cold formed from wire
that is (at least DT) as hard and work hardened as it can become.

What comment?

Quoted message said:

not true. spoke wire, when fully hardened, is in the range 1,500Nmm^-2.
spoke wire when actually used in spokes is in the range 900/1,000Nmm^-2
in 2mm sections, and 1,100/1,300Nmm^-2 in the butted sections.

Are you saying that it's commercially feasible to produce harder
spokes, or that the wire softens a bit as it is processed? If the
latter, it's mox nix. If the former, that's interesting, could you
provide information on sources and prices?

no dude, metal becomes harder as it gets cold worked, including spoke
wire. it is not "as hard and work hardened as it can become" as the
numbers indicate. if the wire were fully hardened, then subject to
processing, it would not have sufficient ductility to sustain any
additional work and would effectively be brittle in use.

Quoted message said:

Why does stress relieving work? Surfaces, including metal, are
irregular unless a crystal surface. Metals are crystalline, composed
of many tiny crystals. So they are irregular. The metal forming
process smoothes out to a large extent these irregularities, the layman
calls them smooth; but closer observation with a microscope reveals
irregularities, holes and projections. Particularlly near the elbow
bend, it's very difficult to polish these irregularities out. And the
holes in the hub and rim are going to be fun to remove irregularities
from.

eh?

Quoted message said:

So, as the wheel is brought near final tension and true, in some cases
these irregularities on the spoke and rim or hub catch each other, and
instead of the nipple rotating another eighth of a turn around the
spoke, the spoke twists. While this may to some extent produce the
desired shortening of the distance from hub to rim, it will shortly be
undone by the next sharp increase/decrease of tension upon that
particular spoke. The stress relieving procedure provides the tension
spike, the spoke returns to the untwisted state, a trifle longer, and
the wheel goes out of true. Another round of truing and stress
relieving seems indicated, and another, until satisfied.

you're confused.

Quoted message said:

Don't be evil. Eschew obfuscation.

Dale Benjamin

In article <[email hidden]>,

jim beam said:

while reluctant to start an epic journey i have no intention of
trying to finish [that of correcting the whole jobstian catalog of
errors]

[censored], jim. You have dedicated your existence in this newsgroup for
years to being Jobst's gadfly.

Tim McNamara said:

In article <[email hidden]>,

jim beam said:

while reluctant to start an epic journey i have no intention of
trying to finish [that of correcting the whole jobstian catalog of
errors]

[censored], jim. You have dedicated your existence in this newsgroup for
years to being Jobst's gadfly.

don't tell me, let me guess the contents of your library:

1. the earth is flat - roger meinsensible
2. my mind is closed - i. r. ignorant
3. i love smoke up my kilt - gill t. perv
4. er, that's it.

"dalebenjamin" <[email hidden]> wrote in message
news:[email hidden]...

(snip)
....

Quoted message said:

latter, it's mox nix

....

Quoted message said:

Dale Benjamin

Es macht nichts!

Cal

jim beam said:

dalebenjamin said:

Howdy Mr beam!

jim beam said:

while reluctant to start an epic journey i have no intention of trying
to finish [that of correcting the whole jobstian catalog of errors] the
following is commentary on a topic recently debated, but which remains
uncorrected in the "faq's" and which continues to mislead casual readers.

I don't think this explanation of Brandt's why the stress relieving
process works is useful, but your criticism is quite acute. I suppose
the article criticized is intended to explain why the stress relieving
procedure works, but would not be much surprised to learn otherwise. I
think the process of stress relieving is well enough explained in Mr
Brandt's book and elsewhere, relating to the construction of bicycle
wheels.

the physical procedure is described, but the theory proposed is based on
a number of gross misconceptions.

I thnk the theory is based upon a number of somethings better left
unmentioned. Theory, hypothesis, better left unmentioned.

Quoted message said:

Quoted message said:

Quoted message said:

from:
http://sheldonbrown.com/brandt/stress-relieving.html

> From: Jobst Brandt Date: November 29, 1999
>
> It appears that the process of stress relieving is obscure to many if
> not most people, because after seeming to have made it clear,
> comments like the above surface. Spokes are cold formed from wire
> that is (at least DT) as hard and work hardened as it can become.

What comment?

Is any comment to be regarded as doubt of a supposed revealed truth?
While it's clear enough to me that Mr. Brandt anguished over every word
and letter of the book, that is far from sufficient grounds to imagine
the book already perfect.

Quoted message said:

Quoted message said:

Quoted message said:

not true. spoke wire, when fully hardened, is in the range 1,500Nmm^-2.
spoke wire when actually used in spokes is in the range 900/1,000Nmm^-2
in 2mm sections, and 1,100/1,300Nmm^-2 in the butted sections.

Are you saying that it's commercially feasible to produce harder
spokes, or that the wire softens a bit as it is processed? If the
latter, it's mox nix. If the former, that's interesting, could you
provide information on sources and prices?

no dude, metal becomes harder as it gets cold worked, including spoke
wire. it is not "as hard and work hardened as it can become" as the
numbers indicate. if the wire were fully hardened, then subject to
processing, it would not have sufficient ductility to sustain any
additional work and would effectively be brittle in use.

So it es macht nichts, not practical to produce harder spokes that
would be workable. Pardon my less than engineering school use of terms
like 'hardness'.

Quoted message said:

Quoted message said:

Why does stress relieving work? Surfaces, including metal, are
irregular unless a crystal surface. Metals are crystalline, composed
of many tiny crystals. So they are irregular. The metal forming
process smoothes out to a large extent these irregularities, the layman
calls them smooth; but closer observation with a microscope reveals
irregularities, holes and projections. Particularlly near the elbow
bend, it's very difficult to polish these irregularities out. And the
holes in the hub and rim are going to be fun to remove irregularities
from.

eh?

The reason the stress relieving procedure is effective is that metal
surfaces, although appearing smooth to the unaided eye, are not
perfectly smooth, as the surface of a crystal is. Metals are
crystalline, composed of many tiny crystals. So they are irregular.
The metal forming processes smoothes out to a large extent these
irregularities, the layman calls them smooth; but closer observation
with a microscope reveals irregularities, holes and projections.

The nipple and spoke are subject to catch, the spoke twists with the
nipple, rather than remaining straight.

Quoted message said:

Quoted message said:

So, as the wheel is brought near final tension and true, in some cases
these irregularities on the spoke and rim or hub catch each other, and
instead of the nipple rotating another eighth of a turn around the
spoke, the spoke twists. While this may to some extent produce the
desired shortening of the distance from hub to rim, it will shortly be
undone by the next sharp increase/decrease of tension upon that
particular spoke. The stress relieving procedure provides the tension
spike, the spoke returns to the untwisted state, a trifle longer, and
the wheel goes out of true. Another round of truing and stress
relieving seems indicated, and another, until satisfied.

you're confused.

Yes, we're all confused, mad to some extent. The comment does little
to clarify areas of disagreement. An instant of entire clarity of mind
is more often regarded as pathological than the contrary.

Dale Benjamin

In article <[email hidden]>,

dalebenjamin said:

I thnk the theory is based upon a number of somethings better left
unmentioned. Theory, hypothesis, better left unmentioned.

I think that you had better do some more research into the debates
before you plunge into this and plow old ground all over again. This has
been discussed to death hundreds of times in this newsgroup. jim beam
is more bulldog like than most, having an unhealthy obsession with
bringing Jobst down a peg or two, but as of yet he has failed to prove
his criticisms. It's always interesting to me that the other mechanical
engineers in this newsgroup don't agree with jim, but he never notices.