Screw and other Threads
Jobst Brandt
symbol of mechanical ineptness in the bicycle industry. This syndrome
is found elsewhere in bicycles. We had that subject a while back when
I mentioned that not even the REMA Tip-Top patch representative knew
why one sand papers a tube before patching. The purpose is to REMOVE
the skin of the inner tube because as should be apparent, tubes ate
made in molds that cause the fine ridges on their surface. These are
caused by the molds in which they are formed,
How does one get a new inner tube out of the mold in which it was hot
formed? The method is to spray the interior of the mold with
mold-release agent before making the next tube. The reason for that is
that each tube takes a large portion of the mold-release with it into
the package in which it is sold.
Sandpaper is used to scrub ff the skin of the inner tube so that the
patch will not "mold-release" in use. When I told this to the Rema
man at InterBike he said I was wrong and that the purpose was to
roughen the rubber to improve adhesion, after which he applied a Rema
patch without sandpaper action, rolled the patch on firmly, and handed
the tube to me. I immediately handed him back the poorly adhered
patch and his jaw dropped as though I was performing magic.
That is classic for the bicycle industry other than Shimano and few
others. I don't believe Regina knew why their used freewheel
sprockets skipped when a new chain was installed. Trying to explain
that might be even more difficult than the Rema technical discussion.
After all that's one technical step farther than mold-release, being
in the realm of threads and heat treatment.
Jobst Brandt
Jobst Brandt
symbol of mechanical ineptness in the bicycle industry. This syndrome
is found elsewhere in bicycles. We had that subject a while back when
I mentioned that not even the REMA Tip-Top patch representative knew
why one sand papers a tube before patching. The purpose is to REMOVE
thirty-six
You're day-dreaming again.
DirtRoadie
> This "tread" goes farther than screw threads, but they are a practical
> symbol of mechanical ineptness in the bicycle industry. This syndrome
> is found elsewhere in bicycles. We had that subject a while back when
> I mentioned that not even the REMA Tip-Top patch representative knew
> why one sand papers a tube before patching. The purpose is to REMOVE
> the skin of the inner tube because as should be apparent, tubes ate
> made in molds that cause the fine ridges on their surface. These are
> caused by the molds in which they are formed,
>
> How does one get a new inner tube out of the mold in which it was hot
> formed? The method is to spray the interior of the mold with
> mold-release agent before making the next tube. The reason for that is
> that each tube takes a large portion of the mold-release with it into
> the package in which it is sold.
>
> Sandpaper is used to scrub ff the skin of the inner tube so that the
> patch will not "mold-release" in use. When I told this to the Rema
> man at InterBike he said I was wrong and that the purpose was to
> roughen the rubber to improve adhesion, after which he applied a Rema
> patch without sandpaper action, rolled the patch on firmly, and handed
> the tube to me. I immediately handed him back the poorly adhered
> patch and his jaw dropped as though I was performing magic.
Frankly I was not aware that you had invented rubber, tubes and patch
kits.
OK, True or false. REMA recommends taking some action prior to
applying glue in order to improve the ability of the glue and patch to
adhere. What they have always recommended is abrading the surface. You
acknowledge that this is desirable and works although you also claim
that you can pull off such a patch immediately after application. So?
You have stated in this group that a patch should not be ridden
immediately after it is applied, but that it becomes nearly impossible
to remove after some curing time.
That has been my experience as well and I, long ago, began using
solvent such as toluene to prepare a tube for patching to accomplish
exactly what you describe.
That a REMA sales rep (you didn't say "REMA engineer" or REMA Product
designer" did you?) did not fully understand what was happening should
be of little surprise. A "sales rep" is just that. I would not expect
a salesman on the floor of a Porsche dealership to have the knowledge
of the Porsche engineers either. Nor would a 7-11 clerk be expected to
understand the technology of a Slurpee machine, even if he was the
company's leading Slupree salesman.
I'm a little surprised that you would expect a sales rep for a tire
patch manufacturer to be a technical wizard. How long have REMA tire
patches been around and how many many engineers do you suppose REMA
presently has on staff for product development?
Jobst give us a break. Don't knock down straw men to assert your
superiority. You have some information to share but trying to
demonstrate that you are more technically knowledgeable that a patch
salesman hardly embellishes your credibility.
I am listening to what you have to say about threads but even there
I'm seeing some assertions that I have difficulty with. You refer to
"theads carrying radial loads" and also to wheel lug nuts that would
loosen on old vehicles. Please explain if I'm wrong, but prior to
having conical seats, lug nuts were just flat nuts and the threads
themselves carried NO radial loads. The nut merely clamped the wheel
snugly up against the hub.
DR
thirty-six
And the cycle pedal axle thread clamps the boss against the crank,
simple. Bending loads within the threads are avoided when the axle is
tight enough. There is no undoing or crank eye failure when
everything is TIGHT.
Tom Sherman °_°
> [...]
> Frankly I was not aware that you had invented rubber, tubes and patch
Jobst invented the wheel.
--
Tom Sherman - 42.435731,-83.985007
I am a vehicular cyclist.
DirtRoadie
Well, that is partially what I wanted to have Jobst address. Simple
example: a nut turning on a bolt has obvious play, both radial and
axial. Thread two nuts snugly against one another and any play, radial
OR axial disappears. That does not fit with the Jobstian hypothesis of
threads.
Mike J. suggested that poor adjustment accounts for bearing wear in
threaded headsets. I'll certainly buy that.
Jobst has not yet described the mechanism by which there can
"fretting" wear in a threaded headest which would not also occur in a
threadless headset, aside from the fact that a threadless headset is
more like to be properly adjusted.
A "locked" threaded assembly has threads butted solidly against one
another and prevents radial movement regardless of whether the locking
is via a threaded lockring or a split clamping nut. Both accomplish
exactly the same function of "binding" the threads frictionally.
To simplify - the concept of threads having "clearance" is red
herring with no meaning when a threaded assembly is tightened with
some measure of torque, i.e. there is NO clearance between the
respective mating helical surfaces of the threads.
DR
thirty-six
"Left hand threads are evil and must be destroyed"
> Mike J. suggested that poor adjustment accounts for bearing wear in
> threaded headsets. I'll certainly buy that.
It doesn't help, but it is essentially due to the improper selection
of lubricant. The very low speeds and high loads of wheel and headset
bearings mean that just slapping in any old grease simply will not
do. The grease basically needs to be oozing out of the headset
bearing and at least close to with the wheels otherwise excessive wear
results.
>
> Jobst has not yet described the mechanism by which there can
> "fretting" wear in a threaded headest which would not also occur in a
> threadless headset, aside from the fact that a threadless headset is
> more like to be properly adjusted.
Yeah, but the REMA guy and the ancients and Jobst is number one at
everything, nobody but him as ever studied a bicycle wheel or been
clever enough to put a chamfer on an internal threading to prevent
cracking. (He knows not what he has done for he complicates it.)
>
> A "locked" threaded assembly has threads butted solidly against one
> another and prevents radial movement regardless of whether the locking
> is via a threaded lockring or a split clamping nut. Both accomplish
> exactly the same function of "binding" the threads frictionally.
>
> To simplify - the concept of threads having "clearance" is red
> herring with no meaning when a threaded assembly is tightened with
> some measure of torque, i.e. there is NO clearance between the
> respective mating helical surfaces of the threads.
Except when you use a grease with a heavy filler as the lubricant.
>
> DR
thirty-six
wrote:
> On 9/10/2010 10:28 PM, DirtRoadie ? wrote:
>
> > [...]
> > Frankly I was not aware that you had invented rubber, tubes and patch
> > kits.[...]
>
> Jobst invented the wheel.
If you mean tension/suspension wheel that'll be Bauer (US) or Cayley
or Donkin (UK), take your preference.
Jobst Brandt
>> This "tread" goes farther than screw threads, but they are a practical
>> symbol of mechanical ineptness in the bicycle industry. This syndrome
>> is found elsewhere in bicycles. We had that subject a while back when
>> I mentioned that not even the REMA Tip-Top patch representative knew
>> why one sand papers a tube before patching. The purpose is to REMOVE
>> the skin of the inner tube because as should be apparent, tubes ate
>> made in molds that cause the fine ridges on their surface. These are
>> caused by the molds in which they are formed,
>> How does one get a new inner tube out of the mold in which it was hot
>> formed? The method is to spray the interior of the mold with
>> mold-release agent before making the next tube. The reason for that is
>> that each tube takes a large portion of the mold-release with it into
>> the package in which it is sold.
>> Sandpaper is used to scrub ff the skin of the inner tube so that the
>> patch will not "mold-release" in use. When I told this to the Rema
>> man at InterBike he said I was wrong and that the purpose was to
>> roughen the rubber to improve adhesion, after which he applied a Rema
>> patch without sandpaper action, rolled the patch on firmly, and handed
>> the tube to me. I immediately handed him back the poorly adhered
>> patch and his jaw dropped as though I was performing magic.
> Frankly I was not aware that you had invented rubber, tubes and patch
> kits.
What gave you that notion?
> OK, True or false. REMA recommends taking some action prior to
> applying glue in order to improve the ability of the glue and patch
> to adhere. What they have always recommended is abrading the
> surface. You acknowledge that this is desirable and works although
> you also claim that you can pull off such a patch immediately after
> application. So? You have stated in this group that a patch should
> not be ridden immediately after it is applied, but that it becomes
> nearly impossible to remove after some curing time.
The Rema man claimed that when he put on a patch, it was on for good
and that the sand paper was there to roughen the surface. Neither is
true and my manually pulling off his patch and giving it to him was a
surprise to him. Some tire patch kits have a solvent to remove mold
release,. Something that was added when roughening the surface failed
to make patches stick. I explained to the REMA man how a cured patch
can be removed, something I put on the FAQ back then. They cannot be
take off by trying to peel then at room temperature.
> That has been my experience as well and I, long ago, began using
> solvent such as toluene to prepare a tube for patching to accomplish
> exactly what you describe.
You'll notice that various patch makers offer a cheese grater metal to
roughen the tube, not remove the skin, the action that is necessary to
make an air tight patch. Patches attached to "roughened" inner tubes
often leak shortly after, something that was apparent at the many tire
patch sessions held Wednesday evenings at my house by local bikies.
> That a REMA sales rep (you didn't say "REMA engineer" or REMA
> Product designer" did you?) did not fully understand what was
> happening should be of little surprise. A "sales rep" is just that.
> I would not expect a salesman on the floor of a Porsche dealership
> to have the knowledge of the Porsche engineers either. Nor would a
> 7-11 clerk be expected to understand the technology of a Slurpee
> machine, even if he was the company's leading Slupree salesman.
He represents REMA at the trade show to instruct dealers how to tell
their customers ho it is done. I don't suspect they sent their
dumbest man and besides, what he said is in their literature that is
offered with their patch kit. There is apparently no one at home
there, engineers apparently having long ago gone elsewhere.
> I'm a little surprised that you would expect a sales rep for a tire
> patch manufacturer to be a technical wizard. How long have REMA
> tire patches been around and how many many engineers do you suppose
> REMA presently has on staff for product development? Jobst give us
> a break. Don't knock down straw men to assert your superiority.
> You have some information to share but trying to demonstrate that
> you are more technically knowledgeable that a patch salesman hardly
> embellishes your credibility.
If I understand you, you think a representative of REMA should not be
expected to understand tire patching. As always there is someone on
wreck.bike who comes to the defense of the bicycle industry when a
blunder is discovered.
> I am listening to what you have to say about threads but even there
> I'm seeing some assertions that I have difficulty with. You refer to
> "theads carrying radial loads" and also to wheel lug nuts that would
> loosen on old vehicles. Please explain if I'm wrong, but prior to
> having conical seats, lug nuts were just flat nuts and the threads
> themselves carried NO radial loads. The nut merely clamped the wheel
> snugly up against the hub.
Wheel rotation around the stud on which it was mounted exerted enough
radial motion to unscrew the flat nut and release the wheel, even
though it was believed that a "properly" tightened set of lug nuts
would hold the wheel. If you do not see the fallacy in that
assessment, then you don't understand why we have conical lug nuts
today without left hand threads on left wheels of cars and trucks (as
they were in the 1950's).
> DR
--
Jobst Brandt
Jobst Brandt
There is a difference between inventing and understanding a process.
I see that escaped you in your education.
>> And the cycle pedal axle thread clamps the boss against the crank,
>> simple. Bending loads within the threads are avoided when the axle
>> is tight enough. There is no undoing or crank eye failure when
>> everything is TIGHT.
I guess you think that large collection of failed aluminum cranks that
is shown here often, was all done by unskilled bicycle mechanics. I
think you should look elsewhere for the cause of these failures and
the reason for left hand threads on left cranks. If you doubt it, try
a tandem shop where the cranks had to be reversed to make sure they
didn't unscrew themselves by precession.
> Well, that is partially what I wanted to have Jobst address. Simple
> example: a nut turning on a bolt has obvious play, both radial and
> axial. Thread two nuts snugly against one another and any play,
> radial OR axial disappears. That does not fit with the Jobstian
> hypothesis of threads.
Where to you see these double nutted applications? Even double nutted
shafts with radial loads cause precession, the threads being one-way.
> Mike J. suggested that poor adjustment accounts for bearing wear in
> threaded headsets. I'll certainly buy that.
Look a bit closer. When you see a fork vibrating fore and aft on a
roughly paved asphalt road, the most flexible part of the fork is the
steer tube between the two head bearings and that flexing, yaws the
20-ball ball-bearing crosswise to its steering rotation... and it does
so in small fretting motion that welds the races to the balls.
That this is fretting motion is shown by the milky finish of the ball
dimples in the inner and outer race. Brinell dents are shiny while
these are not because they are made by a million welds and breaks that
tear out tiny flaws. You'll note that the dimples that cause "indexed
steering" are in the fore and aft quadrant of the races and on both
upper and lower bearings.
> Jobst has not yet described the mechanism by which there can
> "fretting" wear in a threaded headest which would not also occur in a
> threadless headset, aside from the fact that a threadless headset is
> more like to be properly adjusted.
New Shimano threadless head bearings have an approximate conical
contact outside of the ball bearing that is free to swivel while the
ball bearing is a pre-loaded angular contact bearing that cannot
articulate crosswise. This should be apparent because it cannot be
disassembled manually.
> A "locked" threaded assembly has threads butted solidly against one
> another and prevents radial movement regardless of whether the locking
> is via a threaded lockring or a split clamping nut. Both accomplish
> exactly the same function of "binding" the threads frictionally.
That may be your impression, but radial motion from loads will still
cause elastic fretting motion, and as I mentioned, threads are soft
because they cannot be hardened.
> To simplify - the concept of threads having "clearance" is red
> herring with no meaning when a threaded assembly is tightened with
> some measure of torque, i.e. there is NO clearance between the
> respective mating helical surfaces of the threads.
If that is so, then why do conical lug nuts no longer allow wheels to
fall off? Also why do left pedals require a left hand thread to
remain secure.
--
Jobst Brandt
Keiron
".... after which he applied a Rema patch without
sandpaper action.... "
Taken in isolation, this still means he went against his own advice of
'roughening' the tube [prior to installing the patch], probably through
the bravado in trying to prove the point. The fact you could then remove
the patch neither proves your or his hypothesis.
David Scheidt
:threads are soft
:because they cannot be hardened.
I don't care how many times you say this, it still won't be true.
There are all sorts of threads that are hardened.
--
sig 7
Jobst Brandt
>> threads are soft because they cannot be hardened.
> I don't care how many times you say this, it still won't be true.
> There are all sorts of threads that are hardened.
Please give some examples. Attempting to heat treat a thread will
glow its apex while under heating the root. This causes the apex of a
thread to crack while the base remains soft. Therefore, threads are
not heat treated as the Regina FW sprockets clearlydemonstrate as they
deform and wear at tooth faces where the chain bears. This causes
chain skip with a new, in-pitch, chain.
Just in case, you could also try a crude hardness test by placing a
ball bearing on the flat side of a Regina and Shimano sprockets and
strike it with a small hammer to cause a Brinell indentation, the
classic hardness test. I think you'll readily see that the Regina
gets a classic Brinell dimple while the Shimano remains smooth.
Jobst Brandt
David Scheidt
:David Scheidt wrote:
:>> threads are soft because they cannot be hardened.
:> I don't care how many times you say this, it still won't be true.
:> There are all sorts of threads that are hardened.
:Please give some examples. Attempting to heat treat a thread will
ASTM A193 covers a bunch.
Your neighborhood hardware store has boxes of self-tapping machine
screws; they're nearly universally case hardened. They need to hardened
threads to drill, but would be too brittle to drive if the entire
material were hardened. Post thread forming hardening makes them
possible.
Power screw threads are often hardened. Got a vice? I bet it's lead
screws are hardened. Even crappy chinese C-clamps have hardened
screws.
:glow its apex while under heating the root. This causes the apex of a
:thread to crack while the base remains soft. Therefore, threads are
:not heat treated as the Regina FW sprockets clearlydemonstrate as they
:deform and wear at tooth faces where the chain bears. This causes
:chain skip with a new, in-pitch, chain.
That some particular thread isn't heat treated is not evidence that no
thread is.
--
sig 85
Frank Krygowski
>
>
> Wheel rotation around the stud on which it was mounted exerted enough
> radial motion to unscrew the flat nut and release the wheel, even
> though it was believed that a "properly" tightened set of lug nuts
> would hold the wheel. If you do not see the fallacy in that
> assessment, then you don't understand why we have conical lug nuts
> today without left hand threads on left wheels of cars and trucks (as
> they were in the 1950's).
Or as late as 1960, at least in the case of the Fiat sedan I then
drove. Definitely left hand threads on two wheels. I believe they
were flat, not conical, although I can't positively remember.
- Frank Krygowski
Peter S.
> This "tread" goes farther than screw threads, but they are a practical
> symbol of mechanical ineptness in the bicycle industry. This syndrome
> is found elsewhere in bicycles. We had that subject a while back when
> I mentioned that not even the REMA Tip-Top patch representative knew
> why one sand papers a tube before patching. The purpose is to REMOVE
> the skin of the inner tube because as should be apparent, tubes ate
> made in molds that cause the fine ridges on their surface. These are
> caused by the molds in which they are formed,
Just a big thanks for actually explaining this. Until I read the above
on Sheldon's page some years ago, some of my patches failed to work
properly. When I actually understood the various steps in the patching
process I stopped having such patching failures. It also changed my
attitude to patching tubes; before I found it a tedious task where I
repeated some mystical arcane steps and where the outcome sometimes
mysteriously went wrong. But understanding the process gave me
confidence in the outcome, so now it is just a "no problem" job to
patch tubes.
--
Regards
Bad Idea
> symbol of mechanical ineptness in the bicycle industry. This syndrome
jobst can’t control his compulsion to attempt to prove he’s smarter
than
everyone else, so he inadvertently continues to demonstrate not only
his intellectual dishonesty but also his human deficiency.
BTW jobst, has Porsche ever produced heat treated hardened threads
that support radial loads? Please advise.
Frank Krygowski
>
> I am listening to what you have to say about threads but even there
> I'm seeing some assertions that I have difficulty with. You refer to
> "theads carrying radial loads" and also to wheel lug nuts that would
> loosen on old vehicles. Please explain if I'm wrong, but prior to
> having conical seats, lug nuts were just flat nuts and the threads
> themselves carried NO radial loads. The nut merely clamped the wheel
> snugly up against the hub.
In such a situation, any microscopic radial motion of the wheel
relative to the hub would likely induce a microscopic lateral motion
of the bolts or nuts. And I recall reading an engineering research
report explaining in some detail how any such lateral motion would
inevitably cause such a thread to move "downhill." It's mechanically
analogous to, say, placing a book on a smooth incline, where the book
represents the fastener and the incline the mating thread surface.
Any motion that pushes the book laterally (i.e. across the slope) will
also result in the book sliding down the slope. Try it!
Threaded fasteners do the same thing when they move microscopically
within their necessary clearance space. Loctite works as well as it
does not because it's a glue, but because it fills that clearance
space and prevents that microscopic lateral motion.
If I understand Jobst correctly, the conical bearing surface prevents
or greatly reduces that microscopic lateral motion and the subsequent
loosening. In the case of his crank eye failures, I think it also
reduces the stress concentration at the end of the threaded hole. It
may be the latter effect is more important for preventing fatigue
failures there.
In any case, that detail is the sort of thing that might get figured
out by one experienced, competent engineer, after he pondered the
problem for a while. His knowledge would get passed down, perhaps
person-to-person. This is what I was describing in the other version
of this thread, where engineers learn from other engineers on the job.
Of course, the process isn't perfect. Some design features are
subject to being lost when people no longer understand or remember
the original rationale. And example might be radial spokes replacing
near-tangent spokes. "Heck, the front wheel doesn't transmit torque!
We can just make them radial and save 0.4 ounces!!!" Until the flange
pulls away from the hub, that is.
Other design features are never really justified, or were once
justified for reasons that no longer exist, but are still promoted by
fans. Tied and soldered spokes seem to be in that category, despite
what their local fan claims.
But there is benefit to this imperfection in the process. It gives us
stuff to discuss in this newsgroup.
- Frank Krygowski
DirtRoadie
Just trying to make the point that you seem to find great glee in
trying to establish that you know something that NOBODY else does and
set up examples such as this one to make that point.
> > OK, True or false. REMA recommends taking some action prior to
> > applying glue in order to improve the ability of the glue and patch
> > to adhere. What they have always recommended is abrading the
> > surface. You acknowledge that this is desirable and works although
> > you also claim that you can pull off such a patch immediately after
> > application. So? You have stated in this group that a patch should
> > not be ridden immediately after it is applied, but that it becomes
> > nearly impossible to remove after some curing time.
>
> The Rema man claimed that when he put on a patch, it was on for good
> and that the sand paper was there to roughen the surface. Neither is
> true and my manually pulling off his patch and giving it to him was a
> surprise to him. Some tire patch kits have a solvent to remove mold
> release,. Something that was added when roughening the surface failed
> to make patches stick. I explained to the REMA man how a cured patch
> can be removed, something I put on the FAQ back then. They cannot be
> take off by trying to peel then at room temperature.
> > That has been my experience as well and I, long ago, began using
> > solvent such as toluene to prepare a tube for patching to accomplish
> > exactly what you describe.
>
> You'll notice that various patch makers offer a cheese grater metal to
> roughen the tube, not remove the skin, the action that is necessary to
> make an air tight patch. Patches attached to "roughened" inner tubes
> often leak shortly after, something that was apparent at the many tire
> patch sessions held Wednesday evenings at my house by local bikies.
As you have described using an abrasive is a method of removing any
mold release to make a patch adhere. "Roughening" the surface is
certainly an accurate description of how the abrasive is used even if
the result tube surface need not be truly "rough."
The patch kit makers graciously include a simple means of
accomplishing this generally a piece of sandpaper -like material or
the "cheese grater" you describe.
I have never seen a patch kit (much less a small, bicycle-size patch
kit) that included solvent. Your arguments are semantic. You claim
that patch kit manufacturer have not provided the abrasive to "remove
the skin." That's your assumption and another one of your silly straw
men. Even if the patch kit instruction describe "roughening" the area
to be patched, that's a perfectly accurate description of how the
abrasive is intended to be used to make the patch work
properly.
> > That a REMA sales rep (you didn't say "REMA engineer" or REMA
> > Product designer" did you?) did not fully understand what was
> > happening should be of little surprise. A "sales rep" is just that.
> > I would not expect a salesman on the floor of a Porsche dealership
> > to have the knowledge of the Porsche engineers either. Nor would a
> > 7-11 clerk be expected to understand the technology of a Slurpee
> > machine, even if he was the company's leading Slupree salesman.
>
> He represents REMA at the trade show to instruct dealers how to tell
> their customers ho it is done. I don't suspect they sent their
> dumbest man and besides, what he said is in their literature that is
> offered with their patch kit. There is apparently no one at home
> there, engineers apparently having long ago gone elsewhere.
My point exactly.
> > I'm a little surprised that you would expect a sales rep for a tire
> > patch manufacturer to be a technical wizard. How long have REMA
> > tire patches been around and how many many engineers do you suppose
> > REMA presently has on staff for product development? Jobst give us
> > a break. Don't knock down straw men to assert your superiority.
> > You have some information to share but trying to demonstrate that
> > you are more technically knowledgeable that a patch salesman hardly
> > embellishes your credibility.
>
> If I understand you, you think a representative of REMA should not be
> expected to understand tire patching. As always there is someone on
> wreck.bike who comes to the defense of the bicycle industry when a
> blunder is discovered.
No, I have no expectation of who should know what. I think I
accurately described that I would not expect a patch "salesman" to
have full knowledge of the underlying technology of his product any
more than a mere salesman of any product, even if he is the very best
and most knowledgeable salesman in his company. I doubt he would know
the chemical makeup of the patch material or the vulcanizing fluid, or
the source of the raw materials or the process for assembling them
into final products. He might not even have the MSDS memorized. You
have suggested he knew how to use the patch kit. I can hardly imagine
that he would need to know much more. Can we assume that since you
comment on Shimano bicycles components that you must be fluent in
Japanese?
> > I am listening to what you have to say about threads but even there
> > I'm seeing some assertions that I have difficulty with. You refer to
> > "theads carrying radial loads" and also to wheel lug nuts that would
> > loosen on old vehicles. Please explain if I'm wrong, but prior to
> > having conical seats, lug nuts were just flat nuts and the threads
> > themselves carried NO radial loads. The nut merely clamped the wheel
> > snugly up against the hub.
>
> Wheel rotation around the stud on which it was mounted exerted enough
> radial motion to unscrew the flat nut and release the wheel, even
> though it was believed that a "properly" tightened set of lug nuts
> would hold the wheel. If you do not see the fallacy in that
> assessment, then you don't understand why we have conical lug nuts
> today without left hand threads on left wheels of cars and trucks (as
> they were in the 1950's).
Yes, you are precisely acknowledging my point. The early threads of
flat nuts were NOT bearing any radial load whatsoever and, in the
absence of some other means of preventing radial movement of the wheel
(like a conical hub mating against a corresponding concial seat at the
wheel center), the very slight precessional wheel movement about the
studs could cause the nuts to loosen, primarily if they were
insufficiently tightened in the first place. But adding a conical
face to these nuts transfers much or all of the radial load TO the
threads which, when properly secured, were/are capable of handling
such loads without loosening. This is contrary to your hypothesis that
threads are unsuited for bearing radial forces. I will accept your
hypothesis to the extent that _insufficiently_ secured threads are
unsuited for bearing radial forces.
"Secured" means being of a sufficient size and being tightened with
sufficient torque to preclude any movement of the relative parts
whether it is one nut against another or the head of a bolt against a
fixed surface. And, yes, I realize that NOTHING is truly rigid but
let's not assume that we are using, for example, 1/4-20 threads on a
lug nut.
DR
Duane Hebert
"Jobst Brandt" <jbr...@sonic.net> wrote in message
news:4c8ba87f$0$1639$742e...@news.sonic.net...
> David Scheidt wrote:
>
>>> threads are soft because they cannot be hardened.
>
>> I don't care how many times you say this, it still won't be true.
>> There are all sorts of threads that are hardened.
>
> Please give some examples. Attempting to heat treat a thread will
> glow its apex while under heating the root. This causes the apex of a
> thread to crack while the base remains soft. Therefore, threads are
> not heat treated as the Regina FW sprockets clearlydemonstrate as they
> deform and wear at tooth faces where the chain bears. This causes
> chain skip with a new, in-pitch, chain.
Depends on what you mean by heat treating.
The company that I work for does, among other things, process control
systems for heat treatments of different sorts. The furnaces in our shop
process customer orders and there are often screws being heat treated. Gas
nitriding is used
to increase the white layer of steel. This affects the outer layer or shell
hardness (google white layer, heat treating) without making
the interior brittle.
Not my company but http://www.murex.ch/e-schnecken.html explains a bit. I
have no idea if or how this pertains to
bicycles nor what it has to do with the oil/grease argument that I think
started this thread <g>
Jobst Brandt
>>>> threads are soft because they cannot be hardened.
>>> I don't care how many times you say this, it still won't be true.
>>> There are all sorts of threads that are hardened.
>> Please give some examples. Attempting to heat treat a thread will
> ASTM A193 covers a bunch.
> Your neighborhood hardware store has boxes of self-tapping machine
> screws; they're nearly universally case hardened. They need to
> hardened threads to drill, but would be too brittle to drive if the
> entire material were hardened. Post thread forming hardening makes
> them possible.
Those are not screws in the sense of machine screws of which this
thread is about, with "male" and "female" thread interfaces. They
have hot formed threads generated in forming and are not threads as
you find them on BB cups or pedal spindles. Self tapping sheet metal
screws have fairly steep pitch so that the thread has a large smooth
cylindrical shaft. I suppose you have noticed that one can cut a
finger on a machine screw thread. That will not occur with a sheet
metal screw or machine tool lead-screw that has flat topped threads.
There are also dardelet threads that taper and bind on purpose.
> Power screw threads are often hardened. Got a vice? I bet it's
> lead screws are hardened. Even crappy Chinese C-clamps have
> hardened screws.
Yes and there are also cork screws that are a type of thread for
special purposes. A vise does not have hardened lead screws and
turnbuckles have left and right lead screws.
>> glow its apex while under heating the root. This causes the apex
>> of a thread to crack while the base remains soft. Therefore,
>> threads are not heat treated as the Regina FW sprockets clearly
>> demonstrate as they deform and wear at tooth faces where the chain
>> bears. This causes chain skip with a new, in-pitch, chain.
> That some particular thread isn't heat treated is not evidence that no
> thread is.
No machine screw thread is heat treated and we are talking about
machine screws, not sheet metal, lead-screws, or worm drives.
Jobst Brandt
Jobst Brandt
Think of it this way. With the thread pulling normal to the wheel
attachment plane it has only tension to carry while the head of the
wheel stud has a conical face that cannot slide radially under radial
loads as on a pedal spindle face. Therefore the interface is immune
to following the radial wheel load and unscrewing or for that matter
fretting to death in its own mating threads. The left hand thread
achieved that goal, but with more difficulty. That is why we still
have left hand threads on left pedals as GM cars formerly had left
hand threads on left wheels.
> In any case, that detail is the sort of thing that might get figured
> out by one experienced, competent engineer, after he pondered the
> problem for a while. His knowledge would get passed down, perhaps
> person-to-person. This is what I was describing in the other
> version of this thread, where engineers learn from other engineers
> on the job.
> Of course, the process isn't perfect.
It depends on who's listening and thinking.
> Some design features are subject to being lost when people no longer
> understand or remember the original rationale. And example might be
> radial spokes replacing near-tangent spokes. "Heck, the front wheel
> doesn't transmit torque! We can just make them radial and save 0.4
> ounces!!!" Until the flange pulls away from the hub, that is.
> Other design features are never justified, or were once justified
> for reasons that no longer exist, but are still promoted by fans.
> Tied and soldered spokes seem to be in that category, despite what
> their local fan claims.
I suspect that some of that was originally to keep broken spokes out
of trouble, and subsequently mechanics attributed other uses for it.
> But there is benefit to this imperfection in the process. It gives us
> stuff to discuss in this newsgroup.
...and to insult those who present the information.
Jobst Brandt
DirtRoadie
> Someone wrote:
> > Well, that is partially what I wanted to have Jobst address. Simple
> > example: a nut turning on a bolt has obvious play, both radial and
> > axial. Thread two nuts snugly against one another and any play,
> > radial OR axial disappears. That does not fit with the Jobstian
> > hypothesis of threads.
>
> Where to you see these double nutted applications? Even double nutted
> shafts with radial loads cause precession, the threads being one-way.
I used that as any example of a nut being _tightened_ on a threaded
shaft as opposed to simply being threaded onto the same shaft. Play/
clearance between the mating thread surfaces is gone when threads are
tightened. There
> > Mike J. suggested that poor adjustment accounts for bearing wear in
> > threaded headsets. I'll certainly buy that.
>
> Look a bit closer. When you see a fork vibrating fore and aft on a
> roughly paved asphalt road, the most flexible part of the fork is the
> steer tube between the two head bearings and that flexing, yaws the
> 20-ball ball-bearing crosswise to its steering rotation... and it does
> so in small fretting motion that welds the races to the balls.
>
> That this is fretting motion is shown by the milky finish of the ball
> dimples in the inner and outer race. Brinell dents are shiny while
> these are not because they are made by a million welds and breaks that
> tear out tiny flaws. You'll note that the dimples that cause "indexed
> steering" are in the fore and aft quadrant of the races and on both
> upper and lower bearings.
> > Jobst has not yet described the mechanism by which there can
> > "fretting" wear in a threaded headest which would not also occur in a
> > threadless headset, aside from the fact that a threadless headset is
> > more like to be properly adjusted.
OK a flexible steerer tube causes fretting. Let's go with that for
now.
How is it that the steerer tube in a threaded headset configuration
DOES cause fretting while the same tube in a threadless headset DOES
NOT allow fretting? You are the one that said " ...The threaded ones
were perpetually fretting" and "Fretting damage to head bearings
(indexed steering) was also corrected recently by the Shimano
threadless steertube."
( I must also ask what you mean by "recent" and note that Shimano did
not invent the threadless headset)
> New Shimano threadless head bearings have an approximate conical
> contact outside of the ball bearing that is free to swivel while the
> ball bearing is a pre-loaded angular contact bearing that cannot
> articulate crosswise. This should be apparent because it cannot be
> disassembled manually.
What is the relevance of "threading" if a bearing configuration solves
the alleged fretting problem? Why would this bearing configuration not
be usable in a _threaded_ headset?
> > A "locked" threaded assembly has threads butted solidly against one
> > another and prevents radial movement regardless of whether the locking
> > is via a threaded lockring or a split clamping nut. Both accomplish
> > exactly the same function of "binding" the threads frictionally.
>
> That may be your impression, but radial motion from loads will still
> cause elastic fretting motion, and as I mentioned, threads are soft
> because they cannot be hardened.
Yes EVERYTHING moves. But you are now conceding that there is no
thread "clearance" and that the movement takes place while the mating
threads are in contact with one another. That is why they must be
tightened sufficiently - to eliminate this fretting that, by your
standards, cannot be avoided in a meaningful fashion. The real world
shows otherwise. Since others have already done so I won't even
bother to address the issue of hardening threads or suggest that
threads can made in materials that are already "hard," since hardness
is a relative concept.
> > To simplify - the concept of threads having "clearance" is red
> > herring with no meaning when a threaded assembly is tightened with
> > some measure of torque, i.e. there is NO clearance between the
> > respective mating helical surfaces of the threads.
>
> If that is so, then why do conical lug nuts no longer allow wheels to
> fall off? Also why do left pedals require a left hand thread to
> remain secure.
re: Conical lug nuts - I discussed this elsewhere and am looking
forward to your response (but - quick summary - conical lug nuts -
especially conical lug nuts - MUST bear radial forces on the
threads.)
re: Pedals- To be perfectly honest I don't know whether left pedals
do require a left hand thread to avoid falling off. (1) I have never
had a pedal fall off and, (2) So far as I am aware, I have never used
a bicycle that did not have left hand threads on the left pedal.
DR
Jobst Brandt
Oh! Where did you see "great glee"? I thought it useful to pass along
things I discovered when working on machinery. Did you not want to
know how these things work? I'm sorry if learning is such a pain.
I see sanding and roughening as two non parallel description of
sanding off the skin of the inner tube, and roughening hides the
purpose of the action.
> The patch kit makers graciously include a simple means of
> accomplishing this generally a piece of sandpaper -like material or
> the "cheese grater" you describe.
The cheese grater does not get rid of mold release, it just makes cuts
in the surface.
> I have never seen a patch kit (much less a small, bicycle-size patch
> kit) that included solvent. Your arguments are semantic. You claim
> that patch kit manufacturer have not provided the abrasive to
> "remove the skin." That's your assumption and another one of your
> silly straw men. Even if the patch kit instruction describe
> "roughening" the area to be patched, that's a perfectly accurate
> description of how the abrasive is intended to be used to make the
> patch work properly.
I think you may have read where other riders have used solvents. I
prefer not to because it always leaves dissolved rubber and mold
release on the inner tube.
>>> That a REMA sales rep (you didn't say "REMA engineer" or REMA
>>> Product designer" did you?) did not fully understand what was
>>> happening should be of little surprise. A "sales rep" is just
>>> that. I would not expect a salesman on the floor of a Porsche
>>> dealership to have the knowledge of the Porsche engineers
>>> either. Nor would a 7-11 clerk be expected to understand the
>>> technology of a Slurpee machine, even if he was the company's
>>> leading Slupree salesman.
>>>> He represents REMA at the trade show to instruct dealers how to
>>>> tell their customers ho it is done. I don't suspect they sent
>>>> their dumbest man and besides, what he said is in their
>>>> literature that is offered with their patch kit. There is
>>>> apparently no one at home there, engineers apparently having long
>>>> ago gone elsewhere.
> My point exactly.
>>> I'm a little surprised that you would expect a sales rep for a tire
>>> patch manufacturer to be a technical wizard. How long have REMA
>>> tire patches been around and how many many engineers do you suppose
>>> REMA presently has on staff for product development? Jobst give us
>>> a break. Don't knock down straw men to assert your superiority.
>>> You have some information to share but trying to demonstrate that
>>> you are more technically knowledgeable that a patch salesman hardly
>>> embellishes your credibility.
It doesn't take a technical wizard to understand what I have explained
about tire patching. I think you are trying hard to blow this out of
proportion and generate ridicule.
>> If I understand you, you think a representative of REMA should not be
>> expected to understand tire patching. As always there is someone on
>> wreck.bike who comes to the defense of the bicycle industry when a
>> blunder is discovered.
> No, I have no expectation of who should know what. I think I
> accurately described that I would not expect a patch "salesman" to
> have full knowledge of the underlying technology of his product any
> more than a mere salesman of any product, even if he is the very
> best and most knowledgeable salesman in his company.
What do you mean by "full knowledge"? I believe if something as simple
as applying a patch that your company produces, is not asking too much
from a sales representative. In fact, I think it appropriate for such
a person to inform himself about his product as well as he can.
> I doubt he would know the chemical makeup of the patch material or
> the vulcanizing fluid, or the source of the raw materials or the
> process for assembling them into final products. He might not even
> have the MSDS memorized. You have suggested he knew how to use the
> patch kit. I can hardly imagine that he would need to know much
> more. Can we assume that since you comment on Shimano bicycles
> components that you must be fluent in Japanese?
My point was that he did not know how to patch a tire. You may have
missed that in your effort to jump ahead and ridicule what I said.
>>> I am listening to what you have to say about threads but even
>>> there I'm seeing some assertions that I have difficulty with. You
>>> refer to "theads carrying radial loads" and also to wheel lug nuts
>>> that would loosen on old vehicles. Please explain if I'm wrong,
>>> but prior to having conical seats, lug nuts were just flat nuts
>>> and the threads themselves carried NO radial loads. The nut
>>> merely clamped the wheel snugly up against the hub.
>> Wheel rotation around the stud on which it was mounted exerted
>> enough radial motion to unscrew the flat nut and release the wheel,
>> even though it was believed that a "properly" tightened set of lug
>> nuts would hold the wheel. If you do not see the fallacy in that
>> assessment, then you don't understand why we have conical lug nuts
>> today without left hand threads on left wheels of cars and trucks
>> (as they were in the 1950's).
> Yes, you are precisely acknowledging my point. The early threads of
> flat nuts were NOT bearing any radial load whatsoever and, in the
> absence of some other means of preventing radial movement of the wheel
> (like a conical hub mating against a corresponding conical seat at the
> wheel center), the very slight precession wheel movement about the
> studs could cause the nuts to loosen, primarily if they were
> insufficiently tightened in the first place. But adding a conical
> face to these nuts transfers much or all of the radial load TO the
> threads which, when properly secured, were/are capable of handling
> such loads without loosening. This is contrary to your hypothesis that
> threads are unsuited for bearing radial forces. I will accept your
> hypothesis to the extent that _insufficiently_ secured threads are
> unsuited for bearing radial forces.
The radial load of the wheel moved the flat lug nut so that by
precession it unscrewed. That is radial motion that you can simulate
by rotating your index finger in a circular opening with your other
hand (thumb and forefinger) and notice when you rotate clockwise, the
index finger turns counter-clockwise.
> "Secured" means being of a sufficient size and being tightened with
> sufficient torque to preclude any movement of the relative parts
> whether it is one nut against another or the head of a bolt against
> a fixed surface. And, yes, I realize that NOTHING is truly rigid
> but let's not assume that we are using, for example, 1/4-20 threads
> on a lug nut.
Well there you have it. There is no sufficient torque that will
achieve this goal in which you and many others have faith. It isn't
so!
Jobst Brandt
Jobst Brandt
>>>> threads are soft because they cannot be hardened.
>>> I don't care how many times you say this, it still won't be true.
>>> There are all sorts of threads that are hardened.
>> Please give some examples. Attempting to heat treat a thread will
>> glow its apex while under heating the root. This causes the apex
>> of a thread to crack while the base remains soft. Therefore,
>> threads are not heat treated as the Regina FW sprockets
>> clearly demonstrate as they deform and wear at tooth faces where the
>> chain bears. This causes chain skip with a new, in-pitch, chain.
> Depends on what you mean by heat treating.
Mostly inexpensive flame hardening. If you consider the fine 1mm
thread pitch of Regina and other sprocket threads, you'll see that
they would turn blue and crack afterward while the main part of the
sprocket having larger mass, remains soft.
> The company that I work for does, among other things, process
> control systems for heat treatments of different sorts. The
> furnaces in our shop process customer orders and there are often
> screws being heat treated. Gas nitriding is used to increase the
> white layer of steel. This affects the outer layer or shell
> hardness (Google white layer, heat treating) without making the
> interior brittle.
I'd like to see some hardened fine threads on things like freewheel
sprockets. It's the exterior that gets brittle allowing threads to
crack off.
> Not my company but:
http://www.murex.ch/e-schnecken.html
> explains a bit. I have no idea if or how this pertains to bicycles
> nor what it has to do with the oil/grease argument that I think
> started this thread <g>
Forget about the lubricant problem. It's sprocket wear that is not
under control in the "old school" freewheels and well controlled in
splined Shimano sprockets, due to hardening.
Jobst Brandt
Duane Hebert
> Mostly inexpensive flame hardening. If you consider the fine 1mm
> thread pitch of Regina and other sprocket threads, you'll see that
> they would turn blue and crack afterward while the main part of the
> sprocket having larger mass, remains soft.
I think that the "rule of thumb" for gas nitriding is that threads
finer than 2mm should use some different process like ion or
plasma.
At any rate, the statement that you can't harden screws,
is not correct unless you specify either flame hardening or super
fine threads.
>> The company that I work for does, among other things, process
>> control systems for heat treatments of different sorts. The
>> furnaces in our shop process customer orders and there are often
>> screws being heat treated. Gas nitriding is used to increase the
>> white layer of steel. This affects the outer layer or shell
>> hardness (Google white layer, heat treating) without making the
>> interior brittle.
>
> I'd like to see some hardened fine threads on things like freewheel
> sprockets. It's the exterior that gets brittle allowing threads to
> crack off.
The thicker the white layer, the less brittle. On super fine threads,
this is probably not possible though I'm no metalurgist. But certainly many
threaded
surfaces are heat treated. Most of the steel components in a car
are treated.
One of the plant operators paged me last week to let me know that
they had a bunch of bike frames in a furnace. (I had to make sure that
one of them wasn't mine <g>)
Tim McNamara
<76977bd1-f76a-4477...@y12g2000prb.googlegroups.com>,
Bad Idea <bad.i...@gmail.com> wrote:
> On Sep 10, 5:38 pm, Jobst Brandt <jbra...@sonic.net> wrote:
> > This "tread" goes farther than screw threads, but they are a
> > practical symbol of mechanical ineptness in the bicycle industry.
> > This syndrome is found elsewhere in bicycles . . .
>
> jobst canšt control his compulsion to attempt to prove hešs smarter
> than everyone else, so he inadvertently continues to demonstrate not
> only his intellectual dishonesty but also his human deficiency.
>
> BTW jobst, has Porsche ever produced heat treated hardened threads
> that support radial loads? Please advise.
Hi, jim!
--
That'll put marzipan in your pie plate, Bingo.
Tim McNamara
<63203e0b-c033-47d1...@k11g2000vbf.googlegroups.com>,
DirtRoadie <DirtR...@aol.com> wrote:
> On Sep 10, 9:57 pm, thirty-six <thirty-...@live.co.uk> wrote:
> >
> > And the cycle pedal axle thread clamps the boss against the crank,
> > simple. Bending loads within the threads are avoided when the axle
> > is tight enough. There is no undoing or crank eye failure when
> > everything is TIGHT.
This has been shown to be wrong many times already, but Trevor is not
going to admit that. Consideration of lug nuts on car wheels is enough
to demonstrate his inaccuracy.
> Well, that is partially what I wanted to have Jobst address. Simple
> example: a nut turning on a bolt has obvious play, both radial and
> axial. Thread two nuts snugly against one another and any play,
> radial OR axial disappears.
No, in fact it does not. If it did, there would be no market for
products like Loctite or nylock nuts, etc.
> That does not fit with the Jobstian
> hypothesis of threads. Mike J. suggested that poor adjustment
> accounts for bearing wear in threaded headsets. I'll certainly buy
> that.
This is also incorrect. Badly adjusted headsets could exacerbate
headset wear, e.g., spalling from excessive bearing preload, but the
false brinelling that is usually discussed in regards to headsets has
another cause. It is usually thought of as an impact damage, which it
is not.
> Jobst has not yet described the mechanism by which there can
> "fretting" wear in a threaded headest which would not also occur in a
> threadless headset, aside from the fact that a threadless headset is
> more like to be properly adjusted.
The mechanism of wear has been discussed many times previously, DR.
Perhaps you could consider saving yourself some time and the newsgroup
yet another repetitive thread by googling it.
> A "locked" threaded assembly has threads butted solidly against one
> another and prevents radial movement regardless of whether the
> locking is via a threaded lockring or a split clamping nut. Both
> accomplish exactly the same function of "binding" the threads
> frictionally.
If only that were true.
> To simplify - the concept of threads having "clearance" is red
> herring with no meaning when a threaded assembly is tightened with
> some measure of torque, i.e. there is NO clearance between the
> respective mating helical surfaces of the threads.
See above.
DirtRoadie
> > Just trying to make the point that you seem to find great glee in
> > trying to establish that you know something that NOBODY else does
> > and set up examples such as this one to make that point.
>
> Oh! Where did you see "great glee"? I thought it useful to pass along
> things I discovered when working on machinery. Did you not want to
> know how these things work? I'm sorry if learning is such a pain.
In no fewer than 8 threads since 2005 you have seen fit to repeat your
anecdote about how much more knowledgeable you are about tire patches
than one particular REMA rep. OK we get it. You are much smarter than
patch salesman. There isn't much more that can come from that.
>
>
> I see sanding and roughening as two non parallel description of
> sanding off the skin of the inner tube, and roughening hides the
> purpose of the action.
Yes, certainly nobody else would consider use of sandpaper on a smooth
rubber surface to be have any "roughening" effect.
Feel free to use your version of the language.
> > The patch kit makers graciously include a simple means of
> > accomplishing this generally a piece of sandpaper -like material or
> > the "cheese grater" you describe.
>
> > I have never seen a patch kit (much less a small, bicycle-size patch
> > kit) that included solvent. Your arguments are semantic.
> I think you may have read where other riders have used solvents. I
> prefer not to because it always leaves dissolved rubber and mold
> release on the inner tube.
No, in fact I was referring to your comment elsewhere in this thread
that "Some tire patch kits have a solvent to remove mold
release." I have never seen such a thing in a kit. I do use solvent
and have not experienced what you are describing.
>
> It doesn't take a technical wizard to understand what I have explained
> about tire patching. I think you are trying hard to blow this out of
> proportion and generate ridicule.
I think you are doing a wonderful job on your own. It's tire patching.
It's ONLY tire patching. Yet you want to paint the entire industry as
being represented by one individual who you think is an idiot because
he didn't know enough about the inticacies of tire patching.
> What do you mean by "full knowledge"? I believe if something as simple
> as applying a patch that your company produces, is not asking too much
> from a sales representative. In fact, I think it appropriate for such
> a person to inform himself about his product as well as he can.
Maybe. Obviously REMA was derelicty for not having YOU interview the
guy when they hired him.
>
> > Can we assume that since you comment on Shimano bicycles
> > components that you must be fluent in Japanese?
>
> My point was that he did not know how to patch a tire. You may have
> missed that in your effort to jump ahead and ridicule what I said.
No, the point you have repeated over and over is that this the whole
industry is made up of idiots and you have one example by which you
can prove it.
[snip re flat lug nuts vs conical lug nuts ]
> The radial load of the wheel moved the flat lug nut so that by
> precession it unscrewed.
Yes. Nobody is disputing that. The problem is your erroneous
conclusion that conical nuts eliminate any redial forces on the
threads of the lugs nuts.
OK, old flat wheel lug nuts = Radial load NOT borne on threads of lug
nut. True or false?
Conical faced lug nut = Radial load borne by threads of lug nut. True
or false?
Hint: If the conical face of a lug nut is bearing a radial load, then
what is transferring that load so that it can be borne by the
corresponding lug (stud)?
It could hardly be simpler.
Let's also consider what happens when even conical faced lug nuts are
not sufficiently tight, i.e. there is play in the threads. Voila!
Precession!
But rather than think and/or respond honestly, you will ignore this or
give one of your classic smarmy dodges.
You are the one that started the thread about threads (and adding the
word "screw" made it look like it was not even a technical topic) and
your erroneous hypothesis that threaded elements are not suited to
carrying radial loads, yet your lug nut example establishes just the
opposite.
> Well there you have it. There is no sufficient torque that will
> achieve this goal in which you and many others have faith. It isn't
> so!
Ignorance is bliss! But you probably are not quite as blissful as that
patch salesman you found so stupid.
DR
Tom Sherman °_°
W H O O S H !
DirtRoadie
> In article
> <63203e0b-c033-47d1-a009-b7d6ed240...@k11g2000vbf.googlegroups.com>,
>
> DirtRoadie <DirtRoa...@aol.com> wrote:
> > Well, that is partially what I wanted to have Jobst address. Simple
> > example: a nut turning on a bolt has obvious play, both radial and
> > axial. Thread two nuts snugly against one another and any play,
> > radial OR axial disappears.
>
> No, in fact it does not. If it did, there would be no market for
> products like Loctite or nylock nuts, etc.
You are confusing concepts. Being completely snug to the point where
all clearance between mating thread faces has been closed has nothing
to do with whether something is "tight". Similar to your analogy we
would never need a torque wrench either if merely closing the gap
were sufficient. "Finger tight" would do it every time.
> > That does not fit with the Jobstian
> > hypothesis of threads. Mike J. suggested that poor adjustment
> > accounts for bearing wear in threaded headsets. I'll certainly buy
> > that.
>
> This is also incorrect. Badly adjusted headsets could exacerbate
> headset wear, e.g., spalling from excessive bearing preload, but the
> false brinelling that is usually discussed in regards to headsets has
> another cause. It is usually thought of as an impact damage, which it
> is not.
Please don't jump into a discussion of fretting. I was not taking a
position on that. Jobst started a thread regarding threads and seemed
to be asserting that threaded headset were subject to fretting while
threadless ones were not. That 's is an assertion I cannot readily
accept.
> > Jobst has not yet described the mechanism by which there can
> > "fretting" wear in a threaded headest which would not also occur in a
> > threadless headset, aside from the fact that a threadless headset is
> > more like to be properly adjusted.
>
> The mechanism of wear has been discussed many times previously, DR.
> Perhaps you could consider saving yourself some time and the newsgroup
> yet another repetitive thread by googling it.
Rather than suggesting that I Google something please read what I
wrote and have elaborated on here. You are guilty of "seeing what you
want to see." let me make it simple - What distinguishes a threadless
headset from a threaded one with regard to wear?
> > A "locked" threaded assembly has threads butted solidly against one
> > another and prevents radial movement regardless of whether the
> > locking is via a threaded lockring or a split clamping nut. Both
> > accomplish exactly the same function of "binding" the threads
> > frictionally.
>
> If only that were true.
And why is it not? Please think before you answer.
> > To simplify - the concept of threads having "clearance" is red
> > herring with no meaning when a threaded assembly is tightened with
> > some measure of torque, i.e. there is NO clearance between the
> > respective mating helical surfaces of the threads.
>
> See above.
Done. What 's your point?
Perhaps you'd like to tackle the conical lug nut issue. What is your
understanding regarding the radial forces on the threads of a conical
lug nut (as used on a rotating weight bearing wheel)?
DR
Jobst Brandt
>>> Just trying to make the point that you seem to find great glee in
>>> trying to establish that you know something that NOBODY else does
>>> and set up examples such as this one to make that point.
>> Oh! Where did you see "great glee"? I thought it useful to pass
>> along things I discovered when working on machinery. Did you not
>> want to know how these things work? I'm sorry if learning is such
>> a pain.
> In no fewer than 8 threads since 2005 you have seen fit to repeat
> your anecdote about how much more knowledgeable you are about tire
> patches than one particular REMA rep. OK we get it. You are much
> smarter than patch salesman. There isn't much more that can come
> from that.
Try! The item was about how poorly even employees of a leading patch
company are when it comes to understanding the application of their
product. This fits with the general topic of the poor technical
skills of the bicycle industry. My perception is that they don't have
the resources to hire top people even in their own ranks; ones who can
hire similarly skilled engineers.
My postings are about that subject in contrast to the true believers
in bicycling that believe they are equipped with the best quality
equipment. In contrast they have inappropriate materials, poorly
applied and mechanical bugs that have been with us for as much as a
century.
>> I see sanding and roughening as two non parallel description of
>> sanding off the skin of the inner tube, and roughening hides the
>> purpose of the action.
> Yes, certainly nobody else would consider use of sandpaper on a
> smooth rubber surface to be have any "roughening" effect. Feel free
> to use your version of the language.
The problem is that "roughening" is not the goal of the effort but
rather removing mold release to make patches adhere reliably.
>>> The patch kit makers graciously include a simple means of
>>> accomplishing this generally a piece of sandpaper -like material
>>> or the "cheese grater" you describe.
...but don't know why they do so.
>>> I have never seen a patch kit (much less a small, bicycle-size
>>> patch kit) that included solvent. Your arguments are semantic.
>> I think you may have read where other riders have used solvents. I
>> prefer not to do so, because it always leaves dissolved rubber and
>> mold release on the inner tube.
> No, in fact I was referring to your comment elsewhere in this thread
> that "Some tire patch kits have a solvent to remove mold release." I
> have never seen such a thing in a kit. I do use solvent and have
> not experienced what you are describing.
You had best ask bicycle club people what they have experienced on
their rides, especially in areas where thorns cause flats.
>> It doesn't take a technical wizard to understand what I have
>> explained about tire patching. I think you are trying hard to blow
>> this out of proportion and generate ridicule.
> I think you are doing a wonderful job on your own. It's tire
> patching. It's ONLY tire patching. Yet you want to paint the entire
> industry as being represented by one individual who you think is an
> idiot because he didn't know enough about the inticacies of tire
> patching.
It is a typical example along with others about which I have written.
>> What do you mean by "full knowledge"? I believe if something as
>> simple as applying a patch that your company produces, is not
>> asking too much from a sales representative. In fact, I think it
>> appropriate for such a person to inform himself about his product
>> as well as he can.
> Maybe. Obviously REMA was derelicty for not having YOU interview the
> guy when they hired him.
>>> Can we assume that since you comment on Shimano bicycles
>>> components that you must be fluent in Japanese?
>> My point was that he did not know how to patch a tire. You may
>> have missed that in your effort to jump ahead and ridicule what I
>> wrote.
> No, the point you have repeated over and over is that this the whole
> industry is made up of idiots and you have one example by which you
> can prove it.
I think you need to support that claim. I don't believe the term
"idiot" appeared anywhere in what I wrote.
> [snip re flat lug nuts vs conical lug nuts ]
>> The radial load of the wheel moved the flat lug nut so that by
>> precession it unscrewed.
> Yes. Nobody is disputing that. The problem is your erroneous
> conclusion that conical nuts eliminate any redial forces on the
> threads of the lugs nuts.
I never said that although you chose to misinterpret what I wrote to
reflect that view. I think I stated it clearly and where I have
modified pedals and pedal cranks, no more crank failures occurred,
showing the effectiveness of the method, as did the use of conical
lug nuts on cars and trucks.
> OK, old flat wheel lug nuts = Radial load NOT borne on threads of lug
> nut. True or false?
False. If the lug nuts did not get shoved around, they would not have
unscrewed. I guess that is why it took so long to reach production.
People like you could not see the effect.
> Conical faced lug nut = Radial load borne by threads of lug nut. True
> or false?
What do you care. The lug nut cannot rotate and unscrew and has
demonstrated that ability for nearly a half century. What are you
developing in this line of questioning.
> Hint: If the conical face of a lug nut is bearing a radial load, then
> what is transferring that load so that it can be borne by the
> corresponding lug (stud)?
> It could hardly be simpler.
The purpose is to prevent loosening. Obviously the wheel is held in
place each of the attachment bores centered o n the lug and remaining
there. Stop blowing smoke!
> Let's also consider what happens when even conical faced lug nuts are
> not sufficiently tight, i.e. there is play in the threads. Voila!
> Precession!
Just leave them out if you want an experiment with loose retaining
fasteners. The point is that the old style did not stay on, no matter
how tight you made them.
> But rather than think and/or respond honestly, you will ignore this or
> give one of your classic smarmy dodges.
I think you are doing the opposite by putting up straw men.
> You are the one that started the thread about threads (and adding the
> word "screw" made it look like it was not even a technical topic) and
> your erroneous hypothesis that threaded elements are not suited to
> carrying radial loads, yet your lug nut example establishes just the
> opposite.
>> Well there you have it. There is no sufficient torque that will
>> achieve this goal in which you and many others have faith. It isn't
>> so!
> Ignorance is bliss! But you probably are not quite as blissful as
> that patch salesman you found so stupid.
"Stupid" is your term, I found he was as uninformed as many bicyclists
who never questioned the ability of a patch to stick to a tube freshly
out of the mold. Also, that patches, when cured, cannot be removed by
peeling them off. Knowing that, waiting for a patch to cure before
use becomes a realistic part of patching. I also described how to
remove a patch because this was necessary occasionally because people
rode on un-cured patches that began to leak and needed replacement.
Removing the old patch was difficult, so I developed a method described
in the FAQ.
Jobst Brandt
DirtRoadie
[snipped a lot of stuff because we were both just getting annoyed]
> > The problem is your erroneous
> > conclusion that conical nuts eliminate any redial forces on the
> > threads of the lugs nuts.
>
> I never said that although you chose to misinterpret what I wrote to
> reflect that view.
Then let's see if I can understand what you were saying.
First, what is the significance of clearance in threaded elements when
the threads are carrying an axial load by being threaded "together?"
My point was that when that has occurred there is NO clearance between
the mating faces. That means that aside from that which can occur by
flexing there is no radial movement
> I think I stated it clearly and where I have
> modified pedals and pedal cranks, no more crank failures occurred,
> showing the effectiveness of the method, as did the use of conical
> lug nuts on cars and trucks.
The difficulty is in the analogy. In a shaft with a conical exterior
surface fitted into a mating conical recess - the conical interface
can bear virtually ALL redial forces. In contrast, as I described A
conical nut necessarily bears ALL radial forces on its threads, the
fact that it also bears those forces on its nice conical exterior
does not change that.
> > OK, old flat wheel lug nuts = Radial load NOT borne on threads of lug
> > nut. True or false?
>
> False. If the lug nuts did not get shoved around, they would not have
> unscrewed. I guess that is why it took so long to reach production.
> People like you could not see the effect.
I see slight radial movement of the wheel exerting frictional
precessional forces on the nut being the culprit. Not so much any
radial forces on the threads although those probably exist as a result
of the same friction.
Another solution, in fact a better solution, would have been to put
the conical surfaces facing out on the inner end of the studs, to mate
with conical recesses in the back surface of the wheel. The result -
NO radial forces on the threads.
But what WAS done (conical lugnuts) still required the threads to bear
the radial forces/movement. However the conical seat does help
minimize the slight radial movement of the wheel I described above. In
any case I cannot see that the "problem" was solved by removing any
radial forces from the threads - since that was not done.
Now, you were the one describing threads being a poor carrier of
radial forces, and you were the one identifying conical lug nuts as
being an example of a solution to the "problem." So would you care
to withdraw that example as not being relevant?
> > Conical faced lug nut = Radial load borne by threads of lug nut. True
> > or false?
>
> What do you care. The lug nut cannot rotate and unscrew and has
> demonstrated that ability for nearly a half century. What are you
> developing in this line of questioning.
Jobst, you claim that you want to understand, yet you again are doing
exactly what you criticize others for. "It works - why do we need to
understand it?" OR, worse yet, "I have my theory and in MY mind it
fits." Let me see if I can think of an analogy like, for example, an
uninformed patch salesman.
> > Hint: If the conical face of a lug nut is bearing a radial load, then
> > what is transferring that load so that it can be borne by the
> > corresponding lug (stud)?
> > It could hardly be simpler.
>
> The purpose is to prevent loosening.
Yes but how?
> Obviously the wheel is held in
> place each of the attachment bores centered on the lug and remaining
> there. Stop blowing smoke!
Take off your fireman's helmet and put your thinking cap back on.
The lugs nuts which you claim work so well (and I am not suggesting
otherwise) still bear their ENTIRE radial load on their threads
which, you assert, should NOT work so well. But I suppose if they work
we don't have any reason to accurately understand HOW or WHY they
work, do we?
> > Let's also consider what happens when even conical faced lug nuts are
> > not sufficiently tight, i.e. there is play in the threads. Voila!
> > Precession!
>
> Just leave them out if you want an experiment with loose retaining
> fasteners. The point is that the old style did not stay on, no matter
> how tight you made them.
I would suggest that since they relied primarily on axial frictional
forces to keep the wheel from slight radial movement about the studs,
the lugs/studs could have been made to work if they had been suitably
sized and/or suitably torqued.
> > But rather than think and/or respond honestly, you will ignore this or
> > give one of your classic smarmy dodges.
>
> I think you are doing the opposite by putting up straw men.
I'll leave that to you.
> > Ignorance is bliss! But you probably are not quite as blissful as
> > that patch salesman you found so stupid.
>
> "Stupid" is your term, I found he was as uninformed as many bicyclists
OK. "Stupid" means unintelligent and he was merely uninformed.
http://en.wikipedia.org/wiki/Stupidity
Somehow I missed all you references indicating your vast respect for
his "intelligence."
Back to headsets.
Re: fretting - you used the phrase "was also corrected recently by the
Shimano threadless steertube." What is "recently" in this context?
Last month? Last year? Last century? And as I asked elsewhere
regarding the same quote - what is the significance of "threadless?"
DR
Michael Press
<c7ffa37d-402a-4651...@z25g2000vbn.googlegroups.com>,
DirtRoadie <DirtR...@aol.com> wrote:
> Jobst started a thread regarding threads and seemed
> to be asserting that threaded headset were subject to fretting while
> threadless ones were not. That 's is an assertion I cannot readily
> accept.
Did he assert it or not? He is not ambiguous.
--
Michael Press
DirtRoadie
> In article
> <c7ffa37d-402a-4651-aea8-f0dcc400a...@z25g2000vbn.googlegroups.com>,
>
> DirtRoadie <DirtRoa...@aol.com> wrote:
> > Jobst started a thread regarding threads and seemed
> > to be asserting that threaded headset were subject to fretting while
> > threadless ones were not. That 's is an assertion I cannot readily
> > accept.
>
> Did he assert it or not? He is not ambiguous.
If you say so.
He said:
"One can find threads supporting radial loads on bicycles. These
are
for instance, pedal spindles in cranks, BB cups in the bottom
bracket,
wheel bearing cones on axles and head bearings on forks."
"Fortunately there are remedies for these problems,..."
"Fretting damage to head bearings (indexed steering) was also
corrected
recently by the Shimano threadless steertube."
In light of the lack of ambiguity please feel free to tell me just
what he said.
DR
Frank Krygowski
> Duane Hebert wrote:
> >>>> threads are soft because they cannot be hardened.
> >>> I don't care how many times you say this, it still won't be true.
> >>> There are all sorts of threads that are hardened.
> >> Please give some examples. Attempting to heat treat a thread will
> >> glow its apex while under heating the root. This causes the apex
> >> of a thread to crack while the base remains soft. Therefore,
> >> threads are not heat treated as the Regina FW sprockets
> >> clearly demonstrate as they deform and wear at tooth faces where the
> >> chain bears. This causes chain skip with a new, in-pitch, chain.
> > Depends on what you mean by heat treating.
>
> Mostly inexpensive flame hardening. If you consider the fine 1mm
> thread pitch of Regina and other sprocket threads, you'll see that
> they would turn blue and crack afterward while the main part of the
> sprocket having larger mass, remains soft.
It's probably not necessary to harden the threads of a Regina-style
sprocket if your objective is longer sprocket tooth wear. You can
probably just heat treat the sprocket teeth.
We've got a large company in our area that builds induction heat
treating equipment, which uses high frequency alternating magnetic
fields to heat only what needs to be heated. I imagine heating and
quenching only the sprocket teeth would be easy for them. The process
is very controllable.
- Frank Krygowski
Frank Krygowski
>
> You are confusing concepts. Being completely snug to the point where
> all clearance between mating thread faces has been closed has nothing
> to do with whether something is "tight".
I don't understand what you're visualizing there. No matter how tight
you make a threaded fastener, there is still clearance between the
mating threads. The major and minor diameters of the female thread
are still larger than the corresponding (i.e. mating) diameters of the
male threads.
Given that situation, the mated threads can shift laterally w.r.t.
each other, no matter how much tensile load you apply to the thread.
Absent Loctite of other gap-fillers, it's friction that resists such
lateral motion; and while increasing torque on the fastener increases
friction, it can still be overcome.
- Frank Krygowski
Jobst Brandt
> the perfect time to write:
>> Where to you see these double nutted applications? Even double
>> nutted shafts with radial loads cause precession, the threads being
>> one-way.
> I would suggest you examine the cone and lock-nut on any common
> bicycle wheel axle.
> If you look closely, you may also notice that the cone - complete
> with it's internal thread - is hardened.
There are no radial loads on wheels, only vertical and an occasional
longitudinal force from braking or a bump in the road. There is no
circulating load.
Jobst Brandt
DirtRoadie
Interesting. If a load is unidirectional then it is not radial, even
if radially aligned?
What if it changes directions but is still not circulating?
I guess we can rule out headsets as having any radial loads.
DR
DirtRoadie
Your consistency is absolutely impeccable.
"One can find threads supporting radial loads on bicycles. These are
for instance, pedal spindles in cranks, BB cups in the bottom
bracket,
wheel bearing cones on axles and head bearings on forks."
Reference link:
http://groups.google.com/group/rec.bicycles.tech/msg/d757a435c4c64430?hl=en
DR
DirtRoadie
> On Sep 11, 7:48 pm, DirtRoadie <DirtRoa...@aol.com> wrote:
>
>
>
> > You are confusing concepts. Being completely snug to the point where
> > all clearance between mating thread faces has been closed has nothing
> > to do with whether something is "tight".
>
> I don't understand what you're visualizing there. No matter how tight
> you make a threaded fastener, there is still clearance between the
> mating threads. The major and minor diameters of the female thread
> are still larger than the corresponding (i.e. mating) diameters of the
> male threads.
I specifically used the term "mating thread faces" to distinguish over
the empty space that exists between the threads in general. That still
exists in a tightened assembly. But even so, the absence of clearance
between the abutting thread faces precludes any "play," i.e. axial or
radial movement.
Let the angled brackets represent individual threads of M and F
elements
M >
F < As this element (F) is rotated, its threads move up or down
(in this diagram)
M >
F < and into contact (no clearance) with the threads of the M
element
Your description of the diameters of the respective threads is
accurate but is not dispositive of whether the clearance between
thread faces is closed (unless of course the larger diameter of the
male thread is less than the smaller diameter of the female threads,
in which case the threads cannot engage at all.)
> Given that situation, the mated threads can shift laterally w.r.t.
> each other, no matter how much tensile load you apply to the thread.
> Absent Loctite of other gap-fillers, it's friction that resists such
> lateral motion; and while increasing torque on the fastener increases
> friction, it can still be overcome.
True, ANY force can be overcome by a sufficient opposing force. But
that does not establish that such an opposing force exists or can/
will be generated. That is one of the reasons torque wrenches are
used when tightening threaded assemblies. Even a shade-tree mechanic
will readily recognize when a nut or bolt is too loose.
DR
Frank Krygowski
Sorry, but I think you don't understand the mechanics of vibrational
loosening of threads.
Of _course_ there will be no clearance between certain surfaces of a
threaded assembly. Specifically, if a bolt rests head down on a table
and a nut is threaded on that bolt, the upper surface of the bolt's
thread has no clearance between the lower surface of the nut thread in
the area of engagement. That's just the same as saying a book resting
on a slanted board has no clearance between the book and board. This
is true whether that bolt is loaded ("tight") or not ("loose").
But in the nut-bolt assembly, there is radial clearance, and there's
clearance between the opposite surfaces of that helical tread. If
there were not, the nut would be a force fit.
That radial clearance gives the nut the opportunity to jiggle side-to-
side on the bolt, and when it does, the joint is prone to loosening.
Again, it's analogous to sliding that book sideways, perpendicular to
the fall line of the board. Any sideways motion also causes the book
to slide lower. In the bolted assembly, this motion is in a direction
to loosen the bolt.
Tightening the assembly (or placing a heavy load on the book) means
more lateral force is required to overcome friction, but it doesn't
come close to making the motion impossible. OTOH, something like
Loctite that fills the clearance does stop it effectively. Split nuts
can also stop that by being tightened tangentially by screws. Our
tandem's headset has a locknut that works that way.
Talk to the owner of a 1960s Harley-Davidson. As I recall, those guys
know all about vibrational loosening of fasteners, despite big biceps,
torque wrenches, etc.
- Frank Krygowski
Dan O
If the nut is screwed tight against the bolt head (or whatever
intervening object is being held together by this fastener
arrangement), doesn't the lower surface of the nut thread come away
from the upper surface of the bolt thread (i.e. clearance)?
>
> But in the nut-bolt assembly, there is radial clearance, and there's
> clearance between the opposite surfaces of that helical tread. If
> there were not, the nut would be a force fit.
>
> That radial clearance gives the nut the opportunity to jiggle side-to-
> side on the bolt, and when it does, the joint is prone to loosening.
> Again, it's analogous to sliding that book sideways, perpendicular to
> the fall line of the board. Any sideways motion also causes the book
> to slide lower. In the bolted assembly, this motion is in a direction
> to loosen the bolt.
Good explanation. It's not quite like the book sliding down
(gravity), though, is it? Isn't the tendency to loosen just because
that's the only direction that the threaded fastener is apt to move
cumulatively on its own?
I had a curious experience with my square taper BB Stumpjumper. After
mostly sitting for a long time (months, at least), then being ridden
about 100 miles in a couple of days, the left side crank came loose.
The bike had previously been parked (in the bedroom :-) supported
laterally by left crank and pedal - backpedaled against a box - and
the curious part for me was: Is this a coincidence (that it was the
left crank arm that came loose while riding)?
<snip>
DougC
> This "tread" goes farther than screw threads, but they are a practical
> symbol of mechanical ineptness in the bicycle industry. This syndrome
> I mentioned that not even the REMA Tip-Top patch representative knew
>
>
> Jobst Brandt
IRL I have seen more than a couple times that people did not know how to
use patch kits they themselves had bought.
In particular, they thought that you had to apply the patch to the tube
while the cement (that was smeared on the tube) was still WET. They
figured the gloe was old since it wouldn't stay on, and then were amazed
that it worked at all after the cement had dried. The Rema
Ikea-pictogram-instructions show a clock indicating to wait 5-10 minutes
between applying the glue and the patch, but most people seem to ignore
that part since it is counter to every other use of glue they've seen.
If I am helping someone out who doesn't look like they bicycle very
much, I always make it a point to explain that tidbit.
~
Frank Krygowski
> On Sep 12, 8:59 am, Frank Krygowski <frkry...@gmail.com> wrote:
>
> > Of _course_ there will be no clearance between certain surfaces of a
> > threaded assembly. Specifically, if a bolt rests head down on a table
> > and a nut is threaded on that bolt, the upper surface of the bolt's
> > thread has no clearance between the lower surface of the nut thread in
> > the area of engagement. That's just the same as saying a book resting
> > on a slanted board has no clearance between the book and board. This
> > is true whether that bolt is loaded ("tight") or not ("loose").
>
> If the nut is screwed tight against the bolt head (or whatever
> intervening object is being held together by this fastener
> arrangement), doesn't the lower surface of the nut thread come away
> from the upper surface of the bolt thread (i.e. clearance)?
Yes, in that situation the external load on the nut comes from the
clamped object instead of from gravity. Loads are reversed, but
everything else is exactly the same.
All this is much easier to show with props and a surface on which to
draw, or with a projector to display examples. I tried to start with
DR's description, since that's what he was visualizing.
> Good explanation. It's not quite like the book sliding down
> (gravity), though, is it? Isn't the tendency to loosen just because
> that's the only direction that the threaded fastener is apt to move
> cumulatively on its own?
In both cases, the load has a component parallel to the incline, in
the direction to either loosen the bolt or lower the book. The
mechanics are much the same.
> I had a curious experience with my square taper BB Stumpjumper. After
> mostly sitting for a long time (months, at least), then being ridden
> about 100 miles in a couple of days, the left side crank came loose.
> The bike had previously been parked (in the bedroom :-) supported
> laterally by left crank and pedal - backpedaled against a box - and
> the curious part for me was: Is this a coincidence (that it was the
> left crank arm that came loose while riding)?
My bet is on coincidence.
- Frank Krygowski
DirtRoadie
> Sorry, but I think you don't understand the mechanics of vibrational
> loosening of threads.
Apparently, I don't. By your analysis ANY thread will loosen under ANY
vibration. This would include conical lug nuts.
> Of _course_ there will be no clearance between certain surfaces of a
> threaded assembly. Specifically, if a bolt rests head down on a table
> and a nut is threaded on that bolt, the upper surface of the bolt's
> thread has no clearance between the lower surface of the nut thread in
> the area of engagement. That's just the same as saying a book resting
> on a slanted board has no clearance between the book and board. This
> is true whether that bolt is loaded ("tight") or not ("loose").
And this book sitting on this board will ALWAYS move with ANY
vibration?
Is the angle of the board of any significance? Is the coefficient of
friction of any significance? Is the force holding the book to the
board of any significance? (you answer yes below) Is the degree of
vibration of any significance?
> But in the nut-bolt assembly, there is radial clearance, and there's
> clearance between the opposite surfaces of that helical tread. If
> there were not, the nut would be a force fit.
Yes, so?
> That radial clearance gives the nut the opportunity to jiggle side-to-
> side on the bolt,
Not without some further interaction at the thread interface which
inhibits radial movement. It's like having two wedges face to face.
Like this ><. You seem to think that even if these wedges, as
illustrated, are fixed in place vertically (as threads are) that they
can be freely slid past one another with no resistance whatosever at
their mating faces.
> and when it does, the joint is prone to loosening.
> Again, it's analogous to sliding that book sideways, perpendicular to
> the fall line of the board. Any sideways motion also causes the book
> to slide lower. In the bolted assembly, this motion is in a direction
> to loosen the bolt.
So we DO have to have force sufficient to slide the book sideways, do
we?
Then a force which is insufficient to overcome the static friction of
the book will not be sufficient to create this downward slide will
it?
> Tightening the assembly (or placing a heavy load on the book) means
> more lateral force is required to overcome friction, but it doesn't
> come close to making the motion impossible. OTOH, something like
> Loctite that fills the clearance does stop it effectively. Split nuts
> can also stop that by being tightened tangentially by screws. Our
> tandem's headset has a locknut that works that way.
As you say, if the book is more heavily loaded it requires more force
to move it.
You conveniently omit quantities. You are suggesting that because a
motion is not impossible, that it is inevitable. Interesting concept.
> Talk to the owner of a 1960s Harley-Davidson. As I recall, those guys
> know all about vibrational loosening of fasteners, despite big biceps,
> torque wrenches, etc.
Ah! That settles it. Some threaded fasteners come loose. Q.E.D. ALL
threaded fasteners ALWAYS loosen. I don't know how that could have
escaped me.
DR
AMuzi
-snip-
> Try! The item was about how poorly even employees of a leading patch
> company are when it comes to understanding the application of their
> product. This fits with the general topic of the poor technical
> skills of the bicycle industry. My perception is that they don't have
> the resources to hire top people even in their own ranks; ones who can
> hire similarly skilled engineers.
Don't read too much into that.
We had an ace sales woman here in the mid seventies who sold
large numbers of race bikes before we heard her selling
"Reynolds Aluminum 531" frames one day. It happens.
--
Andrew Muzi
<www.yellowjersey.org/>
Open every day since 1 April, 1971
AMuzi
Given typical (marginal to inadequate) installation, it's
usually the left which wiggles loose first, being less
massive than the right at the spindle interface and the left
drives through the spindle.
kolldata
Michael Press
<f3634d1d-1631-44dc...@t11g2000vbc.googlegroups.com>,
DirtRoadie <DirtR...@aol.com> wrote:
This is all out of context. Luckily I can supply the
critical context that you omit. Head set race dimpling
(indexed steering) is not cured by going from threaded
steer tubes to threadless steer tubes. Head set race
dimpling is cured by a change in geometry of head set
races. The improved races _happened_ to appear in
Shimano threadless head sets.
--
Michael Press
DirtRoadie
Thank you. Now, speaking of context, perhaps you can explain why this
was even raised by the OP who originated this thread (the newsgroup
kind) and the prior one about "threads" (the mechanical kind).
DR
thirty-six
Only if the wrong lubricant is used, as in not light oil.
>
> - Frank Krygowski
thirty-six
> On 9/10/2010 6:38 PM, Jobst Brandt wrote:
>
> > This "tread" goes farther than screw threads, but they are a practical
> > symbol of mechanical ineptness in the bicycle industry. This syndrome
> > is found elsewhere in bicycles. We had that subject a while back when
> > I mentioned that not even the REMA Tip-Top patch representative knew
> > why one sand papers a tube before patching. ....
>
> > Jobst Brandt
>
> IRL I have seen more than a couple times that people did not know how to
> use patch kits they themselves had bought.
>
> In particular, they thought that you had to apply the patch to the tube
> while the cement (that was smeared on the tube) was still WET. They
> figured the gloe was old since it wouldn't stay on, and then were amazed
> that it worked at all after the cement had dried. The Rema
> Ikea-pictogram-instructions show a clock indicating to wait 5-10 minutes
> between applying the glue and the patch, but most people seem to ignore
> that part since it is counter to every other use of glue they've seen.
It's not glue (from bones and hide), it's a contact adhesive. Some
though like to live in the past. I've found that in the thickness I
apply the cement that it is dry and ready to use in two minutes.
There is some variance between manufacturers but it is tiny.
Frank Krygowski
> On Sep 12, 9:59 am, Frank Krygowski <frkry...@gmail.com> wrote:
>
> > Sorry, but I think you don't understand the mechanics of vibrational
> > loosening of threads.
>
> Apparently, I don't. By your analysis ANY thread will loosen under ANY
> vibration. This would include conical lug nuts.
If you claim that, you don't understand the analysis.
>
> > Of _course_ there will be no clearance between certain surfaces of a
> > threaded assembly. Specifically, if a bolt rests head down on a table
> > and a nut is threaded on that bolt, the upper surface of the bolt's
> > thread has no clearance between the lower surface of the nut thread in
> > the area of engagement. That's just the same as saying a book resting
> > on a slanted board has no clearance between the book and board. This
> > is true whether that bolt is loaded ("tight") or not ("loose").
>
> And this book sitting on this board will ALWAYS move with ANY
> vibration?
Nobody said that. Leave the straw men alone.
> > But in the nut-bolt assembly, there is radial clearance, and there's
> > clearance between the opposite surfaces of that helical tread. If
> > there were not, the nut would be a force fit.
>
> Yes, so?
So radial clearance does not vanish if a nut-bolt assembly is
tightened. And motion within that radial clearance is an important
mechanism for loosening threaded fasteners.
>
> > That radial clearance gives the nut the opportunity to jiggle side-to-
> > side on the bolt,
>
> Not without some further interaction at the thread interface which
> inhibits radial movement. It's like having two wedges face to face.
> Like this ><. You seem to think that even if these wedges, as
> illustrated, are fixed in place vertically (as threads are) that they
> can be freely slid past one another with no resistance whatosever at
> their mating faces.
Not what I said. Omit the straw men.
- Frank Krygowski
Jobst Brandt
>>>> Where to you see these double nutted applications? Even double
>>>> nutted shafts with radial loads cause precession, the threads
>>>> being one-way.
>>> I would suggest you examine the cone and lock-nut on any common
>>> bicycle wheel axle. If you look closely, you may also notice that
>>> the cone - complete with it's internal thread - is hardened.
>> There are no radial loads on wheels, only vertical and an
>> occasional longitudinal force from braking or a bump in the
>> road. There is no circulating load.
> Interesting. If a load is unidirectional then it is not radial, even
> if radially aligned?
> What if it changes directions but is still not circulating? I guess
> we can rule out headsets as having any radial loads.
Try a bit harder to visualize the interface. A ROTATING RADIAL LOAD,
as we see in pedals and BB bearings. Just try not to be so difficult.
Jobst Brandt
Jobst Brandt
>>> This "tread" goes farther than screw threads, but they are a
>>> practical symbol of mechanical ineptness in the bicycle
>>> industry. This syndrome is found elsewhere in bicycles. We had
>>> that subject a while back when I mentioned that not even the REMA
>>> Tip-Top patch representative knew why one sand papers a tube
>>> before patching. ....
>> IRL I have seen more than a couple times that people did not know
>> how to use patch kits they themselves had bought.
>> In particular, they thought that you had to apply the patch to the
>> tube while the cement (that was smeared on the tube) was still
>> WET. They figured the glue was old since it wouldn't stay on, and
>> then were amazed that it worked at all after the cement had
>> dried. The Rema Ikea-pictogram-instructions show a clock indicating
>> to wait 5-10 minutes between applying the glue and the patch, but
>> most people seem to ignore that part since it is counter to every
>> other use of glue they've seen.
> It's not glue (from bones and hide), it's a contact adhesive. Some
> though like to live in the past. I've found that in the thickness I
> apply the cement that it is dry and ready to use in two minutes.
> There is some variance between manufacturers but it is tiny.
>> If I am helping someone out who doesn't look like they bicycle very
>> much, I always make it a point to explain that tidbit.
Lest you don't look for failures, you might look at patches on tubes
you have repaired with your method and note whether any of them lie
completely flat or domed. Domed REMA patches are ones that separated
during riding as far as they could, the effect ending where air
pressure in the tube presses the patch against the tire casing.
If you cut through a domed patch, you'll see that it is not adhering
in the center of the dome. Check out "Leaky Patches" in:
http://www.sheldonbrown.com/brandt/patching.html
Jobst Brandt
DirtRoadie
> DirtRoadie <DirtRoa...@aol.com> considered Sun, 12 Sep 2010 18:35:15
> bearing geometry and preload method.
I even left out where JB said in the same post "... fortunately the
threadless
steertube is a step in the right direction. The threaded ones were
perpetually fretting, "
Fortunately MP has stepped in to establish that the foregoing
unambiguously does not refer to threaded headsets.
DR
DirtRoadie
Kinda' hard to "visualize" something when you give erroneous examples
of what YOU were thinking.
Sounds like we are now expected to ignore anything you said about
threads and their relationship to headsets because that was all in
error, correct?
Like the the part where you said "... fortunately the threadless
steertube is a step in the right direction. The threaded ones were
perpetually fretting"
Help us out here.
True or false - Threads have nothing to do with headsets fretting.
DR
DirtRoadie
> On Sep 12, 2:44 pm, DirtRoadie <DirtRoa...@aol.com> wrote:
>
> > On Sep 12, 9:59 am, Frank Krygowski <frkry...@gmail.com> wrote:
>
> > > Sorry, but I think you don't understand the mechanics of vibrational
> > > loosening of threads.
>
> > Apparently, I don't. By your analysis ANY thread will loosen under ANY
> > vibration. This would include conical lug nuts.
>
> If you claim that, you don't understand the analysis.
What I understand is that the analysis you offer about vibration, even
if partially accurate, is incomplete.
Please give the following questions some thought:
1. Have there ever been ANY threaded assemblies on operating
machinery (or otherwise subject to vibration) that did not loosen in
use?
2. If #1 = Yes, have any of these assemblies been assembled without a
"thread locking" compound?
3. If #2 = Yes, is it likely that the threads on these assemblies were
different from "normal" threads?
4. If #1,2,3 = Yes, what, under your theory, would allow those
threaded assemblies to stay secured?
Extra credit:
Do the threads of conical lugs have all the characteristics of
"normal" threads?"
Does a conical lug nut carry any radial load?
Do the threads of a conical lug nut carry any radial load?
Do conical lug nuts loosen in use?
Now apply question # 4 above.
> So radial clearance does not vanish if a nut-bolt assembly is
> tightened. And motion within that radial clearance is an important
> mechanism for loosening threaded fasteners.
If what you were saying were true in its _entirety_ there would ALWAYS
be play in ANY threaded assembly. That this can play a _part_ in
loosening is not the whole story. Although for a threaded assembly
which is not tightened it may very well be the whole story.
The point is that radial movement (or degree of radial movement) of a
threaded assembly can be and is constrained in more than one way. Like
a belt and suspenders. Just because there may be no belt does not mean
that the suspenders cannot hold the pants up.
In threads, axial clearance (or lack thereof) affects/limits radial
movement even if radial clearance still exists. External constraints
can also affect radial movement.
I gave the simple example of using two nuts on a threaded shaft (or a
single nut on bolt with a head). When the nut is free it has obvious
play, both radial and axial, on the threaded shaft. Thread that nut up
snugly against another nut or the bolt head and that play disappears.
There can be little question that the radial freedom which was
previously readily apparent has been severely constrained or even
prevented entirely. You seem to be caught up in the notion that
because there is SOME force which may be able to overcome this
constraint, that there is no constraint. That is a bit like saying a
support holding 100 lbs is not a support at all if will collapse
under a load of 200 lbs.
Let's further take this hypothetical dual-nut threaded assembly and
snug the nuts together with minimal finger-force, just sufficient to
remove any obvious play. (I'm envisioning a typical ubiquitous 1/4-20
threading)
I'll hypothesize that the nuts can be loosened by tapping the shaft a
handful of times on a solid surface. (Yes, threads can loosen and I
have never suggested otherwise) Now let's tighten those nuts quite
securely against one another using an appropriate wrench. I'll
hypothesize again that under that this scenario the nuts will not
loosen even if I tap the shaft on that surface all day long. Nothing
has changed in the radial clearance of the threads upon which you base
your understanding, yet the threads stay secured. How would you
account for this?
Otherwise you have not addressed anything I said in any meaningful
fashion. Denial is not discussion.
DR
DirtRoadie
> 3. If #2 = Yes, is it likely that the threads on these assemblies were
> different from "normal" threads?
Correction
3. If #2 = Yes, is it likely that the threads on these assemblies
were "normal" threads?
DR
Frank Krygowski
> On Sep 12, 10:48 pm, Frank Krygowski <frkry...@gmail.com> wrote:
>
> > On Sep 12, 2:44 pm, DirtRoadie <DirtRoa...@aol.com> wrote:
>
> > > On Sep 12, 9:59 am, Frank Krygowski <frkry...@gmail.com> wrote:
>
> > > > Sorry, but I think you don't understand the mechanics of vibrational
> > > > loosening of threads.
>
> > > Apparently, I don't. By your analysis ANY thread will loosen under ANY
> > > vibration. This would include conical lug nuts.
>
> > If you claim that, you don't understand the analysis.
>
> What I understand is that the analysis you offer about vibration, even
> if partially accurate, is incomplete.
It was not intended to be complete. I'm not attempting to give a
complete course on design of bolted joints here. I merely mentioned
that one of your statements was wrong. Here it is:
"...what is the significance of clearance in threaded elements when
the threads are carrying an axial load by being threaded "together?"
My point was that when that has occurred there is NO clearance between
the mating faces. That means that aside from that which can occur by
flexing there is no radial movement."
That's simply wrong. Radial movement can and does occur, and it's an
important mechanism for the loosening of threaded factors. I already
mentioned that it's restricted by friction; however restricted is not
the same as prevented. As I said, "while increasing torque on the
fastener increases friction, it can still be overcome."
And I never said all nuts and bolts must loosen, that was your straw
man. And incidentally, tapping a 1/4-20 screw on a table a couple
times is a poor replication of the service life of most fasteners. If
you want to replicate the Harley-Davidson experience I alluded to, try
tapping that thing on the table a few million times.
I think you should practice typing "What I should have said was..."
It can save a lot of trouble.
- Frank Krygowski
Michael Press
<c9cdd8d7-1fb6-4b4b...@j30g2000vbr.googlegroups.com>,
DirtRoadie <DirtR...@aol.com> wrote:
I am not the best one to ask. I got into this and am
getting out. The secret to conversing with Brandt is to
know exactly what he says and address what he says.
Since some of it is very technical, it requires hard
thought. Trust me, I have had to think very hard to
understand some of what he says, and it always turns
out to be worth having understood.
You react strongly to him. Try to set aside the
reactions for a minute so you can devote all your
attention to what he says. You could ignore him, but
presently you do not. Neither are you obliged to agree
with him.
--
Michael Press
Michael Press
<f8d38fde-f555-4911...@j19g2000vbh.googlegroups.com>,
DirtRoadie <DirtR...@aol.com> wrote:
> 1. Have there ever been ANY threaded assemblies on operating
> machinery (or otherwise subject to vibration) that did not loosen in
> use?
Head bolts on internal combustion engines.
--
Michael Press
DirtRoadie
That was really just a rhetorical question. Your points are noted, but
are nothing new. In light of some of the rambling and seemingly
confused content of what I see him posting recently, I truly wonder
whether he is becoming a bit senile. I have seen a handful of older
people reach the point where they started to decline and became truly
unpleasant to deal with. And that is putting it as nicely as
possible. Oft times these folks settled into a classic "the older I
get, the better I was" punctuated by an openly belligerent/
confrontational attitude. Others in contrast become more mellow.
But JB has never had much of a reputation for any degree of tolerance
so maybe its just the same old thing.
Anyhow, not my problem. And, as you point out, it can be avoided.
Thanks for the feedback.
DR
Jobst Brandt
>> 1. Have there ever been ANY threaded assemblies on operating
>> machinery (or otherwise subject to vibration) that did not loosen
>> in use?
> Head bolts on internal combustion engines.
Certainly, because head bolts are properly used... to hold compression
in the cylinder and to compress the head gasket. There is no lateral
or radial load on those studs. Of course there have been enough
engine designers to have made this standard design.
Jobst Brandt
DirtRoadie
Thanks for jumping in and changing the subject. The discussion was
"vibration," an issue raised by FK, not by me. And that was the
reason for the question.
Now, can I assume that you will stand in and defend for Mr K's
assertions for the duration of this thread. If so please get up to
speed with his position. I think you need to especially be familiar
with old Harleys.
DR
Jobst Brandt
>>>> 1. Have there ever been ANY threaded assemblies on operating
>>>> machinery (or otherwise subject to vibration) that did not loosen
>>>> in use?
>>> Head bolts on internal combustion engines.
>> Certainly, because head bolts are properly used and in tension,
>> holding compression in the cylinder and for compressing the head
>> gasket. There is no lateral or radial load on those studs. Of
>> course there have been enough engine designers to have made this
>> standard design.
> Thanks for jumping in and changing the subject. The discussion was
> "vibration," an issue raised by FK, not by me. And that was the
> reason for the question.
> Now, can I assume that you will stand in and defend for Mr K's
> assertions for the duration of this thread. If so please get up to
> speed with his position. I think you need to especially be familiar
> with old Harleys.
I see no difference there.
Jobst Brandt
DirtRoadie
> On Sep 13, 2:42 pm, DirtRoadie <DirtRoa...@aol.com> wrote:
>
> > On Sep 12, 10:48 pm, Frank Krygowski <frkry...@gmail.com> wrote:
>
> > > On Sep 12, 2:44 pm, DirtRoadie <DirtRoa...@aol.com> wrote:
>
> > > > On Sep 12, 9:59 am, Frank Krygowski <frkry...@gmail.com> wrote:
>
> > > > > Sorry, but I think you don't understand the mechanics of vibrational
> > > > > loosening of threads.
>
> > > > Apparently, I don't. By your analysis ANY thread will loosen under ANY
> > > > vibration. This would include conical lug nuts.
>
> > > If you claim that, you don't understand the analysis.
>
> > What I understand is that the analysis you offer about vibration, even
> > if partially accurate, is incomplete.
>
> It was not intended to be complete. I'm not attempting to give a
> complete course on design of bolted joints here. I merely mentioned
> that one of your statements was wrong. Here it is:
>
> "...what is the significance of clearance in threaded elements when
> the threads are carrying an axial load by being threaded "together?"
> My point was that when that has occurred there is NO clearance between
> the mating faces. That means that aside from that which can occur by
> flexing there is no radial movement."
>
> That's simply wrong.
Thank you for your insightful and detailed articulation of your
position. I stand thoroughly enlightened as a result. Although I
would suggest you give a little more thought to how threads mate.
Along with simple friction, at any given point the is the equivalent
of two wedges (or sets of two wedges) face-to-face resisting radial
motion.
> Radial movement can and does occur, and it's an
> important mechanism for the loosening of threaded factors.
Yes, your repetition makes this true. I think you might want to
rephrase this to "If radial movement can occur, it can be a factor in
the mechanism for the loosening of threaded assemblies." That's a
version I am happy to accept.
> I already
> mentioned that it's restricted by friction; however restricted is not
> the same as prevented. As I said, "while increasing torque on the
> fastener increases friction, it can still be overcome."
You seem to think that the degree of constraint is irrelevant that if
something can be moved by some force, that it WILL be moved by ANY
force.
> And I never said all nuts and bolts must loosen, that was your straw
> man.
You did not say it expressly, but you clearly implied it and you have
done so here by saying "it can still be overcome." Overcome with
what? A sufficient force? Fine. And what constitutes a sufficient
force? ANY force? No, I think not. Go back to your sliding book
analogy. If we don't dislodge the book it does not slide down the
tilted board.
> And incidentally, tapping a 1/4-20 screw on a table a couple
> times is a poor replication of the service life of most fasteners. If
> you want to replicate the Harley-Davidson experience I alluded to, try
> tapping that thing on the table a few million times.
Fine. A million times it is. Do you have time to try it? I proposed
that as a simple example of an assembly where the forces keeping the
threads in place are not "overcome," not as a test for a "Harley
compatible" fastener. And what is it about old Harleys where their
threaded fasteners come loose whereas other vehicles, even of that
vintage did not have the same problem? Must be the Harley mystique.
Couldn't possibly be something as simple as the improper sizing (and
related torquing) of the threaded assemblies for their necessary
service, could it?
> I think you should practice typing "What I should have said was..."
> It can save a lot of trouble.
Thanks so much for answering the questions I posed.
DR
Frank Krygowski
Furthermore, on the cylinder heads I've replaced, close fitting dowel
pins have been used to precisely align head and block. Those pins
would prevent the lateral motion that causes the loosening I've been
describing.
- Frank Krygowski
Frank Krygowski
I think you need to do some outside reading. Try this:
http://www.boltscience.com/pages/josteffect.htm
or other information here:
http://www.boltscience.com/pages/vibloose.htm
Alternately, you can google vibrational loosening or similar topics.
There's a lot to be learned.
- Frank Krygowski
thirty-six
A pedal fixing is a FIXING, not a bearing, not a GYROSCOPE, there is
NO precession in a FIXED joint.
Clive George
Well, precession can be observed, and there doesn't need to be a
gyroscope for that. I think we could agree that in a fixed joint it
doesn't happen, therefore we can deduce that a pedal isn't a fixed joint
using your definition.
thirty-six
For the umpteenth time., none of my old patches on myt few old inner
tubes I now possess are domed. I learnt to correct the error of
assembling the patch wet in my teenage years, although I had been
taught to assemble dry earlier, I tried to quicken the process.
> Domed REMA patches are ones that separated
> during riding as far as they could, the effect ending where air
> pressure in the tube presses the patch against the tire casing.
You've been doing it wrong. Pity you are so unable to accept
observation as science.
>
> If you cut through a domed patch, you'll see that it is not adhering
I HAVE NOT ANY DOMED PATCHES
> in the center of the dome. Check out "Leaky Patches" in:
You are a leaky head.
>
> http://www.sheldonbrown.com/brandt/patching.html
>
> Jobst Brandt
thirty-six
Shite threadings.
>
> DR
thirty-six
> Michael Press wrote:
> >> 1. Have there ever been ANY threaded assemblies on operating
> >> machinery (or otherwise subject to vibration) that did not loosen
> >> in use?
> > Head bolts on internal combustion engines.
>
> Certainly, because head bolts are properly used... to hold compression
> in the cylinder and to compress the head gasket. There is no lateral
> or radial load on those studs.
Except when there is and the cylinder head drifts. Study the Rover K
series engine which uses the cylinder head tie bolt drillings as the
return oilways. The early incarnations of this engine if left to
overheat would soften the plastic head locating dowels and the head
would drift resulting in head hasket failure. The drift is caused by
lateral loads on the head retaining biolts. You dont see it with
studs so much because they dont soften during engine overheat. The
lateral force may be due to a number of issues including the
pressurised oil feed position and a lack of pressure symetry generally
upon the head gasket.
> Of course there have been enough
> engine designers to have made this standard design.
STUDS NOT BOLTS
>
> Jobst Brandt
Peter Cole
Because threads have clearance, the shaft and hole (in pedal to crank)
are centered only with frictional force. When the shaft is loaded in a
plane perpendicular to its axis, the axis of the shaft may shift
laterally relative to the axis of the hole. If you look at the force
vector during a pedal cycle from the frame of reference of the crank,
you'll see the force vector rotating counterclockwise (right side
pedal). What is harder to visualize perhaps is the path of the shaft
axis (from the same frame). The shaft axis must shift in the direction
of the force, so it too describes a (very small) circle, in a CCW
direction. Perhaps the most difficult thing to visualize is that the
path of the shaft axis means it's actually "rolling" on the hole bore,
and rolling CCW induces a CW rotation in the shaft (relative to the
crank). That is "mechanical precession". It is easy to demonstrate by
making a hole with your fingers and rolling a pencil in it and observing
the pencil rotation.
By making the shaft/bore interface conical, the interface becomes
self-centering. It will not shift under load, nor precess under a
circulating load.
Sufficient friction will prevent shifting under load, but the use of LH
threads on BB's and pedals indicate that sufficient friction is
difficult to achieve in those applications.
DirtRoadie
> On 9/13/2010 10:54 PM, Clive George wrote:
> Because threads have clearance, the shaft and hole (in pedal to crank)
> are centered only with frictional force.
No they are centered by virtue of the "wedging" action of abutting (in
contact) thread faces. Those faces are angled with respect to the
central axis. The "clearance" you refer to is between non-abutting
faces.
> By making the shaft/bore interface conical, the interface becomes
> self-centering. It will not shift under load, nor precess under a
> circulating load.
It is self-centering in any case once the threads have reached the
point of engagement where the abutting faces are in contact.
> Sufficient friction will prevent shifting under load, but the use of LH
> threads on BB's and pedals indicate that sufficient friction is
> difficult to achieve in those applications.
This is largely true. There is a reason that a 15mm pedal wrench
http://www.parktool.com/images/products/productimages/det_PW-4_2005729_77106.jpg
is much bigger than a 15mm cone wrench
http://www.parktool.com/images/products/productimages/det_SCW-15_2005729_11066.jpg
Although I, personally, find the latter to be just fine for pedals and
have experienced no issues of pedal loosening nor the threads fretting
into oblivion.
DR
DirtRoadie
> I think you need to do some outside reading. Try this:http://www.boltscience.com/pages/josteffect.htm
>
> or other information here:http://www.boltscience.com/pages/vibloose.htm
>
Thanks for the links. I especially like the second one.
Since you provided the link, I am assuming you believe it is a good
authoritative source and is accurate.
That should makes things easy.
Now please read it. I would say read it "again," except I do not think
you read it in the first place.
That excellent article, that YOU have chosen to cite, is fully
consistent with everything I have said here.
Let's take one simple paragraph from that article.
"It is widely believed that vibration causes bolt loosening. By far
the most frequent cause of loosening is side sliding of the nut or
bolt head relative to the joint, resulting in relative motion
occurring in the threads. If this does not occur, then the bolts will
not loosen, even if the joint is subjected to severe vibration. By a
detailed analysis of the joint it is possible to determine the clamp
force required to be provided by the bolts to prevent joint slip."
Now the article does not specifically address the "wedging" type of
constraint on radial movement of threads, but does acknowledge the
frictional aspect of thread enagagement which limits/prevents such
movement.
But I think you need to give some thought to the former (wedging)
before simply saying "that isn't so."
The article also describes the mechanism of thread locking compounds.
Specifically "The chemical locking category are adhesives..." So much
for your theory.
In this discussion you ramped up your arguing and disengaged your
listening and/or thinking. Sort of a classic "Don't confuse me with
facts - my mind is made up."
Thank you, are we done now?
DR
PS Yes there is a lot to be learned and I AM learning. Are you?
Peter Cole
> On Sep 14, 6:29 am, Peter Cole<peter_c...@verizon.net> wrote:
>> On 9/13/2010 10:54 PM, Clive George wrote:
>
>> Because threads have clearance, the shaft and hole (in pedal to crank)
>> are centered only with frictional force.
>
> No they are centered by virtue of the "wedging" action of abutting (in
> contact) thread faces. Those faces are angled with respect to the
> central axis. The "clearance" you refer to is between non-abutting
> faces.
True, but given that in a pure clamping application, the majority of
installation torque (~90%) goes to friction and the balance to stretch
gives an indication of the relative magnitudes.
In any case, I don't really think that's important to the situation of
mechanical precession. If you consider a screw fastener in cross
section, you'll see that for there to be lateral movement, one set of
mating thread faces must "climb", while the other one drops. When this
happens, the shaft axis tilts. That is precisely what happens when a
bending load is applied. The components of a threaded fastener are
elastic, including threads.
>> By making the shaft/bore interface conical, the interface becomes
>> self-centering. It will not shift under load, nor precess under a
>> circulating load.
>
> It is self-centering in any case once the threads have reached the
> point of engagement where the abutting faces are in contact.
Yes, but the question is how well the interface will stay centered under
bending load.
>> Sufficient friction will prevent shifting under load, but the use of LH
>> threads on BB's and pedals indicate that sufficient friction is
>> difficult to achieve in those applications.
>
> This is largely true. There is a reason that a 15mm pedal wrench
> http://www.parktool.com/images/products/productimages/det_PW-4_2005729_77106.jpg
>
> is much bigger than a 15mm cone wrench
> http://www.parktool.com/images/products/productimages/det_SCW-15_2005729_11066.jpg
I think the wrench size difference is mostly because of the potentially
much larger torque needed to remove pedals. A quick look for Shimano
specs shows a (min) pedal installation torque of ~25 ft-lb, while cone
locknuts are spec'ed at 8-18. Not as large a difference as the wrench
sizes would imply.
> Although I, personally, find the latter to be just fine for pedals and
> have experienced no issues of pedal loosening nor the threads fretting
> into oblivion.
The real rest would be if you could make the same claim without LH
threads. The load on a cone is not circulating, unlike pedal and BB
threads which are. Mechanical precession will (given typical chirality)
work to tighten the threads.
As for fretting, if there's precession driven loosening, there's
movement at the interface (fretting). If precession driven loosening
never occurred, there would be no need for LH threads on components with
circulating loads. Bending of the threaded interface causes motion
between the mating surfaces if they're not constrained. The conical seat
constrains, typical threads do not.
DirtRoadie
What the heck, let's go back to conical lug nuts, circulating radial
loads and thread clearance.
There are several assumptions (axioms) to which you subscribe.
See if these are accurate from your perspective.
1. Threads have clearance therefore radial movement is unconstrained.
2. Radial movement in a threaded fastener is what causes loosening.
3. By #2, radial movement in a flat lug nut is the reason for it
loosening.
4. By # 2 and 3, the radial movement in a flat lug nut is the result
of the aforementioned thread clearance.
Now we have two other assumptions which
1. Flat lug nuts loosen
2. Conical lug nuts do not loosen
The issue is simply "flat" vs. "conical." We have not assumed any
other variations.
So what accounts for the difference in behavior? The presumption can
only be that it is the conical exterior surface of the conical nut.
That conical surface must somehow negate the radial movement at the
thread interface since that is what we have assumed is causing the
flat nuts to loosen. Seems obvious that the conical nut is nicely
seated in a conical seat in the wheel and therefore it cannot move
radially.
But that, of course, assumes that the wheel is fixed so that it has no
freedom to move radially around the studs. What prevents such movement
of the wheel? Simple, it is held nicely in place by the lug nuts
(which, of course, have a threaded interface with the studs).
Hmm....
So we have a model in which the wheel keeps the nuts from moving
radially with respect to the studs while the nuts keep the wheel from
moving radially wrt the studs.
A fine example of "bootstrapping."
Bottom line: conical lug nuts do not remove threads (with their
supposed radial clearance) from the equation. If conical lug nuts work
(or since they work) there are other factors which account for the
success of the system.
DR
Jobst Brandt
>>>>> This "tread" goes farther than screw threads, but they are a
>>>>> practical symbol of mechanical ineptness in the bicycle
>>>>> industry. This syndrome is found elsewhere in bicycles. We had
>>>>> that subject a while back when I mentioned that not even the
>>>>> REMA Tip-Top patch representative knew why one should sand paper
>>>>> a tube before patching. ....
>>>> IRL I have seen more than a couple times that people did not know
>>>> how to use patch kits they themselves had bought. In particular,
>>>> they thought that you had to apply the patch to the tube while
>>>> the cement (that was smeared on the tube) was still WET. They
>>>> figured the glue was old since it wouldn't stay on, and then were
>>>> amazed that it worked at all after the cement had dried. The
>>>> Rema Ikea-pictogram-instructions show a clock indicating to wait
>>>> 5-10 minutes between applying the glue and the patch, but most
>>>> people seem to ignore that part since it is counter to every
>>>> other use of glue they've seen.
Well, allowing the glue to "DRY" before applying the patch is a way of
generating leaky patches. The patch should be applied when the thin
swipe of rubber glue hasn't lost its sheen but is well jelled. In
this condition it makes full contact with the red REMA patch base and
chemically bonds with it. Because this is the best way to make
un-removable patches, the cellophane packaging must be removed from the
applied patch so the volatiles can escape and the patch can
elastically attach to the tube.
>>> It's not glue (from bones and hide), it's a contact
>>> adhesive. Some though like to live in the past. I've found that
>>> in the thickness I apply the cement that it is dry and ready to
>>> use in two minutes. There is some variance between manufacturers
>>> but it is tiny.
Call it what you like, it is rubber cement... and don't "DRY" it as
you describe.
>>>> If I am helping someone out who doesn't look like they bicycle
>>>> very much, I always make it a point to explain that tidbit.
>> Lest you don't look for failures, you might look at patches on
>> tubes you have repaired with your method and note whether any of
>> them lie completely flat or domed.
> For the umpteenth time., none of my old patches on myt few old inner
> tubes I now possess are domed. I learnt to correct the error of
> assembling the patch wet in my teenage years, although I had been
> taught to assemble dry earlier, I tried to quicken the process.
There is a place between dry and liquid that you seem to have missed.
Most of my "research" on the matter was replacing leaky patches on
tires of bikies who attended my Wednesday tire patch evenings where we
repaired tubular tires and clincher inner tubes.
>> Domed REMA patches are ones that separated during riding as far as
>> they could, the effect ending where air pressure in the tube
>> presses the patch against the tire casing.
> You've been doing it wrong. Pity you are so unable to accept
> observation as science.
You assume I have these problems on my own inner tubes, but I made
these discoveries on other peoples tires. How to remove a well cures
but partially adhered patch was also discovered in my kitchen where I
had to heat them to pull them off and put on a new one with yet
undried glue.
>> If you cut through a domed patch, you'll see that it is not
>> adhering in the center of the dome. Check out "Leaky Patches" in:
http://www.sheldonbrown.com/brandt/patching.html
> I HAVE NOT ANY DOMED PATCHES
> You are a leaky head.
I see you solve problems by insults. You might review that tactic.
Jobst Brandt
Jobst Brandt
>> Because threads have clearance, the shaft and hole (in pedal to
>> crank) are centered only with frictional force.
> No they are centered by virtue of the "wedging" action of abutting
> (in contact) thread faces. Those faces are angled with respect to
> the central axis. The "clearance" you refer to is between
> non-abutting faces.
That's what the bicycle industry thought for more than a century, but
Rick Hjertbergs collection of broken cranks at the pedal eye it
witness to the error in that thinking.
>> By making the shaft/bore interface conical, the interface becomes
>> self-centering. It will not shift under load, nor precess under a
>> circulating load.
> It is self-centering in any case once the threads have reached the
> point of engagement where the abutting faces are in contact.
I thought the example of the automotive conical lug nut might make
that more apparent, but I see it missed its target.
>> Sufficient friction will prevent shifting under load, but the use
>> of LH threads on BB's and pedals indicate that sufficient friction
>> is difficult to achieve in those applications.
> This is largely true. There is a reason that a 15mm pedal wrench:
http://www.parktool.com/images/products/productimages/det_PW-4_2005729_77106.jpg
> is much bigger than a 15mm cone wrench:
http://www.parktool.com/images/products/productimages/det_SCW-15_2005729_11066.jpg
> Although I, personally, find the latter to be just fine for pedals
> and have experienced no issues of pedal loosening nor the threads
> fretting into oblivion.
Don't believe that. I have a Campagnolo cone wrench with one jaw
split off by a guy who was trying to remove a pedal with it. There is
a lot of ftictional torque in that joint, but not enough to prevent
fretting damage to the crank.
Jobst Brandt
Jobst Brandt
>> I think you need to do some outside reading. Try this:
http://www.boltscience.com/pages/josteffect.htm
>> or other information here:
http://www.boltscience.com/pages/vibloose.htm
> Thanks for the links. I especially like the second one. Since you
> provided the link, I am assuming you believe it is a good
> authoritative source and is accurate.
> That should makes things easy. Now please read it. I would say read
> it "again," except I do not think you read it in the first place.
> That excellent article, that YOU have chosen to cite, is fully
> consistent with everything I have said here.
However, there is no mention of a typical pedal spindle or BB cup that
has a rotating load and unscrews by precession, the more important
side effect of misused screw threads.
> Let's take one simple paragraph from that article.
> "It is widely believed that vibration causes bolt loosening. By far
> the most frequent cause of loosening is side sliding of the nut or
> bolt head relative to the joint, resulting in relative motion
> occurring in the threads. If this does not occur, then the bolts will
> not loosen, even if the joint is subjected to severe vibration. By a
> detailed analysis of the joint it is possible to determine the clamp
> force required to be provided by the bolts to prevent joint slip."
We aren't concerned with vibration and the article doesn't mention an
example where this sort of vibration occurs. Thar's too bad because
there is a lot of ground to be covered in that subject.
> Now the article does not specifically address the "wedging" type of
> constraint on radial movement of threads, but does acknowledge the
> frictional aspect of thread enagagement which limits/prevents such
> movement.
I don't understand what you mean by "wedging" in threads. There is
contact friction on the pressure surfaces in a thread but these are
not enough to prevent cars from losing wheels on the road. That
problem was solved by the conical lug nut that changes the loading
geometry of wheel attachment as has the conical face on bicycle pedal
spindles that formerly required left hand threads to stay engaged.
> But I think you need to give some thought to the former (wedging)
> before simply saying "that isn't so."
I think you need to explain the effect and how it is used in the areas
of interest.
> The article also describes the mechanism of thread locking
> compounds. Specifically "The chemical locking category are
> adhesives..." So much for your theory.
That is what makes the whole item questionable. You can demonstrate
pedal fretting motion after applying thread-lock. Thread locking
compounds are far softer than steel, so in a high load environment
putting the load on the thread-lock doesn't have a beneficial effect.
> In this discussion you ramped up your arguing and disengaged your
> listening and/or thinking. Sort of a classic "Don't confuse me with
> facts - my mind is made up."
> Thank you, are we done now?
No! you have a way to go to return to practical effects not based on
imagined effects.
> PS Yes there is a lot to be learned and I AM learning. Are you?
Not from what you describe!
Jobst Brandt
Frank Krygowski
I _think_ what "DirtRoadie" is imagining is that, because the thread
form has 60 degree angles, it is impossible for the male thread to
move laterally within the female thread. I think he'd say such motion
is possible only with square threads. It's nonsense, of course.
He also seems to think that since friction exists, lateral motion is
impossible. That's also nonsense, of course.
And I think he's taken a website devoted to vibrational loosening of
threads, picked one paragraph which says, in effect, "if relative
motion doesn't occur, threads won't loosen," and somehow
misinterpreted it as "SINCE relative motion doesn't occur, threads
can't possibly loosen." That's also nonsense, of course.
Aside from that, we've had some topic drift in this thread. I
attempted to correct his misapprehension that there is no inter-thread
clearance by citing vibrational loosening and its mechanisms. I think
he's now arguing against that as well as against precession motion,
pretending neither happens.
I'm sure he'll energetically correct me if I've gotten any of his
ideas wrong. And that he'll energetically deflect the discussion if
I"ve gotten them right!
I think the guy has never seen a threaded fastener come loose.
- Frank Krygowski
DirtRoadie
> Someone wrote:
> >> Because threads have clearance, the shaft and hole (in pedal to
> >> crank) are centered only with frictional force.
> > No they are centered by virtue of the "wedging" action of abutting
> > (in contact) thread faces. Those faces are angled with respect to
> > the central axis. The "clearance" you refer to is between
> > non-abutting faces.
>
> That's what the bicycle industry thought for more than a century, but
> Rick Hjertbergs collection of broken cranks at the pedal eye it
> witness to the error in that thinking.
And my cousin had a coin collection. What's your point?
I assume you are referring to this:
http://www.pardo.net/bike/pic/fail-001/FAIL-001.html
And of course you are ignoring the part at the bottom where "Ric
says: Pedal eye failures seem ominous but not some decisive
majority."
So it is your position that the clearance is between _abutting_
faces?
> >> By making the shaft/bore interface conical, the interface becomes
> >> self-centering. It will not shift under load, nor precess under a
> >> circulating load.
> > It is self-centering in any case once the threads have reached the
> > point of engagement where the abutting faces are in contact.
>
> I thought the example of the automotive conical lug nut might make
> that more apparent, but I see it missed its target.
I have invited you to address that elsewhere.
Probably not as good an example as you think for reasons I have
described.
I'm looking forward to your response that.
> >> Sufficient friction will prevent shifting under load, but the use
> >> of LH threads on BB's and pedals indicate that sufficient friction
> >> is difficult to achieve in those applications.
> > This is largely true. There is a reason that a 15mm pedal wrench:
>
> http://www.parktool.com/images/products/productimages/det_PW-4_200572...
>
> > is much bigger than a 15mm cone wrench:
>
> http://www.parktool.com/images/products/productimages/det_SCW-15_2005...
>
> > Although I, personally, find the latter to be just fine for pedals
> > and have experienced no issues of pedal loosening nor the threads
> fretting into oblivion.
> Don't believe that. I have a Campagnolo cone wrench with one jaw
> split off by a guy who was trying to remove a pedal with it. There is
> a lot of ftictional torque in that joint, but not enough to prevent
> fretting damage to the crank.
Right. I am not entitled to rely upon my own experience nor use MY
tools on MY bikes in the manner I choose and which has proven to be
appropriate for me. I install my pedals and I remove them. They don't
loosen, never have, and I have yet to see anything suggesting any
fretting problem. Maybe it will show up in hundred years or so. Not
saying it isn't happening but if it is, it is not a problem and I have
no reason to believe that it will become a problem.
I am not suggesting that anybody needs to do anything the way I do,
just offering my perspective. I am obviously doing everything wrong
since my bikes don't break and fall apart as yours do.
DR
Clive George
> Right. I am not entitled to rely upon my own experience nor use MY
> tools on MY bikes in the manner I choose and which has proven to be
> appropriate for me. I install my pedals and I remove them. They don't
> loosen, never have, and I have yet to see anything suggesting any
> fretting problem.
Do your pedals have LH threads on the left? Do you know why most
people's pedals have LH threads on the left?
If your pedals are the conventional sort, congratulations, you're taking
advantage of the get-round people discovered a long time ago. To prevent
precession undoing the pedals, you need a LH thread on the LH pedal.
However taking advantage of other people's knowledge isn't the same as
understanding why things work. Do you understand why you need a LH
thread on a LH pedal?
David Scheidt
:>>>> other use of glue they've seen.
:Well, allowing the glue to "DRY" before applying the patch is a way of
:generating leaky patches. The patch should be applied when the thin
:swipe of rubber glue hasn't lost its sheen but is well jelled. In
:this condition it makes full contact with the red REMA patch base and
:chemically bonds with it. Because this is the best way to make
:un-removable patches, the cellophane packaging must be removed from the
:applied patch so the volatiles can escape and the patch can
:elastically attach to the tube.
Cold vulcanizing cements consist of a solvent, fine rubber, a
vulcinizing accelerant, a sulphur donor, and other assorted chemical
magickry. On application, the solvent attacks the tube's rubber,
allowing the rubber in the cement to bond with it. You've now got an
area of unvulcanized rubber, which, as unvulcanized rubber, is sticky.
You then stick the unvulcanized rubber surface of the patch onto the
prepared cement, and they stick together. The vulcanizing
accelerators and other chemical magicks vulcanize the two pieces
together over a rather long period, days or weeks, depending on the
temperatures.
I fail to see why leaving the solvent in place aides in the process.
I clearly see how it hinders it.
--
sig 95
DirtRoadie
Yes, yes and yes. And I get by just fine using a discarded 15 mm cone
wrench for pedals. Probably precisely because of the LH threads among
other things. Feel free to burn me at the stake. I am a heretic!
Nobody should be allowed to use a cone wrench on pedals, much less
make blasphemous claims that it works and causes no difficulties.
But thanks for setting me straight and explaining everything to me and
telling me why it has worked.
I might otherwise have continued doing the same thing that has served
me well for years!
Come to think of it, I'm going to do that anyhow.
DR
Clive George
> On Sep 14, 10:46 am, Clive George<cl...@xxxx-x.fsnet.co.uk> wrote:
>> On 14/09/2010 17:38, DirtRoadie wrote:
>>
>>> Right. I am not entitled to rely upon my own experience nor use MY
>>> tools on MY bikes in the manner I choose and which has proven to be
>>> appropriate for me. I install my pedals and I remove them. They don't
>>> loosen, never have, and I have yet to see anything suggesting any
>>> fretting problem.
>>
>> Do your pedals have LH threads on the left? Do you know why most
>> people's pedals have LH threads on the left?
>>
>> If your pedals are the conventional sort, congratulations, you're taking
>> advantage of the get-round people discovered a long time ago. To prevent
>> precession undoing the pedals, you need a LH thread on the LH pedal.
>>
>> However taking advantage of other people's knowledge isn't the same as
>> understanding why things work. Do you understand why you need a LH
>> thread on a LH pedal?
>
> Yes, yes and yes. And I get by just fine using a discarded 15 mm cone
> wrench for pedals. Probably precisely because of the LH threads among
> other things. Feel free to burn me at the stake. I am a heretic!
> Nobody should be allowed to use a cone wrench on pedals, much less
> make blasphemous claims that it works and causes no difficulties.
Nobody is saying that. Nobody has a problem with you acknowledging the
reason your pedals work is that there's an LH thread on the LH pedal.
However you've been happily arguing that an RH thread will work on an LH
pedal. You might not realise that you've been doing so, but that would
indicate a lack of understanding on your part.
DirtRoadie
> On 14/09/2010 19:08, DirtRoadie wrote:
> Nobody is saying that. Nobody has a problem with you acknowledging the
> reason your pedals work is that there's an LH thread on the LH pedal.
>
> However you've been happily arguing that an RH thread will work on an LH
> pedal. You might not realise that you've been doing so, but that would
> indicate a lack of understanding on your part.
Ah! I see. I have to acknowledge WHY what I do has worked. I didn't
realize the rules were so strict. Is that because of my posting here
or is it true for all my activities.
I described using a cone wrench on pedals. Nothing more, nothing
less. I did not mention RH or LH threads. I did mention that I have
not had a pedal loosen nor seen any sign of fretting wear. Those are
true statements. Was I in error for describing that?
I have no idea where you come up with the nonsense that I have "been
happily arguing that an RH thread will work on an LH pedal."
Before you post again, please describe in detail how the internet
works. For if you do not acknowledge how it works you should not be
allowed to use it. Right?
Now come on now, is this group really such a bunch of jerks?
DR
Clive George
> On Sep 14, 12:15 pm, Clive George<cl...@xxxx-x.fsnet.co.uk> wrote:
>> On 14/09/2010 19:08, DirtRoadie wrote:
>
>> Nobody is saying that. Nobody has a problem with you acknowledging the
>> reason your pedals work is that there's an LH thread on the LH pedal.
>>
>> However you've been happily arguing that an RH thread will work on an LH
>> pedal. You might not realise that you've been doing so, but that would
>> indicate a lack of understanding on your part.
>
> Ah! I see. I have to acknowledge WHY what I do has worked. I didn't
> realize the rules were so strict. Is that because of my posting here
> or is it true for all my activities.
If you wish to debate why something happens, knowing about it is useful.
You are engaging in that debate, and demonstrating you don't know enough.
> I described using a cone wrench on pedals. Nothing more, nothing
> less.
That is not true.
> I did not mention RH or LH threads. I did mention that I have
> not had a pedal loosen nor seen any sign of fretting wear. Those are
> true statements. Was I in error for describing that?
They may be true, but they're not the whole truth.
> I have no idea where you come up with the nonsense that I have "been
> happily arguing that an RH thread will work on an LH pedal."
"No they are centered by virtue of the "wedging" action of abutting (in
contact) thread faces. Those faces are angled with respect to the
central axis. The "clearance" you refer to is between non-abutting
faces."
This implies any thread will do, LH or RH. It ignores the problem that
people have been trying to explain to you.
Go back further in the thread and you can find other examples.
DirtRoadie
Jobst Brandt
>>>>> other use of glue they've seen.
>>> Well, allowing the glue to "DRY" before applying the patch is a
>>> way of generating leaky patches. The patch should be applied when
>>> the thin swipe of rubber glue hasn't lost its sheen but is well
>>> jelled. In this condition it makes full contact with the red REMA
>>> patch base and chemically bonds with it. Because this is the best
>>> way to make un-removable patches, the cellophane packaging must be
>>> removed from the applied patch so the volatiles can escape and the
>>> patch can elastically attach to the tube.
>> Cold vulcanizing cements consist of a solvent, fine rubber, a
>> vulcanizing accelerant, a sulfur donor, and other assorted chemical
>> magickry. On application, the solvent attacks the tube's rubber,
>> allowing the rubber in the cement to bond with it. You've now got
>> an area of unvulcanized rubber, which, as unvulcanized rubber, is
>> sticky. You then stick the unvulcanized rubber surface of the
>> patch onto the prepared cement, and they stick together. The
>> vulcanizing accelerators and other chemical magicks vulcanize the
>> two pieces together over a rather long period, days or weeks,
>> depending on the temperatures.
> I fail to see why leaving the solvent in place aides in the process.
> I clearly see how it hinders it.
As mentioned, the solvent is part of the action and if allowed to dry
before placing the patch, it's effects are lost. That is why a
freshly places patch should be allowed to cure, after which it is not
manually removable as in my example with the REMA man. It will
require heating and much force, a method I have had to employ often on
failed patches whose remainder cured after leaking.
Jobst Brandt
Frank Krygowski
>
> Yes, yes and yes. And I get by just fine using a discarded 15 mm cone
> wrench for pedals. Probably precisely because of the LH threads among
> other things. Feel free to burn me at the stake. I am a heretic!
> Nobody should be allowed to use a cone wrench on pedals, much less
> make blasphemous claims that it works and causes no difficulties.
FWIW, we own two Bikes Friday. To pack them for flight in their
suitcases, pedals must be removed. The manufacturer supplies a tool
kit with each bike, and the pedal removal tool is their custom pedal
wrench, about 6" long.
It works. Despite the small installation torque, the pedals don't
unscrew. That's because of the precession action. And on the other
hand, removing pedals is (for us) usually easy, I think because we
tend to put low mileage on these bikes. However, after we used them
in Europe for many hundreds of miles, it was a bit of struggle to get
the pedals off for packing - again, I assume that's because of the
precession action.
I remember packing our full-sized touring bikes into boxes to ship
back, after a coast-to-coast 4000 mile tour. I did not have a full-
size pedal wrench with me, and getting the pedals off was a major
struggle with the wrenches available. Again, I assume that's because
4000 miles of precession, some with big pedal forces, had _really_
tightened them.
- Frank Krygowski
Jobst Brandt
>> Nobody is saying that. Nobody has a problem with you acknowledging
>> the reason your pedals work is that there's an LH thread on the LH
>> pedal.
>> However you've been happily arguing that an RH thread will work on
>> an LH pedal. You might not realise that you've been doing so, but
>> that would indicate a lack of understanding on your part.
> Ah! I see. I have to acknowledge WHY what I do has worked. I
> didn't realize the rules were so strict. Is that because of my
> posting here or is it true for all my activities.
When presenting arguments to a contrary point of view, the reader is
entitled to know what makes your description more accurate than the
one to which it conflicts.
> I described using a cone wrench on pedals. Nothing more, nothing
> less. I did not mention RH or LH threads. I did mention that I
> have not had a pedal loosen nor seen any sign of fretting wear.
> Those are true statements. Was I in error for describing that?
Then you might explain why Campagnolo chose to make pedal wrenches
twice as thick and have more than twice as long a lever as cone
wrench, especially after I mentioned that using a cone wrench for
pedal removal broke a cone wrench.
> I have no idea where you come up with the nonsense that I have "been
> happily arguing that an RH thread will work on an LH pedal."
You did so by vaguely refuting the purpose of left hand threads on
left pedals. Fess-up!
> Before you post again, please describe in detail how the internet
> works. For if you do not acknowledge how it works you should not be
> allowed to use it. Right?
I didn't think you were so out of touch with communication to need an
explanation.
> Now come on now, is this group really such a bunch of jerks?
I think only the ones who use crude language and insults to put forth
their beliefs fit that description.
Jobst Brandt
Jobst Brandt
>>>>> other use of glue they've seen.
>>> Well, allowing the glue to "DRY" before applying the patch is a
>>> way of generating leaky patches. The patch should be applied when
>>> the thin swipe of rubber glue hasn't lost its sheen but is well
>>> jelled. In this condition it makes full contact with the red REMA
>>> patch base and chemically bonds with it. Because this is the best
>>> way to make un-removable patches, the cellophane packaging must be
>>> removed from the applied patch so the volatiles can escape and the
>>> patch can elastically attach to the tube.
>> Cold vulcanizing cements consist of a solvent, fine rubber, a
>> vulcanizing accelerant, a sulfur donor, and other assorted chemical
>> magickry. On application, the solvent attacks the tube's rubber,
>> allowing the rubber in the cement to bond with it. You've now got
>> an area of unvulcanized rubber, which, as unvulcanized rubber, is
>> sticky. You then stick the unvulcanized rubber surface of the
>> patch onto the prepared cement, and they stick together. The
>> vulcanizing accelerators and other chemical magicks vulcanize the
>> two pieces together over a rather long period, days or weeks,
>> depending on the temperatures.
> I fail to see why leaving the solvent in place aides in the process.
> I clearly see how it hinders it.
As mentioned, the solvent is part of the action and if allowed to dry
before placing the patch, it's effects are lost. That is why a
freshly placed patch should be allowed to cure, after which it is not