Minnesota Winters

Tom Keats wrote:
In article ,
Tom Sherman writes:
Tom Keats wrote:
In article ,
writes:
Tom Keats wrote:

[...]
We don't (didn't?) want a "small" amount of pin/spindle[/crank]
contact. We want (wanted?) ~full~, tight contact all along the
length of the pin. That calls for proper fitting, not cheap-assed
swage-fitting where the pin is fat in one localized spot, and loose
(or loosening) everywhere else.
Well you can't do that anyway, because that would not leave cranks
180=C2=B0 apart as they should be.
Oi, bloody hell! Please, not the Q-factor thing again!
How does how convexly tapered pegs in squarely tapered
holes fit, do with crank spacing anyways?[...]
I think you misunderstand. The desired alignment is having the cranks be
180° apart in plan view, and has nothing to do with pedal tread width.

It doesn't matter when attachment points are fixed.

Things on a bicycle get automagically aligned when you
install them, right?

Anyways, I kinda like getting info out of Jobst.
Sometimes it's like tickling silk out of silkworms --
ya feel bad about the way you do it. But in the long
run, so many people get the benefit. Or at least,
they get the information. Whether or not they use it
is up to them.

Jobst is a capacitance of experience. We'd be pretty
stupid to disregard or discard that away. Even if your
stoopid American cotter pins are so fat that you can't
stick 'em in their holes, or yer kids are too fat to
play rugby -- a barbaric game played by civilized people.
As opposed to, and alternated by tennis.

There are no 'fit' issues, given the right part. 8mm, 9mm, 9.5mm cotters
are each quite uniform and cylindrical. Pins fit easily with fingers in
the bore of the crank. On this we agree.

However, a pin in use will 'walk' in use under load if not properly
preloaded with a good amount of pressure.

--
Andrew Muzi
www.yellowjersey.org/
Open every day since 1 April, 1971
** Posted from http://www.teranews.com **

jim beam wrote:
On Sun, 28 Dec 2008 18:51:47 +0000, jobst.brandt wrote:

Tom Keats wrote:

If I had a bike with cotter cranks that needed servicing, I would take
it to the shop with proper tools, such as Mr. Muzi's. A cotter pin
that does NOT require significant force to insert will NOT form a
press fit,
OK. You want an oversized something forced into a weakened hole,
thereby further weakening it.
What an American approach.
which is what this interface requires to function as intended.
The interface requires proper fitting of crank, spindle and cotter pin.
And yet you want everything to depend on some fat guy/thing.
How typical.
Well, if that's what you want, knock yerself out. Shove barrel-chested
pins into your cranks, spread your metal apart, and see what happens.
That settles it for me. You have no idea what cottered cranks are and
how thy work.

that's clearly not true.




Not only that, but you show a lack of understanding of
force transmitting mechanical interfaces, yet you choose to others who
do, how it should be done in the vaguest of terms.

so, great and mighty jobst brandt the expert engineer, how do you
reconcile pedal spindle thread fretting with cotter pin [supposed] non-
fretting??? by your logic, all you'd need to do is over-tighten the pedal
into the crank arm so it wedges hard enough. because that's what you're
asking us to take on faith for cotter pins - which were notorious for
getting chewed.

Well, yes and no.

Professional track bikes were still commonly equipped with premium
forged steel pinned cranks in my youth. And I commonly work on vintage
professional quality bikes with quite well made (and pretty!) steel
pinned cranks. Properly set, the pins are reliable.

Cheaply made, poorly machined cranks or cranks with pins bashed in by
hammer at home or, as Mr Keats suggests, merely drawn up by the nut, are
indeed failure prone. The pins will move under load. Once there is
movement the facet of the pin against the spindle becomes notched.

--
Andrew Muzi
www.yellowjersey.org/
Open every day since 1 April, 1971
** Posted from http://www.teranews.com **

In article ,
(Tom Keats) wrote:

In article ,
Tom Sherman writes:
Tom Keats wrote:
In article ,
A Muzi writes:

The manufacturers of steel pinned cranks seem to feel a heavy cast steel
press with 42:1 leverage driven forcefully ( an able man puts out about
80 pounds with both arms just below shoulder height) is a better
approach. That is a humongous amount of pressure.

Here are two clever designs, a VAR #7 crank press and a set of S+S couplers:
http://www.yellowjersey.org/photosfromthepast/VAR07.JPG

When these cranks were still common, even new premium quality Sugino
cranks on Sugino spindles would fail in a day or two of riding when the
assembler neglected to remove, lubricate and press the pins properly.

For forcing barrel-chested or wrongly-sized cotter pins
into straight-tapered holes, I'm not surprised.

But cotter pins are not barrel-chested. I actually have a
few in my stock -- I've slid dial calipers down them, and
there's no widening in their middles. Straight taper pins;
straight taper holes. As it should be, as long as there's
a perfect fit with no slop.

Although one might get a small amount of pin/spindle contact by drawing
up the nut, the forces at that contact will work it free and deform the
pin's surface in short order if the pin moves at all.

We don't (didn't?) want a "small" amount of pin/spindle[/crank]
contact. We want (wanted?) ~full~, tight contact all along the
length of the pin. That calls for proper fitting, not cheap-assed
swage-fitting where the pin is fat in one localized spot, and
loose (or loosening) everywhere else.

And the only reason to "lubricate" cotter pins (w/ appropriate
grease) is to be able to easily pop them out in order to service
the BB. They don't fail from inadequate greasing.

Might bend the threaded section when driving them out, but
that goes with the territory. And there's an acquirable
"touch" for avoiding that. Well, it's mostly luck.

If I had a bike with cotter cranks that needed servicing, I would take
it to the shop with proper tools, such as Mr. Muzi's. A cotter pin that
does NOT require significant force to insert will NOT form a press fit,

Okay. You want an oversized something forced into a weakened
hole, thereby further weakening it.

What an American approach.


which is what this interface requires to function as intended.

The interface requires proper fitting of crank, spindle and
cotter pin.

And yet you want everything to depend on some fat guy/thing.

How typical.

Well, if that's what you want, knock yerself out. Shove
barrel-chested pins into your cranks, spread your metal
apart, and see what happens.

Do you know that bolts and nuts are torqued down heavily?
Why is that? What happens when cylinder head bolts are not
tightened sufficiently?

Engineering fact: in some applications a bolt that is not
sufficiently tightened will break where a sufficiently
tightened bolt will carry the load.

--
Michael Press

In article ,
Michael Press writes:
In article ,
(Tom Keats) wrote:

In article ,
Tom Sherman writes:
Tom Keats wrote:
In article ,
A Muzi writes:

The manufacturers of steel pinned cranks seem to feel a heavy cast steel
press with 42:1 leverage driven forcefully ( an able man puts out about
80 pounds with both arms just below shoulder height) is a better
approach. That is a humongous amount of pressure.

Here are two clever designs, a VAR #7 crank press and a set of S+S couplers:
http://www.yellowjersey.org/photosfromthepast/VAR07.JPG

When these cranks were still common, even new premium quality Sugino
cranks on Sugino spindles would fail in a day or two of riding when the
assembler neglected to remove, lubricate and press the pins properly.

For forcing barrel-chested or wrongly-sized cotter pins
into straight-tapered holes, I'm not surprised.

But cotter pins are not barrel-chested. I actually have a
few in my stock -- I've slid dial calipers down them, and
there's no widening in their middles. Straight taper pins;
straight taper holes. As it should be, as long as there's
a perfect fit with no slop.

Although one might get a small amount of pin/spindle contact by drawing
up the nut, the forces at that contact will work it free and deform the
pin's surface in short order if the pin moves at all.

We don't (didn't?) want a "small" amount of pin/spindle[/crank]
contact. We want (wanted?) ~full~, tight contact all along the
length of the pin. That calls for proper fitting, not cheap-assed
swage-fitting where the pin is fat in one localized spot, and
loose (or loosening) everywhere else.

And the only reason to "lubricate" cotter pins (w/ appropriate
grease) is to be able to easily pop them out in order to service
the BB. They don't fail from inadequate greasing.

Might bend the threaded section when driving them out, but
that goes with the territory. And there's an acquirable
"touch" for avoiding that. Well, it's mostly luck.

If I had a bike with cotter cranks that needed servicing, I would take
it to the shop with proper tools, such as Mr. Muzi's. A cotter pin that
does NOT require significant force to insert will NOT form a press fit,

Okay. You want an oversized something forced into a weakened
hole, thereby further weakening it.

What an American approach.


which is what this interface requires to function as intended.

The interface requires proper fitting of crank, spindle and
cotter pin.

And yet you want everything to depend on some fat guy/thing.

How typical.

Well, if that's what you want, knock yerself out. Shove
barrel-chested pins into your cranks, spread your metal
apart, and see what happens.

Do you know that bolts and nuts are torqued down heavily?
Why is that? What happens when cylinder head bolts are not
tightened sufficiently?

Engineering fact: in some applications a bolt that is not
sufficiently tightened will break where a sufficiently
tightened bolt will carry the load.

Tightening a bolt with a nut applies a lateral force.
That's a good thing, especially when everything fits.

But carriage bolts (or stove bolts for that matter) don't
have midsection bulges in them in an attempt to apply radial
force to the components they're trying to hold together.

But cotter pins != bolts.

But in modern 3-piece cranks,
tapered square nubs == cotter pins.

The difference in opinion is about the efficacy of
radial vs lateral tightness.

Maybe those 3-piece, tapered/square spindle nubs should
have some flare or bulge designed into them.

Maybe they do.

That's something to check out with the dial calipers.


cheers,
Tom


--
Nothing is safe from me.
I'm really at:
tkeats curlicue vcn dot bc dot ca

On Sun, 28 Dec 2008 19:15:16 -0800, Michael Press wrote:

In article ,
(Tom Keats) wrote:

In article ,
Tom Sherman writes:
Tom Keats wrote:
In article ,
A Muzi writes:

The manufacturers of steel pinned cranks seem to feel a heavy cast
steel press with 42:1 leverage driven forcefully ( an able man puts
out about 80 pounds with both arms just below shoulder height) is a
better approach. That is a humongous amount of pressure.

Here are two clever designs, a VAR #7 crank press and a set of S+S
couplers: http://www.yellowjersey.org/photosfromthepast/VAR07.JPG

When these cranks were still common, even new premium quality
Sugino cranks on Sugino spindles would fail in a day or two of
riding when the assembler neglected to remove, lubricate and press
the pins properly.

For forcing barrel-chested or wrongly-sized cotter pins into
straight-tapered holes, I'm not surprised.

But cotter pins are not barrel-chested. I actually have a few in my
stock -- I've slid dial calipers down them, and there's no widening
in their middles. Straight taper pins; straight taper holes. As it
should be, as long as there's a perfect fit with no slop.

Although one might get a small amount of pin/spindle contact by
drawing up the nut, the forces at that contact will work it free
and deform the pin's surface in short order if the pin moves at
all.

We don't (didn't?) want a "small" amount of pin/spindle[/crank]
contact. We want (wanted?) ~full~, tight contact all along the
length of the pin. That calls for proper fitting, not cheap-assed
swage-fitting where the pin is fat in one localized spot, and loose
(or loosening) everywhere else.

And the only reason to "lubricate" cotter pins (w/ appropriate
grease) is to be able to easily pop them out in order to service the
BB. They don't fail from inadequate greasing.

Might bend the threaded section when driving them out, but that goes
with the territory. And there's an acquirable "touch" for avoiding
that. Well, it's mostly luck.

If I had a bike with cotter cranks that needed servicing, I would
take it to the shop with proper tools, such as Mr. Muzi's. A cotter
pin that does NOT require significant force to insert will NOT form a
press fit,

Okay. You want an oversized something forced into a weakened hole,
thereby further weakening it.

What an American approach.


which is what this interface requires to function as intended.

The interface requires proper fitting of crank, spindle and cotter pin.

And yet you want everything to depend on some fat guy/thing.

How typical.

Well, if that's what you want, knock yerself out. Shove barrel-chested
pins into your cranks, spread your metal apart, and see what happens.

Do you know that bolts and nuts are torqued down heavily? Why is that?
What happens when cylinder head bolts are not tightened sufficiently?

cylinder heads are not a very good analogy - the bolts are torqued to
create a gas seal, not support mechanical load.





Engineering fact: in some applications a bolt that is not sufficiently
tightened will break where a sufficiently tightened bolt will carry the
load.

"in some applications"???

"jim beam" wrote:
On Sun, 28 Dec 2008 01:33:32 -0600, Tom Sherman wrote:

[...]
Translation - I do not read with an anti-Jobst agenda. YAWN


it's not anti-jobst, it's anti made-up bull**** - that's where you're
making your huge mistake. i'll dish it out to /anyone/ that pollutes the
knowledge pool with misinformation and underinformed guesswork. just like
we saw with nate, it's the lies and bullying that keep people with real
information away. and that's just plain WRONG.

YAWN

--
Tom Sherman - 42.435731,-83.985007
LOCAL CACTUS EATS CYCLIST - datakoll

"jim beam" wrote:
On Sun, 28 Dec 2008 02:45:46 -0600, Tom Sherman wrote:

Tom Keats wrote:
In article ,
Tom Sherman writes:

Press fits are designed to have things crammed together with high
force and deformation of the parts involved. Would you ride a square
taper crank that you could push onto the spindle by hand?
That's a way different matter from swaging, and you know it!

Press fitting a cotter is not swaging in primary intent either.

you don't have experience of cotter pins then - they come out deformed.

What part of "primary intent" do you not understand?

--
Tom Sherman - 42.435731,-83.985007
LOCAL CACTUS EATS CYCLIST - datakoll

On Sun, 28 Dec 2008 23:03:05 -0600, Tom Sherman wrote:

"jim beam" wrote:
On Sun, 28 Dec 2008 01:33:32 -0600, Tom Sherman wrote:

[...]
Translation - I do not read with an anti-Jobst agenda. YAWN


it's not anti-jobst, it's anti made-up bull**** - that's where you're
making your huge mistake. i'll dish it out to /anyone/ that pollutes
the knowledge pool with misinformation and underinformed guesswork.
just like we saw with nate, it's the lies and bullying that keep people
with real information away. and that's just plain WRONG.

YAWN

hmmm, the seeker of truth and purity when it comes to andre jute affects
disinterest when it comes to correcting the mistakes of his flawed hero.
how perverse. and lightweight.

On Sun, 28 Dec 2008 23:05:04 -0600, Tom Sherman wrote:

"jim beam" wrote:
On Sun, 28 Dec 2008 02:45:46 -0600, Tom Sherman wrote:

Tom Keats wrote:
In article ,
Tom Sherman writes:

Press fits are designed to have things crammed together with high
force and deformation of the parts involved. Would you ride a square
taper crank that you could push onto the spindle by hand?
That's a way different matter from swaging, and you know it!

Press fitting a cotter is not swaging in primary intent either.

you don't have experience of cotter pins then - they come out deformed.

What part of "primary intent" do you not understand?

what part of "not intended to be deformed" do /you/ not understand?
lightweight.

In article ,
l (Tom Keats) wrote:

In article ,
Michael Press writes:
In article ,
(Tom Keats) wrote:

In article ,
Tom Sherman writes:
Tom Keats wrote:
In article ,
A Muzi writes:

The manufacturers of steel pinned cranks seem to feel a heavy cast steel
press with 42:1 leverage driven forcefully ( an able man puts out about
80 pounds with both arms just below shoulder height) is a better
approach. That is a humongous amount of pressure.

Here are two clever designs, a VAR #7 crank press and a set of S+S couplers:
http://www.yellowjersey.org/photosfromthepast/VAR07.JPG

When these cranks were still common, even new premium quality Sugino
cranks on Sugino spindles would fail in a day or two of riding when the
assembler neglected to remove, lubricate and press the pins properly.

For forcing barrel-chested or wrongly-sized cotter pins
into straight-tapered holes, I'm not surprised.

But cotter pins are not barrel-chested. I actually have a
few in my stock -- I've slid dial calipers down them, and
there's no widening in their middles. Straight taper pins;
straight taper holes. As it should be, as long as there's
a perfect fit with no slop.

Although one might get a small amount of pin/spindle contact by drawing
up the nut, the forces at that contact will work it free and deform the
pin's surface in short order if the pin moves at all.

We don't (didn't?) want a "small" amount of pin/spindle[/crank]
contact. We want (wanted?) ~full~, tight contact all along the
length of the pin. That calls for proper fitting, not cheap-assed
swage-fitting where the pin is fat in one localized spot, and
loose (or loosening) everywhere else.

And the only reason to "lubricate" cotter pins (w/ appropriate
grease) is to be able to easily pop them out in order to service
the BB. They don't fail from inadequate greasing.

Might bend the threaded section when driving them out, but
that goes with the territory. And there's an acquirable
"touch" for avoiding that. Well, it's mostly luck.

If I had a bike with cotter cranks that needed servicing, I would take
it to the shop with proper tools, such as Mr. Muzi's. A cotter pin that
does NOT require significant force to insert will NOT form a press fit,

Okay. You want an oversized something forced into a weakened
hole, thereby further weakening it.

What an American approach.


which is what this interface requires to function as intended.

The interface requires proper fitting of crank, spindle and
cotter pin.

And yet you want everything to depend on some fat guy/thing.

How typical.

Well, if that's what you want, knock yerself out. Shove
barrel-chested pins into your cranks, spread your metal
apart, and see what happens.

Do you know that bolts and nuts are torqued down heavily?
Why is that? What happens when cylinder head bolts are not
tightened sufficiently?

Engineering fact: in some applications a bolt that is not
sufficiently tightened will break where a sufficiently
tightened bolt will carry the load.

Tightening a bolt with a nut applies a lateral force.
That's a good thing, especially when everything fits.

But carriage bolts (or stove bolts for that matter) don't
have midsection bulges in them in an attempt to apply radial
force to the components they're trying to hold together.

I am not aware of barrel shaped cotter pins on steel cranks.

But cotter pins != bolts.

But in modern 3-piece cranks,
tapered square nubs == cotter pins.

I do not follow this.


The difference in opinion is about the efficacy of
radial vs lateral tightness.

Do not follow this, either.


Maybe those 3-piece, tapered/square spindle nubs should
have some flare or bulge designed into them.

The square cross section on the spindle is tapered
exactly for the purpose of applying a preload
normal to the spindle-crank interface. The pre-load
is compressive all around, so that when force is applied
to the crank that puts a load on some portion of the
interface that tends to move the crank away from the
spindle, it is subtracted from the pre-load. When the
pre-load is sufficiently large, pedaling forces are
not sufficient to overcome the pre-load and the
fit remains tight. If the pre-load is not sufficient
the crank wobbles on the spindle and deforms.

Cotter pin cranks have the same problem. They must
be installed with sufficient pre-load to prevent
wobble and deformation under pedaling loads.



Maybe they do.

That's something to check out with the dial calipers.

--
Michael Press