Anyone know ANYTHING other than a cotterless crank puller for a
bicycle that uses a 22mm X 1mm thread?? Looking for something to mount
a bike pedal on to chuck it in the lathe to do some modifications.

Is your lathe metric or standard threading capability? if it's metric,
simply make up an arbor with a round piece to clamp in the chuck and a
stud threaded with the correct thread. With a single point threading
tool almost any thread is possible.

In article .com, woodworker88
says...

Is your lathe metric or standard threading capability? if it's metric,
simply make up an arbor with a round piece to clamp in the chuck and a
stud threaded with the correct thread. With a single point threading
tool almost any thread is possible.

Another interesting point being that 1 mm pitch is darn close to
26 tpi:

1mm = 0.0394 inch

26 tpi pitch = 0.0385 inch

Over a quarter inch of engagement (typical length of
puller threads on a cotterless crank) the total error would
be about 0.0002 inch. Your lathe's leadscrew might not be
that accurate.

Jim


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Better check your math there, Jim. I think it's more like 0.0059 inch error
over 1/4".

I am not certain what the original poster is looking for but he might visit
bikenashbar.com and search "crank puller" for some ideas.

Carmine Castiglia
PalmOS apps for engineers and machinists
http://www.infosystemspro.com/palmosapps.htm



"jim rozen" wrote in message
...
In article .com,
woodworker88
says...

Is your lathe metric or standard threading capability? if it's metric,
simply make up an arbor with a round piece to clamp in the chuck and a
stud threaded with the correct thread. With a single point threading
tool almost any thread is possible.

Another interesting point being that 1 mm pitch is darn close to
26 tpi:

1mm = 0.0394 inch

26 tpi pitch = 0.0385 inch

Over a quarter inch of engagement (typical length of
puller threads on a cotterless crank) the total error would
be about 0.0002 inch. Your lathe's leadscrew might not be
that accurate.

Jim


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please reply to:
JRR(zero) at pkmfgvm4 (dot) vnet (dot) ibm (dot) com
==================================================

In article , Carmine Castiglia
says...

Better check your math there, Jim. I think it's more like 0.0059 inch error
over 1/4".

Hmm, math's not my strong suit but here goes:

1 mm = 0.0394 inch, and 26 tpi = 0.0385 inch.

So over an inch, the accumlated lead error would be the difference
between the two:

0.0394 - 0.0385 = 0.0009 inch total.

The accumulated error over a quarter of that distance would one
quarter of that number:

0.0009 / 4 = 2.3 e-4 inch

Unless I've crossed something up somehow.

Try fitting a 26 tpi thread gage into a 1mm pitch one. You'll see.
A 25 tpi thread would be even close, but then not many lathes cut that.
Loose change gears perhaps?

Analog computers rule. :^)

Jim


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In article , Carmine Castiglia
says...

Better check your math there, Jim. I think it's more like 0.0059 inch error
over 1/4".

Ah, I did the calculation correctly - but it was for the pitch error in
*one* thread.

For a quarter inch length of 26 tpi, there are about six threads,
so the *accumulated* error is indeed about six thou.

Sorry for the confusion - but I think this could be a passable way
for him to fabricate a fixture.

Jim


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please reply to:
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