On Tue, 06 Jul 2010 02:40:40 +0000, DoN. Nichols wrote:

But the real question is whether you can cut a Morse thread with
a 1.5 mm pitch. Without that, you could make everything else right, but
not be able to make something which would accept the nosepiece. The
precise thread in inch units would be 16.9333 TPI. 17 TPI would be
close but not close enough 0.0667" error in a 1" thread with 0.058" per
thread, so it would be over a full thread in error.

With a standard gearset for an HF minilathe, 16.9231 is as close as
one can get to 16.9333 TPI, and 17.0182 for 17, via ABCD gear sets
{40 50 65 55} and {50 45 55 65} respectively.

And 17 TPI is not likely to be found on any lathe gearbox
anyway. 16 TPI is common, 18 TPI fairly common, but 17 you would have
to find gears for -- or better metric conversions gears for the lathe.
And since it has an inch leadscrew pitch, you could not use the
threading gauge -- you would have to keep the half-nuts engaged and hand
crank the spindle backwards to the start of each threading pass.

BTW The drawbar for the Morse taper shank ER-32 adaptor is cheap
enough (LMT # 2224) at $4.29 so why take the time to make one?

--
jiw