In article ,
Bob Engelhardt wrote:
Al A. wrote:
... the threading dial I use on my
1024 (the twin of yours...) is from a 9" South Bend, same 8TPI lead
screw, but the gear on the threading dial is 32 teeth. ...

Your dial is rotating at half the speed (relative to the lead screw) as
a 16 tooth dial. Does that mean that your dial has twice as many marks?
There are 4 marks on my Logan dial: "1" & "2" 180 degrees apart and a
"|" between them.

My 12x24" Clausing (with an 8 TPI leadscrew) has four numbered
markings 1, 2, 3 & 4, with four index marks half way between them. I
suspect that is what you would need with a 32 tooth pickup gear.

BTW One thing which I have not seen mentioned yet in this thread is
that you will either have to cut your teeth at a slight angle
(to match that of the Acme thread on the leadscrew), or to mount
the shaft of the dial at an angle to allow the gear faces to
line up with the leadscrew thread. It is not much of an angle
(precisely how much depends on the diameter of the leadscrew in
combination with the thread pitch. (It calculates out to 2.28
degrees with a 1" diameter 8 TPI leadscrew.) In either case,
you may have to make corrections to the gear form to compensate
for the angle.

Be glad that you're not making a threading dial for a Metric
leadscrew. That has to have four different gears -- all of which mesh
with the leadscrew, one at a time, to handle all of the pitches common
in the metric system. (This is one of the places where the Imperial
system works out easier, because so many of the threads are a power of
two relationship with other threads.) When you need to handle a 1.00mm,
0.80mm, 0.60mm, 0.45mm and other such, the design of a threading dial
gets a bit more complex. And, of course, there is an additional bit to
the threading charts to tell you which pickup gear to use with a given
thread. :-)

Good Luck,
DoN.
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