Nick Hull wrote:
Since there is no load on the teeth, tooth form is not important.

Good point. That will make one easier to find. Except ...

Ned Simmons wrote:
Ignoring the tooth form, which Nick has responded to, you
won't be able to buy a stock gear of the proper pitch.

Oh, no! That means I'll *have* to buy a dividing head (to make my own
gear on the mill). I'm sure that my wife will understand. VBG

If I did the math right, you'd need a 25.133 diametral pitch
gear (8 x pi)...

IIRC, the formula: (# teeth + 2) / OD gives the DP. In this case:
(16+2)/.715 = 25.17. Pretty close - it has to be an approximation, that
"teeth + 2" is just too simple to be dead on.

Since the tooth form will be wrong, you might consider a
design that would allow disengaging the thread dial when
it's not being used, especially if this is a lathe that
doesn't have a separate shaft for the regular feeds, i.e.,
the lead screw is always turning.

I'm just using the basic design from the Logan (a pivoting assembly),
which allows disengagement. But the Jet does have a separate lead
screw, so I'm covered twice.

Thanks for the replies,
Bob