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Cross Slide TPI

It took ten turns to move 1 inch so the lead is 10 threads per inch? 10x 7/16 The diameter was .435
 
It took ten turns to move 1 inch so the lead is 10 threads per inch?
Tada ! :D Yeah, 10tpi.

The math should always work out. At 10tpi, if you have a radius reading dial, your dial will be 100 graduations from zero back to zero, in one full turn, or .100". And thus 10 x .100" = 1".

A direct reading dial would be 200 grads in a full turn, but each grad on a direct dial moves cross slide by .0005", though you're still at 10tpi. Regardless, still 10 full turns to move cross slide 1".

Another way to check tpi. Open up your digital calipers to 1". Drop the two points of calipers into the valleys of threads, and then count the peaks of threads in between the two points.

As far as diameter, I don't happen to know off the top of my head, but acme thread on old US machines is an easy relatable number. . . 7/16", 1/2" whatever.

On cross slides however, Its nearly always LEFT hand acme thread. So if you're shopping or thinking of solutions, make sure its left handed acme thread.
 
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