jim n judy wrote:

I am making a 5c collet holder. I am at the point that I want to thread
the holder for the collets. One set of instructions say to bore the
hole 1.175 and thread 20 tpi to a pitch diameter of 1.205. Another
article says to bore the hole 1.191 and thread 20 tpi till collet spins
on freely. This is quite a bit difference between the two. Anybody know
which is correct?


Come on, you're a machinist, right? Do just a little shop math. Thirty seconds
of trigonometry and a few button pushes on a calculator and you will know the
minimum bore (for 100% thread depth) and then from there you can figure out how
much slop you want. One thing you might think about is the actual thread shape
on your collets - are they full sharp, or are they slightly flatted at the crests?

GWE