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Does anyone know what the minor diameter is for the outside thread on a 5C collet? It's a 1.238-20 thread but I can't seem to find a minor diameter for it. I know there's a formula for calculating it but that escapes me at the moment. Chin

Ed
Take a look here ED Marv probably has a calculator programmed up already...
(07-31-2013, 06:42 AM)Mayhem Wrote: [ -> ]Take a look here ED Marv probably has a calculator programmed up already...

You beat me to it Darren. I just visited that thread and thought I'd post the formula for others to enjoy.

TD = MD - 0.013*DOT/TPI

where:

TD = tap drill diameter
MD = major diameter
DOT = desired depth-of-thread expressed as percentage

Ed
Here it is as an Excel calc:

[attachment=5811]

Yes - I'm home alone and bored. Although, I've just found a 10.5" Douglas shaper for sale that I'm thinking of enquiring about...