doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com L C Smith question.

A #6 screw has an OD of .138", a #7 = .151" & a #8 = .164".
A #0 screw is .060" with each succeeding # stepping up (or down) in increments of .013". For any screw size larger than an 0 multiply the number by .013" & add .060". I don't recall how small they go but I know there is an #00 (.047"). Smallest I recall ever tapping was an #0-80, which I did in heat treated 17-4 stainless, it was a "Bear" but only broke 1 tap out of a good number of holes. That one I bumped the Servo feed lever on a Bridgeport Mill with the tap in the hole & a guide on top. Naturally when the table fed it just snapped her right off flush, didn't actually break it while tapping. Murphy's Law just caught up with me. This was my last hole & was getting near the end of the table where the Servo motor was.

Miller I have a few 0-80 taps but never had any reason to tap anything. Every once in a while I will pick one up and just look at it. I don't think I have a tap handle small enough to hold it. The smallest I ever taped with is 2-56 and that was scaring enough.

David;
I used a knurled aluminum ring with a set screw to clamp to the lower part of the tap's shank. I then had a steel sleeve bored for a close fit to the shank to guide the tap & keep it in line with the hole. This was placed in a collet in the Bridgeport. Should have dis-connected that Servo, only problem I had.