Quote:
Originally Posted by ulflyer
BTW: whats a "P" drill. I have lots of drills but nothing labled like that.
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For precision work, you need drills that are in between fraction of inch (or metric) sizes. For instance, if you use a 1/4" drill to make a hole for a 1/4" bolt, it might be rather tight, and you'd like it to be a few ten thousandths larger. Not a problem with wood or plastic, but hard steel is another issue in things like precision auto or aero applications.
So, they make number size drills for the smaller needs, starting from 80 to 1 and then going to letter sizes at around 1/4" from A to Z. Not likely to find them at Tru-Value, but your machinist has sets.
Cheers, Bob