Drill bit tolerances
On Oct 2, 6:17*pm, "Michael Koblic" wrote:
What is the expected tolerance of drill bits? I have a set of fractional,
letter and number drills. No.12 to 15 (including 3/16") seem to produce the
same size hole.
I've used the shank of drill bits as gages; they measure within .001"
of
the marked size.
As for the holes, the #12 makes a hole bigger than #13 and smaller
than
#11 (i.e. look at the gap between sizes), unless it's dirty/bent/dull.
Fractional drills, some of 'em, have been off by .005" recently, but
they
might have been made-for-WallyWorld.
People who need real precision don't use twist drills, of course, for
the final dimensions.
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