On May 5, 12:08*pm, "Joe AutoDrill" wrote:
Anyone know why this is?

Seems to me that if you are starting with a blank that is large enough to
make the 1/2" tap, you might as well make the shank the same as the 3/8" but
the standard is significantly smaller.

1/2" taps have a 0.367" round and a 0.275" square

3/8" taps have a 0.286" round and a 0.381" square

What am I missing here?

Regards,
Joe Agro, Jr.
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V8013-R

Look in the Machinery's Handbook. There are specs listed for taps,
including the shank diameter. 3/8" tap shanks are larger than 7/16" or
1/2" taps. No one knows why, or the history. But there is the
standard...

I have yet to get an answer for this..