DIYbanter - View Single Post

wrote:

you comment that breaking taps you've broken

MOSTLY 1/4-20.

I mostly build small stuff....
It seems like some tap sizes are more fragile than others....
I don't think I've ever broken a 4-40 or 10-32,
I have broken several 6-32 and 1/4-20's
(About the largest hole I ever tap)

Are some taps sizes more prone to breaking than others?

Paul

YES! And the infamous #6-32 is one of the worst. The 'standards' are not
as well thought out as they should have been, and some sizes of screws
have too small a 'root' relative to their overall size. This makes the
screws (and the taps) weak and prone to breakage.

The coarser the pitch, the deeper the tread, and the weaker the root of
the screw. For a number six screw, 32 TPI is too coarse, but it is the
common standard. #6-40 is a better screw, but not as common.

Dan Mitchell
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