RE: Breaking off a tap?!

[Chris Kantarjiev <cak@dimebank.com>]

> Question. Why do taps have such long threaded portions? I
> can understand the tapered lead-in section but why the long
> parallel section?

There are three kinds of hand tap: taper, plug and bottoming. Plug
and bottoming taps typically have a fairly short threaded section
supported on a thinner shaft. All three types have a slightly
different diameter, with the bottoming tap being the only one
that is at full thread depth.

I think that the reason taper taps have a longer threaded section
is that they gradually deepen the threads as you get farther in,
and take advantage of the many threads to help support the load of
cutting the new ones.

The intent is that the machinist will use all three types of tap
to properly thread a blind hole. You can get away with using
just a taper tap for a through hole in relatively thin material.

Good cutting fluid is a must when tapping.

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