On Sat, 11 Jun 2011 10:09:15 -0500, "Pete S"
wrote:

A guy just emailed me to comment on my "taptips" page,
http://www.spaco.org/taptips.htm

I said that I don't allow any (plain)carbon steel taps in my shop.
He commented that gunsmiths DO use carbon steel taps because they tend to
break a lot, but are easy to remove by smashing them.
I don't do any gunsmithing- the idea of drilling into someone's gun
barrel scares the dickens out of me. But here's my question:
Isn't maybe, the REASON the little taps break often that they ARE carbon
steel?

Yes. But the fellow was absolutely correct as well. Ive had to EDM out
strong taps..and carbide ones. Not fun..not fun at all.

And just for information, how DO you tap a 2-56 or 4-40 or whatever hole in
a gun barrel? If you can only go 2 or 3 threads deep, you can't start with
a taper or even a plug tap, can you?

Yes. Grind off the point and start the threads, then put in a bottoming
tap..or grind a bottoming tap from a regular one.

Are gun barrels hardened/hardened and tempered or are they just an annealed,
tough steel like 4140?

All of the above G


Pete Stanaitis
---------------

"As physicists now know, there is some nonzero probability that any object will,
through quantum effects, tunnel from the workbench in your shop to Floyds Knobs,
Indiana (unless your shop is already in Indiana, in which case the object will
tunnel to Trotters, North Dakota).

The smaller mass of the object, the higher the probability.
Therefore, disassembled parts, particularly small ones,
of machines disappear much faster than assembled machines."
Greg Dermer: rec.crafts.metalworking