"Pete S" wrote in message
...
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?

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?

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

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

Most holes for sights are 6-48.
The barrels are usually just tough steel, but the receiver is where you do
most of the drilling and tapping, and they can be all over the place.
You start the tap with a guide so a lot of starting taper isn't needed.

Carbon steel taps are slightly harder than HiSpeed. They are also more
brittle and shorter lived. That's ok, most gunsmiths I know only use them
once.
They also grind the shank on them down to weaken it. That way, if it breaks,
it'll break at the shank and not down in the hole.
The real old timers would reharden them to cut really hard materials.
Also, if it does break off, You can soften a carbon steel tap with a torch.
It is easier to drill that way.


Paul K. Dickman