wrote in message
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I routinely have to tap 6-32 holes in the sides of 6061 aluminum 1/4
round by the hundreds. I thought I had it wired for a while, because I
was able to go through about 500 pieces before breaking a tap. Not the
end of the world. But today I broke 4 to go through the same amount.
I'm doing it the same way I did in the past, but something is going
wrong.

At any rate, I feel it's the lateral movement that is hurting me. On
the ones where I'm able to get the tap to go in perfectly straight,
you can feel that there's less resistance. The problem is that because
it's a round, it is very hard to get the piece clamped so the hole is
perfectly straight. I've been using a power drill, mainly because it
allows me to kind of adjust the angle a little if I feel too much
resistance. I would prefer to use a drill press with tap head, but I
don't know how you would align the hole with the tap properly, since
the part is round.

I'm not sure how they would do this in automated tooling. I guess
maybe do both the hole and tap at the same time somehow. I can't put
each piece in a clamp and move it each time, because that would take
forever. So I'm kind of at a loss right now. Breaking $40 of taps a
day isn't an option. Not to mention the time spent remaking the parts,
as the tap almost always breaks off without anything left sticking out
to extract it.


Others ideas look good.

I've a similar job. I've mounted the motor/chuck from an old battery drill
adjacent a linear drawer slide with an angle bracket on it. I've wired a
reverse switch to the motor. I hold the work against the angle plate and
slide it on/off the tap controlling motor dirction with the other hand. I
can knock out M3 threads thru 2.5mm aluminium in about 10 seconds each.
Oddly enough I've been using methylated spirits for cutting fluid (flammable
I know). It seems to work ok and clean up is easy.