You don't say what's attached to the rod, but if you're going to end up
putting screws into the holes, see if you can't just use self-tapping
screws.
I can't imagine how you're able to drill or tap that many holes anywhere
near where they need to be with a handheld drill motor.
I wouldn't even attempt 50 holes in round stock, let alone 500 without a
drill press and some sort of improvised fixture.
And a good cutting lube.
And good lighting.
A cheap Chinese drill press costs about $50, but may not last long, but a
better drill press would run for quite a while, but that's a lot of stopping
and restarting.
Cheap AC motor machines don't reverse to remove the tap, so a balanced
handwheel on top of the spindle pulley would allow the operator to back the
tap out (6 turns, maybe).
A better solution would be a cheap drill press, but replacing the AC motor
with a DC motor which would be reversible, and could handle the repeated
stopping and starting much better.
There wouldn't be much coasting to deal with, but an electric brake
(normally on when motor is stopped) would almost eliminate any coasting of
the motor armature and spindle motion.
If the drill was properly guided to hit the centerline, a cheap quick change
hex bit chuck (the kind available for swapping bits in drill motors) would
be adequate for that size drill and tap. They would both be too small to
just grind a 1/4" hex on their shanks, but a little lathe work with some
1/4" hex brass would turn out some hex adapters very quickly.
Instead of swapping the drill and tap repeatedly, the combo drill-tap tool
would most likely last a long time if guided, supported and aligned
properly, rather than being run with a handheld drill motor.
Those are some impressive quantities that you were able to do by hand,
though.
--
WB
..........
metalworking projects
www.kwagmire.com/metal_proj.html
wrote in message
...
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.