On Fri, 4 Jan 2008 18:34:59 +0000 (UTC), Todd Rich wrote:



Slowest speed on the press is 240 rpm. I'll look into a 3/4" hole saw.


That gives you 24 sfpm. Plenty slow. Don't bother with the hole saw.

Clamp a piece of scrap under the web that you're drilling through. That will
stop the drill grabbing when it exits the hole. If necessary hold the scrap on
with a couple of 10-32, or similar, screws. The scrap should be thick enough
that the drill isn't going to come through it before it's cleanly out of the
metal that's being drilled. Drill a pilot hole the same size as the web on the
3/4" drill. Don't drill the pilot hole noticeably bigger than this. Then drill
away using the tapping oil.

Use reasonable pressure and you'll find that the drill cuts surprisingly
easily. You've removed the major inefficiency (smearing the metal out of the
way with the web) and you've still got enough metal being cut to avoid the
drill grabbing and chattering. If you have too large a pilot hole, the drill
will grab and you'll chip the cutting edge. DAMHIKT

I don't promise that it'll work for you, but it works for me!


Mark Rand
RTFM