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On Tue, 18 Nov 2008 08:55:01 +0700, Good Solder Schweik
wrote:

On Mon, 17 Nov 2008 16:17:46 +0100, "Edgar"
wrote:


"Good Solder Schweik" wrote in message
. ..
Try drilling a half inch hole in a piece of 1/4 inch stainless on the
mast head fitting with your puny little battery drill. you'll
understand why the A.C. equipment is needed.

I needed to drill a 1/4 hole in a thick stainless bracket on deck so I could
fix a shackle for the end of a jackstay.
I blunted three HSS drills without making much impression at all so went to
a really good tool shop they have here and explained the problem.
They sold me a cobalt steel drill especially intended for stainless and it
went through the stuff as if it was not there, producing long unbroken
strands of swarf that looked like springs.
It was a very expensive drill but the job was done in a few minutes and the
cost of several ordinary drills and lots of my time saved was worth it.
After the job was finished the cobalt steel drill still looked and felt so
sharp that it might have been new.

You can drill stainless with normal High Speed Steel drills. The
secret is that stainless work hardens easily so you must run the drill
at low RPM with high feed pressure.


You mean low speed, high torque, as supplied by my battery powered
drill? Amazing!