From: jonathon (jemery@execpc.com)
Date: Sun Oct 17 2004 - 16:44:56 PDT
>The secret to drilling armour is to use a slow cutting speed. Reduce
>the drill RPM down to a few hundred (at most) a minute and the
>armour will drill just like mild steel.
Not knowing the alloy content of the steel your talking about but I might
suggest that the other secret which applies to many of "these kinds of
alloys" is to feed hard. Slow drill speed but high feed rate, and of course,
as you stated, lots of oil or coolant. Even with a slow speed you may still
end up wearing out the drill from work hardening of the plate unless your
feed rate is high enough to get under that layer. This also applies to
stainless steel in most cases also. As to drills, just get a good american
or european made drill, M2 (HSS) or M42 (cobalt) Do not buy Chinese drills
ever and do not waste your money on a carbide drill if your using a hand
drill and if fact I'd say don't bother with carbide at all unless you have a
very controlled machining environment. Just my $0.01.
later,
je
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