On Fri, 20 Aug 2010 07:38:59 +0200, "Steve Lusardi"
wrote:

All stainless will work harden. Some alloys more than others. (304 is easy) The general rule is to use a fast feed, low RPM and a
broad nose on the tool. Of course this assumes the lathe is stiff enough to handle the increased load. Small lathes makes these
jobs very difficult. My suggestion is to use M42 cobalt tools (8% Cobalt) and more tool relief angle to reduce tool drag. Carbide
cannot support the amount of relief required. Normal HSS isn't hard enough and all tools must be SHARP. Please also consider using
a cool mister. Anything to resist temperature rise also helps.
Steve

MACHINIST MATRA:
304 she's a whore, 303, she's for me.

If you can change material you'll save a ton o' grief. These are about
the same except you can't weld 303.

When I cut 304 on the Monarch 10EE, I'd set the feed at leat .005 and
take a miniumum cut of .025 even for the finish pass. Forget about a
spring pass. In back gear for more torque if over one inch. Slow
speeds. I use cutting oil on stainless. The only other job I use oil
on is threading.

On the Mazak M4 (20 hp gear head - 16,000 lb. machine) negative rake
carbide tooling and coolant will cut SS all day long. A big rigid
machine do help.