wrote in message
oups.com...
I traid a quick conversion in my head to the units I am familar with
and think you, and I think you might do a lot better with a higher
cutting speed. 50 meters / minute is 164 sfm ( I pulled out my
calculator ) and at the low end of recommended speeds for carbide.

Dan

The lesson that should have been learned here is carbide should have long
ago been abandoned in favor of HSS and proper tool geometry. Carbide is a
miserable failure on small machine tools--------the only success it
typically enjoys is the incredible ability to allow the operator to avoid
learning to properly sharpen cutting tools. I hardly think that's a good
thing.

A comment on surface finish. Mild steel, which appears to be the topic
of discussion, is amongst the worst of materials to machine in that it loves
to tear. Only when carbide is employed along with a high surface speed and
proper depth of cut and feed will it cut otherwise. The addition of
lead to steel makes it machine beautifully----so if you'd like some success
with surface finishes, try machining some of it. Your metals supply house
could provide you with proper designations.

304 stainless is ugly to machine, but tends to cut with a good surface,
assuming you have a sharp tool, and don't run it too fast. If you're
intent on using carbide, be certain you do *not* use a C5 or C6 grade. C2
is the proper grade, and it makes a serious difference in tool life and
success. Better yet, for a small lathe like you have, a properly ground HSS
tool with positive rake and a chip breaker is even better. If you'd like
to machine stainless that is fun to cut, buy 303 either S or Se, each of
which are free machining, unlike 304. It cuts with a clean surface,
although not quite as shiny as does 304. 416 is also a free machining
grade, and is capable of heat treatment, should you have need.

Good luck!

Harold