Kelly Jones wrote:

Hi all. I just got a new lathe for Christmas and I have been trying it out.
I have been trying to turn a piece of unknown CRES from about 0.75 OD to
about 0.38 OD. I have tried various speeds and feeds but still keep getting
a very rough finish. The finish is so bad that it looks as is the metal is
being torn rather than cut. The surface is full of small slivers that would
cut your hand i a heartbeat. I am having similar problems with an unkown
carbon steel, although not as bad. I have checked the Machinery's Handbook,
the Army metal working PDF, and some engineering reference books I have, but
no help. I thought that I might even be using the tools wrong (cutting on
the wrong face) but I can't seem to find the source of the problem. The
lathe is a Grizzly 12 X 36. Any ideas?


You are either using a really pointy tool or a dull tool or both.

A good finishing tool is rounded when you look at it from the top, and
_sharp_ when you look at it from the side. If it's sharp when you look
at it from the top and dull when you look at it from the side then
somebody got things mixed up.

Is it the tool that came with the lathe? If so, it's probably too dull.
I had to sharpen up the tools that came with my Smithy before they'd
make decent cuts.

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com