"Rich Grise" wrote in message
...
Cydrome Leader wrote:

Does HSS leave nicer finish when sharp than carbide on these materials?
Considering tiny pieces of the tips broke off the carbide cutters I have,
I can't really test this anymore.

FWIW, in the shop where I sit, they have a diamond wheel where they can
grind new points on carbide inserts; carbide is the only thing anybody's
allowed to use it on.

Good reason -- high speed steel, or any ferrous metal, will eat your diamond
wheel alive. Steel really likes carbon, when you get it hot, and it doesn't
care how much the carbon costs. d8-)


My first thought was rake, chip relief, and whatever you call the
height of the cutter, but then again, brass is kinda mushy in those
circumstances. I was once trying to turn down a piece of copper, and
the bit bit into the copper and the part bent like toothpaste.

Good Luck!
Rich

Copper or any soft-to-medium copper alloy, especially yellow brass, will
grab a tool if the work or the tool aren't rigidly supported (MUCH shorter
overhangs are allowed than with steel), and if there is enough positive rake
to make the tool want to grab. Small lathes, including my SB 10L, are among
the machine tools that are vulnerable.

Standard lathe-bit side- (usually) or front (sometimes, as in plunge
cutting) rake for turning brass, as a safe starting point, has been negative
5 degrees, for over 100 years. However, most applications are done closer to
zero rake. Negative rake is tricky, too, sometimes causing the tool to
skate.

Harold's recommendations were spot-on.

--
Ed Huntress