"Wayne" wrote in message
news
Wayne wrote:
Is a set screw with a rockwell hardness of c45 too hard
to turn down with a HSS bit?
Or in other words what would be the maximum B & C numbers
that could be cut with HSS?
Thanks,
Wayne D.

I use HSS tooling to modify setscrew and socket head cap screws all the
time. Not to be a smart ass but as long as it's softer than the tool
you should be able to make it work. I recently had to make some cone
point set screws, I used HSS tool bits and held the setscrews in a 5C
collet. Actually you get a nice finish quite easily.

Regards
Paul

Thanks! I didn't have any concept on how hard the setscrew was in
relation to HSS. If the hardness of the set screw wasn't listed, I
would've just gotten and cut them without thinking about it.

Wayne D.

High speed steel, professionally hardened, typically runs from Rc 64 to Rc
72. The high end is the exotic powder-metallurgy steels.

The upper limit for workpiece hardness, for cutting with HSS tools, usually
is taken to be Rc 40 - 45. So you're right at the margin. Above Rc 40, tool
life goes to pot in a hurry. Above Rc 45, you're better off with something
else, but you can get away with some limited cutting if tool life isn't an
issue.

--
Ed Huntress