On Feb 15, 11:08*pm, Tim Wescott wrote:
...
Thanks for asking this question -- after looking at the links Gunner gave
I now understand why I lose an end mill every time I try to cut steel.
Next time I'll try for more patience.
Does lubrication and/or coolant help?
Tim Wescott

I made up a spreadsheet chart of cutting speeds for my mill with the 6
belt settings and spindle speeds for rows and common tool diameters
for columns. When the usual 600 RPM isn't appropriate it's easy to
look up the nearest speed and find its belt setting.

Motor Head RPM .125 .250 .500 ...
Low Lg 600 20 39 79
Low Med 350 11 23 46

600 RPM gives ~80 FPM on a 1/2" end mill, which has worked well for me
on all but hardened steel where I'd use carbide anyway.

Name-brand USA HSS end mills stay sharp a long time with a little
cutting oil brushed on whenever the smoke disappears. The cheap blue-
tube ones seem to require much lower speed or they dull very quickly
in steel, so I save them for aluminum.

Jim Wilkins