Steve,
I found some 440C and have made the basic cuts for the buttcap and bolster. I have a .500 in. 45 degree dovetail and would like to use it on the bolster and buttcap. Problem is I have no idea what RPM to use for this tool. I have already burned up a few endmills learning how to use the mill and would like to avoid burning up this cutter. Any suggestion on a cutting speed. The mill is a Grizzley 3358.
Thanks,
Dan

Dan,
The short answer is 191 rpm, the long answer:

rpm=3.82*sfm/dia
feed=rpm*ipt*#teeth

3.82 is a constant for this formula

sfm - for 400 series SS, 40 surface feet per minute is a good starting point with coolant, 25 sfm without coolant

ipt - .001 to .0015 inch per tooth is a good starting point

So a 1/2" dia HHS 6 flute no coolant would be:
rpm=3.82*25/.5=191
feed=191*.001*6=1.15 inches per minute

With coolant:
rpm=3.82*40/.5=305
feed=305*.001*6=1.83 inches per minute

The above information is for HSS (High Speed Steel), with cobalt you can increase your sfm by 25%, with carbide you can increase sfm by 150-200%.

Steve

Thanks Steve, I will use this speed and the formula for future applicatiions.
Dan