I read alot of postings on how fast people are cutting, How do they know. I have looked through Mach 3 and do not see an IPM setting. This is a home built(not by me) and I am curious.

Thanks

IPM is the F word in a G01/G02/et al. line on a milling machine.

G1 X1. Y1. F10.

...gives you a cut at ten inches a minute.

Alot of times you can get the "feeds and speeds" from the people that sell you the tooling. Then go about 1/3 to 1/2 the feeds and speeds that they recommend, thats if you have a large beefy machine. Smaller machines you need to go slower on.

There is no magical way of setting speeds and feeds for someone that don't have a machining background. Any old toolmaker, that dont know anything about cnc or speeds and feeds, should be able to just look at the machine when its cutting and say it needs more or less feed, and or spindle speed. It also depends on if you have coolant or not, and what the material is that your cutting.

High Speed steel endmills: If the chip's are blue or burned, the RPM's are to high, If the mill breaks, the feeds are to fast.

Unfortunatly, you are going to have to break a few end mills, untill you learn.