This video goes over the below formula to help you quickly set speeds and feeds for your tools to run them in your CNC. 

How to set tool RPM Formula: Ex: 4 Flute .5” Solid Carbide End Mill 

3.82 X (Surface Feet Minute) / Diameter of Tool = RPM Surface Feet Minute (SFM) – will be provide to you from your tool provider and dictated on what material you are running. In this case tool mfg. recommends 180 SFM. 

Example: 3.82 X 180 (SFM) / .5 = 1,375 RPM 

How to set tool Feed Formula: Ex: 4 Flute .5” Solid Carbide End Mill 

(Feed Per Revolution) X RPM = Feed 

In mild steel the tool mfg. recommends .0025 per tooth. That means 4 flutes X .0025 to get Feed Per Revolution (FPR) = .01 FPR 

Example: .010 (FPR) X 1,375 RPM = 14 in/min 

Summary: In mild steel we will run this .5” end mill at 1,375 RPM with a 14 in/min. feed rate.