balle endmill broyage attechment; Dynamic spindlespeed and feedrate for ball end mill 3D . For example, using a 2flute, .250" ball end mill at 980 sfm with a .002" ipt chip load, and a .020" DOC (axial and radial): When the endmill is parallel to the surface (cutting with the side), I get a 15,000 rpm spindle speed, and 111 ipm feed rate ...