H H h h 9 MACHINED SURFACE ROUGHNESS Surface roughness in the radial direction, i.e. during side milling (contour or bottom of a slot milled with a disc milling cutter) is calculated using the following formula: Substitute milling cutter diameter for DC. 3 3h = 12 ( DC - DC2 - fz2) DC DC 4 2 4 2 1 1 1 2 3 4 1 2 3 4 fz fz fz fz fn fn fn fn 773