Oct 08, This means the speed of the cutting surface will be fairly high even at low RPM compared to an end mill. For example, the Surface Feet per Minute cutting speed SFM for high speed steel is about 67 SFM. For a 2quot diameter slitting saw with 110 teeth cutting 12L14 steel, the calculations would be as follows RPM SFM x 12 247 Tool Diameter x P.