2. Finding the feed speed in mm/min You know - Diameter of workpiece Feed size inrpm From the chart you select the feed in mm/min Example: Spindle speed: Feed: 1200rpm 0,06 mm/rev. Results in feed speed: 70 mm/min Feed (mm/rev) (in/rev) 0,2 0,1 0,05 0,02 0,01 100 200 500 Spindle speed (rev/min) 21 1000 2000 3000