Calculate machining depth for drills and countersinks This program calculates the machining depth required to achieve a chamfer of the desired diameter when using center drills, spot drills, and countersinks. It also calculates the correct depth to send a twist drill to achieve a full-diameter hole of the desired depth.The program compensates for flats on the ends of countersinks and for the chisel point on the ends of spot drills and twist drills.All standard tool angles are evaluated. Inch and metric modes.