Mill drills are an alternative to a milling machine. These combine a belt driven drill press with the dual coordinate abilities of the milling machine's table for flexibility and efficiency. A locking collet prevents the cutting tool from falling away from the spindle when lateral forces are experienced against the bit. The JMD Milling Drilling.Grinding takes place in “open” space which makes the retention time longer and adjustable compared to crushers. Theoretical size reduction and power ranges for different grinding mills [image (135-6-1)] AG SAG Mills Autogenous Grinding (AG) Mill. Wet or dry Primary, coarse grinding (up to 400 mm feed size) Grinding media is grinding feed.