Drill bit shank A hex shank can be grasped by a 3-jaw drill chuck or held in a chuck specifically for hex shanks. Quarter-inch hex shanks are common for machine screwdriver bits and have spread from that application to be used for drill bits that are compatible with screwdriver machinery. The diameter of an SDS and SDS Plus shank is 10 millimeters. (The SDS Max is 18 millimeters.) The SDS shank has the advantage of fitting into a simple spring-loaded chuck, so that bits are simply pushed into the chuck without tightening. This shank and chucks made for it are especially suited to
Drill bit shank a Morse taper and this allows the chuck assembly to be removed and directly replaced with the shank of a Morse taper drill bit. A range of sleeves may be used to bring the size of the smaller Morse tapers up to the size of the drive spindle's larger taper. Sockets are also available to extend the effective length of the drill as well as offering a variety of taper combinations. The detail image shows a Morse taper shank on a 16 mm diameter drill bit. Square taper drills were also used for large ratchet drills, for drilling large holes,