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 relatively large holes in thin material. They remove material only from the edge of the hole, cutting out an intact disc of material, unlike many drills which remove all material in the interior of the hole. They can be used to make large holes in wood, sheet metal and other materials. "Center drill bits", occasionally known as Slocombe drill bits, are used in metalworking to provide a starting hole for a larger-sized drill bit or to make a conical indentation in the end of a workpiece in which to mount a lathe center. In either use, the name seems appropriate,