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 of poor finish. The two fluted drill bit also has a tendency to grab on any protuberance (such as flash) which may occur in the product. A hollow cylindrical bit which will cut a hole with an annular cross-section and leave the inner cylinder of material (the "core") intact, often removing it, is also called a core drill bit or annular cutter. Unlike other drills, the purpose is often to retrieve the core rather than simply to make a hole. A diamond core drill bit is intended to cut an annular hole in the workpiece. Large bits of similar shape