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 hole. They have advantages over Forstner bits when boring into end grain. Bits are commonly available in sizes from diameter. Sawtooth bits are available up to diameter. Originally the Forstner bit was very successful with gunsmiths because of its ability to drill an exceedingly smooth-sided hole. The center bit is optimized for drilling in wood with a hand brace. Many different designs have been produced. The center of the bit is a tapered screw thread. This screws into the wood as the bit is turned, and pulls the bit into the wood. There is no need for any force to