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
Down-the-hole drill as the system basically relied on gravity. Debris from the hole was baled out using a baling tube with a clack valve, which was periodically dropped on a winch to capture the slurry, which was then brought to the top of the hole to be discharged. It was only when the DTH system came along that many of the problems associated with the other systems were overcome - with the DTH system the energy source is constantly behind the drill bit, the drill tubes (or drill string) are rigid being only slightly less in diameter than the drill bit, copious