Rotary hammer is a power tool that can perform heavyduty tasks like drilling and chiseling hard materials.Similar to a hammer drill in that it also pounds the drill bit in and out while it is spinning. However, they use a piston mechanism instead of a special clutch, making it possible to drill bigger holes much faster. With force that the usual masonry bits are no longer adequate. Their smooth shanks would be pounded loose from the tool's chuck in a few seconds. Require special bits which lock into them and continue spinning while smashing away. Jams are most often caused by hitting reinforcing steel or by a worn bit. In both cases the drill must be disengaged from the bit and the jammed bit backed out of the hole with vise grips or monkey wrench. Some bits utilize a full carbide "four-cutter" head with a geometry that makes jamming ...