- August 31, 2010, 11:13 am
Drills with a percussive action (such as hammer drills, jackhammers or pneumatic drills) are usually used in hard materials such as masonry or rock. The drill bit is gripped by a chuck at one end of the drill, and is pressed against the target material and rotated. The earliest drills were probably bow drills. The hammer drill is similar to a standard electric drill, with the exception that it is provided with a hammer action for drilling masonry.
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