Hammer Drill
A Hammer drill (as distinct from a rotary hammer drill) is a rotary drill with a hammering action. The hammering action provides a short, rapid hammer thrust to pulverize relatively brittle material and provide quicker drilling with less effort. A hammer drill is perfect for drilling holes in masonry or stone. It is also used to drill holes in concrete footings to pin concrete wall forms and to drill holes in concrete floors to pin wall framing.

Using a Hammer Drill
Before you can use a hammer drill, you must select a bit and fasten it inside the chuck - the receptacle that holds the bit in place. In some models, you have to do this manually with a chuck key. Insert the bit fully into the chuck, and turn the key clockwise in one of the three holes to ensure that each jaw makes contact with the bit. Other models come with a keyless chuck; after you insert the bit, grasp the chuck firmly with one hand and run the drill to fasten the bit in place.

Use sharp drill bits to make drilling easier, reduce the load on the motor, and lengthen the drill's life. Keep the drill's air ports clear of debris to protect the motor from overheating.

The hammering action is rated in blows per minute, or bpm. Variable-speed hammer drills can turn out up to 40,000 bpm. Most models are reversible and include a switch that lets you convert them to a standard drill. Some are cordless. A detachable side handle helps steady the tool and prevents it from twisting your wrist if the drill jams during use. Some hammer drills also have vacuum-assisted dust-collection systems, with suction brackets positioned near the bit. This is an especially useful feature when drilling concrete in an enclosed basement.

A hammer drill can easily break a wrist if the bit jams on a piece of aggregate, so it's best to choose a model with a clutch that disengages the drive mechanism in case of a jam.

Caution
Wear safety goggles when using any power tool.
Make sure the bit is properly centered and tightened before you begin work. A loose or poorly aligned bit is inaccurate and unsafe.

Author: Carl Robinson
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