Rotary hammer drills are hand-held power tools that are used to cut into or chip away various materials including brick, cement blocks, concrete, wood, steel and stone. Most manufacturer's rotary hammer drills allow for separate or combined use of the hammer and rotation functions. A rotary hammer drill can be used either as a simple rotating drill to make precision holes in objects, a miniature version of a jackhammer to pulverize and chip objects or as both, a jackhammer that bores holes and chips away at the inside of them. Using both functions at the same time is the most efficient way to bore a hole that does not require precise dimensions.
According to The Encyclopedia of Alternative Energy and Sustainable Living, this type of power tool uses weights to create impact forces. A weight inside the tool moves back and forth against the attachment providing movement to the attachment. They offer a hammering action that provides short, fast thrusts that pulverize materials making drilling easier.
Most rotary hammer drills can accept different types of attachments. Many standard and metric-sized drill bits can be fit onto rotary hammer drills. They can also be fitted with scraper and chisel attachments. Each attachment has its practical applications.
Most manufacturers offer rotary hammer drills that have variable speeds. Low speeds are employed for fine impacting and drilling. High speeds are ideal for fast, efficient impact and drilling applications.
Rotary hammer drills are sometimes prone to jamming. Many rotary hammer drills feature a clutch that prevents damage to the motor in instances where the tool jams. The part of a rotary hammer drill that can jam is the bit or attachment. They can get stuck in the material they are trying to manipulate. When this happens, the attachment must be removed from the tool and backed or pulled out of the material with vise grips or monkey wrenches.
There are several rotary hammer drill manufacturers. Some companies that offer lines of rotary hammer drills are DeWalt, Bosch, Makita, Milwaukee and Panasonic. Rotary hammer drills can cost anywhere from just under $100 to $300.