subject: Bosch Hammer Drill [print this page] Bosch Parts - A bosch parts, also known as a "rotary hammer", "roto-drill" or "hammering drill", (see also rotary 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. Lower power units are usually titled as "hammer drills." Higher power units, usually labeled "rotary hammers," tend to be larger and provide bigger impact forces. Modern units allow the hammer and rotation functions to be used separately or in combination, i.e., hammer mode, drill mode, or both. When used in the hammer mode, the tool provides a drilling function similar to a jackhammer. The definitive origin of the first hammer drill is a matter of discussion. Hilti had a rotary hammer on the market in 1967 and the Milwaukee Electric Tool Corporation claims that in 1935, it was selling a lightweight 1/4-inch electric hammer drill.
Hammer drills are well suited for drilling holes in masonry or stone. They are also used to drill holes in concrete footings to pin concrete wall forms and to drill holes in concrete floors to pin wall framing. The hammering action helps to break up the masonry so that it can be removed by the drill bit's flutes.
Types of hammer drills
There are two main types of hammer drill, percussion and rotary hammer. With percussion drills the chuck has a mechanism whereby the entire chuck and bit move forward and backwards on the axis of rotation, the motion is tied to the rotation of the chuck. Typically this type of drill can be used with and without the hammer action but it is not possible to use the hammer action alone as it is the rotation which causes the hammer motion. The second type uses a different type of chuck which allows the bit to move forwards and backwards independently and is usually powered pneumatically. As such this type of drill can be used in hammer-only mode which has certain advantages when dealing with very hard substances.
A hammer drill has a specially designed clutch that allows it to not only spin the drill bit, but also to punch it in and out (along the axis of the bit). The actual distance the bit travels in and out and the force of its blow are both very small, and the hammering action is very rapidthousands of "BPM" (blows per minute) or "IPM" (impacts per minute). Although each blow is of relatively low force, these thousands of blows per minute are more than adequate to break up concrete or brick, using the masonry drill bit's carbide wedge to pulverize it for the spiral flutes to whisk away. For this reason, a hammer drill drills much faster than a regular drill through concrete or brick.
