By User:LPNalini @timeAndDate(1274310307)
A rotary hammer is a type of drill employing a piston mechanism to provide a hammering action in order to more effectively drill through hard, dense materials, most commonly concrete. Rotary hammers are also sometimes used to drill steel, though a rotary hammer is not necessary for drilling steel, and certain rotary hammers are multi-use, appropriate for both concrete and steel.
Generally speaking, rotary hammers will be more powerful than the wider class of hammer drills and usually specifically designed for concrete work. A good rotary hammer will be equipped with the following:
* Variable Speed Handle Actuator
** Allows the operator to ease the bit into the material, starting at low power/speed and building up.
* Safety Clutch
** Disengages the rotational motion until pressure is applied to the bit end, so the drill will not spin when not being used even though the motor idles. Also, many clutches will include a mechanism to disengage the rotational motion if the drill bit jams, which will prevent damage to the machine and to the operator.
* Rotary Switch
** Many rotary hammers can have the rotational motion switched off to provide a simpler, hammering action, for chipping or breaking concrete.
** Also, the same switch should allow for the hammering motion to be switched off and the tool to be used as a conventional drill.
It is important also to pay close attention to both the rated torque and maximum RPMs of a rotary hammer you are considering. Higher torque means higher power, which will allow you to drill into stronger concrete quicker and deeper. High RPMs will get a job done quicker, however, more importantly pay attention to the ratio between torque and RPMS. Consider two rotary hammers rated for the same maximum RPMs, if one is rated at a higher torque than the other it will be the much better tool. If we divide RPMs by torque (i.e. Torque / RPMs) we would like this number to be as high as possible. Finally, most good rotary hammers will have a variable speed motor, this will allow you to keep the motor in low-range to ease the bit into materials and get a good bite.
Rotary hammers are always "sized", a specification indicated by a dimension (usually in inches). A 1 1/8 inch drill will accept a bit as large as 1 1/8 and usually smaller. A 2 inch drill will accept a bit as large as 2 inches, etc.
Rotary Hammer Bits
Rotary hammers must be equipped with specific bits designed to withstand the high impact forces associated with the tool, as well as the stress of drilling through concrete. Over the years, three main standardized bits have survived in this category, each defined by the mechanism by which it locks onto the chuck. Check the rotary hammer you are considering to determine what type of bit you will need to use in it. The three categories of bits are:
* SDS Bits
* SDS-Max Bits
* SPLINE-SHANK Bits
Rotary hammers may or may not be able to accept bits from multiple categories, so make sure to have the right tooling to fit the right equipment.
Top Sellers
Here are some of the top selling rotary hammers on the market today.
