QIMO Professional Power Tools QM-3201 20mm 600W Rotary Hammer

1. stepless speed switch 2. Three function 3. BMC packing 4. Strong power motor 5. All plastic body more safe

Rotary hammers are similar in that they also pound the drill bit in and out while it is spinning. However, they use a piston mechanism instead of a special clutch. This causes them to deliver a much more powerful hammer blow. One can drill bigger holes much faster. Rotary hammers have such force, in fact, that the usual masonry bits are no longer adequate. Their smooth shanks would be pounded loose from the tool's chuck in a few seconds. Therefore, they require special bits which can lock into the rotary hammer and continue on spinning while smashing away.

A number of "special shanks" have been developed by various manufacturers. Over the years a fair number of these proprietary systems evolved, but the remaining shanks in use today are: SDS, SDS-MAX, and SPLINE SHANK.

Rotary hammer drills have an oil filled gearbox, which allows them to operate durably despite the large forces and shocks they receive and the grit-filled environments where they are often used.

Apart from their main function of drilling concrete, the rotary action can be switched off and use is made of just the percussive force. Chisel and point accessories are used for small chipping jobs.

The type of work they do means that they need to have a clutch which cuts in when the drill bit jams. This stops the violent wrenching motion that a drill without a clutch would cause when stopped suddenly from full speed, saving both drill and operator from damage.

Jams are most often caused by hitting reinforcing steel or by a worn bit. In both cases the drill must be disengaged from the bit and the jammed bit backed out of the hole with vise grips or monkey wrench.

 Worn masonry drill bit

A worn drill bit will still drill a horizontal hole, although of a slightly smaller diameter than one created when it was new. When a drill like this is used to drill holes down into a concrete slab, the flutes are so worn that they can no longer lift the dust out of the hole; the concrete dust packs up in the hole and jams the bit.

QIMO Professional Power Tools QM-3201 20mm 600W Rotary Hammer