Standard drills will barely make a chip in concrete or brick. That’s why contractors drilling holes in a home’s foundation use rotary hammer drills like this new Hitachi DH50MRY. In addition to the standard spinning bit, it slams a weight—the hammer—forward to create a sort of jackhammer effect to crush masonry as it drills. But all that pounding beats the heck out of your hands and arms. The Hitachi is one of the first to integrate a counterweight to absorb recoil. The result is a safer and easier-to-control drill that’s still concrete’s worst nightmare.
Sliding back and forth inside a cylinder, the piston compresses air to create a pneumatic effect that drives the hammer forward.
Two thin metal strips support the counterweight, which can sway just enough to absorb up to 25 percent of the recoil from each hammer strike, sparing your hands.
A set of gears transfers the motor’s rotation to two places: a 90-degree cam that turns the bit, and another gear that drives the piston back and forth.
A variable-speed motor spins the drive shaft.
The grooves on the bit remove debris from the hole, clearing the way for more destruction.