Tool experts field test and rate nine hammer drills.

Hammer drills are beasts among tools, often punished by long, brutal run times. The "hammer" consists of two unmeshed gears. The first, a gear disc attached to the motor, spins against the second, mounted at the back of the chuck. As the gear teeth collide, vibration or "hammering" results.

We tested the following hammer drills: Bosch 1194AVSRK; the DeWalt DW515; the Fein 638; the Freud FPD182R; the Hitachi DV20V2; the Makita HP2020N; the Metabo 751; the Milwaukee 5378-20; and the Porter Cable 7751.

We outfitted each tool with the same type of new bits for each test phase: carbide for masonry and auger bits for wood. The test criteria also included the following: Amps, Rpm range, Bpm (blows per minute), Balance and Weight, and Price.