PowerTools
Drill, Hammer Drill, Rotary Hammer, Impact Driver: The Four-Tool Taxonomy
The four common rotary power tools look similar but solve different problems: a regular drill for general holes and small screws, a hammer drill for the occasional brick hole, a rotary hammer for concrete and masonry, and an impact driver for driving screws. Names are misleading because hammer drills barely hammer and rotary hammers are really hammers that happen to rotate.
Rotary Hammer Pneumatic Mechanism: Free-Floating Piston Driven by a Swash Plate
A rotary hammer turns rotation into percussion using a swash-plate bearing that wobbles a cylinder back and forth, driving a free-floating piston that slams an anvil through a trapped air column. The 'pneumatic' label refers to that air gap, not external compressed air, and the gap is what lets the user lean on the tool without jamming the mechanism.
Impact Driver Mechanism: Spring-Loaded Hammering Without a Clutch
An impact driver turns sustained motor torque into short rotational hammering bursts using a sprung mass with ball bearings that ride U-shaped grooves in a drive shaft. When resistance spikes, the hammer mass jumps backward, clears a lug on the anvil, and slams forward, delivering torque too fast for the operator's wrist to feel or for a Phillips bit to cam out.
Keyless Three-Jaw Drill Chuck: How Back-Torque Locks the Bit
A keyless three-jaw drill chuck holds round-shank bits using three angled toothed jaws driven by a threaded sleeve, with a sloppy bearing-pin assembly that lets the motor spin the chuck open or closed but locks the chuck when the user twists it by hand against a stationary shaft.
Know Art 'Hammer Drills Don't Hammer' Video Review
Know Art's December 2025 high-speed-camera explainer on the four common drill types is the most useful single video for someone deciding which power tool to buy, even though it doubles as a Festool product showcase. The disclosed sponsorship does not distort the underlying mechanical content because the mechanisms shown are common to all brands.