An auger drill bit bores deep, clean holes through thick timber in one pass, pulling itself in with a threaded screw tip so the drill does most of the work. This collection covers wood auger bits in short and long lengths plus earth auger bits, for timber framers, deck and pergola builders, electricians running cable through joists, and fencing contractors.
Choosing an auger bit
- Length. The Bosch PRO Auger Drill Bit in standard lengths handles beams, posts and joists. For bolt holes right through a laminated beam or for reaching past an obstruction, the Bosch Hexagon Wood auger bit 450mm gives the extra reach.
- Diameter. Both Bosch augers come in a range of sizes; use the size selector to match your bolt, dowel or conduit.
- Shank. A hexagon shank, as on the 450mm Bosch bit, will not slip in a keyed or keyless chuck under the high torque an auger produces.
- Wood or ground. For fence posts and planting holes, the Makita Earth auger drill bit 200 x 800 mm is a soil auger for a powered earth drill, not a woodworking bit.
Auger bit vs spade bit vs forstner bit
An auger has a screw tip and a single spiral flute that lifts chips out of a deep hole, so it is the tool for anything over about 50 mm deep in solid timber. A forstner bit leaves a flat-bottomed, clean-sided hole for hinges and counterbores but clogs if you go deep. Choose the auger for structural holes and run it in a low-speed drill with a side handle, because the screw tip pulls hard. See forstner bits for the fine-work option and cordless drills for a drill with enough torque.
These bits are in stock at Power Tool Services in Claremont, Cape Town, with nationwide courier delivery. Our staff drill with augers daily and can advise on size and drill pairing.
