Impact Drivers

Impact drivers drive screws and hex-shank fasteners using the same rotational hammering principle as an impact wrench, scaled down to a 1/4" hex collet. The blows let the tool seat a long screw into dense material without the operator having to lean on it, and without the bit camming out and chewing the head — which is the usual way a drill fails at fastening. Compared with a drill/driver they are shorter, lighter and considerably more capable at the one job they do; compared with an impact wrench they are for fasteners rather than bolted joints. The compact class suits overhead and confined work and spends most of its life in a pouch rather than a case. The full-size class carries the torque for structural screws, lags and long runs of fastening. Bit retention is a 1/4" hex collet, so the whole impact-rated bit range fits — and impact-rated is the point, because a standard insert bit will shatter under the blows. Bits and holders are in Accessories & Consumables. Sold bare where a battery platform already exists, or as a kit.

For anything beyond occasional use, buy impact-rated bits by the box. The torsion zone built into an impact bit twists slightly under each blow and absorbs the shock that snaps a rigid insert bit, and the difference in cost per bit is recovered the first time one does not shear off inside a fastener. A magnetic bit holder speeds bit changes and adds reach into recessed work; a locking holder keeps the bit in place when it does not. Four-mode drivers with a self-tapping screw mode ease the start on sheet metal, and the quieter hydraulic-drive models are worth considering for indoor and occupied-building work, where a conventional impact driver is genuinely loud enough to need hearing protection over a full day.