Screwdriver

Also called: turnscrew

A screwdriver is a hand tool for turning screws: its tip is shaped to fit into a slot or a shaped recess cut into the screw's head, so that twisting the handle twists the screw with it and drives it into or out of the wood.

Three basic kinds

Porter (1999) grouped workshop screwdrivers into three basic kinds. The plain or rigid-blade screwdriver is the simplest: the whole tool turns with the wrist, one twist at a time. The ratchet screwdriver adds a mechanism in the handle so the blade can be reset to a new grip without the tip leaving the slot, useful in a tight corner where a full wrist turn will not fit. The spiral ratchet, or pump, screwdriver goes further again: pushing down on the handle drives a spiral grooved shaft round, so the screw is driven or withdrawn by a pumping action rather than by twisting the wrist at all. Its shaft can also be locked short inside the barrel by a knurled collar, turning it into an ordinary rigid or ratchet driver for jobs where the full pumping stroke will not fit.

Turnscrew or screwdriver

The tool has two names either side of the Atlantic. Wearing (2010) pointed out that British joiners traditionally called it a turnscrew, while the American name is screwdriver, and noted that the difference is telling: a screw properly cut and started should only need turning, not the hard work implied by driving one in.

Older forms

Hasluck (1907) described two older patterns still worth knowing. The gimlet-handle screwdriver, shaped like the bulbous handle of a gimlet, he rated as having certain proved advantages for grip. The brace screwdriver is simply a screwdriver bit held in an ordinary carpenter's brace, letting the sweep of the brace supply the turning force; Hasluck judged it useful for driving good-sized screws easily and quickly, since the brace's leverage spares the wrist the work a hand-held driver would otherwise ask of it.

Slot and cross-slot tips

Screw heads take either a single straight slot or a cross-shaped slot. Joyce (1987) explained why the cross form became common: a single slot lets the driver's tip climb up and skate out of the slot as the turning force builds, which can send it skidding across the surrounding wood, whereas a cross slot resists that upward creep and so is less likely to slip and mark the work.

Beyond driving screws

A screwdriver earns its keep at other jobs around the bench. Its flat tip will push an oversize saw tooth back into line where the teeth are too fine for a proper saw set, and its blade doubles as a rough burnisher for turning over the edge of a cabinet scraper. Woodworkers also use one to prise dowel plugs free, and, because the shank slides easily under loose bark, to strip bark from freshly felled pine while the cambium layer beneath is still soft enough to let it peel away whole.