Auger

Also called: auger bit, twist bit

An auger is a long boring tool with a spiral body that cuts a round hole in wood as it is turned, the spiral both cutting the wood at its tip and carrying the loosened waste up and out of the hole behind it.

How it bores

Most augers pull themselves into the wood rather than needing to be pushed. Goss (1888) described the tapered screw point found at the tip of most auger bits: besides centring the auger in its motion, that lead screw draws the bit into the work, so the arm turning the tool supplies the twisting force rather than downward pressure. Behind the point, the spiral body does two jobs at once, cutting a clean circular wall as it turns and lifting the waste chips clear of the hole so they do not clog the cut. Audels (1923) distinguished a single twist auger, in which the cuttings are thrown to the centre of the hole and come out easily, from a double twist auger, whose spiral crowds the cuttings against the wall of the hole, where they are more likely to jam between the tool and the wood.

Kinds of bit

Joyce (1987) listed several patterns built for different jobs: a solid centre auger bit, an extra strong general-purpose pattern with generous chip clearance for ordinary work, and a solid nose auger bit, built with an unbreakable tip for tough or awkward boring, including holes bored at an angle. Older catalogues describe the screw auger bit, its twisted shank ending in a fine lead screw, of which Hasluck (1897) named the Gedges pattern as one common make. Audels (1923) also described an unusual pattern guided not by a centre point at all but by its circular rim, which let it bore any arc of a circle and follow a curved path regardless of grain or knots, leaving a smooth surface behind it. A hollow auger is a different tool again, built for chairmaking: it fits over the end of a round rung rather than boring into solid wood, and cuts a finished tenon and its shoulder together in one pass, the depth of cut controlled by a stop and the rung kept level under the tool as it works.

Boring by hand

Older manuals agree on the technique even where they differ on detail. Hasluck (1897) recommended standing over the work and boring downwards for the most power, with a little grease on the bit to ease its passage, and noted that large augers saw little use in cabinet work, where smaller sizes were preferred. Fairham (1920) stressed starting the bore carefully, since trying to cut with only one side of the twisted bit engaged in the wood caused real difficulty. Boring along the grain took more effort than boring across it: Riley (1905) noted that when an auger bit follows the grain, the worker must add real pressure, because the screw feed alone does not draw it through on its own. A well-kept bit should not need much of that pressure at all: Goss (1888) judged that a sound auger bit should cut freely and advance into the work without much pushing on the brace, and that one which does not is in poor condition and needs sharpening. The essayist George Sturt (1923), writing about his own workshop, remembered simply needing a sharp auger for some of the jobs he did, a reminder that this was as much a matter of upkeep as of tool design.

Machines and modern echoes

The auger's basic action was carried over into powered mortising. Hayward (1950) described mortises cut either with a hollow chisel and auger together, the auger bit spinning inside a square-sided chisel that squares off the round hole it bores, or with a rotary miller bit instead. Auger bits are made to fit a hand brace and, as Frid (1979) pointed out, will not fit an electric drill's chuck, which needs a different, straight-shanked bit; he also warned that an auger bit can be hard to start cleanly in end grain. The auger's centring lead screw sets it apart from the later Forstner bit, which Bird (2004) explained cuts a clean, overlapping hole guided by its rim rather than pulled in by a screw point. The word survives, too, in the modern screw trade: Noll (2002) described production screws fitted with an auger point, a small nib under the head that lets the screw drill a pilot hole for itself as it is driven, instead of needing one bored first.