Jack plane

Also called: jack

A jack plane is an all-purpose hand plane, a tool with a flat sole and an angled blade, called the iron, set into it, used for the first and roughest stage of flattening a board straight off the saw. Hasluck (1897) put its place in the sequence plainly: "the jack plane is the first applied to the wood after it has been sawn."

Why the iron is curved

A jack plane is expected to take off wood fast, not leave it smooth, and its cutting edge is shaped for that job. Goss (1888) explained that because the plane is "used for heavy work and frequently removing shavings as thick as one-sixteenth of an inch", a straight edge like a chisel's would dig two sharp corners into the wood at every stroke, cutting a rectangular channel and tearing the shaving out rather than slicing it away cleanly. To avoid that, Goss noted, the jack plane's cutting edge "is never straight, being for the jack-plane slightly curved", so the shaving thins toward each side and the plane can be worked hard without gouging. Porter (1999) makes the same point in modern terms: a smoothing plane, used for a fine finishing cut, only has its very corners rounded off to stop them digging in, while a jack plane iron carries a stronger curve across its whole width, made to clear wood quickly rather than leave a polished surface.

Rough work, then trueing

The jack plane is only the first plane in a sequence, not the last. Nicholson (1832) described how a board, once "planed first by the jack plane, and afterwards by the trying plane", is said to be "tried up", and the whole process is called trying: the jack takes off the worst of the saw marks and any wind, or twist, in the board, and the longer trying plane, or fore plane, follows to true the surface flat and straight. Audels (1923) noted that a fore plane's iron is ground to a straight line rather than curved, and set for a finer cut than the jack's, so it can true the surface the jack has already roughed out. Ellis (1908) described the technique directly: work the jack plane's rough cut "straight across" the board, then test the result by turning the plane up on one of its edges and sighting the gap between sole and board, which shows at a glance whether the timber is hollow or round. Hasluck (1907) added a piece of shop practice worth keeping: leave a faint trace from the jack, what a joiner calls a witness mark, the last hint of the original saw or weathered surface, before reaching for the trying plane, so there is still a visible check on how much has been removed. Not every job needs the full sequence. Goss (1888) pointed out that it is not always necessary to follow the jack plane with both a smooth plane and a fore plane; for rougher carpentry the jack's own work may be enough.

Name and form

Joyce (1987) traced the plane's name to the idea of a jack of all trades, a tool fit for any task, reserved for the roughest work even though it is made as precisely as any other bench plane. That rough-and-ready reputation shows in the advice given to beginners: Hayward (1950) suggested that anyone keeping to only three planes should make one of them a wooden jack plane around fifteen inches long, as the plane most likely to be reached for first. Nicholson (1832), comparing it with the trying plane that follows it, noted that the jack plane's handle, its tote, is single, while the longer trying plane carries a second handle for the extra strength that longer, harder strokes demand.