Planer thicknesser

Also called: thicknesser, surface planer, jointer, planing machine

A planer thicknesser is a workshop machine that does two jobs a joiner would otherwise do by hand with a long hand plane: it trues one face and one edge of a board flat and square, and then planes the board down to an even thickness all along its length.

Two jobs, and sometimes two machines

The first job, jointing, means flattening a board's face and squaring up an edge to it before anything else is done to the timber; Bird (2004) described the machine that does this, a jointer, as essentially an inverted plane, one mounted upside down so its blades face up and the timber is pushed over them, and likened the whole machine to a large motor driven bench plane. The second job, thicknessing, takes a board that already has a true face and skims the opposite face until the whole board is an even, chosen thickness from end to end. In Britain these two jobs are commonly built into one machine, the planer thicknesser that gives the entry its name; Wearing (2010) took the combined machine as his example, noting that with a planer thicknesser, or with timber that has already been planed and bought in ready dimensioned, the boards can be brought to their finished thickness with very little cleaning up needed afterwards. Several American writers in the pack, by contrast, treat jointing and thicknessing as the work of two separate machines, a jointer and a thickness planer; Frid (1979) remarked that an old, outdated jointer and thickness planer can often be picked up cheaply and will still turn in work every bit as good as a machine bought new.

The hand plane behind the machine

Before machines took over the work, the same two jobs were done with hand planes, and the vocabulary carried across. Hasluck (1897) called the jointer plane the longest and most perfect plane in use, brought in after the shorter jack plane had already done the rough work of taking a board down close to size. Audels (1923) explained why the shorter fore plane was often reached for instead by a working carpenter: being shorter than a jointer, it is easier to handle, though the trying plane, in his words simply a small jointer, was ground and set the same way, its cutting edge kept straight and set fine for a smooth, true cut. Goss (1888) made a similar point: the jointer and the fore plane serve much the same purpose, and a full sized jointer is really only needed for large surfaces that must be planed dead accurate. On the machine, the same chip breaking action is built into the cutter itself; Jones (1920) described lips on a surface planer's cutters that do the same job as the cover iron, what is now usually called the cap iron, on an ordinary hand plane, and noted that the cutter block is often slotted along its length so that shaped moulding cutters can be fitted and the machine put to moulding work as well as flat planing.

Using it safely

A purpose built thicknesser is not the same machine as a jointer being pressed into thicknessing work, and the two carry different risks. Joyce (1987) warned that although an experienced hand can bring a panel down to an even thickness on an overhand surface planer, a jointer without its own separate thicknessing table beneath, doing so safely takes real practice, and is a genuinely dangerous way to work. Porter (1999) made the safety point explicit: on a machine of that kind used for thicknessing, the part of the cutter block left exposed above the surfacing table has to be guarded along its whole length. Ordinary jointing carries its own hazards for the cutters rather than the operator: Frid (1979) advised keeping plywood off the jointer altogether when it comes to trimming its edges, since the glue bonding the panel's plies will nick the blade, and recommended checking the jointer's own knife setting with a straight edged stick rather than by eye.

Sizing the board to the machine

A planer thicknesser has a fixed maximum width, and timber sometimes has to be cut down to suit it; Wearing (2010) gave the example of ripping boards narrower to go through smaller machinery, such as a planer or thicknesser of only 150 millimetres, six inches, capacity. At the sawmill end of the trade, a related but much larger process goes by a related name. USDA (2021) and Hoadley (1980) rely on much the same definition of lumber: timber that has been through a sawmill and its planing mill and had nothing further done to it beyond being sawn, resawn where needed, run once lengthways through a standard planing machine, cut to length, and matched. Hasluck (1897) noted that by his time the conversion of logs and baulks into scantlings, boards and battens was already done almost entirely by machinery, often with a single engine driving the saw, the planing machine, and a mortising and dovetailing machine besides.