Scribing

Also called: scribed joint

Scribing is fitting a piece of wood to whatever it must sit against by tracing that surface directly onto the piece and paring or cutting the edge away to match, rather than working to a measured line. It covers everything from a skirting board following an uneven floor to a dovetail pin traced from its tail.

Fitting a piece by scribing

Scribing, as Tredgold (1871) defined it, is "the cutting away of the edge of a board in order to make it fit exactly to a plane surface", and skirting boards are the common example, with their lower edge scribed to follow the floor. The same idea is used wherever a flat piece must meet an irregular one. Screens and partitions can be cut a touch smaller than their opening so that they can be scribed in afterwards, and a fillet scribed to the ceiling line closes the remaining gap where a cabinet is built to full ceiling height. Cupboards built into an existing opening are finished either with planted scribing fillets, strips added on to cover the join, or with wide stiles scribed to the wall on site. Where a wall is out of plumb, a cover mould, a strip of moulding laid over the join, can be used instead of scribing to hide the gap. A curved fanlight is fitted the same way, one piece at a time: the fitting is finished, as Hasluck (1907) described it, "by scribing it into the rebate, one piece at a time".

Scribing in frame joints

Some joinery work recognises only three ways to join two moulded members: the butt, the mitre, and the scribe. A scribed joint holds its looks as timber shrinks, where a plain mitre does not: "any shrinkage of either member of the frame in the latter case produces an unsightly gap, whilst shrinkage does not affect the appearance of the scribed joint," as Ellis (1908) put it. On a moulded frame, the member carrying the mortise has its moulding pared back to a square shoulder before the scribing is done, and the same applies where an ovolo, a rounded, convex moulding profile, is scribed onto a rail joint: the wood is pared square down to the tenon first. On sash bars, a shaped templet can mark the scribed profile directly, cut to the reverse of the moulding, though a truer outline comes from first mitreing the moulding on both sides of the bar with a side templet, and only then working from that outline.

Marking a scribe

The basic tools are a try square and a scriber, a marking tool ground to a sharp point, and a dedicated marking tool of this kind can also draw circles or arcs as part of the layout. Some scribing tools carry a shaped face meant for tracing curved work. Marking across the grain with a knife severs the surface fibres cleanly and guards against tear-out, splintering pulled up ahead of the cut; an awl leaves only a ragged line if used the same way. A tenon's shoulder is scribed once a marking gauge has been set to the tenon's length, and a rafter's plumb cut can be scribed using a square set to the rise-and-run figures marked on its body and tongue. In dovetailing, shaping the pins ahead of the tails, then tracing the pins onto the tails, lets the visible-face cut go first and leaves room to true the line afterwards. Where a piece has both ends trapped between fixed points, it can be cut overlong and swung across the room to lay out its internal scribed joint. In timber-frame work, a layout aid can speed the scribing of a brace by letting it be shaped and fitted without taking the frame apart.