Plough plane

Also called: plow plane, grooving plane

A plough plane is an adjustable plane for cutting a groove, a long channel ploughed into a board, using interchangeable blades to cut grooves of different widths.

What it is

Ellis (1908) defined the plough as 'An adjustable grooving plane.' It is normally bought together with a set of eight interchangeable blades of various widths: Fairham (1920) noted: 'When a plough plane is bought it is usual to procure eight plough bits or blades of various sizes to fit the plane.' A grooving tool of the plough type is best equipped with a range of eight or more cutters, and for regular grooving work most workers favour the metal-bodied version, typically fitted with that many. A smaller version with just three narrow cutters works well enough for someone who grooves only now and then.

How it cuts

The plane's steel skate, a metal plate on the sole that rides in the groove already begun, backs up the cutting blade as it works. A blade of the right width is chosen and fitted into the body in the usual way, its edge set to project slightly beyond the skate, and the wedge is then driven tight to lock it in place.

The dado grooving plane

A related tool, the dado grooving plane, also called a trenching plane, cuts grooves that run across the grain rather than along it. Nicholson (1832) described it as 'a channel plane, generally about three eighths of an inch broad on the sole, with a double cutter and stop, both placed before the edge of the iron which stands askew; it throws the shaving off the bench.' The skewed iron, a blade set at an angle to the direction of travel rather than square across it, is what throws the shaving clear in this way. A stopped groove, one that does not run the full length of the board, can also be cut with an electric router, but doing it the traditional way, with a hand plane or a small circular saw, tends to be messier. Grooves in frame stiles and rails, the upright and horizontal members of a frame, can likewise be cut with a plough or grooving plane, a router, or a circular saw.

Loose-tongue joints

Once two boards are jointed edge to edge, each is grooved to a depth equal to half the width of the loose tongue, a separate thin strip called a feather, that fits into both grooves and joins the boards. If it is the right width, an ordinary grooving plane can also cut these grooves in place of a plough plane. In one worked example, fitting a plinth, the skirting-like base board at the foot of a wall or cabinet, against a floor fillet, a thin guide strip fixed to the floor, a groove was cut by running a grooving plane against a guide strip matched to the plinth's thickness.