Marking knife

Also called: striking knife, scribing knife

A marking knife is a sharp knife used to score precise layout lines in wood before cutting or fitting a joint.

Why use a knife

The edge makes a narrow incision instead of the broad mark left by a pencil. That cut gives a saw, chisel or plane a definite boundary and helps the fibres break cleanly at the line. Use a light pass first rather than forcing the blade into the surface.

Set out a joint

Hold the knife against a try square, a tool for marking a right angle, when laying out a shoulder or cross line. A marking gauge can carry the same line parallel to a reference edge. Mark the boundary around the work where the joint requires it, and keep the waste, the part to be removed, on the correct side of the incision.

Work across the grain

Across the grain, the knife severs the upper fibres and leaves a clean guide for the following tool. Keep the blade sharp and make the cut shallow enough to control; a blunt or heavily pressured edge can bruise the surface instead of defining it. The same tool can set out a groove or transfer a mating line.

Use it with care

Keep fingers behind the direction of travel and let the reference tool or board support the knife. A marking knife is for layout, not for prising waste or levering a joint. Recheck the line against the drawing and the mating piece before committing to a cut.