Crucible Planing Stop

Toothed Crucible planing stop in the Roubo style, embedded in the end of a block of wood about 3" × 3" × 12". The block is friction-fit into a mortise in the benchtop and moves up and down with mallet taps. A planing stop is as important as the workbench's face vise and has almost endless uses.

Blacksmith-made stops can be tricky to install: you need to drill a stepped hole in the block or heat the shaft in a forge and burn it in, and the block may split. The Crucible planing stop is made from ductile iron, so it can take a beating and will not shatter even if hit with a steel sledge, unlike typical grey iron. The teeth and the angle of the head are based on A.J. Roubo's 18th-century planing stop.

It is also easy to install. Drill a full-depth hole in the block with a 5/8" (16 mm) spade bit and clear out the chips. Drop the shaft into the hole, where it stops about 1" from the bottom, and knock it a few times with a hammer; the stop cuts its way in and beds itself in place.

The teeth come ground to a sharpness suited to woodworkers learning to use a toothed planing stop: they grab the work but are not so sharp that they will cut you. Once you are comfortable, you can file the underside of the teeth so they grab even harder. The teeth may leave marks, commonly found on antique furniture and marks of handwork like the scallops left by a plane. If you don't like them, you can easily plane them away.

Facts:
Ductile iron that will not shatter
Teeth and angle based on Roubo's 18th-century planing stop
Installs in a 5/8" (16 mm) hole
Cast and ground in Illinois, USA