When chopping mortises by hand, beginners often find it difficult to maintain precise control of the chisel. The result is a mortise that is incorrectly sized, with walls that are out of square. To help them correct this, I teach the following method.

It starts in the usual way, with sharply scored lines made with a marking knife and marking gauge. But then you define those lines further by chiseling shallow ramps leading up to each line. The next step is to clean out the space between the lines with a small router plane set for a 1/16-in.-deep cut. This leaves short mortise walls. Use those as a guide for the rest of the process, resting your chisel against them as you chop out the mortise.

Not only does this approach allow any woodworker to chop clean, functional mortises, but it also trains them on the proper chisel orientation and feel for chopping a mortise, helping to establish the correct muscle memory.

If you are cutting a through-mortise, create the same shallow mortise walls on the other side before chopping, which will ensure clean results on both sides.

—Justin Masone, Washington, D.C.

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Justin Masone, a sales executive for a scientific company, is a longtime hobbyist woodworker and boatbuilder. He teaches hand-tool woodworking to beginners in his garage workshop, as well as general woodworking in a six-month alternative education program for young adults at the Alexandria Seaport Foundation in Alexandria, Va.

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