The chair’s frame is assembled without any nails and is instead held together with mortise and tenon joinery.

The mortise (figure 1) above, is a rectangular hole that corresponds exactly in width, thickness, and depth to the tenon (figure 2) which is inserted into the mortise. The result is an exceptionally strong and durable joint.

To begin, double lines are scribed with a marking gauge to outline the tenon (left). The marking gauge is also used to outline the walls of the mortise (right).

A bench chisel works around the soon-to-be tenon, creating small valleys by slicing-up to each scribe line. This will help with the sawing.

The tenon begins to take shape as its sides (called cheeks) are sawn away with a carcass saw along the scribe lines.

The excess wood is sawn away along the valleys made earlier with the bench chisel.

The cheeks of the tenon are further refined with a wide bench chisel. This cleans-up the saw marks and brings the tenon to its final thickness.

Excess wood along the tenon’s base (called a shoulder) is sliced away with a narrower bench chisel.

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Now we turn to the mortise. Small slices are made along the scribed-out mortise’s length using a square bodied mortising chisel. This helps to guide the chisel as the mortise continues to be chopped-out.

Using a mallet, the chisel is pounded into the mortise. The chisel is used as a lever to pry-out chunks of wood and produce a square void. This process is repeated until the desired depth is achieved.

An 18th century menuisier chops a mortise.

The finished mortise and tenon unassembled (left) and assembled (right).

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