Master the Mortise & Tenon

Setting your marking gauge to the tool lets you use the width of your chisel to determine the width of the mortise.

In furniture making, while carcases and drawers are dovetailed together, tables and chairs have mortise-and-tenon joinery. In this article, I make a through mortise and tenon three different ways. First by hand, second with a hollow-chisel mortiser and table saw, and third with a plunge router and band saw.

In 1991, I had a very nice commission to make about a dozen pieces of Egyptian furniture for the Newark Museum in New Jersey. I had the opportunity to see the real, original ancient pieces and make measured drawings to do the work. The pieces I had to make are more simple ones which are less well known than the spectacular furniture from the tomb of King Tutankhamun.

This stool at left is a copy of a New Kingdom craftsman stool. I made it 2″ higher than the original. The Egyptians were squatting before they had stools and the low height of the stool was designed for sitting in this squatting position.

Clamp the leg securely to your bench and chop halfway through. Then flip the leg over and complete the mortise from the other side.

All the stools have through mortise-and-tenon joints with the seat rails meeting above and below one another at the legs. Some of the stretchers are the same way. Some tenons are pegged and some are wedged; the ancient stools were held together by the webbing. I glued mine.

The seats on the stools are also different. Some have a solid, curved seat carved from four planks, others are woven with reed and rush fibers, while still others have holes on the inner edge of the seat rails and are woven with simple double-braided rush webbing that looks like caning. The ends of all the strands are carefully knotted below the holes and hidden from sight. I made a bed in this manner for the museum.

Chop and Saw by Hand
To do mortise-and-tenon joints by hand, you have to do a lot of marking. After stock preparation, you mark the corner of the legs with a scribble to indicate the outside corners. With a square and a sharp pencil, mark the thickness of the seat rail 1/2″ below the top of the leg. Flip the leg and mark first under the lower rail’s location. For a through mortise and tenon, transfer these lines to the outside of the legs. Make sure you end up with pairs. Mark the location of the stretchers at the bottom in the same way.

To locate the tenon shoulder from the rail ends, mark the seat rails and stretchers, using the width of your leg as your guide, plus 1/4″ (which is how much the tenon sticks out from the leg). Measure the width of your stool and mark your other shoulder.