Mortise & tenon joints

John Bullar moves on to discussing mortise & tenon joints and how they are traditionally used in furniture making, beginning with hand tool methods, before looking at a few powered techniques.

This month we’re going to look at mortise & tenon joints of the type traditionally used in furniture making. The strength of the joints holding furniture together is one of the main factors infl uencing the quality of a finished piece. Solid wood furniture (the type most people prefer when going to the expense and trouble of having it hand-made) benefits from being fitted together with traditional woodworking joints.

Mortise & tenon joinery (like dovetailing, which we will look at in GW316) is an evolved technique – it has been tested and refined over centuries to take account of solid wood’s strengths, weaknesses and seasonal movements. We will start using exclusively hand tools and then look at a few powered techniques.

Hand-made joints

The essential tools you will need are a try-square, a marking gauge and a finebladed knife for marking. To chop out the mortise you will need a sturdy chisel with a razor-sharp edge and preferably straight un-bevelled sides . You will also need a small tenon saw and a wooden-jawed vice or workmate to hold the wood while cutting.Trying to make joints on distorted wood is more trouble than it’s worth, so if you buy ready-planed wood check how straight and square its edges are. It is not uncommon for wood-yards to sell distorted timber due to poor machine work or seasonal movement. If this is the case, either find a better source or else plane it square yourself . I would always recommend making trial joints on scrap wood, especially if you are not fully familiar with the technique or if the joint is diff erent from ones you have made before.

Marking out the size