No glue here! The Woodworking Guru looks at the loose-wedged mortise & tenon joint, an easy, strong and attractive joint for a variety of applications
Not all woodworking joints are held in place with glue. In fact, there are circumstances where it is useful for a joint to be easy to dismantle – for instance, so that a large piece of furniture may be readily moved. However, when assembled, the joint must be firm and rigid. The loose-wedged mortise & tenon has all the strength of a normal joint but can be rapidly undone. It may be used in a number of situations, and is most commonly found on the rails of large refectory tables. It also has the advantage of being adjustable,and can be tightened simply by driving the wedge in deeper.
1. Start by marking the shoulder line on the tenon member. Leave a generous tenon length at this stage – it should be at least one and a half times the thickness of the mortise member. Mark the tenon width, which should be at least one-third the thickness of the tenon member.
2. Transfer the tenon width onto the mortise member, then square the lines round with a try square.
3. Using a mortise marking gauge, mark thetenon thickness onto the mortise member, between the two marked lines. Do this on both sides.
4. Remove the waste from the mortise with a chisel. Take small cuts and work halfway through on one side, then turn the workpiece over and work through from the other side, to ensure a neat finish.
5. Saw the waste off the tenon with a tenon saw. Cut the shoulders first and then remove the cheeks.
6. Assemble the joint. It should be a sliding fit. Make sure the shoulders are even and then mark the thickness of the mortise member on the top of the tenon.
7. Remove the tenon member and using a try square, mark a line about 3mm behind the line you have just drawn; this will become the back of the mortise for the wedge. Carry this line around the tenon.
8. The wedge should be cut with a slope of 1-6, and its thickness should be no more than one-third the thickness of the tenon. Its length should be about three times the width of the tenon.
9. Mark the slope of the wedge on the side of the tenon with its back up against the marked line. Carry the line around the tenon with a try square. Use the mortise marking gauge to mark the thickness of the wedge on the tenon.
10. Pare out the mortise with a chisel, again working from both sides. Be careful to follow the marked line on the tenon side in order to get the correct angle for the wedge. Assemble the parts and drive the wedge in to pull the joint up tight.
11. The finished joint should look something like this.