The stock for this exercise and the finished sizes are the same as used in Lesson 19 (Halved Cross).

This exercise illustrates a variety of modifications of the common mortise and tenon, and, when properly understood, should enable one to make any of the large variety of modifications. All of the irregular-shaped tenons depend upon care in selecting the proper order for working the various angles and shoulders, and in always keeping a face, or definite surface,.to line from, and working carefully to the lines at each step. Where a part of the tenon is to be cut away as in Lesson 23 (Frame Mortise And Tenon), frame mortise and tenon, and in this exercise you must be especially careful to keep the surface of the tenon correct from edge to edge, so that when a part of the tenon is cut away you will not lose your correct edges.

Fig. 111. Haunched Mortise and Tenon.

With these facts in mind you should be able to make this exercise from the drawing by reviewing Lesson 23 (Frame Mortise And Tenon). The difference between these exercises is in the leaving of a shoulder on the tenon to fit into the groove which extends the entire length of the piece that contains the mortise. This arrangement is common to joints used about paneling. The groove is usually worked with a plow; but in this case you will work it by drawing gauge lines at each edge of the groove and at the ends, and remove the waste material with a chisel.