If preferred, a coping saw can be used to advantage in trimming out the series of overlapping holes. For knockdown furniture the tenon is cut longer than the depth of the through mortise, the protruding extension being drilled to receive a wedge or dowel, set close enough to the outer face of the mitered member to key the tenon firmly in place. In most cases the tenon has one or more shoulders on the side or sides against which the greatest stress is anticipated. For additional strength, when the stock is wide enough, double mortises and tenons are preferred, affording the advantages of two smaller mortises with stiff sides instead of one wide mortise with springy sides. When grooved framing is used, a haunched tenon is cut to fill the gap made by the fulllength groove. To cut a double haunched mortise and tenon, first square the stock, then with a try square lay out the tenon shoulders on all four sides. For the haunch, mark a second line a distance above the shoulder line approximately equal to the depth of the groove, if it is not too deep. Gage the thickness of the tenons on the edges and end, and apply the same gage setting to the mortises in the other member to insure a clean fit. Last of all, gage the width of the tenons on both faces and bore a hole at the base of the center division. The slot between the twin tenons is not cut down entirely to the shoulder in the case of grooved material, for the same reason that a haunch is cut-to give added strength by filling the groove. From here on, the tenons can be cut out entirely with a hack or tenon saw. The procedure outlined in Figure 1.29 will insure the best results. Sharp corners can be later pared out with a tangfirmer chisel if necessary. The ends of the tenons are chamfered for the same reason that the ends of blind dowels are rounded. The mortises can be first bored out with the auger bits gaged to stop at a depth about %е in. deeper than the length of the tenons, to accommodate surplus glue and imprisoned air. The bit should be 34« in. narrower than the tenon to CABINETMAKING ¦Mo Bore Fig. 1.29. Steps in cutting double haunched tenon from tongue and groove stock. insure a snug fit after chiseling, in order to provide thorough bracing support ar to relieve the glue from excessive strain. The fit of the tenons in the mortis should not be so tight as to bulge them, however. A through tenon can be wedged for added strength, as shown in the diagrai (Figure 1.28). In this case, as well as in that of the blindwedged tenon, th mortise must be cut slightly fanshaped at its extreme end to accommodate th butt ends of the wedges. Perhaps the most useful of the mortise and tenon joints for furniture construction is the mitered tenon, used to secure the maximum length of the two tenons meeting at corner mortises. These are common joints for securing the aprons of tables to the legs, and are nothing more than two haunched single or double tenons with their ends mitered as illustrated in Figure 1.