Fig. 252. Keyed Mortise-and-Tenon Joint.
Gage the sides of the wedge hole on both upper and lower surfaces of the tenon. After cutting the mortise and tenon, bore and chisel out the hole for the wedge, taking care to cut the side toward the end on a bevel to fit the wedge.
No. 40. A tusk tenon or shoulder tenon is one in which the tenon proper is quite thin but is reinforced by a thicker shoulder called a "tusk." The upper shoulder is beveled. The object of this form is to weaken the mortised member as little as possible but at the same time to increase the strength of the tenon. It is used in joining tail beams to headers in floor framing.
Fig. 267-40 Tusk tenon
No. 41. A double mortise-and-tenon consists of two tenons side by side in one piece fitting into two corresponding mortises. It is used in joinery, as in door-frames, but not in carpentry.
Fig. 267-41 Double mortise and tenon