This line will be the inside of the hole for the wedge, and the 1/16" is deducted to make sure that the key wedges against the mortised member.

On the upper surface of the tenon, lay off toward the end the width of the wedge at this point, A B, Fig.
252, and square across.

On the under surface, lay off the width of the wedge at this point, C D, and square across.
[Illustration: 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_, Fig.

267, 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.