—[Fig. 157] shows the tenon, the mortise in the second member into which the tenon fits, the mortise in the tenon and its key or wedge.
Fig. 158.
88. Directions for Key
:—Keys are made in quite a variety of shapes. Some of the simple forms are shown in [Fig. 158]. Where two or more keys of the same size are to be made, it is customary to plane all in one piece. (1) Plane a face side, a face edge, gage and plane to thickness. If there is more than one key, saw each to length. (2) Shape the remaining edge as desired. The lines AB and CD, [Fig. 158], indicate the points at which measurements are to be made to determine the length of mortise in the tenon which is to receive the key. These lines should be laid off at a distance apart equal to the thickness of the tenon.
89. Directions for Tenon.
—(1) Measure from the end of the piece the length of the tenon, and mark with a knife point. Where tenons are to be cut on both ends of a piece, measurement is frequently made from the middle of the piece each way to locate the shoulders. Should there be any variation in the length of the piece from what it should be, this difference will then be equally divided at the ends. This is done when it is more important to have the distance between the shoulders of a definite length than that the tenons be of correct length. (2) Square knife lines entirely around the piece at the knife point mark. (3) Set the gage equal to the distance required from the face edge to the nearest edge of the tenon and mark on both sides, as far as the shoulder marks, and on the end. (4) Repeat, setting the gage from the face edge to the farther edge of the tenon. If the two members are of the same width and the tenon and mortise are to be equally distant from the face edge, both tenon and mortise should be gaged with the same settings. Frequently, the gage settings are obtained from the rule indirectly. The rule is laid across the piece and the width or thickness of mortise or tenon marked with the point of a knife blade, [Fig. 159]. The spur of the gage is then set in one of these points, the block being pushed firmly against the face; the thumb-screw is then fastened, [Fig. 160]. The second setting is obtained in a similar manner from the same edge or side. All the pieces are marked for the first width before resetting. (5) After having laid out the mortise in the tenon, rip to the gage lines and cross-cut to the shoulder lines, paring if necessary. (6) Slightly bevel the ends of the tenon.
Fig. 159.