Rule For Mortises
: AN ANALYSIS OF TENONING, MORTISING, RABBETING AND BEADING
Fig. 206 shows such an example. You will notice this in doors particularly, as an example of work.
The next consideration is, shall the mortises be cut entirely through the piece? This is answered by the query as to whether or not the end of the
enon will be exposed; and usually, if a smooth finish is required, the mortise should not go through the member. In a door, however, the tenons are exposed at the edges of the door, and are, therefore, seen, so that we must apply some other rule. The one universally adopted is, that where, as in a door stile, it is broad and comparatively thin, or where the member having the mortise in its edge is much thinner than its width, the mortise should go through from edge to edge.
The reason for this lies in the inability to sink the mortises through the stile (A, Fig. 207) perfectly true, and usually the job is turned out something like the illustration shows. The side of the rail (B) must be straight with the side of the stile. If the work is done by machinery it results in accuracy unattainable in hand work.