Dreadnought File.—At [Fig. 175] is a sketch of a portion of a dreadnought file. This has superseded the old-fashioned home-made float used to clean out the sides of a mortise.
| Fig. 172.—Clamping. | Fig. 173.—Tenoning Narrow Rail. |
| Fig. 174.—Inserted Tenons. | Fig. 175.— Dreadnought File. |
| Fig. 176.—External and Internal Joints. | Fig. 177.—Setting out Stiles and Rails for Tenoning. |
General Rule.—In practically all cases where a single tenon is used the thickness of the tenon should be one-third the thickness of the timber. This leaves the timber at each side of the mortise the same strength as the tenon.
Mortise and tenon joints for inside work may be united with glue. If, however, the work has to stand the weather a better method is to unite the joint with white lead, which is run down to the required consistency with good outside varnish.
Setting Out the Joint.—The principal use of the mortise and tenon joint is in the construction of various types of framing, such as door and window frames. In one or other of its many and varied forms it may be classed as the most important joint in the general woodworking trade. The joint may be used as an internal one, as shown at the lower rail, [Fig. 176], or as an external joint, as the upper rail of the same illustration.
Whatever type of framing has to be made, it is necessary that the face side of the wood be planed up straight and out of winding, and the face mark (as shown in [Fig. 176]) pencilled upon it. The best edge of the timber should next be planed up true in length, and square to the face side, and the edge mark (X) clearly placed upon it.
The marking gauge is now set to the desired width, and gauge lines are marked on the wood, after which the waste wood is planed off until the timber is the required width. The thickness is gauged and treated in a similar manner, except in such cases where the finished work is to be of a rough and ready character.
The Two Stiles (or uprights) have their faces turned to touch each other, as shown at [Fig. 177], and their length may be anything from 1 in. to 3 ins. longer than the required finished size. This waste wood at each end of the stiles (see arrow HO) is of importance to the work, as it prevents to a great extent the bursting of the mortise whilst cutting the hole or when knocking together the work. The small projection is called the "horn," and it is cut off after the frame has been put together.