Woodwork Joints | Page 8

deface the work.
[Illustration: Fig. 71.--Joints used in the erection of a Queen Post Roof Truss.]

THE BRIDLE JOINT
A bridle joint is often defined as the reverse of a mortise and tenon, and is chiefly used in the carpentry and joinery trades. The name probably originated from the fact that it bears some resemblance to the manner in which a bit slips into the horse's mouth and is fastened to the bridle. There are fewer varieties of the bridle joint than of the halved or the mortise and tenon; and this being the case we may take the opportunity of giving a few detailed directions, with explanatory illustrations, on the setting out and the making.
[Illustration: Fig. 72.--Simple Bridle Joint.]
Fig. 72 shows a bridle joint in what is perhaps its simplest form, the separate pieces being given at the left and the completed joint at the right. A joint of this type may be applied in nearly all cases where a halved or a mortise and tenon joint could be used. Bridle joints have an advantage as regards appearance over the mortise and tenoned variety in cases such as Fig. 73, which shows an occasional table leg fitted to the circular top framing. The bridle joint here allows the grain of the leg to run through to the top, and gives a better and more workmanlike appearance to the completed article.
[Illustration: Fig. 73.--Table Leg Bridle-jointed to Rail.]
Fig. 74 is a "Mitred bridle joint," the part a showing the upright portion separated. This is a most useful joint for positions similar to that shown in the small glass frame, Fig. 75. The wood framing in this case is only 1-3/8 in. in width, and if a mortise were used it would have to be exceptionally small. The shaped rail at the bottom of this frame again shows the application of the bridle joint.
Fig. 76 shows an "Oblique bridle joint," used in many instances as a brace, or strut, to prevent framing from racking. (See also Figs. 31 and 32.)
Fig. 77 is a "Stopped bridle joint," used in positions where the top or bottom edge of the work meets the eye, and where, if the rail were allowed to run through, the end grain would appear unsightly.
[Illustration: Fig. 74.--Mitre Bridle Joint.]
[Illustration: Fig. 75.--Mirror Frame with Bridle Joints.]
Fig. 78 is a so-called bridle-joint at the corner of a frame. This is also called an "Open slot mortise and tenon joint," a good strong, serviceable joint which can be used instead of the closed mortise and tenon type, its advantage being that less labour is required in the making. (See also Fig. 169.)
Fig. 79 is an "Oblique angle bridle joint," used in similar positions to the above, but when the two pieces meet at an acute angle at the end of a frame.
Fig. 80 shows the application of the bridle joint to a roof truss. Two sketches are shown at the joining of the tie beam and the principal rafter. The joint a is the type generally used. (See also Fig. 71 for the joints in a queen post roof.)
[Illustration: Fig. 76.--Oblique Bridle Joint.]
[Illustration: Fig. 77.--Stopped Bridle Joint.]
[Illustration: Fig. 78.--Bridle Joint at Corner of Frame.]
[Illustration: Fig. 79.--Oblique Angle Bridle Joint.]
[Illustration: Fig. 80.--Application of Bridle Joint to Roof Truss.]
SETTING OUT AND MARKING.--It is a safe rule, when setting out a bridle joint, to divide the thickness of the timber into three equal parts. This will leave the timber on each side of the tongue equal to the thickness of the tongue, thus giving uniform strength to the joint. The bridle joint is chiefly used for connecting the internal parts of wooden frames. It is stronger than the halving joint, and, owing to its peculiar construction, requires little in the way of pegs, screws or nails to secure it in position. Fig. 81 illustrates the joint, both open and closed.
To understand the method of setting out and marking, glance at the sketch, Fig. 81. It is not necessary that the bridle piece A be the same width as the cross piece B; but it must be remembered when setting out the joint with the marking knife or pencil that the width marked W on piece B must be equal to the width W on the piece A. The timber should be fairly accurately sawn or planed to the same thickness, and all edges should be square and true.
The wood is placed upon the bench, and the joint marked out by using a marking knife or penknife blade and the try square. A knife blade is much better than a pencil, as the sharp edge severs the fibres of the wood and gives a finer line than the pencil. It is not always necessary to exactly square and trim the end of piece A; it may with advantage in many