This section is from the book "Cyclopedia Of Architecture, Carpentry, And Building", by James C. et al. Also available from Amazon: Cyclopedia Of Architecture, Carpentry And Building.
A simple mitered joint may be made stronger by the introduction of a spline, which is inserted at the joint in a direction perpendicular to it. This is shown in Fig. 75. The spline used in this way is also known as a "feather." It strengthens the joint very considerably, and a joint of this kind is a great improvement over the simple mitered joint. The spline or feather should be about 3/4 inch wide and about 3/8 inch thick. Its length, of course, varies with the width of the pieces which meet at the joint. Great care must be taken in ploughing out the grooves into which the spline fits, for if they are not exactly the same distance from the corner on each of the pieces the finished joint will not be neat and true. Rabbeted Miter Joint. There are two or three variations of the simple mitered joint made by rabbeting one piece on the other at the corner, so that the miter goes only part way through each piece. One of these joints is shown in Fig. 76, in which only one of the pieces is rabbeted and the other piece has a simple miter. This form of joint can only be used when one piece is somewhat wider than the other, so that it can be rabbeted a little and still have a miter which will match the miter on the narrower piece. If both pieces are of the same width, this can not be done. Wherever it is possible, however, this joint is an excellent one to use.
Fig. 74. Miter Joint.
Fig. 77 shows another way of rabbeting a mitered joint which is much better than the method shown in Fig. 76. This can be done when both pieces are of the same width or when they are of different widths. It is much stronger than the other method but requires a little more material than the simple mitered joint, as some must be cut away from one piece to form the rabbet and thus much of the timber is wasted. Very often, however, it happens that this timber would have to be used in any case and, when this occurs, the waste need not be considered. The increased strength of the joint would seem to be worth much more than the small additional amount of material which is required.
Rabbeted-Mitered-and-Splined Joint. In Fig. 78 is shown a joint which is mitered and at the same time rabbeted and splined. In order to accomplish this, one piece is cut at an angle of forty-five degrees and then rabbeted to the thickness of the other piece. The other piece is then cut with a miter to natch that left on the first piece and also cut to match the rabbet.
Fig. 7.5. Miter with Spline.
Fig. 76. Rabbeted Miter Joint.
GRACE MEMORIAL CHAPEL, CHICAGO, ILL.
Interior of Gray Pressed Brick; Trimmings of Terra-Cotta of Color and Finish Similar to Bed ford Stone. Floor of 9-in. Welsh Quarries; Chancel Floor of Mercer Tile. For Exterior, See Vol. I, Page 10; for Detail of Wood-Carving, See Vol. II, Page 10.
SOUTH ELEVATION STABLE FOR MR. J. S. HANNAH, LAKE FOREST, ILL.
Shepley, Rutan & Coolidge, Architects, Chicago, Ill. For Location, See Vol. I, Page 74; for Exterior and Plans of House, See Vol. I, Pages 74 and 90.
Both pieces are ploughed to take a spline, and thus a very strong joint is formed which combines the advantages of the mitered joint and the rabbeted or splined joints. The spline in this case should be about 3/8 inch thick and about 1 1/8 inches wide and should, in all cases be of hard wood.