Material. - The same pieces as before, after removing the pinned joint. Work. - To.lay out, cut, and fasten a stub-mortise joint.

Use the same methods and measurements in marking as in Exercise 11, except that the tenon is to be 7/8" long, and the mortise 1" deep, and 1" from the end of the piece. Fig. 1 represents the work laid out, the lines a, a, marked with try-square and knife, and the lines b, b, with the marking-gauge. After cutting the tenon, a very small chamfer, about 1/8", may be cut on its end without marking.

The holes bored by the center-bit should not be more than 1" deep. When a large number of holes are to be bored the same depth, a wooden stop is made by boring a hole through a block of wood, so that the stem of the bit will pass through it, but of proper thickness to prevent the tool cutting beyond the required amount.

In removing chips from the mortise, do not pry with the chisel on the sides and ends. In testing the mortise, hold the chisel against the side, and note whether it is square or inclined. The mortise and tenon should fit very snugly.

With the tenon in place, bore with a J" auger-bit a hole through the bottom of the mortise-piece, and into the middle of the tenon-piece about 3", as shown in Fig. 3. This is to receive an iron bolt. At 1 1/2" from the shoulder, and on the inside of the tenon-piece (a, Fig. 3), cut with chisels a hole large enough to receive the nut (b, Fig. 3) of the bolt. The head, d, of the bolt should have a washer, c, to prevent it crushing the wood. In some cases it is necessary to sink the head flush with the surface, as at a, Fig. 4.

The stub-mortise is extensively used in heavy machine-frames.

Fig. 5 shows a blind-mortise, used in making furniture. Sometimes the end of the tenon is spread with wedges, as at a, b, Fig. 6.

Fig. 7 shows a form of stub-mortise used in heavy railroad-trestles. The timbers are secured by iron straps spiked to the sides.

Fig. 8 is a form of joint used in trusses, the broken line a showing the shape of the tenon.

Ex. 13.

Fig. 1

Fig. 2

Fig. 3

Fig. 4

Fig. 5

Fig. 6

Fig. 7

Fig. 8