To Make A Pin (). Select a piece of straight-grained material, in this case 4" or 5" long, and, by use of the chisel, reduce it in section to a square whose side is slightly greater than the diameter of the hole it is to fit. Then take off the corners, making it an octagon in section, and point one end. All this will be best accomplished if the piece is held by the bench-hook, as indicated by Fig. 194.

Fig. 194

168. Drawboring is a term applied to a method of locating pin holes so as to make the pin draw the tenon into the mortise. Fig. 195 shows the relative position of the holes before the pin is inserted. It is evident that a tight-fitting pin will have a tendency to make the holes in the mortise and tenon coincide, and thus draw the two pieces together. The holes may be located on the mortise and tenon by direct measurement; or the cheeks of the mortise may be bored through and the tenon inserted, and marked by putting the bit into the hole already bored and forcing its point against the tenon. The tenon may then be withdrawn and bored, the point of the bit being placed a little nearer the shoulder of the tenon than the mark.

Fig. 195

Fig. 196

Scale, 3"= l' plan Face A.

Elevation Face B.

End.

The practice of drawboring is not to be commended, and, if indulged in at all, great care and discretion must be exercised. In many cases, it puts a strain on the joint which is nearly equal to its maximum resistance, and but little strength is left to do the work for which the joint is made. Frequently, the mortise or tenon is split and rendered practically useless.

Exercise No. 10.

Keyed Mortise-and-Tenon Joint (240-245).

The stock required is 1 5/8" X 1 5/8" X 16", from Exercise No. 4; it is shown with the necessary lining by Fig. 196. The finished piece is represented by Fig. 197.

169. The lining differs from that of the preceding exercise in the following respects: the position of the line b is changed as indicated by the dimension figures, and the position of lines e and f, which extend around the piece, is changed to correspond; the mortise is made longer on face B than on face D, giving one oblique end, as indicated by the dotted line i, face A.

Fig. l97 Scale, 3"=l'

Plan.

Elevation.

As regards the tenon, the line g is added at a distance from d equal to the thickness of the piece on the line b, face A; the point h is located on face A, and on the opposite face C, and the line gh drawn on both faces. The mortise r' is to be cut as in the preceding exercise, and one end made oblique as indicated by the figure.

To form the tenon the portions marked r are to be removed. First, beginning at g, cut along the oblique line gh; then, beginning at k, the two lines kj; and, finally, define the shoulders of the tenon by cutting on the line d. This order will save all the lines as long as they are needed.

170. A study of the finished piece will show that the tenon is inserted from the face D, and pushed over so that the splayed edge of the tenon, gh, bears on the splayed end of the mortise, i, leaving an open space at the other end of the mortise to be filled by the key. See Fig. 197.

The key should be planed from a piece 5" or 6" long. It should be uniform in width and nearly so in thickness, there being but a slight taper near the end which is to be driven in advance; this end should be pointed like a tenon. It is best to drive the key from the inside in the direction indicated by the arrow, Fig. 197.

The piece is to be finished in accordance with the appearance and dimensions shown by Fig. 197.

Exercise No. 11. - Plain Dovetail.

The stock required is two pieces, each 7/8" X 3 3/4" X 4", edges jointed parallel, and one end squared. (The material may be worked up as one piece 7/8" X 3 3/4" X 8", which, after being planed to width, may be cut in two with the back-saw, thus giving the squared ends required.) The working-faces used in preparing the material may also be used in laying off the lines. To avoid confusion one piece will be called X and the other Y. Fig. 198 shows the lining necessary for X and Y respectively. The finished joint is shown by Fig. 199.

171. Lay off on all four faces of each piece, 7/8" from the squared end, the line ab, Fig. 198. Fasten X in the vise, and on its squared end lay off lines as gh, Fig. 198. Remove the piece from the vise, and with the bevel set "1 to 4" (29), project on the faces A and C oblique lines as ef. The portions which are to be removed to form the mortises, are marked r. Put the piece in the vise again, and with the back-saw cut down the oblique lines as ef. With a chisel, used as in cutting an ordinary mortise, remove the material between the lines. If preferred, part of it can be removed by boring a hole as indicated by the dotted outline. The hole will make the chiseling easier, but in so small a piece of work it is doubtful whether there is anything gained. The piece X having been finished, fasten Y in the vise, working-end up and working-face outward. Place the working-face of X on the working-end of Y, as shown by Fig. 200, taking care that the line ab on X is in the same line with the working-face of Y. Holding the work in this position, and guided by the mortises in X, scribe on the end of Y the oblique lines as gh, Fig. 198. Remove Y from the vise, and with the beam of the square on the working-end, project to ab lines as ef from the extremities of the oblique lines just made. The portions marked r and r' are to be removed to form the "pins." Those on the outside marked r' may be removed entirely with the saw; those on the inside (r), partly with the chisel, as in the case of the mortises in the piece X.