Fig. 251. A piece of wood is to be chamfered on the edges, and at one end the chamfer is to be stopped with an inclined face, and at the other with a curve, making a segment of a circle.

This exercise, though it appears easy, is really too difficult to be attempted earlier in the course.

The sketches of the finished exercise need only be made, as shown in fig. 251. The wood required is a piece of deal or bass-wood about 1 ft. long and 1 1/2 in. square; any piece of waste wood will do, however.

With a thumb-gauge and pencil draw lines on face and edge 3/8 in. from the angle, and. at one end make two straight lines at 45° to these lines to make the mitred end of the chamfer, and at the other end sketch a curve on each face to guide in making the curved end of the chamfer. Notice, that, though the chamfer itself is to make a quarter of a circle, the lines on the edges are not nearly such marked curves.

To find the precise line involves an interesting problem of solid geometry : but this is unnecessary, and the eye can be relied upon to aid in making a sufficiently satisfactory curve.

Commence chamfering by roughly removing the waste, holding the chisel as in fig. 252. In doing this, it will be found in which direction the cutting is the easier, and, when the chamfering is nearly done, including the ends, make one steady shearing cut the entire length of the chamfer, holding the chisel obliquely with the face downwards, as in fig. 252, and finish the mitred end, as in fig. 253, the face of the chisel again being downwards.

The operator in this case is resting the left fore-arm on- the bench, to assist in steadying the chisel, and the cut made should make a good clean intersection with the face of the chamfer and then cease. On no account cut too deeply. To complete the curved end the chisel is turned over so that the back is downwards, and this, too, is finished with one cut, the handle being gradually depressed to make the cutting follow the line of curve.

Fig. 251.

Fig. 252.

Fig. 253.

The difficulty here is to make the curve run uninterruptedly into the level portion of the chamfer. Fig. 251 shows this end being finished, but here the operator is resting his left fore-arm on the bench screw to steady the cutting.

Fig. 254.

The curved end may be finished with glass-paper, but the level portion and the mitred end should on no account be touched after the chisel has done its work.