Material

Maple, 3 3/4" x 3 3/4" x 5".

Exercise

-To turn a sphere 3 1/2" in diameter.

Care must be taken in the preliminary steps to have the dimensions as given.

Turn the material to the form and dimensions shown in Fig. 98, and with a pencil mark the lines shown - one in the centre first, and the other two at the same distance on each side of it. Next, cut the material to the form shown in Fig. 99, using the outer lines and the corners at the stem as guides. Find the centre of each of the sloping faces, and then mark on all three faces the lines shown in Fig.

99. Next, cut the stem on which the work is revolving to a diameter of 11/16 inch, as shown in Fig. 100, and using the corner where the stem joins the body and the lines on the faces as guides, cut the work to the form shown in Fig. 100. Use the skew chisel as a scraping tool, as in Fig. 77, and dress off the corners, making the work to be as nearly spherical as possible, as shown in Fig. 101, taking care to leave the centre of each face untouched. Next, cut off the stems on which the work revolved, keeping the spherical form at the ends.

Fig. 98.

Fig. 99.

Fig. 100.

Fig. 101.

Prepare a chuck of the form shown in Fig. 102, and fit it to the ball, as shown. The ball may be held in place by putting a small piece of thick leather against the outermost end and bringing the cone-centre into contact with the leather. The ball may be pressed into closer contact with the chuck by advancing the cone-centre.

Fig. 102.

Place the ball with its axis in nearly the same position it had while it was revolving between the centres, and remove the eccentric portions with the skew chisel, used as a scraping tool; then change the position of the ball in the chuck by a small amount and again scrape off the eccentric places, and so continue until the ball is a true sphere.

Varnish and polish it before removing it from the chuck.