Fig. 32 shows a small plunger, the pattern for which is shown in Fig. 33. We will use a vertical core with this pattern, therefore A will be the top surface of the pattern, the arrow indicating the direction in which the pattern is withdrawn from the mold.

Fig. 32. Small Plunger.

Fig. 33, Pattern for Small Plunger.

The pattern may be turned from a solid block 3 3/4| in. square and 1 5/8 in. thick, or may be made from two pieces, as shown in the sectioned right end view of Fig. 33. A hole 1 in. in diameter and | in. in length is to be cored out, and also a hollow chamber 1 1/2 in. in diameter and 1/4 in. in length at the end of this hole. Fig. 32 shows the hollow chamber at B and also the hole which is to be threaded after the casting: is made.

Fig. 34 shows the necessary core print for this pattern, and is placed as shown at C, Fig. 33. Only one core print is needed, as the core hole does not extend way through the casting.

No special directions should be necessary for turning this pattern if proper care is taken in turning the fillet at D, Fig. 33, and the necessary allowance for shrinkage and finish are made.

The half core box for this pattern is shown in Fig. 34, A. This is an isometric drawing and clearly shows the various parts of the core box. A and D are the end pieces. B is made first from a clear pine block large enough to finish 1 7/8 in

Fig. 34. Core Print for Plunger.

long, 2 1/4 in. wide and 1 1/2 in. thick. The ends of the block must be accurately squared so that with pieces A and C perfect joints may be formed. The piece Chad better be made from a stick 2 1/4 in. long, 1 1/2 in. wide and 1/4 in. thick. The grain of this piece will then be at right angles to the centre line of the core box and there will be no danger of the block splitting when it is nailed to B. This piece is cut to the outline of the hollow chamber B, Fig. 32, and therefore all surfaces must be made absolutely smooth and especial care taken in finishing the core box so that no core sand will adhere to this part of the core box when the cores are made. Both B and C of the core box should be carefully tested before being glued up.

Fig. 34A. Half Core Box for Plunger.

The ends are then to be fastened on and the core box finished as usual. The piece B must be made exactly the right length, otherwise the hollow chamber will not come at the required place in the casting.