In molding patterns made as above, the molder will require a lifting plate. The lifting plate is anchored to the top of the cope block and will lift the center of the mold without any liability of its dropping.
The patterns for this lifting plate can be made as follows: From a piece of stock 3/4 inch thick, band saw six pieces, as shown in Fig. 179, making them about 3/4 inch smaller all around than the space between the two adjoining arms and the inside of the rim. Chamfer one edge all around so as to leave the vertical edge about 1/4 inch thick. Band saw six pieces from 1 3/8-inch stock to the proportions shown in Fig. 180, and reduce the thickness at one end so as to form a draft. These pieces are drawn from the mold endwise, and the casting appears as shown in Fig. 181. Three circular pieces of stock 1 1/2 inches in diameter by 1 inch thick are furnished to form bosses, which are tapped for a 5/8-inch or 3/4-inch rod.
Fig. 180. Lifting Plate Arm.
Fig. 181. Assembled lifting Plate for Six-Arm Pulley.
An ordinary rule is to make the outside diameter of the hub twice the diameter of the shaft. The two half hubs - one on each side of the arms - are usually loose and are held central by a single dowel pin. Their diameters are adapted to the size of the shaft upon which the pulley is to run, and the length is proportioned to the width of the rim as well as its diameter. The length of the hub should be about two-thirds the width of the rim, except in the cases of tight and loose pulleys, where the hub should be a trifle longer than the width of the rim, and it may then project about 1/3 inch on the sides in contact, and 1/4 inch on the outside.