Fig. 2782.
“Let it be required to cast a pillow block to contain a babbitt-metal bearing. In this case there requires to be a cavity to receive and hold the babbitt metal. This is provided by casting ridges of metal around the edges of the bearing, as shown in [Fig. 2781], at d e and on each side at f, the pieces d e may be made solid with the pattern, but those for the sides must be removable, having dovetails as at c c to hold them in position while being moulded, or in place of the dovetails, wires as at f f may be employed, in either case the pattern would be extracted from the mould, leaving the side strips to be removed afterwards. If, instead of a pillow block, a bracket or frame, such as in [Fig. 2782], were required, it must be moulded in the direction of the arrow, and in that event it would be desirable to core out the journal bearing. This would be accomplished by providing a core print to block up the whole opening b. A suitable core box for the bearing would be as in [Fig. 2783]. The core print must project below the casting so as to form in the mould a core print for the core, and it is obvious that the core itself must be made of increased depth to the amount allowed for core print; hence the end piece b, [Fig. 2783], is increased in thickness to the amount allowed for core print.”
Fig. 2783.
Patterns for cylindrical bodies, especially those that are hollow and thin, are constructed in pieces by a process termed “building up.” The pieces are usually segments of circles, and the manner of marking them is as follows:—
Fig. 2784.