66 PATTERN-MAKING i< I I of buckets. The supplementary open spaces are equivalent to the extra length allowed on cores to enter print impressions. But in this case the cores are simply set to lines described on a levelled bed of sand, and, mutually abutting by their supplementary portions, they complete the ring. Plain, rectangular boxes are rammed on a core bench. A bottom board is necessary when bosses and other fittings have to be located correctly. The sides fit this with dowels or with strips on the board. Often one or Fig. 24.óCore Box with Strickle for Curved Portions two faces of a core are curved. Then, when practicable, strickling is resorted to (fig. 24), as it is also for the upper plane faces of cores. This economy in curved portions is that due to the saving of timber and of the time occupied in shaping it to the curves. CHAPTER II Examples of Work Pattern-making includes many departments. The work done on patterns for a brass foundry is wholly different from that done on patterns for the heavier castings of the marine engine, the locomotive, and the larger types of pumps, while the making of core boxes for gas and automobile cylinders calls for special ingenuity and skill. The construction of patterns for cranes, gear wheels, pipes, and columns, each enlists the services of men who have developed into specialists. In every large shop certain groups of patterns go to men who seldom handle anything else. But a trained, intelligent man is, or should be, able to take up any branch of his trade when required to do so. The principles that underlie the practice are unchangeable. It is from this chiefly, the general standpoint, that the subject will be regarded in this section.