It is a rare occurrence for long castings to leave the molds perfectly true and level. When cooling off in the sand, they often buckle out of shape. It is necessary, as in the case of drainage cover castings, for instance, to have them level, so that when the horses and vehicles oass over them, they will not tilt or shake. These castings are usually straightened In the blacksmith's shop in the following manner:

Take, for example, a grating like that shown here, which is used by street railways to allow the surface water to drain into the sewers, and which has to fit very snugly the recess of the trap box in which it lies. The casting is placed in the fire, and heated to a dark cherry red, when it is taken out and placed upon the anvil upside down. Two blocks of iron, about the size of a half brick, are placed at either end of the casting, and a section of car rail the length of the casting is placed on top. A couple of clamps are slipped over the rail and casting, in the center or where the buckling of the casting appears. The bolts of the clamps are then screwed up, at the same time using the wrenches with a quick turn, until the hollowness of the grating is about one-eighth of an inch more than necessary, which is tried by means of a straight edge. When the clamps are removed, the hollowness will be gone, and the casting will be found to be perfectly level.

Fig. 158 - Straightening buckled castings.