It was stated in Pattern Making" that a gland could 1t moulded so as bo make its own core. This is illustrated by Fig. 23 as described in connection with Fig. 28. It may also be moulded with a vertical or a hori-Bontal core. When moulding with a vertical core the work of ramming the drag is done in precisely the same way as when the pattern made its own core as in Fig. 23. When the drag is core in position while the iron is being poured and is cooling. When the casting is removed from the sand the chaplets will be found imbedded in the iron. The projecting parts, which were imbedded in the sand of the mould are cut off" and the balance allowed to remain.
Chaplets are also made in the form of studs as shown in Fig. 48. When in this shape they simply rest upon the core or sand and are entirely imbedded in the metal of the casting. They are not adjustable. Each one is suited to a single thickness of metal. They are used where many castings of the same thickness are used. Where these thicknesses vary, the chaplet shown in Fig. 47 is usually the only one used.
The use of rusty chaplets should always be avoided. The hot metal striking the rust decomposes it. This forms a gas that suddenly expands and is likely to cause an explosion. The result may be the destruction of the mould. The force of such an explosion may be sufficient to be felt for a distance of from six to eight feet.
The forms of chaplets arc not confined to the two shapes shown in Figs. 47 and 48. They may be of a great variety suited to the particular place in which they are to be set. They all belong, however, to one of the two types illustrated, that is, those held by being partly pushed into the sand and those resting on the cores or mould.