While standard dimensions of the cylindrical core prints are not universally used, many large corporations operating pattern shops and foundries have adopted a standard, and the economy of this practice should recommend it to all. Most foundries will keep on hand cylindrical dry-sand cores, whether the cores are made in wood or in metal core boxes or with the core machine.
The value of the fixed taper and length to the cope core print is most apparent. This form can then be made at one end of the core box, and the machine-made cores can be ground to a fixed angle by having a guide table fitted to the emery-wheel stand. A foundry equipped in this manner can always fit a pair of prints to the pattern and be sure that the cope end of the vertically set cores will fit the print mold. It will also save the pattern maker the expense of turning a pair of prints every time their use is required. A pattern shop, having a dozen pattern makers employed, will get a dozen different forms to the cylindrical core prints if no standard is followed, and much time will be used in the foundry filing cores to fit.
Fig. 184. Proportions of Staudard Core Print.
If you know where the pattern is to be sent, better find out if the foundry has a standard for their stock cylindrical cores, and build your core prints to conform to it.
There need be no standard length for the prints of a horizontally set core, for in this case the print should be long enough to give a seating sufficient to hold the core from either settling or rising. The upward strain of a core during pouring will be greater than the downward strain due to its own weight.
Dry-sand cores are usually kept in stock from 1-inch up, by eighths, viz, 1-inch, 1 1/8-inch, 1 1/4-inch, etc. All core prints used on patterns considered here will use prints dimensioned according to Fig. 1S4, unless they require a change in size due to extreme length and weight of the core, or to some special process of molding.