Castings without Patterns
The sketch shows a method of making small castings that I have used for several years and the castings so produced are strong and very durable, almost equal to the ordinary casting. The idea may be of considerable value to inventors and home mechanics.
A Mold Made in Plaster without a Special Pattern and Run with a Soft Metal
A Mold Made in Plaster without a Special Pattern and Run with a Soft Metal
The mold is of plaster of Paris, held in a wood frame or box, and all that is required in the way of a pattern is a plain block or anything that will produce an impression of the general outline of the casting, as shown in the sketch. After the impression is made the mold should be dusted thoroughly with black lead. The journal bearings are then located, holes drilled in the hardened plaster and wood pins set as shown. These pins must be of hard wood and of a diameter to suit the finished size of the bore. Brass tubing of a suitable size is cut off to the length required and placed on the wood pins. These pieces of tubing will be the brass bushings in the finished castings. Babbitt metal is melted and poured into the mold. Before pouring the metal it is well to be sure that the plaster is thoroughly dry.
The mold is as shown, and the upper side of the metal is at all times exposed to the air. This makes it necessary to have all core prints on the under side, as this side will be the one in view when the casting is finished, and the upper side, as the casting lies in the mold, will be the inside or unexposed side. In case of curved work, reinforcing strips of sheet brass should be placed in the mold and imbedded in the casting, as shown in the sketch by the dotted lines.
A little practice will enable anyone to produce very neat cored castings. and when the brass bushings are fitted to size and faced off, and the casting painted, a piece will be produced thatwill compare in finish and general usefulness with anything of the nature that could be bought. Do not treat the brass tubes with soldering flux unless necessary, for they should be removable so that they can be replaced when worn.—Contributed by J. B. Murphy, Plainfield, N. J.