Society for Amateur Scientists Beginner's Corner | |||
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Beginner's
Corner LITTLE ways of doing common operations, devised and used by different workers, are extremely numerous; scarcely any two do a job alike, in fact. Ed. C. Rizzo, R.F.D. 1, Cold Spring, Ky., tells how me makes laps. In a wooden mold 1" wide, 24" long and 1/4" deep, lined with wax paper, he pours melted pitch, lets it cool, removes it, peels the paper off and, in a warm room, cuts the strip into 1" squares. Each of the four sides of each square is then cut with a reentrant curve, the result being a prepared facet, shaped like a four-pointed star. These are attached to the warmed tool with turps. The object of the star-shaped facets is that, after cold-pressing and swelling out, such a shape becomes a square; while a square, as commonly used, tends to become a circle. (Whether a lap made of squares is superior to one made of circles is a separate question.) To make a pitch lap free from bubble holes, Edward Lenard, 4854 N. Austin Ave., Chicago, heats the pitch in a double boiler, stirring it often; then removes the inner receptacle and holds it 6" above a low flame until the pitch is thin enough to pour redially, stirrong all the while. |