A mixture of 30 parts zinc to 70 parts aluminum gives a light and durable alloy for gage rods and caliper legs. The gage rods must be steel tipped for the alloy is soft and wears away too rapidly for gage points. James A. Pratt.
Howard, R. I.
A good alloy for casting pattern letters and figures and similar small parts in brass, iron or plaster molds is made of lead, 80 parts, and antimony, 20 parts. A better alloy would be lead, 70 parts; antimony and bismuth, each 15 parts. To insure perfect work the molds should be quite hot by placing them over a Bunsen burner. The writer has had thousands of pattern letters and figures made in this manner. Oscar E. Perrigo.
An anti-friction metal of most excellent quality and one that I have used with success for a bearing on an internal grinding shaft, which was 5-16 inch diameter, 7 inches long, and 5 inches in the bearing, and run at a speed of 36,000 R. P. M. is made as follows: 17 parts zinc, 1 part copper, 1½ part antimony; prepared in the following way: Melt the copper in a small crucible, then add the antimony and lastly the zinc, care being taken not to burn the zinc. Burning can be prevented by allowing the copper and antimony to cool slightly before adding the zinc. This metal is preferably cast into the shape desired and is not used as a lining metal because it requires too great a heat to pour. It machines nicely and takes a fine polish on bearing surfaces. It has the appearance of aluminum when finished. Use a lubricating oil made from any good grade of machine oil to which 3 parts of kerosene have been added. Herrmann G. Kroeger.