Page:Popular Science Monthly Volume 90.djvu/953

 Popular Science Monthly

��937

��Rigid Joints for Making Models in Thin Sheet Metal

IN making some small models in tin I used the joint illustrated for connecting the parts, which is original as far as I know. The joint as in- „___J ,^ J~l

��dicated is a rigid one and lends itself well to tin, soft sheet iron, sheet brass or sheet copper. It can be used in manv places

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��A simple joint for any soft sheet metal

��arts and crafts works. In the illustration the part marked A is superimposed on B, the two tabs on A are bent backward, while the four tabs lie almost flat, then they are squeezed together tightly with pliers or lightly hammered. — R. S. Melvin.

��Making a Valve-Grinder of an Old File

WHERE there is no grinding outfit at hand a substitute can be readily made from a piece of old mill-file, as shown in the illustration. The file is annealed and a piece cut from it large enough to cover the valve-seat ; then it is drilled cen- trally and tapped. Into this tapped hole is pro- vided a threaded rod with a squared end, having a locknut to hold it firmly in place. The piece of file is then tempered and used as a cutter on the valve- seat by turning with a brace or breast drill.

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��The file cutters true up valve- seats quickly

��Preventing a Tire from Sticking to the Vulcanizer Mold

THE sticking of tires to the mold after vulcanization has always been a great source of annoyance to repairmen. The best applications heretofore used as pos- sible preventatives have been unsatisfac- tory in some respects. Therefore the dis- covery by a repairman of the availability of a material which overcomes this trouble will be welcomed by vulcanizers. Since the discovery is so simple, the wonder is that no one has reported it before. The substance used is nothing more nor less than cocoa butter and is applied as follows :

��Clean the mold thoroughly with fine emery paper. Then after allowing it to warm up a little, go over it with a piece of cheese-cloth saturated with the cocoa butter. Next wipe till glassy and apply soapstone. This method of preparing the mold has been tried and found to work perfectly.

��Dividing Line into Odd Spaces with Ordinary Rule

ROUGH shop sketching for showing minor operations does not, of course, need to meet the accurate standards of the work sent down from the drafting rooms. However, at times such sketches must be to some sort of a scale, accomplished with any tools available for the purpose.

The sketch shows a very practical way of dividing a line of given length into a certain number of parts without a regular scale for the purpose. Suppose a 2-in. line on the center of a bolt is to be divided and spaced off into 17 equal parts. The two ends of the threaded portion are laid off to 2 in. and parallel lines are drawn to the left. A standard scale is laid between the two lines in such a manner as to cover exactly 17 equal divisions on it. In this case it would be 8ths or 2^^ in. These are marked off to the right and carried over with the T-square or its substitute

���Spacing odd dividing lines for the threads of a bolt with the use of a rule

to the 2-in. center line of the bolt. The same results could be secured with a pair of small dividers, taking only the first space marked off by the rule or the line A-B, then spacing it with the points on the 2-in. center line. The above principle can be applied to many other shop propositions, where rather primitive methods must secure fairly accurate results. — F. VV. Bentley.

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