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 



TTfT 



m 



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. 



^ 



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. 



