956 



Popular Science Monthly 



2-11/16 in. in diameter. A 

 can do this on a circle cutting 



A into disks 



tinsmith 



machine in a few minutes. Care should be 



taken not to bend these disks. 



The 3-in. aluminum disks B, 11 of which 

 can be used, should now be clamped 

 between the two 3-in. brass disks C, all 

 edges lying 

 flush, and a 

 17/64-in. hole 

 drilled through 

 the exact center 

 of the entire 

 pile. If held in 

 a vise care 

 should be taken 

 not to bend the 

 disks by using 

 too much pres- 

 sure, also if pos- 

 sible the jaws of 

 the vise should 

 be lined up par- 

 allel to each 

 other, to pre- 

 vent uneven 



pressure. 

 In case 



The types of disks 

 and washers to be 

 placed on machine screw 



the 

 experimenter 

 desires to make his own disks from the 

 aluminum sheets, it will be found a simple 

 matter to saw out all the 3-in. disks at once, 

 by clamping the squares between the two 

 3-in. brass plates mentioned, and following 

 the outline of them with a hack-saw. When 

 this has been done all of the disks can be 

 put in shape with a file. 



After the center holes have been drilled in 

 the 3-in. disks, and while they are still 

 clamped between the brass disks, 6 holes 

 3/8 ii^' in diameter should be drilled as near 

 to the edge of the disks as possible. These 

 can be equally spaced around the cir- 

 cumference. 



The smaller aluminum disks are now to 

 be clamped between the 3-in. disks of brass, 

 in such a manner that the centers of all lie 

 in a straight line. While held in this 

 position a 17/64-in. hole should be drilled 

 through these aluminum plates, using the 

 holes in the brass disks as guides. 



Now through the entire set of plates just 

 mentioned, four 3^-in. holes must be made 

 equidistant from each other, with their 

 centers 5/16 in. from the center of the 

 17/64-in. hole in the middle of these plates 

 as shown at A. All burrs around these 

 holes must be removed with a flat file, 

 when the disks are separated. 



Next, the cardboard sheets, mentioned 

 under the list of materials, should be cut 

 into 3 in. squares and drilled through the 

 center with a 17/64-in. drill as shown at D. 

 They should then be clamped between the 

 smaller aluminum disks, say 5 disks on each 

 side, and held together by one of the large 

 machine screws mentioned, which can be 

 passed through the holes in the center of 

 the aluminum and cardboard. By sawing 

 around the outside of the aluminum disks 

 with a hack-saw, all of the cardboard 

 squares can be sawed into disks 2^ in. in 

 diameter at one time. 



As soon as the above steps have been 

 taken, 24 of the cardboard circles should be 

 made into washers by sawing out the 

 centers to form a round hole ^ in. in 

 diameter. This can be accomplished with 

 a coping saw in a very short time. 



When the work mentioned above is 

 completed, the 3-in. aluminum disks B 

 should be clamped between most of the 

 cardboard washers, about 10 to a side, in 

 such a manner that the centers of the 

 washers and the disks line up throughout. 

 By starting from the center hole with a 

 coping saw, as in the case of the cardboard 

 washers, the centers of the large aluminum 

 disks can be sawed out to the same extent 

 as the cardboard washers. 



If the instructions so far have been 

 adhered to, 4 sets of plates and washers 

 should be the result as illustrated. The 6 

 cardboard disks with the 17/64-in. holes 

 are not shown in the drawing. All the 

 rough edges and burrs should be removed 

 from all parts with a flat file, due care being 

 taken not to bend the metal pieces. 



All of the small aluminum disks when 



The apF>earance of each of the two halves 

 after being cut in two with a hack-saw 



completed should be perfectly flat across 

 the surface when tested with a straight edge 

 in several directions. The best and easiest 

 way to straighten the plates which are 

 warped, is to heat each one separately over 

 a blue flame for a few seconds, taking care 



