Page:Popular Science Monthly Volume 90.djvu/972

 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

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