Page:Popular Science Monthly Volume 91.djvu/628

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��Popular Science Monthly

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��FIG. 9

��Entire details of all the parts necessary in the construction of a universal motor that is especially adapted to drive a fan on the ordinary vacuum cleaner used for household purposes

��7/16 in. in diameter, rough, to be turned as shown in Fig. 3. The threads may be cut in the lathe at the same time that the shaft is being turned. Now bore a %-m. hole through the center of the stack of 90 2 by 2-in. iron and then varnish the plates. When dry slip them on the shaft and clamp them between the two iron washers. Do not tighten the nuts too much or stripped threads will result. Now proceed to turn the armature to a diameter of 1% in. Be very careful not to feed the lathe tool too fast or it will cause the

��plates to turn on the shaft. Now lay out the eleven slots as shown in Fig. 4. The drilling should be done in a drill-press and the armature set in a jig so that the shaft will be parallel to the drill. Great care should be used to get the slots absolutely parallel to the shaft and accurately spaced. With a hack saw cut through the i/i6in. of metal on the diameter of the laminae and smooth up with a small file.

The shaft can now be finished to 34 m - in diameter. This should not be done earlier because it would twist out of shape

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