Click
for
larger image. |
While a junior in mechanical engineering at
The University of Tennessee, and doing watch repair part time in my
trailer village home, I decided to design and build a miniature
electric motor—just for the fun of it. Because of school work, it
required several months to find the time for the project. However,
it was finally completed in about nine months. The shunt wound,
universal type motor is handmade using watchmaking tools. It is
mounted on a 5/8-inch long, black plastic base and has ruby watch
jewels for the rotor bearings. The armature uses metal from a nail
and the stator is from drill rod. Its construction was delayed for
quite some time until I finally located enamel wire small enough for
the windings at the Westinghouse Corp. The wire is about the
diameter of the human hair. The most difficult problem during the
motor construction was the fabrication of the commutator. To
demonstrate its ability to run, two short, sharpened wires were
soldered to the terminals of a flashlight C cell. The distance
between these was adjusted so the two input terminals riveted
through the motor base could be set down on the sharpened ends of
the wires. From input current measurements, the motor was calculated
to consume slightly over 1/1,000,000 horsepower. Such a motor would
not be very unusual in today’s world. However, 57 years ago it was
considered quite extraordinary. And I had great fun building and
demonstrating it. It has remained in a little metal box in my
watchmaker’s bench all the years since it was built.
|
