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292 THE BOY ELECTRICIAN

The bearings are made by driving two pins into a couple
of corks so that the pins cross each other as shown in the
upper right-hand corner of Figure 242.

They must not be at too sharp an angle, or when the ar-
mature is placed in position, the friction of the shaft will
be so great that it may not revolve.

The motor is assembled by placing the ’armature in the
bearings and then mounting two bar magnets on either
side of the armature. The magnets may be laid on small
blocks of wood and should be so close to the armature that
the latter just clears When it is spun around by hand.
The north pole of one magnet should be next to the
armature and the south pole of the other, opposite.

Connect two wires about one foot long and No. 26 B. & S.
gauge in diameter to a dry cell. Bare the ends of the wires
for about an inch and one half.

Take the ends of the two wires between the forefinger
and thumb and bend them out, so that when the armature
is revolved they can be made just to touch the ends of the
wire on the armature, or the “ commutator sections,” as
they are marked in the drawing.

Give the armature .a twist so as to start it spinning, and
hold the long wires in the hand so that they make contact
with the commutator as it revolves. '

Very light pressure should be used. If you press too
hard, you will prevent the armature from revolving, while, ‘
on the other hand, if you do not press hard enough, the
wires will not make good contact.

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