Two small washers, serving as collars to bear against the inside of the bearings and keep the armature in the field should be soldered to the shaft as shown in Figure 13.
The Base is cut from any ordinary piece of wood and should be in the form of a rectangular block about two and one-half inches by one and seven-eighths inches wide, and one-half inch thick.
The completed motor is shown in Figure 24. Be sure that the armature does not scrape against the field at any point but clears it by about one-sixteenth of an inch all around. The brushes are fastened under a small clamp made from a strip of tin held down at each end by a small wood screw. The brushes are made by flattening the end of a piece of copper wire with a few light hammer blows. The brushes can be best adjusted under actual working conditions when the current is passing through the motor.
One end of the field winding is connected to the brush marked "C," in Figure 24. The other brush, "A" and the other end of the field winding, "B," form the terminals to which the battery is connected. This forms what is known as a series connected motor, because the armature and the field are in series and the current must pass from one to the other.
FIG. 24.—The completed Three-pole Motor.
After you have finished assembling the motor, put a drop of oil on the bearings, make certain that the brushes are properly adjusted, connect the battery, and your motor is ready to run. One or two dry cells should furnish sufficient current to run the motor at high speed.
HOW TO MAKE THE SIMPLEX OVERTYPE MOTOR.
The method of construction which has been outlined in making the two Simplex motors, just described, also lends itself to the construction of many other simple and interesting forms of motors.
Figure 25 shows a form of motor which is essentially the same as that shown in Figure 24 except that the field has been turned upside down and the armature is at the top of the motor instead of the bottom.