*The Commutator Core* is formed by cutting a strip of paper five-sixteenths of an inch wide and about five inches long. It should be given a coat of shellac on one side and allowed to get sticky. The strip is then wrapped around the shaft until its diameter is three-sixteenths of an inch. *The Base* is cut from any ordinary piece of wood and is in the form of a block about two by one and one-half by one-half inch. [Illustration: Fig. 248.—The Complete Motor.] *Assembling the Motor.* The parts must be carefully prepared for winding by covering with paper. Cut a strip of paper one-half inch wide and one and one-eighth of an inch long and give it a coat of shellac on one side. As soon as it becomes sticky, wrap it around the top bar of the field magnet. The armature is insulated in exactly the same way, taking care that the paper covers the entire flat portion. The field and armature are now ready for winding. It is necessary to take proper precautions to prevent the first turn from slipping out of place. This is accomplished by looping a small piece of tape or cord over it. The next two turns are then taken over the ends of the loop so as to embed them. Wind on three layers of wire and when in the middle of the fourth layer embed the ends of another loop, which may be used at the end of the fourth layer to fasten the end so that it will not unwind. After the winding is finished, give it a coat of shellac. The winding of the armature is somewhat more difficult. The wire used for winding both the armature and the field should be No. 25 or No. 26 B. & S. gauge double-cotton-covered. In order to wind the armature, cut off about five feet of wire and double it back to find the center. Then place the wire diagonally across the center of the armature so that there is an equal length on both sides. Place a piece of paper under the wire at the crossing point to insulate it. Then, using one end of the wire, wind four layers on half of the armature. Tie the end down with a piece of thread and wind on the other half. The ends of the wire are cut and scraped to form the commutator segments. Figure 246 shows how this is done. Bend the wires as shown so that they will fit closely to the paper core. Bind them tightly into position with some silk thread. Use care so that the two wires do not touch each other. Cut the free ends of the wires off close to the core. When finished, the relative positions of the armature and the commutator should be as shown in Figure 248. The brushes are made by flattening a piece of wire by a few light hammer blows. The brushes are fastened under a small clamp formed by a strip of tin held down at each end with a wood screw. They can be adjusted to the best advantage only under actual working conditions when the current is passing through the motor. One or two dry cells should be sufficient to operate the motor. [Illustration: Fig. 249.—Details of the Motor.]