the paper from the armature ring and see that the armature revolves freely in the bearings without touching the inside of the field at any point.  The supports are then removed and the solder turned up in a lathe, or otherwise finished.  The shaft of the armature, Fig. 4, is turned up from machine steel, leaving the finish of the bearings until the armature is completed and fastened to the shaft.

The armature core is made up as

[Illustration:  The Assembled Bearing Frame on the Field Core and the Armature Shaft Made of Machine Steel]

follows:  Two pieces of wrought sheet iron, 1/8 in. thick, are cut out a little larger than called for by the dimensions given in Fig. 5, to allow for finishing to size.  These are used for the outside plates and enough pieces of No. 24 gauge sheet iron to fill up the part between until the whole is over 3/4 in. thick are cut like the pattern.  After the pieces are cut out, clamp them together and drill six 1/8-in. holes through them for rivets.  Rivet them together, and anneal the whole piece by placing it in a fire and heating the metal to a cherry red, then allowing it to cool in the ashes.  When annealed, bore out the inside to 1-11/16 in. in diameter and fit in a brass spider, which is made as follows:  Procure a piece of brass, 3/4 in. thick, and turn it up to the size shown and file out the metal between the arms.  Slip the spider on the armature shaft and secure it solidly with the setscrew so that the shaft will not turn in the spider when truing up the armature core.  File grooves or slots in the armature ring so that it will fit on the arms of the spider.  Be sure to have the inside of the armature core run true.  When this is accomplished, solder the arms of the spider to the metal of the armature core.  The shaft with the core is then put in a lathe and the outside turned off to the proper size.  The sides are also faced off and finished.  Make the core 3/4 in. thick.  Remove the core from the lathe and file out slots 1/4 in. deep and 7/16 in. wide.

The commutator is turned from a piece of brass pipe, 3/4 in. inside diameter, as shown in Fig. 6; The piece is placed on a mandrel and turned to 3/4 in. in length and both ends chamfered to an angle of 60 deg.  Divide the surface into 12 equal parts, or segments.  Find the centers of each segment at one end, then drill a 1/8-in. hole and tap it for a pin.  The pins are made of brass, threaded, turned into place and the ends turned in a lathe to an outside diameter of 1-1/4 in.  Make a slit with a small saw blade in the end of each pin for the ends of the wires coming from the commutator coils.  Saw the ring into the 12 parts on the lines between the pins.

The two insulating ends for holding these segments are made of fiber turned to fit the bore of the brass tubing, as shown in Fig. 7.  Procure 12 strips of mica, the same thickness as the width of the saw cut made between the segments, and use them as a filler and insulation between the commutator