Making a Practical Vacuum Cleaner 



I. — Details in the construction of the universal motor 

 By L. E. Swindell 



THE machine described is not a difficult 

 piece of apparatus to construct, and 

 it will do the work equally as well 

 as a standard make. However, building 

 it yourself will not reduce the cost to any 

 appreciable degree. The only thing gained 

 will be the satisfaction of saying "I made 

 it myself." The essential parts are a high, 

 speed electric motor to drive the centrif- 

 ugal fan, and a suitable case with a shoe 

 or nozzle to collect the dust from the floor 

 and discharge it into a cloth bag which 

 retains the dust and releases the air. 



The following materials are necessary 

 in the construction of the vacuum cleaner. 



Materials for the Motor 



90 pieces transformer iron 0.015 in - thick, 3^ 



in. sq. 

 90 pieces transformer iron 0.015 ln - thick, 2 in. sq. 



1 shaft, cold rolled steel Y% in. diameter and 



7% in. long 



2 bolts x /i in. diameter and 4 in. long, threaded 



1 % in. on each end 

 2 hardwood blocks 3^ by 3^ by 1 in. 



1 piece iron h /% by 7 by Ys in. 



2 iron washers 1 Yz in. diameter, %-'m. hole 

 2 8-32 brass screws 1 in. long 



2 pieces brass tubing Y\ by Y\ by % in. (inside 



measure) 

 4 fiber washers % in. square, J^-in. hole, 1/16 in. 



thick 

 1 commutator, 22 segments 

 Yl lb. No. 26 gage enameled magnet wire 

 % lb. No. 29 gage enameled magnet wire. 



Materials for the Shoe 



Enough sheet iron 1-16 in. thick 

 15 soft iron rivets }/$ by % in. 



6 8-32 brass screws Y in. long 



I cylinder of brass 1Y3 in. long by Y% in. diameter 

 J^-in. hole 



1 piece of fiber 1 in. thick 2 by 2 in. square 



2 pieces iron % by Y% by 14 in. 



1 hardwood handle 3Y2 ft. long, iYs in. diameter 



If you can secure a fan motor of suitable 

 size you will save yourself considerable 

 time and labor. For the benefit of those 

 who cannot obtain a motor, or who wish 

 to build their own, the necessary directions 

 will be given for the construction. If a 

 motor cannot be procured some machine 

 work on a lathe and drill-press must be 

 done. 



The Motor 



The motor is of the alternating current 

 series type, wound for use on no- volt 

 circuits. It may also be used on direct 

 current. The field for use on direct current 

 could be of solid iron, but for alternating 

 current it must be laminated because of 

 eddy-currents and excessive heating. 



The dimensions of the field magnet 

 are given in Fig. 1. A stack of transformer 

 iron 2>)/2 m - square and \Yi in. thick should 

 be clamped between two hardwood blocks 

 by means of the two 4-in. bolts as shown 

 in Fig. 2. Now proceed to turn the mass 

 of iron and wooden blocks to a diameter 

 of 3/<£in. Use a high speed and a very 

 sharp tool, cutting toward the lathe chuck. 

 The center should be turned out to a 

 diameter of 1 9/16 in. The wooden blocks 

 should now be removed and the pole 

 pieces machined. This is the most difficult 

 for the amateur to do. If the directions 

 are followed and a little patience used, a 

 neat job will result. If a row of holes are 

 drilled between the pole pieces just inside 

 the 2 J/2 m - diameter, the remaining ma- 

 terial can be easily removed with a sharp 

 cold chisel and finished with a round file, 

 The laminae can now be taken apart and 

 each varnished with black insulating var- 

 nish. When dry, reassemble the laminae 

 and proceed to wind the field. 



Each pole is surrounded by a coil of 

 200 turns of No. 26-gage enameled magnet 

 wire thoroughly insulated from the iron 

 by empire cloth. The wire should be 

 wound on by hand so that it will occupy 

 as little space as possible. The field poles 

 should be thoroughly insulated by means 

 of strips of empire cloth wound tightly 

 around them and then varnished. The 

 leads should be brought out and the coils 

 connected in series; i.e., the end of one coil 

 should be connected with the beginning 

 of the other. The two free ends should be 

 brought out and protected from injury, 

 and the finished field set aside while the 

 armature is built. 



The armature is of the usual drum type, 

 with eleven drilled slots to receive the 

 windings. The shaft is of cold rolled steel, 



611 



