Build a simple machine to ease the pain of winding coils. Posted here is Part 1 which shows you how to build the coil winder. Part 2 (which I don't have) is building the speed control. Just borrow your wife's sewing machine foot control instead.
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Electrical Coil-winding Machine Here is a coil winder that features a variable speed control, automatic counter and can be built inexpensively By HAROLD P. STRAND Craft Print Project No. 265 Part 1 U NLESS you have a metal-turning lathe, or some similar machine capable of holding and turning a coil-winding form at a slow speed, winding a coil having hundreds of turns on it can be quite a chore. To answer the need for such a machine for those of you interested in making home-built electrical devices requiring coils for special size transformers, solenoids, etc., the electric-motor driven winder shown in Fig. 1 has been developed. The winder is powered with a used Hoover vacuum-cleaner motor purchased at a repair shop for $5. It is of the ac-dc or universal type which is subject to speed control with a variable resist- ance or reactor and is of a large heavy-duty type. The foot controlled reactor (Fig. 1), for which building plans will be included in Part 2 of this article, has an infinite number of speed control steps, will not heat up in use, wasting power, and has no wip- ing contacts of the type usually employed with a resistance control. When purchasing the vacuum-cleaner motor, turn it on and observe the commutator. There should not be apprecia- ble arcing at the brushes which could indicate a short in the armature winding. Failure to run at its customary high speed is another indica- tion of defective arma- ture windings. However, worn carbon brushes could also produce these effects, so check the FEBRUARY, 1957 Variable speed, foot-control switch regulates speed of motor when winding coil. Photo A shows how mag- net wire is hand guided from spool to coil windings. length of the brushes— they should be at least 7/16 in. long. Alsb check the armature-shaft bear- ings for wear. Remove the motor from the clean- er and attempt to move the fan and shaft from side to side. Any side movement indicates worn bearings. A little end play, in and out movement of the shaft, is permissible, however. Select a motor having a 187
Transcript
Electrical Coil-winding MachineHere is a coil winder that features a variable speedcontrol, automatic counter and can be built inexpensively
By HAROLD P. STRAND
Craft Print Project No. 265
Part 1
UNLESS you have a metal-turning lathe, orsome similar machine capable of holdingand turning a coil-winding form at a slow
speed, winding a coil having hundreds of turnson it can be quite a chore. To answer the needfor such a machine for those of you interested inmaking home-built electrical devices requiringcoils for special size transformers, solenoids, etc.,the electric-motor driven winder shown in Fig.1 has been developed.
The winder is powered with a used Hoovervacuum-cleaner motor purchased at a repair shopfor $5. It is of the ac-dc or universal type whichis subject to speed control with a variable resist-ance or reactor and is of a large heavy-dutytype. The foot controlled reactor (Fig. 1), forwhich building plans will be included in Part 2of this article, has an infinite number of speedcontrol steps, will notheat up in use, wastingpower, and has no wip-ing contacts of the typeusually employed with aresistance control.
When purchasing thevacuum-cleaner motor,turn it on and observethe commutator. Thereshould not be apprecia-ble arcing at the brusheswhich could indicate ashort in the a r m a t u r ewinding. Failure to runat its customary highspeed is another indica-tion of defective arma-ture windings. However,worn carbon brushescould also produce theseeffects, so check the
FEBRUARY, 1957
Variable speed, foot-controlswitch regulates speed ofmotor when winding coil.Photo A shows how mag-net wire is hand guidedfrom spool to coil windings.
length of the brushes—they should be at least7/16 in. long. Alsb checkthe armature-shaft bear-ings for wear. Removethe motor from the clean-er and attempt to movethe fan and shaft fromside to side. Any sidemovement indicatesworn bearings. A littleend play, in and outmovement of the shaft, ispermissible, however .Select a motor having a
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Left, Cleaning disassembled motor with rag moistened in kerosene. Right, Clean commutator with fine sandpaperto inspect it ior grooves or ridges.
A 150-watt lamp is connected in series with motor toreduce its speed when test running.
3/8 in. dia. shaft on it.After purchasing a motor in the best possible
condition, take it apart and clean with keroseneor carbon-tet. First remove the brush holders andbrushes from their supports on the insulated ring.Then remove the two screws at the ring of theoutside bearing cap, disassemble the motor as inFig. 2. When cleaning, do not immerse the woundparts in cleaning fluid, merely wipe them off witha cloth dampened with the cleaning fluid or brushoff the dirt if it is dry and loose. Clean the arma-ture commutator with fine sandpaper as in Fig.3. If ridges or grooves appear on the commutatorafter cleaning, have it turned down in a lathe andlightly sand smooth. Then clean out any depositsbetween the segments, which might cause shorts,by scraping with a thin but sharp tool. A quicktest for shorts or grounded wiring in the arma-ture can be made by having it tested on a growlerat your local automotive generator repair shop.If it is found that new armature-shaft bearingsare needed, they can best be installed at avacuum-cleaner repair shop while you have themotor apart. At this time also saw off the % in.armature shaft so that it will project only 1 in.beyond the outside edge of the bearing when as-
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sembled. Be sure to apply a drop or two of lightmachine oil on the bearings when assembling themotor and install new brushes if the old ones areworn down to under 7/16 in. in length. Since thesemotors operate in a clockwise direction, whenfacing the shaft, change the direction of rotationby interchanging the two brush leads. Later,after testing the motor, adjust the insulated brushring so that the brushes will be located at a point
SCIENCE AND MECHANICS
where the speed and torque of themotor will be at maximum. Thesemotors were also designed to op-erate in a vertical position andhave a drilled shaft and wick tosupply oil to the lower bearing.To operate in a horizontal posi-tion, drill a 1/16-in. hole at the topside of the extended end of thebearing so that oil can be applieddirectly to this bearing. After re-assembling the motor, test run itwith a 150 watt lamp connected inseries as in Fig. 4 so that the mo-tor will ope ra t e at a r e d u c e dspeed. Check the commutationand let the brushes run in to agood fit.
Make the motor bracket (Fig.5A) and fasten to the motor flangewith three bolts. To make theslotted holes used to fasten thebracket to the base, drill threeVi-in. holes side by side and fileto a slot by hand or with the filingmachine (Fig. 6) described in theHome Electrical Handbook Vol. 3.Since it is difficult to purchase a1-1/2 in. dia. V-belt pulley with a3/8in. bore, a 1/2 ODx3/8 ID bushing is placed inthe 1/2 in. hole of the pulley. Drill through thebushing so that the pulley setscrew can be tight-ened down against the motor shaft.
Make the base (Fig. 5B) next by gluing twopieces of 3/4 plywood together to form a 1-1/2in. thick piece. Have a 1/16 in. thick piece of sheetsteel cut to the exact size of the plywood base atyour local sheet-metal shop and fasten to the basewith six #6x1 in. fh screws countersunk flushwith the steel base top. Dress the edges of thesteel top with a sanding disc and slightly roundthe top corners with a file. Then lay out and drillthe holes for the motor bracket and spool support.To finish the base, give it two coats of gray painton the edges and bottom of the plywood and at-tach four 3/4 in. dia. rubber headed tacks to theunderside at the corners for feet.
After purchasing the counter, (see Materials
List for source of supply) make the counter sup-port bracket (Fig. 5C). Since the counter mustrotate at a one-to-one ratio with the polishing-head shaft, a pulley having the exact same di-ameter as the small pulley on the polishing-head(Fig. 7) must be made for the counter shaft. Ifyou have a metal-turning lathe this becomes afairly simple matter. Make the pulley for a round,rubber vacuum cleaner belt. Drill and tap thepulley for a 6-32 set-screw to fasten it to thecounter shaft. If you do not have a metal turn-ing lathe, purchase the two 1-1/2-in. pulleys seenin Materials List. Bore one to 1/2 in. for polishinghead and bush the other to suit counter shaft.A chain and sprocket drive (Fig. 6) which costsabout $5 for parts, would assure accuracy.
The winder parts can now be assembled to thebase for testing. Loosen the set-screw in thesmall pulley of the polishing head, slide the
FEBRUARY, 1957 189
Left, Alternate drive design using chain and sprocket assures positive accuracy in counting number of turns.Right, Making accuracy check of counter by turning polishing head shaft by hand a counted number of times.
A cotterpin retains spool and spring which appliesbraking action on spool to prevent spinning.
threaded shaft and slip the vacuum cleaner belton the small pulley. Reassemble the shaft andplace a 6 in. dia. V-belt pulley on the end of theshaft having the left-hand threads. Bolt the mo-tor to the base first. Then, with the V-belt on themotor and polishing head pulleys pulled taut andin line with each other, mark the base for thepolishing head mounting bolts, drill and fastenthe head to the base. Locate and mount thecounter on the base in the same way.
To check the counter drive for accuracy, mounta hand-tight drill chuck on the polishing-headspindle and grip a piece of wire bent to the shape
of a handle in the chuck jaws as in Fig. 7. Thenmark the chuck or 6 in. pulley with a spot ofpaint or crayon so that the number of revolutionscan be counted as the crank is turned. Set thecounter at zero, turn the crank exactly 10 timesand note the number of turns registered on thecounter. If there is much of a difference in pulleydiameters it will show up on the counter as overor under 10 turns. If the error in pulley diameteris only very slight, the counter will probablyregister accurately over so few turns. However,since even a slight error will be cumulative,it is well to try a hundred or more turns of thecrank if 10 turns show up accurate. If the figureson the counter are less than the number turnedby hand, it indicates the pulley on the counteris larger than the pulley on the polishing head.If the figures are more than the number turnedby hand, the pulley on the counter is smallerthan the polishing head pulley. You can reducethe diameter of either pulley by putting it ina lathe and turning the bottom of the pulleygroove down. It is also possible to place a turnof narrow friction tape at the bottom of thepulley grooves to make the size correction.
After testing the counter and making the cor-rections if needed, make the holder for the mag-net-wire spool as detailed in Fig. 5D. Fasten theholder to the base with two bolts and using nutsas in Fig. 8. If various width spools of wire areto be used, make the bar longer and drill severalholes spaced to suit the spools. Allow space forthe washers and spring compressed enough tosupply some braking action on the spool so thatwhen the winding is stopped, the spool will notspin around and tangle the wire.
Part 2 appearing in the next issue (on saleFebruary 28) will describe the construction of thevariable speed, foot control switch.
