# Help with AF 336 and 326 large motor rewind



## oldflyernut (Feb 17, 2016)

Have acquired two AF steam locomotives (336 and 326) both with large motors. The field coils and armatures need rewired. Is there specific wire gauge (believe 18 AWG for field and 22 AWG for armature) and length and turns of wire for rewind of each? Any references on how to do this? The armatures have small gaps so winding will be tricky. Already tried twice but unsuccessful as armature shorted out to shaft. Thanks!


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## AmFlyer (Mar 16, 2012)

Yes, there is a reference book published in 2001 by Robert A Hannon. There were two versions of the super armature, both use 50 turns of#25 wire wound counterclockwise. The super field uses between 140 and 150 turns of 22 gauge wire.


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## flyernut (Oct 31, 2010)

Super armatures should use 3 9 foot sections of #24 wire.
Super fields should use 30 feet of #22 wire...Both items use enameled wire.


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## AmFlyer (Mar 16, 2012)

The resistance range specified in the manual is .8 to 1.0 ohms for each of the three armature windings and for the field winding. It would be easy to check the resistance of the length of wire prior to starting the rewinding process.
The manual states the armature uses 25 gauge wire, but it does not provide a reference source. For example did the author get that from the factory procurement spec or did they use a micrometer on an existing field winding to estimate the wire gauge. 24 gauge is far more common than 25.


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## oldflyernut (Feb 17, 2016)

If the tables I referenced are correct, the following resistance applies for #22, #24, and #25 copper wire:

AWG Resistance Ohms/1000 ft 
#22 16.14
#24 25.67
#25 32.37

To achieve 1 ohm of resistance the required length of wire would be 62 ft for #22, 39 ft for #24, and 31 ft for #25. Thus, if it appears #25 wire should be used. Does this make sense?


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## AmFlyer (Mar 16, 2012)

The manual I reference has only the number of turns, it does not give the length of the wire. One reason for this is the factory machine wound the motor parts and the wire was stretched during the winding process. Eyeballing the super armature it looks like each turn would take about 2" of wire, times 50 turns is 100". Darn close to the 9' Flyernut posted.
Measuring between any two commutator poles uses 18' of wire, so the armature wire should have a cold DC resistance of .05 ohms/foot to be between .8 and 1.0 ohms.


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