Rewinding an Armature
Courtesy of Carl Blum
For the folks with failing armatures in their vintage locomotive, consider
rewinding them. The enamel covered wire is inexpensive and the work is just a
little tedious. I had a little Lionel diesel switcher
burn up so I took the motor apart and rewound the armature. Here are the steps:
1) Make notes of the route the wire takes from where they start at the commentator.
2) Fine the coil that is on top and was wound last and clip one end loose. Count the turns as you unwind it. Repeat with the remaining coils. Most of the motors we have are three pole, but there are some four and five pole motors out there. Your hands may get dirty from the burned enamel, remember "that" smell. Also you may find a break in the wire, just keep a record of the turns.
3) Check the diameter of the wire with Calipers or a Micrometer so you can order replacement wire. If you are really cheap you could unwind an old transformer with the same size wire, but that is a load of work and you run a risk of scraping the enamel off.
4) Check any insulators that were under the wire. You might want to touch them up with enamel, I use nail polish.
5) Now reverse the winding process. Start where you took the last winding off and wind the new wire on. You can do this by hand, but help is nice. I used my Unimat Lathe driven by the motor from my Erector Set. I also rigged a mechanical counter to the spindle to count the turns for me. As you finish each winding solder it to the commentator.
6) When all the coils are finished it is a nice touch to coat the windings with more enamel, some companies soak their coils, this locks the wines in place and keeps them from buzzing from the magnetic field changes.
7) Reassemble your motor, put it back in the locomotive and give it a go!
Good Luck. Carl.