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Repulsion motor armature and stator cleaning?

Adam Kelker

Plastic
Joined
Jul 27, 2009
Location
Bentonville Arkansas
Hoping I'm in the right forum here. I guess this applies to alot of motors.


I have a couple Delta R.I. motors apart and the necklace springs on the way (and believe me, that was hard to find). Bearings from Accurate tomorrow.

The problem with the motors was that they would not start with force on the shafts. Upon further inspection, the spring to the necklace assemblies were stretched. As well, the motor shop guy that looked at these threw in the towel and showed me the wire on one of the armatures that came loose. I have re-soldered the wire, re-insulated the winding and was looking into cleaning the stator and armature. This prick gave me one motor back in pieces and I still have to go back to see if he still has a cover plate and bearing. I'm livid:angry::angry: I'm on my own.

The black rotor has also been turned to the point that it may not have another left so this will probably be it's last repair.

Here lies the confusion. I have asked motor shops and people that have worked on motors what is up with cleaning these. No one gives a straight answer or complete if any in regards to the armature and stator.




Are these coated with something?
How do you clean these if they have rust or over-spray from insulating?
Can you spray insulating varnish on them if these were previously cleaned wrong?
I think I read somewhere about not using anything electrical or metal or abrasive or something and stay out of the laminations but I don't really understand this so I was hoping the big mystery could be unraveled.
If these were previously cleaned wrong, can you just solvent wipe and insulate with red varnish to fix?

I also had (still have) Chinese bench grinder that I cleaned the rust off and now it smokes so I'm sure I did something wrong. My thought is that many motors could be saved if this subject was clarified.

I have searched for this and have found nothing.
I'm hoping to get the answers here and save me and future lookers from ruining their motors. Thankyou.:typing:

I know we all like pictures so here you go:
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Motors

I would lightly sand the commutator(with sandpaper), install new binding cord, and clean the slots between the bars. The next step is to have the armature checked on a "growler" with the necklace removed to see if it is shorted. You have already soldered the broken wire connection the one bar. Check the direction on the rotating brush carrier where it is held on the end bell to insure it is fully moved to the end of its travel. This determines the direction of rotation. If it is in the middle the motor will not start.

JRW
 
I would lightly sand the commutator(with sandpaper), install new binding cord, and clean the slots between the bars. The next step is to have the armature checked on a "growler" with the necklace removed to see if it is shorted. You have already soldered the broken wire connection the one bar. Check the direction on the rotating brush carrier where it is held on the end bell to insure it is fully moved to the end of its travel. This determines the direction of rotation. If it is in the middle the motor will not start.

JRW

I'm not sure what you mean by binding cord. I also noticed that the stator has some spots where the varnish may have rubbed off but it really looks like the stator wires (that hang out the end in bundles) may be just plain wire and the film I see is a residue. The motor shop guy had it on a bench and banged it around I think. It doesn't look to be varnish. I'm wondering how critical the stator needing varnish is. It looks like the are so close together that they would rub against and short out anyways. ???????????

It also looks like he may have taken the brushes out and just put them back in however. It will be a guessing game as to orientation. I'm thinking I will have to put a piece of sand paper under the comutator and turn to reseat the brushes properly and then use an armature stick to finish.
 
Wires

Adam
The wires that connect to the commutator are bound with a heavy lacing cord to prevent centrifugal force from pulling the wire out of the solder joint. The bare wires at the ends of the 'bundles' (Coil groups) evidently have the varnished scraped off and should be re-coated with an insulation varnish such as "Glyptal" Ordinary urethane varnish works fine in low voltage motors. Your motor shop should have an internal 'growler' to check the coil groups for shorted windings.

There is an excellent electric motor repair book from the past by the name "Electric Motor Repair" by 'Rosenberg and Hand'

JRW
 
Adam
The wires that connect to the commutator are bound with a heavy lacing cord to prevent centrifugal force from pulling the wire out of the solder joint. The bare wires at the ends of the 'bundles' (Coil groups) evidently have the varnished scraped off and should be re-coated with an insulation varnish such as "Glyptal" Ordinary urethane varnish works fine in low voltage motors. Your motor shop should have an internal 'growler' to check the coil groups for shorted windings.

There is an excellent electric motor repair book from the past by the name "Electric Motor Repair" by 'Rosenberg and Hand'

JRW

Looks like that is gone too. I need that book. I can't believe that that motor would have not had that lace. Any idea how to replace the lace? I don't have the book yet. (yet!)
 
Wrap

To wrap the wires, lay down a short section of cord, folded so a loop is on one side. Then wrap several turns of cord tightly around the wires close to the commutator. When you have a wrap layer similar to the other armature, pull the loose end under the wrap layer with the first section of cord. It does not hurt to tie a knot using the ends. Cut off the long ends and apply the sealing varnish.

JRW
 
Look carefully at your commutators. Any bars that show evidence of brush arcing are likely to have broken or poorly soldered leads. I would clean old motors like this very carefully, as the insulation is likely to be fragile. There are aerosol sprays for the purpose, but I have used kerosene and mineral spirits. You do not want to use anything that might soften the varnish, such as acetone or lacquer thinner. If you can't find a regular motor varnish, I have used shellac or epoxy to coat the windings. Do wind some string around the windings next to the commutator on the red armature, and seal it up with something.

It would be much better if an experienced motor repairman would do the work for you but it is understandable that they often refuse such work.
 
For cleaning the last .001" of muck of the commutator, I use a glass fibre scratch brush (over here £4). Then clean out between the copper sections with a hacksaw blade with its teeth ground off, then finally run the scratch brush down the gap to clean out any debris.
The brushes, if looking at the ends they seem to be an even colour, put a small chamfer on the leading (or both!) edges, so they will ride up and down over irregularities in the diameter of the copper sections. Use a bit of 200 grade "wet'n dry" carborundum paper (as used for car bodies) under each brush in turn just to produce a small quantity of dust. Blow out dust.
As for your "missing" binding, difficult to know what to do, tightening bits of string around 50 year old bits of wire sounds like dicing with death. What you really want is an epoxy paint (1 fluid ounce?) to daube onto the winding as you rotate the armature. I think the standard glue will be too thick to penetrate the wires very far without poking it with a stick and risking more damage. There also is the question of out of balance weight. I wonder if super glue would work?
Frank
 
Based on the condition of the armature, what approach would you take on general cleanup?

Century, 2HP, single phase, SEP 1942.

Thank you



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