Repairing small universal motor - dipping?
Repairing small universal motor - dipping?
(OP)
Hi all, I wanted to know if anyone could help me repair a small universal motor. The motor itself isn't expensive, however, the manufacturer is not in this hemisphere and shipping would be ridiculous! I have unwound the failed field coil and am preparing to order some magnet wire. The coil itself was pretty well stuck to itself, but not to the paper separating it from the shell. I am assuming that they used some kind of clear polyurethane or varnish. Can anyone help me find a suitable product that would not require baking? I dont think my wife would approve of our only oven being used for that purpose :p The motor is a 110vac, 15a.
Thanks in advance!
Thanks in advance!





RE: Repairing small universal motor - dipping?
Al.
RE: Repairing small universal motor - dipping?
Bill
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"Why not the best?"
Jimmy Carter
RE: Repairing small universal motor - dipping?
RE: Repairing small universal motor - dipping?
What would be my method of rewinding? Use magnet wire that is already coated, wind the motor then spray this on or spray every few wraps? Something else?
Thanks!
RE: Repairing small universal motor - dipping?
Forgive me if you are already aware of the fact but its vital to wind the coil with a wire/wires of the same diameter and with the same number of turns as the original. The second coil will also have been stressed and it would be a good idea to rewind it at the same time using the same former or process to ensure the two coils are, as near as possible identical and have similar volumes and resistances.
RE: Repairing small universal motor - dipping?
RE: Repairing small universal motor - dipping?
Bill
--------------------
"Why not the best?"
Jimmy Carter
RE: Repairing small universal motor - dipping?
RE: Repairing small universal motor - dipping?
Bill
--------------------
"Why not the best?"
Jimmy Carter
RE: Repairing small universal motor - dipping?
I have heard of folks using regular polyurethane finish and drying it in layers with a heat lamp (wind a few layers, brush the poly on and dry) . The spray-on Krylon enamel should be a much quicker drying product and may not need the heat lamp.
I wound a similar motor in a circular saw once just for the experience of doing it. Did not dip or bake and it lasted several years of intermittent use before one of the ends came loose from the brush connection and I threw it away like I should have done at first. The local electric motor shop measured the wire for me, and I believe he got me some that was larger than original. The winding was really tight to fit in the space, but the saw ran fine.
RE: Repairing small universal motor - dipping?
I think they are generally oil-impregnated sintered bronze: the sintered metal behaves like a honeycomb which stores oil, which then wicks to the bearing surface. Google 'Oilite' for a bit more info.
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If we learn from our mistakes I'm getting a great education!
RE: Repairing small universal motor - dipping?
The point I was trying to make was the failure mode when the clearance became excessive.
Bill
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"Why not the best?"
Jimmy Carter
RE: Repairing small universal motor - dipping?
RE: Repairing small universal motor - dipping?
Agreed! Usually accompanied by a horrible noise if the driven load is a fan.
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If we learn from our mistakes I'm getting a great education!