dc permanent magnet motor repair

[jackpine]

The up-down motor on my lt-40 locked up and blew the breaker. With 3000 hrs on the mill I assumed the brushes were bad and bought a new brush kit. When I took it apart I found that one of the permanent magnets had come loose from the case.

How do you clean the inside of the case and the outside of the magnet and what type of adhesive shuld I use to re-attach the magnet? The brushes still have some life in them but think I will replace them anyway if I can re-attach the magnet

[rbarshaw]

Steel wool on the steel, scrape all the old glue off and get rid of any little pieces of metal that stick to the magnet, just keep wipeing it till all are off. For glue, any epoxy that will take heat without loosing its bond or softening. dont paint the metal or magnet first, this will give a poor glue bond. The orentation of the magnet is important, don't get it reversed.

[Magicman]

I would clean it good with carburetor cleaner as suggested above and use 24 hour type JBWeld.

[jackpine]

Thanks for the replies
I bought and installed a new motor because WM no longer lists this motor as a replacement part. The Wisconsin WM dealer had one in stock however.

My intention is to re-build the old one to keep as a spare for both the up-down and travel motor.

Bill

[bugdust]

If I recall WM sent a special tool to hold everyting in place while reassembling.

[r.man]

Jackpine, I had good luck a few years ago repairing an ATV permanent magnet starter using Five Minute epoxy. The repair was still holding the last I heard.

[octam1]

I know this is an old thread but does anyone have any suggestions on what you can use to remove a magnet that was epoxied back into a motor case upside down (with the wrong oreientation) in order for it to be glued back in the correct way?

Im not sure what kind of epoxy was used when they glued it back in but I can tell by looking at it and the dirt pattern on the magnet that they put it back in reversed so the motor wont do anything but humm a little bit...

[jason.weir]

maybe a small propane? torch - heat the epoxy up to the point it fails...  Be careful as you might loosed the adjacent magnets..

-J

[octam1]

I thought about heating it, but was affraid the excessive heat would kill the magnet... I'm trying to find out if there is a solvent that will disolve it, that is not impossible to find locally... but not having much luck as of yet...

Thanks, and any help anyone can offer would be great...

[Larry]

If it is quick set epoxy it won't take much heat to break the bond.  If 24 hour or JB Weld it will take a lot of heat.

No solvent that I know of will work.  It is subceptable to fracture.  You might give it a quick rap with a drive punch and see what happens.

[mad murdock]

during the process, prior to re-glue, if you want the cleanest surface possible go the auto-parts store or a good hardware store and get some Methyl-ethyl-ketone.  MEK is the best degreaser/cleaner out there, but be advised, use in a well ventilated area, as it is powerful cleaner, will clean your clock if you whiff too much of it.  We use it in aircraft maintenance for surface prep, and after applying it with a clean lint free rag or cloth, you will have nothing left on the surface but metal.  It will dissolve some plastics, so use nitrile gloves, and a good charcoal filtered respirator.  FWIW. 

[rbarshaw]

I have worked with several motors like you mention here and will say that if you use any kind of mechanical force it is very likely to fracture the magnet, I have not had any success with that route. Heat is the best choice, however excess heat will cause a loss of strength of the magnet and rapidly cooling it, ie; water, could fracture it also. Sorry I don't have much good news. If you can get a pry edge under it I would use heat and gentle pry pressure.

[36 coupe]

The glue that is used to hold the magnets in place is not waterproof.Tried to write waterproof in caps.Not a computer nerd just a farmer , mechanic and electronic service man.I dont care if some body writes in capital or not.Use epoxy to put the magnet back in place the same way it came out.My first pm motor I fixed was on a sprayer pump.You cant leave these motors out in the weather.New stuff is designed to self destruct.