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(ET) ET motor magnet re-glueing



To all with unglued magnets,

I don't know why so many of us think an unglued magnet means you should scrap the motor shell.  If you check the archives you'll find a posting I made describing how I have successfully re-glued magnets on two different permag motors, admittedly not Elec-Trak motors.  Maybe I should start a business doing this, but then again, I suspect the success rate would be on the order of 70 to 90%.  I'm pretty sure I wouldn't want to deal with the unhappy owners of the 10 to 30% of failed re-gluing attempts.

You've got nothing to lose, so why not try it.  Below I've copied the text from my old 2004 posting describing my method.

Steve Naugler

I have had that (magnets coming unglued) happen on two DC motors in the past, although neither were 
for the Elec-Trak.  One had a broken magnet which I fixed by gluing the magnet pieces as close together as possible. (The other
had an unbroken but loose magnet.)

I was able to repair both of those motors with epoxy. I used the normal cure high strength like you can find in Home Depot, but do not use the 5 minute stuff. It cures faster at the expense of lower strength. I VERY, VERY thoroughly cleaned the motor shell and the magnet with solvent, smeared the epoxy on, and placed the magnet back in its original postion. This may take some doing because sometimes the magnets will fight you. You need enough epoxy to leave no gaps between the magnet and the shell, but as little as possible so that the magnet is as close to the shell as possible. You will want to clamp the magnets in position for a two reasons. 1. The first is that once glued you can't get the magnet off. You need to get the right position the first time. 2. The second is that you actually want extra epoxy to be squeezed out. It is important that the magnets are as close to the shell as possible. Use a spring clamp so that clamping force is maintained as the magnets move closer to the shell. Now wait for the epoxy to cure hard, at least overnight. The clamps can come off and they stay off. Think you're done? Nope. This epoxy will be highly stressed, so I recommend a post cure. What I did was place the shell on one of those electric oil filled radiators set on low, covered the shell with a box making a mini oven, and let it stay there for 24 hours. The shell reached about 150 to 160 degrees and stayed there for the entire time. You can also use a kitchen oven if your spouse or significant other will let you. (Mine didn't, hence the radiator style heater.) Use two cookie trays, one on the lower rack, and one on the upper rack, Place the motor shell on the upper tray. The lower tray protects the motor shell from radiant heat which could get the shell too hot. Set the oven to warm, and "bake" for 12-24 hours. Bill Gunn had bad luck with fixing magnets, so he wouldn't do it at all after a few failed attempts. But in Bill's case a 25% failure rate would have been intolerable. In our cases, if the option is trashing the motor shell, I'd go for it. Steve Naugler