(ET) Magnets gone bad....

[Chris Zach <cz alembic crystel com>]

It's been a year for magnets. In the spring one of my older fat mower 
motors had a magnet drop out, the symptom is the motor keeps tripping 
the overload switch on top and runs a bit slower and is a bit harder to 
turn than the other motors. Opened it up, magnet had dropped and broken 
into 3 pieces. Put it aside for the summer, used another motor.

Today I was mowing and heard another motor drop out. Sure enough it was 
warm, turned with a bit more difficulty. Took the tractor in, took the 
armature out, yep magnet had cracked and a part had broken off.

Problem is this was one of the "new" motors I had bought a number of 
years ago so I know its history and it's not been run that long. That's 
not good, as it could mean that the glue from the factory is starting to 
let go or the factory people did a crap job of gluing the magnets in.

Regardless I went back to the first motor and started working. I have 3 
pieces of plywood cut so that two of them can slide between the magnets 
on the side to press them against the wall and a third is driven between 
them to space them against the motor walls. I coat them with JB Weld, 
put them in with the spacers, let it dry for 24 hours. That seems to 
re-secure them, well when they are intact...

This one. Sucked. I cleaned off the 3 parts using my bench wire wheel, 
cleaned out the inside of the shell with a drill wire wheel, and coated 
everything with JB Weld. Then the clock was on, I had about 10 minutes 
before it set and getting the 3 (now 4 as the middle one broke as well) 
into the shell turned out to be a nightmare. Finally got all the parts 
in (they push against each other, the wall, and of course are attracted 
to the BIG MAGNET on the other side), we will see if the glue holds as 
it was being smeared everywhere. Still JB is good stuff, so we'll see.

Tomorrow I'll use the jigs on the new motor and glue its part back on. 
Fortunately it only had a part break off and the rest of the magnet is 
intact, but it's still bothering me about the glue. With that done I 
should be able to get back underway.

Never dull. Is anyone else having magnet failure, so far I have repaired 
4 fat motors and two magnets on the leaf vacuum motor (which uses 4 
magnets, two had come off)

C