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I have this big hub motor i am having to repair. The magnets in it came loose. Upon closer inspection, it looks like they were never glued, or the spinning magnets ground away the surface. Some of the magnets got destroyed..I was able to find replacements. Luckily they are a common size.
anyway, i got all the magnets installed and mocked up..had to use a lot of spacers to get them all evenly spaced.
Now I need to find some sort of adhesive to bond the magnets.. these magnets are stupid strong. just a few of them on each side of my hand had some incredible force. I need something that can handle a wide range of temperatures. and bond with the metals Nickle and Iron
Any suggestions, I'm guessing some sort of epoxy..

The hub that the Magnets are in.
Is it a plastic, metal, or one of the newer carbon composites?

Reason I'm asking, is that getting a good bond with on some plastics can be nearly impossible.
Especially if it has aged, and is breaking down.


Signed: Janitor Tzap

this has an Iron core... nothing special

Just got this thing again..

Hard to say exactly but it seems like you have two paths at least. One is a semi flexible thick adhesive like gorilla glue or an epoxy suitable for both surfaces like JB weld or similar metal capable repair epoxy. Either should fil gaps, the flexible one might hold up to thermal stress better.

I use Loctite U-09FL, a urethane based epoxy. It has great adhesion and stays somewhat pliable. I bond the edges of aluminum discs to polypropylene, a notoriously difficult plastic to bond, with great success. My source is McMaster-Carr, and It comes in a twin tube cartridge, for the common hand squeezed application gun. Yes, it's in the high end cost bracket, but as the commercial said years ago " A Little Dab'll Do Ya!

Note: Loctite also has other products in the same urethane group, and a tech support staff that is quite helpful.

i sent out a few messages to a few adhesive companies and this one came back..

Loctite sez >>> We have a magnet bonding product that we would recommend in these situations, AA 331 Magnet Bonder adhesive. This is specifically designed to bond magnets and for motor assembly. It will not have any problems with the temperatures either.

And Permabond TA4246 65ML Kit.

I think I might like the Loctite better,, It's also used to bond huge magnets to speakers.. As a Kid I tried to separate them. the whole magnet and steel plates came off the speaker basket before the magnet separated from the steel plates. But, the stuff cost about 45$ a tube....No mix, just apply and let it cure...

Janitor Tzap >> It's all metal stuff. The rotor is iron core, the magnets are typical rare earth / neo types..
I contacted Loctite and they recommended Loctite 324 and 7387 Activator..
said that it is great for motors and speaker magnet assembly.. So I ordered it.. Supposed to be good for up to 300F.
I doubt that the motor will get that hot ever.
Anyone else ever repaired any Hub motors or BLDC types ?
Tech tip, Mind your fingers when reassembling, those motors like to slap together..

Sorry,

For some reason I was thinking of a 12Vdc or 24Vdc Muffin type Fan.

Yeah, the Locktite two part epoxy, should work.
I wonder if that's similar to the old Alum-Epoxy?
Haven't seen the stuff in many years now.


Signed: Janitor Tzap

I got things done, the stuff came in Saturday morning.. That was fast..
The stuff is not to mix, you apply the adhesive to the metal, and the activator to the magnets, Then stick em together..The adhesive is a thick amber looking goo. The activator is a clear liquid.
I thought i was in trouble, I was using the spacers i used to mock up the magnets..but when i got to the last magnet, I almost couldn't get the last one in..I had to really force it in, but it fits....
I hope to start reassembling it this week.. just gotta be super careful assembling it, those magnets will pull the rotor in very aggressively. Keep fingers clear!! I seen where someone used a big gear puller to slowly put them together.. I'll have to see if i have one large enough to do the job, Otherwise I might have to use hands and feet..lol Slow it as much as possible going together..
Stay tuned.

Well, I got things partially assembled this weekend..Had to use hands and feet to control / slow the motor slapping together,, It did not go good, Those magnets are stupid powerful. it yanked the rotor into the stater. all is well,, Since the motor was apart when i got it, I'm logically thinking i got the right end caps on the correct sides..I'll have to test fit the motor onto the vehicle to make sure, before i assemble any farther.. Stay tuned...

Well, Things didn't go so well with the motor. I got it all back together, only to discover that it doesn't run. it'll jump here and there, apon further troubleshooting, I discovered that the PO must have replaced all the magnets and got the wrong size, The magnets aren't long enough to trigger the hall sensors properly. So now I have to replace them all with wider magnets, If i can find them., I need 2" x 3/4 x 1/8.
Current magnets are N42 strength, I did find some that are N52 Strength, I've heard that things can be too strong as far as motors go..
Other fun part is now. I think I need to find a solvent now to remove the wrong sized magnets.. they were only 1.5" long.