Brushless outrunner - broken magnet

[docrob]

I have a Welgard brushless outrunner A28/14/06 that I had installed in my Depron Mig-21. The plane suffered an unfortunate maiden flight crash and the motor seems to have suffered in the bargain.

The motor can was dented slightly, the shaft was bent and on opening the motor it was seen that one of the magnets inside the can was chipped. A buddy of mine machined a new shaft for me and the motor spins smoothly around the new shaft. At upto half throttle the motor seems to behave itself but in the half to full throttle range, the motor seems to miss and heats up real quick.

I'm wondering if:
1. this magnet can be replaced
2. replacing the magnet will solve the problem
3. the motor can be salvaged at all?

Anyone?

Thanks in advance, Bob.

Doc

[Rajesh L G]

Oh no, that beatiful mig-21 :eek:

Replacing magnet should help. The tricky part is that the magnet should be matched well with the other ones in there.

If you have spare magnets and hall sensors from old cdrom drives, you can rig up a meter for measuring relative magnet strengths. Check DIY electronics group for details. Better to place the magnet in the bell and take reading because the metal backing can affect it.

You can always replace all magnets with new ones if you can't get a match.

-- Regards, Rajesh

[docrob]

Thanks, Rajesh, appreciate your help. Yes :( that beautiful Mig 21. It sure looked good for the 10 seconds it was in the air.

Doc

[docrob]

And here's (http://www.delhirc.com/migfinal.wmv) the video that caused it. Rt. click and save as.....

Doc

[rvincent]

Wow Doc that's a shame. The shaft is easy, the dent really is no big deal either, the magnet though............................................ .......................... that could be tough to match? Can you measure it and let me know the length, height, and thickness? I looks very simular to a couple motors I have laying around that MAY match it?

[docrob]

I can send you the whole can if you want, Bob.

Doc

[docrob]

I tried, and since I don't have a calliper, getting precise measurements is impossible.

Doc

[rvincent]

Yeah do that :) Send me the whole kit and kaboodle and I'll see what I can with it :)

[docrob]

OK, Bob, you got it. I'll send you a PM when it's on it's way, in the meantime, could you please send me your postal address, where I need to ship it?

Thanks a lot, really appreciate your help.

Doc

[kapilsinghi123]

Hello Everybody

I am an Electronics Engg and presentely working on Brushles motors

I have taken a CD rom motor and to increase its power i have opened it rewound it and want to replace its week magnets with the strong magnets

But not able to find the strong magnets in India

Can anybody tell from whare in India can i get these strong magnets ???

Thanks

[claytonbing]

Is there an equivalent motor shaft that I could buy at my LHS to replace my bent Welgard shaft? The only place I have found replacement shafts was on BPhobbies, and they are sold out. Also, how do you remove the shaft. I loosened the two hex nuts up top and I remove the clip and washer from the backside. Now what? It won't come out still. The whole casing will slide around a little bit, but the shaft is still solidly in place?

[docrob]

Do you have the same motor, the A28/14/06 ?

Not too sure if you can get replacement shafts at LHSs, I got mine machined by a friend. If you have the same motor, I can send you some spare shafts.

Remember, these are REALLY strong magnets, you'll need a lot of force to pull the motor out of the can, and make sure you keep your fingers out of the way, the motor tends to snap back in the can pretty good and can pinch some skin on the way :eek: . My buddy, Ravi, found that to his cost when he was trying to pry the two apart.

Doc

[claytonbing]

I got my original prop shaft bent back correctly...I had tried and tried by just using pliers on the end of the shaft, but while I got it back close, I still could not get it perfect...then I realized, well hey, if it got bent so easily with the prop on, maybe the best way would be to bend it back with the prop on. So I reattached the prop/prop adaptor, and that gave me the right leverage and with some tinkering I now have it back perfect.

Doesn't fix your magnet problem, but hopefully helps some!