How to separate magnet from shaft? - RC-Monster Forums

littlegiant · **How to separate magnet from shaft? -** 06.07.2009, 11:21 PM

I have this KB45 motor but I kinda screwed up the output shaft a little after grinding it down from 6 to 5mm diameter. The output shaft is sort of tapered now so pinions move around abit.

I intend to make a new motor shaft but how do I remove the magnet from the shaft? I've tried using acetone, freezing and hammering, twisting but they don't seem to work.

I wouldn't want to try using heat for fear of demagnetizing the rotor magnet.

Anyone has any good idea to go about doing this correctly?

What's_nitro? · 06.07.2009, 11:27 PM

Quote:

Originally Posted by littlegiant

I wouldn't want to try using heat for fear of demagnetizing the rotor magnet.

I would not have tried hammering for fear of dismembering the rotor magnet!!!

I recommend buying a new rotor. With any luck you can find a used motor to pull one out of for cheap money.

lincpimp · 06.07.2009, 11:28 PM

What size is it? I have both a l can and xl can motor for sale.

littlegiant · 06.07.2009, 11:32 PM

Quote:

Originally Posted by lincpimp

What size is it? I have both a l can and xl can motor for sale.

Oh. It will be the kb45L cans. Gimme a price. :D

florianz · 06.08.2009, 03:51 AM

I had the same problem, tried to get a 5mm shaft myself... well, of course it didn't work. then I wrapped the magnet with paper and ductape, and went to a company who are doing cnc-stuff and had it done there.

littlegiant · 06.08.2009, 04:10 AM

Quote:

Originally Posted by florianz

I had the same problem, tried to get a 5mm shaft myself... well, of course it didn't work. then I wrapped the magnet with paper and ductape, and went to a company who are doing cnc-stuff and had it done there.

u mean the company separated the magnet from the shaft and put in a new one?

Or did they just grind down the shaft output portion from 6 to 5mm?

florianz · 06.08.2009, 04:33 AM

Quote:

Originally Posted by littlegiant

u mean the company separated the magnet from the shaft and put in a new one?

Or did they just grind down the shaft output portion from 6 to 5mm?

sorry... they grinded it down to 5mm. depending how cool the guys are they do it for a few bucks. in my case it was a bit difficult for them, cos the results of "my work" didn't make it easier for them...

I don't think that you can seperate the magnet from the shaft without destroying it. on the other hand, I had some loose rotors and glued them to the shaft.

littlegiant · 04:49 AM

Oh and by the way i just had to say this. Kb45 owners shouldn't be worrying about the rotor magnet debonding from the shaft at all. The damn magnet just could not be seperated from the shaft no matter what I tried.

scarletboa · 06.08.2009, 12:26 PM

Quote:

Originally Posted by littlegiant

Oh and by the way i just had to say this. Kb45 owners shouldn't be worrying about the rotor magnet debonding from the shaft at all. The damn magnet just could not be seperated from the shaft no matter what I tried.

my rotor seperated from the shaft in my KB45-8xl. now, i'm debating whether or not i should try grinding the shaft to 5mm on my KB45-12l.

littlegiant · 06.09.2009, 04:34 AM

Quote:

Originally Posted by scarletboa

my rotor seperated from the shaft in my KB45-8xl. now, i'm debating whether or not i should try grinding the shaft to 5mm on my KB45-12l.

Oh man, I am so jealous of you. How did you seperate your rotor magnet from the shaft? I've been trying to do that. I want a new rotor shaft. I think you got lucky. Did you overheat your kb45? Do the KB XL rotor magnets come in a single piece?

:D

NovakTwo · 06.09.2009, 10:33 AM

We separate the shafts from the magnets by putting the rotors in one of our ovens at extremely high heat.

This heats the epoxy until the shaft can be pulled out.

littlegiant · 06.09.2009, 10:54 AM

Quote:

Originally Posted by NovakTwo

We separate the shafts from the magnets by putting the rotors in one of our ovens at extremely high heat.

This heats the epoxy until the shaft can be pulled out.

Wun the magnet get demagnetise?

NovakTwo · 06.09.2009, 10:59 AM

Quote:

Originally Posted by littlegiant

Wun the magnet get demagnetise?

Yes. That's why we separate them.

Then we can re-magnatize the magnets.

littlegiant · 06.09.2009, 11:25 AM

Quote:

Originally Posted by NovakTwo

Yes. That's why we separate them.

Then we can re-magnatize the magnets.

OoooH I guessed that part right.

Anyway how do you magnetise a demagnetised magnet?

J57ltr · 02:03 PM

With a strong magnetic field. When I worked for Western Atlas we had a Zapper that we plugged in and set the magnet into a cradle that was surrounded by an electromagnet. It was set for about 3 large pulses that would take a AlNiCo magnet from being so weak that it couldn't pick up a paperclip to strong enough to pick up a 25 lb weight. I am sure it would be the same type of operation but the poles would be oriented so that the N and S are perpendicular to the length of the rotor. I would like to know exactly how this is done also. Things like how many amps @ Volts and how many turns are in the electromagnet and what gaquge the wires are.

Jeff

I suggested using Locktite for retaining sleeves to glue a rotor back onto the shaft after it came loose to a friend of mine and it worked great, but you have to heat it to over 400F to get it to seperate.