Magnet motor in Argentina

[Jdo300]

Hi Everyone,

Here are a few notes concerning the demagnetization of magnets. The way to reduce the effect is to simply not force the magnets too close to each other. If you check the BH curves for most materials, it shows the critical field strength for which the magnet will start to weaken. The reason NEO magnets hold their strength so well is because the BH curve is linear for the most part whereas materials like Ceramic and Alnico have non-linear curves. In the case of the Torbay motor, since we want the magnets to be close to get the most repulsive effect, I suggest that we just go with Neos for the stator and rotor, and also try to use the same sized Neos in both the stators and rotors so that they will be evenly matched magnetically. But if you do use a bar magnet like in Stefan?s simulations, it could greatly improve the demagnetization problem because the north pole attracting to the stators can actually remagnetize the magnets over time.

God Bless,
Jason O

P.S. Stefan, I also noted that the strongest force was when the gap was at 90 degrees to the rotor magnet.

[hartiberlin]

Hi Jason, I agree totally, don?t use for the first prototype
to close distances between stator and rotor magnets,
I guess the distance should be at least 5mm and it will
have a positive effect, if you use a long bar magnet as shown
in my second last simulation picture, which attracts the one side of the magnets,
so attraction and repellation comes after each other again and again.
This will not weaken the magnets too soon !

Also it might be, as Neodym magnets are conductive,
that these will have eddy currents inside them which might
make them weaker, but this has to be tested.
Maybe the first rebuilders could test, if the magnets get
warm during operation of the motor ?
If they will get warm, this is a sign of eddy currents
inside the magnets and then only nonconductive magnets will
work... But I guess for now Neodym magnets will
be okay for the first prototypes as they also can be got pretty cheaply
these days via Ebay.

[Jdo300]

Hi Silverdragonrs,

Based on your description, it appears that the black magnets you were using were weak ferrites. Most hard drive magnets nowadays are Neos so I'm guessing that?s what you had. And yes it would be expected that a neo (even a small one) can instantly kill any thin ferrite magnets (especially ones thin like refrigerator ones). You can find some more Neos from old hard drives and also online for cheap if you get small ones. If you can't find any Neos, I would suggest using ceramic block magnets like they carry at RadioShack. Just make sure that you use the same kind/size mags in both the stator and rotor so they won't demagnetize each other as fast. But refrigerator magnets are a big no no, they will die almost instantly in the presence of a neo.

God Bless,
Jason O

[silverdragonrs]

a large factory just redid the computers and i got all of their old ones (ever heard of airborne express shipping?) i now have well over 500 harddrives that are useless. i had a fealing about them so i kept them all...... im a packrat... so yeah i have plenty of neos... averaging two to four per harddrive. so yeah ill have between 1000 and 1500 neos available... the hard part is the hand cramp taking them all apart... and the magnets are usually glued down so removal (without breaking the magnet) is averaging around 80% success rate.

if anyone needs a few i would be glad to share... (but you got to pay shipping as i have 35 cents to my name)

thanks,
danny

ps i forgot to mention that i did not have a problem with the harddrive magnets just the bar magnets

[silverdragonrs]

i have plenty of rescourses so i am going to rebuild again from scratch... this time i will not bolt it down to the workshop bench and instead keep it mobile. i completely forgot i have a webcam on this computer (im usually on the ones in the workshop) so once i get it going i will provide video... give me a day to redo everything.

thanks
danny