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Old 11-22-2018, 08:40 PM
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soundiceuk soundiceuk is offline
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Join Date: Oct 2011
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Quote:
Originally Posted by gyula View Post
Hi Paul,

What is missing for me is the free rotation of the floating rotor in the center: I would expect it to spin for a relatively long time after
you give some spinning to it by your fingers.
See this levitating toy what I mean:
https://www.youtube.com/watch?v=QU-Px0VjQ2w

What I suspect is that free rotation is hampered by eddy currents induced in the Alu side walls close to the floating rotor magnets.

I think there are static fields like I tried to indicate roughly in the picture, see attachment.

Can you can detect magnetic field on the outer side of the Alu wall? Does say an small pin or a small nail remain attracted to
the outer side of the Alu wall as I tried to indicate in the picture?

If you can detect stray fields from the magnets at the outside wall, then the fields penetrate the Alu structure
so this may cause the eddy current braking effect against rotation.

Unfortunately, you would need to build a wooden or plastic structure instead of the Alu one to get rid of
the breaking effect if this is the case. I do not know how the magnets are arranged
inside the cylindrical Alu holders (I did not follow your full work here), so maybe I am wrong with my eddy current suspect.

Your work is awesome, by the way.

Gyula
Gyula, yeah, I think your right the paramagnetism is producing a weird effect that adds friction. Its magnetic friction!

I might be able to get away with the frame but you have a point!

Magnets get sucked over to the frame, so the magnetic field is there.

I just tested a 24mm spanner and it almost held it off the ground to the outside of the frame, so field is strong.

Might have to be all made from 316 Stainless.

Will look amazing polished up!
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Last edited by soundiceuk; 11-22-2018 at 08:45 PM.
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