iTopSpin

Please login or register.

Login with username, password and session length
Advanced search  

News:

Author Topic: Magnetic turns, new levitation  (Read 150 times)

ta0

  • Administrator
  • Olympus member
  • *****
  • Posts: 12538
    • www.ta0.com
Magnetic turns, new levitation
« on: July 05, 2021, 09:37:30 AM »

Jeremy posted a video of an interesting magnetized top. The same guy, who seems to make a living from playing with magnets, also posted these two very interesting videos that involve rotating magnets.

Magnetic non-contact gear box:

https://www.youtube.com/watch?v=1w5Ol05blLE

The input and output rotate in different directions, although I'm guessing a slight change could make them rotate in the same direction.

Magnetic locking/levitation by rotating fields:

https://www.youtube.com/watch?v=r3E52XdTTNI

Apparently this is somewhat of a new effect, first published this year. From Hamdi Ucar's paper:

Quote
This is a report on a dynamic autonomous magnetic interaction which does not depend on polarities resulting in short ranged repulsion involving one or more inertial bodies and a new class of bound state based on this interaction. Both effects are new to the literature, found so far.

Another video with a much more detailed explanation:

https://www.youtube.com/watch?v=V5FyFvgxUhE&t=0s

Logged

ta0

  • Administrator
  • Olympus member
  • *****
  • Posts: 12538
    • www.ta0.com
Re: Magnetic turns, new levitation
« Reply #1 on: July 05, 2021, 04:45:02 PM »

The input and output rotate in different directions, although I'm guessing a slight change could make them rotate in the same direction.

I found a Wikipedia page on magnetic gears. This would be a "second order" gearbox. It says that the number of stator poles (in this case the bolts) should be either equal to the difference or the sum of the number of pairs of magnets. If it's the difference they spin in the same direction and if it's equal to the sum they spin in opposite directions. In this case there are 16 and 4 magnets, or 8 and 2 pairs of magnets. There are 10 stators so they spin in opposite directions.
Logged

Jeremy McCreary

  • ITSA
  • Demigod member
  • **********
  • Posts: 3297
    • MOCpages
Re: Magnetic turns, new levitation
« Reply #2 on: July 05, 2021, 05:35:57 PM »

I found a Wikipedia page on magnetic gears.

Never knew magnetic gears were a thing till just now. I find the one in the very first video here very cool and kind of counterintuitive. But the concept behind magnetic spur gears is pretty straightforward.

https://youtu.be/2ZVkILFdeSI

The basic design for this Repulsatron came to me while fooling around with some very old LEGO train coupling magnets. Here, all the magnets on both rotors have their south poles pointing outward. Harmonic repulsion transfers the torque from the motorized driver (red) to the follower (yellow).

Any attraction between rotors killed the effect, so alternating polarities were out.
« Last Edit: July 05, 2021, 06:27:21 PM by Jeremy McCreary »
Logged
Everything in the world is strange and marvelous to well-open eyes. -- Jose Ortega y Gasset

ta0

  • Administrator
  • Olympus member
  • *****
  • Posts: 12538
    • www.ta0.com
Re: Magnetic turns, new levitation
« Reply #3 on: July 11, 2021, 11:19:18 PM »

I tried the non-polar dynamic magnetic levitation. I was successful, using both water and copper to dampen the instabilities.





For safety reasons I used a driving magnet with a center hole so I could slide it on a tool shaft. The cylindrical magnet is magnetized along a diameter (contrary to most magnets) what is what you need in this case. For the levitated magnet I tried both a cylindrical magnet and a cube magnet (both a little larger than the driving magnet).
I used the same rotary tool (Dremel 3000) as on the video above. It has continuous speed control, which is very important as it has to be fine tuned. It's a very cool and interesting effect. Sometimes it attracts, sometimes it repels. Inside the water I could get the magnet to orbit the axis of the tool pretty fast (but much slower than the spinning of the driving magnet). I need to experiment more.
Logged