Magnetic levitation is a beautiful thing to watch. Seeing small objects wobble about while seemingly hovering in thin air never gets old. If you want something suitably distracting in this vein for your own desk, consider building this levitating turbine from [JGJMatt].
The build uses a combination of 3D printed parts and metal rods to form a basic frame. The turbine is also 3D printed, making it easy to create the complex geometry for the curved fins. Rare earth magnets are then slotted into the parts in order to create the levitation effect. Two magnets are fitted to each frame piece, and one magnet is inserted into each end of the turbine. When aligned properly, the turbine will hover over the frame and can spin freely with almost no friction.
One concession made to functionality is a sewing needle inserted into the turbine. This presses against one part of the frame in order to keep the turbine from being pushed out of the magnetic field entirely. It’s possible that with very careful attention to detail in alignment, the pin could be eliminated, but it makes the system far more robust and reliable to have it there.
Floating in the magnetic field, a simple puff of air is enough to set the turbine spinning for quite some time. It makes for a captivating desk ornament, and one that can be tinkered with by changing the turbine blades for different performance. It may be frivolous, but at the larger scale, magnetic levitation is put to more serious uses like high-speed transport. Video after the break.
18 thoughts on “Building A Levitating Turbine Desk Toy”
If it’s in a vacuum, what’s going to make the turbine blade spin?
What’s it going to do in a solar/wind generation system?
It all sounds too complicated.
It’s not that complicated.
Don’t think of a turbine, but a flywheel. The more mass it have, the more energy you can store.
Now the motor. A motor can be a generator: power in, movement out. Movement in, power out. It’s reversible.
If you lock the flywheel in a vacuum, with the motor/generator inside, and only wires coming out, you have very little energy losses. The magnetic suspension is very close to frictionless, and if you mechanically disconnect the motor axle when not in use, it can freely spin for a long time.
Now you can wire the motor to a wind turbine, and every time there’s enough wind, the power it generates goes into the motor, connects the axle to the flywheel and speeds up the flywheel. Same with solar power.
Every time you need power, you turn the motor into a generator, slowing down the flywheel and generating power.
“Limitless cycles” mechanical battery.
Check out the ’emb’ or electromechanical battery brought to you byb the late great Richard Post of livermore nat. labs – https://www.llnl.gov/file-download/download/public/20451 .
There they use centering coils in the rotor to avoid the centering needle.
I saw a post recently about high efficiency solar cells powering small blinking lights. Perhaps with a clever implementation of some solar cells and coils, you could keep the rpm above the point of instability in indoor lighting conditions if there were some sort of capacitor or just spinning reserve involved. Since the friction is very low if you remove the pin, even a changing static field could possibly provide enough torque to keep the system spinning.
The needle is required to maintain stability (see Earnshaw’s theorem).
Just to note before anyone wastes their time trying:
“It’s possible that with very careful attention to detail in alignment, the pin could be eliminated”
Not possible. Not without active control or a superconductor involved. Earnshaws Theorem shows why.
A DYNAMIC magnetic system can be stable (as shown by the `levitron’ top and several other configurations), though it is still not a deep well of stability. In this case, the turbine would need to be spinning to position it, and the rate would need to be held fairly constant.
The needle makes this practical, and, in my opinion, adds to, rather than subtracts from, the elegance.
You can put a pair of magnets in place of the needle. But a needle is more elegant, stable, and cheaper.
“There are, however, several exceptions to the rule’s assumptions, which allow magnetic levitation.
Earnshaw’s theorem has no exceptions for non-moving permanent ferromagnets. However, Earnshaw’s theorem does not necessarily apply to moving ferromagnets, certain electromagnetic systems, pseudo-levitation and diamagnetic materials. These can thus seem to be exceptions, though in fact they exploit the constraints of the theorem.
Spin-stabilized magnetic levitation: Spinning ferromagnets (such as the Levitron) can, while spinning, magnetically levitate using only permanent ferromagnets. (The spinning ferromagnet is not a “non-moving ferromagnet”.
Switching the polarity of an electromagnet or system of electromagnets can levitate a system by continuous expenditure of energy. Maglev trains are one application.
Pseudo-levitation constrains the movement of the magnets usually using some form of a tether or wall. This works because the theorem shows only that there is some direction in which there will be an instability. Limiting movement in that direction allows levitation with fewer than the full 3 dimensions available for movement (note that the theorem is proven for 3 dimensions, not 1D or 2D).
Diamagnetic materials are excepted because they exhibit only repulsion against the magnetic field, whereas the theorem requires materials that have both repulsion and attraction. An example of this is the famous levitating frog (see Diamagnetism). ”
According to Wikipedia: Yes, if you do it just right. This device above uses Pseudo-levitation by using a wall and tether (needle). By spinning the magnets (already being done above) you can do without the needle.
It would not be stable the moment the RPM fell below some low value. Basically, it would have to be constantly spinning to actually levitate.
@Sandro: Right, thus the whole point of moving vs non-moving. I think you could just have the floating bit off to the side, possibly in a stand of some sort, then move it to the levitation part whenever you feel like spinning it up.
I wonder if you could put it into some sort of always-moving-due-to-gravity type situation. The magnets keep it up, gravity pulls it down, a spin results, and that stabilizes the levitation. I’m not sure what that’d look like, and it sounds an awful lot like some free energy garbage, but I would imagine it would eventually stop moving just as things eventually fall out of orbit. It would just take longer than if you only spun it by hand due to the mechanics of it all.
I gave this some thought, and I think a half circle with a descending ramp might give us pendulum motion without a whole lot of friction. It could roll down some opposing magnets and settle into a back and forth motion for what might be a while before it eventually turns sideways and stops due to a loss of centrifugal force. It might also stall out near the top of the circle as it falls back towards earth. This could be fun for the trial and error experience. I might try building one.
I think you meant to write DIAMAGNETIC not dynamic, unless you’re referring to something else completely, like some magnets that have good hair and excellent presentation skills or something.
Dynamic = changing. For levitation, you generally need some form of dynamic system – moving magnets, switching field, active control, etc. Static (not changing) systems generally can’t levitate, with diamagnetic materials being the exception.
Diamagnetc materials are subject to the same law: a static system can not be in a stable equilibrium (to say it short)
Superconducting systems are the only exception, and that is due to some really really weird features of superconductors. It has been a long time since I needed to worry about the details (think back to the days of bubble memory, several career paths ago), but IIRC, the magnetic pinning mechanism is analagous to a dynamic system from the point of view of Earnshaws thm.
For powering this have a look at ‘mendocino motor’
I build one here http://zoelen.byethost31.com/2013.htm#2013-15
This is cool but how is this different from the ones found in science museum gift shops? My kids had one of these in their room until they broke/lost the acrylic shield that held the pin in place. They are a pain to get back aligned once it falls out of the field.
It isn’t … other than it is home made. I have one that I bought years ago. Still on my shelf.
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