Having Magnet Troubles. 2

[Chizl]

I've not dug into magnets and attempting anything like this so it's my first run. I'm a software engineer of 35 years and for the last year I do a lot of CAD (Fusion 360) design, then build tools and such with my 3D resin printers. I came up with this great idea, as we all have before we try it, and it's something that doesn't exist, which should of been my first clue. In the last couple of month, I've been trying to work out a way to build a maglev train set, but with standard earth magnets, not electro magnets. I thought I had everything working well in my head as it's designed a lot like this:

.

I purchased 60x10x3mm earth magnets, for the track. I then built a T structure that looks a lot like a single sided train track with the magnet flat on top. I then bought some 6x3mm round earth magnets that would be used for the train guide that wrapped around the track. This takes 6 of the round magnets for each leg on the train. Two on top (1 each side), two on bottom (1 each side), and two in the middle (1 each side).
Below is what the legs look like and the "n" and "s" is where the magnets setup towards the center.
[pre]---s---------s---
s s
---n-- --n---
[/pre]
I then started thinking I should make the legs longer.
[pre]---s---------s---
s s
n n
---n-- --n---
[/pre]
Because of curves in a track, I use a 10mm wide leg in front and 10mm wide leg at the back of the engine with and create 1 center leg for each car since they are connected together, kind of hold each other up. Rear car will be the reverse of the front car.

But then I started thinking of equal push, means it will have to go side to side, unless there is some serious distance between the train and the track, side to side and top/bottom. Balancing this is crazy to get any of this to actually float right. After months of different designs, hundreds of prints, I'm hitting walls and getting frustrated. The train will lay flat or if I pull up on it, it stays up and leans sideways.

What I'm looking for here is a Magnet GOD that can tell me, am I going to down an impossible project here or is there something better I can attempt?

 

[3DDave]

Modulating electromagnets is how height is controlled. There are some relatively high temperature superconducting material suitable for such use; I've seen permanent magnets form a track with a superconducting (liquid Nitrogen temps?) levitating car.

I cannot recall where, but I remember seeing a proof for why unconstrained levitation is not possible with static magnetic fields.

Here's a writeup:

https://gravity.wikia.org/wiki/Magnetic_levitation

https://en.wikipedia.org/wiki/Earnshaw's_theorem

 

[Chizl]

Thanks for your input. Based on that, I found this.. I have a lot more reading to do, but I think this pattern is leading me on a new path.

[URL unfurl="true"]https://math.ucr.edu/home/baez/physics/General/Levitation/levitation.html[/url]

Toy that exploits this method.

It's funny, because now I'm going back to my original design, which was causing me some magnet havoc. This was the track connectors, I came up with, but keeping the magnets apart since I had N pointing up on the outer part and S pointing up in the inner, no matter what kind of glue I put in there, would suck one magnet over into the other. ha. Now I think I need to revisit this though, but made the track 52mm wide, which is making the train much bigger than I wanted.

 

[electricpete]

> I cannot recall where, but I remember seeing a proof for why unconstrained levitation is not possible with static magnetic fields.

Earnshaw's theorem

I'm not sure that prohibits op's original idea because the arms reaching under the rail can give some mechanical constraints.

for op - Google maglev train with permanent magnets ...and you'll find all kinds of DIY'er stuff

https://www.youtube.com/watch?v=0ZuIG487Z08

=====================================
(2B)+(2B)' ?

 

[Chizl]

The problem I'm running into with the arms reaching under the rail, which is also magnetic, is balance. When they all resist the same, you get an unbalanced structure that tips to one side. I'm now thinking of taking 4 of the 60x10x3mm magnets, and binding them like 4 sided square. But also looking at magnetic shielding to see if this can help with the unused magnetic side that is also throwing the balance off. This would make a 60x16x10mm bar. This way all external facing will be a single pole. I have no idea if this thought will work and getting this to bind this close together with a single pole pushing against each other will be a fight, but I'm one to break things 1000 times, before I figure out how to make it work.

EDIT: BTW I love the video, my only issue is there still physical contact, still drag, and I'm going for the impossible float with no drag outside of air itself.

 

[electricpete]

In the video, the magnet is supporting the weight but the clear plastic side rails are providing a stabilizing effect (constraint) to prevent it from tipping over.

That's what Earnshaw's theorem says you need. It says you can't levitate purely with static magnets, you need additional constraints for stability.

> I'm going for the impossible float with no drag outside of air itself.

I see now your own UCR.edu link talked about Earnshaw's theorem and there is a section called "Exceptions" which are essentially violations of the assumptions that go into the theorem... it makes sense to me to focus on one of those approaches, or else expect that you'll have some degree of mechanical constraint/restraint to improve stability.

=====================================
(2B)+(2B)' ?

 

[Chizl]

this is what I'm looking to do... There has to be a push and pull resistance for it to levitate as he turns it upside down, after several tries.

Youtube

 

[3DDave]

Here's how the levitation system is constructed:

https://www.youtube.com/watch?v=TFWeEL63Hzs

 

[Chizl]

I know it can be done fairly easy with Super Conductors, but I'm attempting not to buy Liquid Nitrogen constantly. I've been looking into Paralytic Carbon/Graphite and Bismuth. Bismuth will require me to have a structure for the Bismuth above and below the train as well as a larger magnet above it all. Kind of hiding the train at that point unless I make this a like a levitating sky car, hummm maybe. Paralytic Carbon/Graphite is interesting, but don't think it can handle the weight. I can make the cured resin body .5mm thick before the train becomes too bridal and I still think the body might be too heavy.

 

[Compositepro]

That is pyrolytic carbon.