# No lube smooth magnetic cube



## Cubed Cuber (Apr 30, 2017)

Hello everyone,
Post here if you have any ideas of a magnetic cube.

My idea is that you place the magnets against each other so that your cube can be smooth if you loosen to tension up a bit.


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## CornerCutter (Apr 30, 2017)

Cubed Cuber said:


> My idea is that you place the magnets against each other so that your cube can be smooth if you loosen to tension up a bit.


If you make the magnet polls against each other then the puzzle won't aline correctly.


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## Cubed Cuber (May 1, 2017)

But wouldn't it be smooth though?
And also, if you tighten the tensions up a bit it would become more stable.


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## CornerCutter (May 1, 2017)

Cubed Cuber said:


> But wouldn't it be smooth though?
> And also, if you tighten the tensions up a bit it would become more stable.


It might work. It would be fun to try.


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## Mastermind2368 (May 1, 2017)

I will make a cube with it if someone gives me the magnets.


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## Cubed Cuber (May 1, 2017)

I don't know where to get the magnets.
Even though I used to have othello magnets that should fit if you glue them on, but I lost them.


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## CornerCutter (May 1, 2017)

Mastermind2368 said:


> I will make a cube with it if someone gives me the magnets.





Cubed Cuber said:


> I don't know where to get the magnets.
> Even though I used to have othello magnets that should fit if you glue them on, but I lost them.


Ebay for $1. Happy waiting(1 month)


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## JustAnotherGenericCuber (May 1, 2017)

Cubed Cuber said:


> My idea is that you place the magnets against each other so that your cube can be smooth if you loosen to tension up a bit.


Dmcubing tried this and it did not work at all.


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## DMCubing (May 1, 2017)

JustAnotherGenericCuber said:


> Dmcubing tried this and it did not work at all.


Exactly. I exaggerated the effect by using fairly strong magnets (N38 and N42 opposing each other). Terrible results.


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## Cubed Cuber (May 2, 2017)

thanks


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## xyzzy (May 3, 2017)

Placing the magnets so that they repel when the layers are aligned is really bad for a really simple reason.

When you have the polarity configuration so that the magnets attract with aligned layers, having aligned layers is a _local energy minimum_. There are essentially 8 local minima as you go through a full revolution: 4 when the layer is fully aligned and 4 more when it's about 45° off from aligned (exact angle depends on magnet placement), although the latter minima represent a much smaller energy gradient compared to the former and, for our purposes, may be ignored.

But if the polarities are such that the magnets repel with aligned layers, you've flipped the signs of all the potential energy formulae and now your local energy minima turn into local energy _maxima_. This means that the pieces will actively try to move away from being aligned. It's like balancing a pen on its tip: that's the highest-energy position, so it's not stable and it'll fall off pretty quickly without external intervention.

Cubes turn worse when the layers aren't fully aligned, so if you set it up so that the layers are essentially never aligned, of course you get a cube that turns worse. It's not rocket science.

That's not to say that making use of magnetic repulsion to reduce friction is impossible or anything; it's just that this naïve approach of flipping half of the magnets doesn't work. If you could somehow stuff some magnets and superconductors in a cube, they could conceivably repel no matter how the layers are aligned, resulting in basically zero friction apart from whatever mysterious mechanism is keeping the cubies attached to the core.

(I haven't touched electromagnetism in like six years, so my knowledge is a bit rusty and the speculative bit about superconductors is probably incorrect in some way.)


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## Cubed Cuber (May 3, 2017)

thanks


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## Ghost Cuber (Jun 14, 2017)

DMCubing said:


> Exactly. I exaggerated the effect by using fairly strong magnets (N38 and N42 opposing each other). Terrible results.


I was just going to link that video!


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## gavinz (Jun 15, 2017)

A GTS2 with 5x1.5mm N35 magnets are smooth without lube


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## One Wheel (Jun 15, 2017)

Repelling magnets in the corners and centers would repel when the layers are misaligned. I think that should work. You could also possibly do the same thing with extra magnets in the edges, but centers would be simpler and more reliable. Either way could easily be combined with the standard attracting setup, although it would mean 72 magnets in a 3x3. (Probably 96 if you went with extras in the edges, depending on piece design.)


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## I_<3_SCS (Jul 13, 2017)

xyzzy said:


> Placing the magnets so that they repel when the layers are aligned is really bad for a really simple reason.
> 
> When you have the polarity configuration so that the magnets attract with aligned layers, having aligned layers is a _local energy minimum_. There are essentially 8 local minima as you go through a full revolution: 4 when the layer is fully aligned and 4 more when it's about 45° off from aligned (exact angle depends on magnet placement), although the latter minima represent a much smaller energy gradient compared to the former and, for our purposes, may be ignored.
> 
> ...



WOW!!! Good explanation!!!


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## EntireTV (Jul 13, 2017)

Impossible to assemble imo


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