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 Post subject: Help orienting Pyraminx Crystal edges
PostPosted: Sat Dec 08, 2012 9:25 pm 
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I picked up my pyraminx crystal for the first time today. I've never been very good at the megaminx, so I had to experiment quite a bit with the corners. Finally got them. Positioning all the edges was no problem. On the last layer, I have 3 edges that need to be flipped. I can flip two at a time but never three. I'm beginning to think this is impossible. Is it possibly related to the hidden megaminx centers, like the parity on the void cube? I was afraid of that scenario. That's why I never tried to solve it before.

If at all possible, explanation / hints / sentences would be preferable to algorithms.

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 Post subject: Re: Help orienting Pyraminx Crystal edges
PostPosted: Sun Dec 09, 2012 12:01 am 
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Joined: Thu Dec 31, 2009 8:54 pm
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It is impossible to have an odd number of flipped edges. If everything else is solved on the puzzle and you have three flipped edges then pry one out and manually orient it correctly.

I made a video for fixing the orientation of pieces in pairs:
Simple Pyraminx Crystal edge-flip commutator

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 Post subject: Re: Help orienting Pyraminx Crystal edges
PostPosted: Sun Dec 09, 2012 7:39 am 
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Thanks, Brandon. I guess this is what happens when you let students play with your puzzles! Makes me wonder if any of my other puzzles are in an unsolvable state...

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 Post subject: Re: Help orienting Pyraminx Crystal edges
PostPosted: Sat Dec 15, 2012 9:15 am 
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Joined: Wed Apr 13, 2011 8:37 am
Location: Germany
Hi guys,

I use a different technique to orientate the edges.

I use Konrads notation for dodecahedral puzzles.
Assume the last face has yellow color, I use easy commutator to make the face yellow. By example R L R' L'
This commutator flips two edges. The position of edges doesn't matter.

After this I use this to make a 2x2 swap:
R L' R' L L DR' L' DR
This doesn't flip edges.

It's always possible to solve all edges with this technique.
This technique is adaptable to the faceturning starminx.

I found this while I tried rline's solution for faceturning starminx.
But I was not able to memorize 3 or more setup moves. So I invented this technique. The other commutator destroyed triangles on ft starminx.

Cheers,
Andrea


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 Post subject: Re: Help orienting Pyraminx Crystal edges
PostPosted: Tue Jan 22, 2013 4:37 am 
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bmenrigh wrote:
It is impossible to have an odd number of flipped edges. If everything else is solved on the puzzle and you have three flipped edges then pry one out and manually orient it correctly.

I made a video for fixing the orientation of pieces in pairs:
Simple Pyraminx Crystal edge-flip commutator


The way you hold the puzzle does not reflect how easy it is to do that: flip one edge in 3 turns, position the other edge then flip the second with the inverse of 3 first turns. Finally undo the positioning turn.

With only BASIC understanding of commutators doing this 2-flip is really trivial :wink:

Per

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