4x4 Picture Cube

[dude_500]

I have a 4x4 picture cube. I can solve the whole thing except there is one center that has the 4 pieces not properly oriented. How do I move them around without wrecking the rest of the cube?

 

[rjohnson_8ball]

I have a 4x4 picture cube. I can solve the whole thing except there is one center that has the 4 pieces not properly oriented. How do I move them around without wrecking the rest of the cube?

Are the center pieces together correctly so that all you need to do is rotate the center cluster by 180 degrees? (If instead you have 2 cubies swapped in the 2x2 center, then look at other centers for another 2 cubies swapped.)

If all you need to do is rotate the center cluster by 180 degrees just do
(L R U L' R' U2)*2.

 

[dude_500]

it's cubies within a cluster. When I switch two to fix them, it messes up another two... Is there an algorithm that JUST switches two center cubies and doesn't move ANYTHING else?

 

[rjohnson_8ball]

I do not think it is possible. If you cannot find 2 other center cubies swapped, look at edge cubies. Maybe a cubie on one edge is swapped with one on another edge? (Or both on the same edge!? Then the whole edge is flipped.)

 

[Kenneth]

It is possible if the rest is not solved. If the whole cube is solved and only two centres are wrong... then something is wrong (like two centres for example =)

 

[cmhardw]

It is possible if the rest is not solved. If the whole cube is solved and only two centres are wrong... then something is wrong (like two centres for example =)

On a 4x4 supercube the parity of the corners must match the parity of the centers. So to answer your question it is absolutely impossible to swap 2 centers and affect nothing else. The absolute minimal side effect that must occur is the swapping of 2 corners in addition to the swapped 2 centers.

Disassemble your cube and put it back together solved, that is not a possible state for a 4x4 supercube.

Chris

 

[rjohnson_8ball]

Chris tends to know his stuff, big time. You might have another pair swapped somewhere which is hard to see on your picture cube. If 2 corners are not swapped, then maybe there are 2 other center cubies swapped in a subtle way?

 

[mrCage]

Hi

If all but the centers of one face is already solved there is only a few options left.

- 3-cycle
- 2 2-cycles (swaps)
- 2-cycle and 4-cycle are indeed impossible.

By the way, on a 4x4x4 there is NO center pieces that can rotate/orient. They have to move to another location to be "oriented". Every odd size regular cube has 6 rotateable centers, just like the 3x3x3 cube.

The easiest fix for these last centers is one or two commutators. Too many cases to list them all. I'm lazy since im at work now

Please feel free to PM me if you need any particular center commutator.

- Per

 

[rjohnson_8ball]

dude_500, I just had to investigate this further. I played with a 4x4 super cube in GabbaSoft and discovered exactly what you asked for -- a way to swap cubies on only one 2x2 center (such as the F face center) with no effect to anything else:
( r f ' r ' f ) F ( f ' r f r ' ) F ( r f ' r ' f ) F2 ( f ' r f r ' )
If the center cubies on the F face point like this:

< <
^ V

then the sequence will produce:

V V
V V

where <, >, ^, V indicate cubie pointing left, right, up, down. Although this looks like only 2 cubies get swapped, there is also a 90 degree twist, so actually this sequence swaps 3 cubies. (Top right to top left, to bottom left, and back to top right.)

 

[dude_500]

that should do it. Thanks for PM'ing me, I wouldn't have found this for a while.

I can't try it now because my gf has the cube but I'll have her try it tonight and let you know if it works out

 

[rjohnson_8ball]

( r f ' r ' f ) F ( f ' r f r ' ) F ( r f ' r ' f ) F2 ( f ' r f r ' )

The alg is simple to understand. Let X = ( r f ' r ' f ). Then we get:
X F X' F X F2 X'

X shifts 6 center cubies to make a "6 dot pattern", almost like you would see on a 3x3. Then turn F, and undo the dots using X'. You will notice an F cubie has moved to U and U cubie to F and the other faces got restored. Now turn F, make the 6 dot pattern again. Then F2, and undo the dots. Note the sequence resembles Sune: R U R' U R U2 R'.

 

[jonathan]

can some one teach me how to solve a 4x4 rubiks cube plx

 

[rjohnson_8ball]

can some one teach me how to solve a 4x4 rubiks cube plx

The Beginner sticky topic, "Introduction to Speedcubing for Beginners" mentions where to look for 4x4 help. Also, see the "How To" forum outside of the Beginner forum. Also, try the Search button on the top menu bar of this site -- especially for something you suspect might be a common question.