Wednesday, October 10, 2012

Constrained Cube Ultimate

The Constrained Cube is a twisty puzzle which is another production of TomZ and Calvin's Puzzles. Each face is constrained in a different way. On the Ultimate version, one face is free, once face is completely fixed, two faces are constrained to turn 90° only, and two are constrained to turn 180° only.

The Basic Plot

  1. Solve edges.
  2. Place corners.
  3. Orient corners.
Step 1: Solve Edges

Solving the edges is fairly simple. We start by ensuring each face is in its correct starting position. The blue and green faces should be able to turn either clockwise or anticlockwise. The red and orange faces should be able to turn clockwise only.

To place the white edges, start by putting them on the top face with the white colour on the front face. If the white colour is on the top face, simply carry out an edge piece series to flip the edge. Then place the white edge in its position (on the bottom face) with one EPS.

The middle edges can be placed just as for a standard cube.

To solve the top edges, start by placing the two edges opposite the 4th unplaced middle edge. Once this is done, we will either have the last three edges in a 3-cycle, or else will need to swap two of them. If they are in a 3-cycle, place them with an EPS. If they need to swap, then turn the top face one turn, then re-solve the edges as above.

This is a long-winded explanation for a simple process, as this video will show.

Step 2: Place Corners

We first place (and automatically orient) the white corners. We hold the white face on the bottom. Since the yellow (top) face can turn freely, we turn this face until a white corner, with its white sticker on top, is directly above its position on the bottom face. If a white corner does not have its white sticker on the top, then we carry out a corner piece series to bring the white sticker to the top. Then, we carry out (FR'F'R)x3. This is simply three edge piece series in a row.

Once the white corners are placed, we only need to place the yellow corners. We use corner piece series to place these, and orient them if easily possible. 

Step 3: Orient Corners

At this point, all but two or three corners are in their position and oriented. The final two or three corners need orienting. 

We carry out a very simple sequence which twists the UFL corner anticlockwise, and the UBL corner clockwise. The sequence is as follows:

Clockwise CPS (U R U' L U R' U' L')
Anticlockwise CPS (U' L' U R U' L U R')

This video will convince you how easy it all is.

And that's it. Your Constrained Cube is now solved. I trust this site has been helpful. If you have any questions or want some clarifications, please use the comments to do so.

To have a look at all the constrained cube varieties, click the banner below.


  1. Hi,

    Why you using this algorithms in step 2 and 3 ?

    I solve the cube with the ultimate solution, first place the edges than corners (the white first) and then do the end game.

    im sure the ultimate solution is longer than this solution, but no memorized is needed.

    1. Hi aviron

      I did say in the corners video that if it's easily possible, just to use the corner piece series to solve corners normally. But what I found was that most of the time it was quite difficult to do the setup moves to carry out the end game on the last 3 corners. So instead of that, I've offered an alternative method which is easier to deal with.

      If you've found it always easy to carry out the end game with CPS, then I'm very impressed!

    2. Thanks chareves,

      The end game indeed took me lots of time to complete, what i like in the ultimate solution is that you don't need to memorized at all, and each time is a real challenge to solve it.

      Thanks again.

  2. Hi aviron

    It's interesting to ponder what the ultimate solution actually is for these kinds of puzzles. Marshall only did it for the 333, the 444, the 555, the 222 and the pyraminx. All other puzzles he didn't do. So with something like the constrained ultimate cube, if I solve it as I've done here, using the corner orientation at the end, does that still count as ultimate solution? I think so, but that's obviously for debate. I think a bit part of the U.S. is making things as simple as possible. And so you as long as it involves the CPS and/or the EPS, I think it's all good.

    Thanks for your comments.