Robbie's 7-Cube Tutorial

The 7x7x7 version of the Rubik's cube, sometimes known as the V-Cube 7 at least in its original design (also invented by Panagiotis Verdes) is like the 3-cube and the 5-cube, in that it has fixed centers on all six sides, which means there isn't much danger that you'll solve the centers out of order and then have to swap them. Only now, you need to build 5x5 centers of each matching color, and surround them by 1x5 edges of the same two colors, before you can proceed with a glorified 3-cube solution. I might as well also acknowledge that the colors of the 7-cube that I own and use are a bit different from normal Rubik's cube colors. In fact, the 6-cube also had a different color scheme from my other stickerless cubes, but this model takes the cake with its decidedly pink shade of red.

Moving on, we see that the 7-cube's 218 cubies comprise 150 one-sided "center" pieces, 60 two-sided "edge" pieces and the usual eight three-sided corner pieces (because a cube has eight corners, innit). There are somewhere around 1.95 times 10 to the 160th power possible ways to scramble a 7-cube, and yet the current world record for fastest single solve is 1 minute, 35.68 seconds, again by our old buddy, Max Park. He also holds the record for mean of three solves at 1 minute 42.12 seconds. I feel no shame in admitting that I can entertain myself with a 7-cube for anywhere between 20 and 30 minutes, and that's a single solve.

Let's make this a quickie, up to a point. I mean, it's once again simply a scaled-up version of the same problem presented by the 6-cube on down. You scramble it:

Solve the centers starting with white, then yellow, then two adjacent colors on the middle layers:

Now, size up the last two remaining centers at "up" and "front."

Using the reliable old same-colored-bars-chasing-each-other-around-corners, giving the up-side a half-turn and dialing the disturbed slice back into place, do as much as you can to reduce this jumble to two mostly solved centers. This calls for trial and error, spatial reasoning, and a bit of creative thinking.

Now let's see if we can't fix two of the still-wrong squares at the same time, using another variant of the technique revealed in my 6-cube tutorial. First, dial that third layer from the right up (R₃):

Second, crank the top layer a quarter-turn in the direction that puts the two questioned pieces in line to be replaced by the correct color (that's U'):

Third, dial up both of those slices (L_2-3'):

Fourth, twist the top layer in the opposite direction (U):

Fifth and sixth (which you'll have to absorb from a single photo, due to a bad exposure), dial that first slice back down (R₃') and twist the "up" layer in the previous direction but one (U'):

And seventh, dial that pair of slices back down (L_2-3):

You can see that I still have three odd pieces to swap between the last two centers, but I already showed how to do that in my previous tutorial, so let's skip to that being done:

That brings us to the step of matching up edges. While there were times in the 6-cube where you could complete an edge in one step, that seldom happens in the 7-cube. So, expect to do a lot of partial edge solves (like this instance of four-out-of-five yellow-orange edge pieces):

Then, as a separate step, adding that fifth yellow-orange piece to the edge, like so:

For ye OCD sufferers, here's that completed edge with the centers healed:

I made it through the Last Two Edges crisis using the 4x4 L2E algorithm, though (again) I didn't record it for your viewing pleasure because I'm still in that awkward state of trial and error where my attempts sometimes don't succeed and have to be undone and redone a different way. If you're persistent, or you're brighter than me by enough to generalize how to go about this, you'll figure it out and you'll be doing it in less time than it took me today – though I feel I did rather well, considering. It's basically that U₂'-R-U-R'-F-R'-F'-R-U₂ algorithm, with refinements based on which pieces you're trying to swap. Generally, it seems to help if you start with two matching pieces facing each other on the layer that gets the U-slice moves at either end of the formula, but if you get a weird result, repeat the formula to return to the previous state, then flip things around a bit and see if you can't get it to work again.

And now we come to two of the three or four instances of Edge Parity that confronted me at the end of the L2E step. See this wacky green-orange edge?

Rule of thumb: Assume the center piece on the edge is correct, then plug into the OLL Parity formula the subscript of the slice (or slices) you want to flip to orient all the pieces on that edge the same way. So, start with R₂':

Followed by U2:

Then L₂:

Followed by F2:

Then L₂':

Followed by another F2:

Now R₂2:

And a U2:

And an R₂:

And another U2:

And an R₂':

Followed by yet another U2:

Then an F2:

And another R₂2:

And a final F2:

We'll get through this second example of the Edge Parity in half as many pictures. It's the same algorithm, except we're moving both the 2- and 3-slices together. Here's how it looks to start with:

Here's how it looks after R_2-3' and U2:

Then L_2-3 and F2:

And then L_2-3' and F2:

Now R_2-32 and U2:

R_2-3 and U2:

R_2-3' and U2:

And finally, F2-R_2-32-F2:

There were no more surprises after this in today's 7-cube solve. No OLL or PLL parities, and nothing else that disturbed the settled routine of a 3-cube solve wrapped around a bunch of 5x5 centers. Moving the outer layers was sometimes a bit tricky, due to all those tiny pieces locking horns with each other, but I have a nice, smooth-moving 7-cube, and so I forgive the pinkness of its "red" side. I bought the both of them, 6 and 7, from the same seller on Facebook Marketplace, and I've been pretty happy with my purchase – though, as I recall, they came to me scrambled and when I tried to solve them, I was stymied by one of the corners on the 6-cube having been taken off and put back on wrong. I had to prise it apart and snap it back together before I could complete the solve. Watch out for that kind of thing if you get one of these puzzles and proven procedures for solving them don't seem to work. Don't go mad. Go creative!