How to solve the 3x3x4 Cube
The 3x3x4 Cube is a normal Rubik's cube with an extra layer. Similarly to the Domino Cube, the Up and Down faces can turn 90° but the rest of the faces (i.e. Left, Right, Front and Back faces) can only turn 180° at a time (if you're not sure why, try turning the Right face 90° and see if you can move any other faces!). Its solution isn't similar to either the Rubik's cube or the Rubik's revenge despite its similar dimensions. Read on to find out how to solve the 3x3x4 cube!
Notation
F = Front
B = Back
L = Left
R = Right
U = Up
D = Down
The following is new notation different from the normal cube notation thanks to the extra layers:
u = up
d = down
Part 1
Step 1
The first step to solve the 3x3x4 cube is correctly placing the edge pieces in one of the middle two layers.
Aim
The first three edge pieces of the layer can be done intuitively. If you're lucky the fourth edge piece will also fall into place but if not to swap the front-right-top piece with the front-right-bottom piece, marked by an X each, do the following
Algorithm: F (Dd) F (Dd)' F
Step 2
Step 2 is to solve the edge pieces in the other middle layer.
Aim
To swap two pieces in the same layer, marked by an X each, arrange as follows. This diagram is a view from the back, so you will need to arrange it like this and then turn it round before performing the algorithm!
Algorithm: R F (Dd)' F (Dd) R (Dd)' F (Dd) R (Dd)'
In order to swap two middle edges (i.e. swap the two X pieces with each other and the two Y pieces with each other) then use the following algorithm:
Algorithm: (Uu)2 R F u2 F R (Uu)2
Step 3
The next step is to solve the centres and there are a few different algorithms we can use. You will need to decide which scenario your scrambled cube falls into.
Aim
If you have two of the same colour centre pieces in one layer, then use the following algorithm to move it from the bottom left to the upper right, marked with an X each, or vice versa.
Algorithm: R (Dd)2 F (Dd)2 F (Dd)2 F R
In order to swap the pieces marked with an X, i.e. the front-bottom centre piece with the right-bottom centre piece, perform this algorithm:
Algorithm: F (Uu)' F (Uu)2 R F (Uu)2 F R (Uu)' F
To swap the bottom-front and bottom-back centre pieces, again marked with an X, use the following: (note this is a view of the left face, before using the algorithm make sure you turn your cuboid).
Algorithm: R (Dd)2 R (Dd)2 R (Dd)2
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Part 2
Step 4
Now to place the corners onto the correct face. This can be done through intuition alone.
Aim
Then you need to move them into their correct positions. Use the below algorithm to swap the two corners in the bottom back marked with an X each.
Algorithm: R F D' F D R D' F U F U'
Step 5
The final step to solve the 3x3x4 cube is to place the edge pieces on the up and bottom layers correctly.
Aim
Firstly, get them into the correct layer, you can swap the bottom left and upper left edges (marked with an X) using this:
Algorithm: R D2 F D2 F D2 F R U2 R D2 F D2 F D2 F R
The final part is to rotate the edge pieces into their correct positions. You can swap the bottom-back and bottom-front edge pieces with the following algorithm. The diagram shows the left face, twist your cube into the correct position first.
Algorithm: R D2 R D2 R D2
The following algorithm will swap the bottom-front and bottom-right edge pieces (marked with Xs):
Algorithm: F U' F U2 R F U2 F R U' F