 This stage completes the first two layers by building two 1x2x3 blocks on either side of the Line made in the previous stage. Because all edges are now oriented it is possible to complete this stage using just R, U and L moves.

### Contents

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### Basic Block Building Strategy

In order to reduce this step into bite-sized chunks which can be recognised and executed quickly, the step is split into four parts:

1. left-hand 1x2x2 block
2. right-hand 1x2x2 block
3. left-hand 1x1x2 block
4. right-hand 1x1x2 block

The order of execution depends on the situation. In general the 1x2x2 block should always come before its connecting 1x1x2 block, otherwise more moves will be required later.

### 1x2x2 Blocks

To build a 1x2x2 block a D-layer corner and two edge pieces are needed (a D-face edge and a mid-slice edge). Building the block involves first building a 1x1x2 block with the corner and one edge piece. The other edge is then placed into the correct mid-slice position (FL/BL/FR/BR) and connected to its block by rotating the U-face.

The first 1x1x2 block can either be built with a D-face edge or a mid-slice edge. Because there is freedom to fully rotate the R and U faces without breaking anything up, these initial 1x1x2 blocks are very easy to make. The examples below show the four basic cases:

Corner + mid-edge in U-layer

Corner + mid-edge in R-layer

Corner + D-edge in U-layer

Corner + D-edge in R-layer

Once the first 1x1x2 block is built, it is connected with the third edge in the mid-slice. It can be done in one of two ways, depending on whether the block is being connected with a D-layer or mid-slice edge. The two cases are shown below:

Connection with D-face edge

Connection with mid-slice edge

### 1x1x2 Blocks

Constructing the 1x1x2 blocks is usually done by connecting them in the U layer, in a similar manner to Fridrich F2L. However, there are no cube rotations, and only L, R and U moves are used. The three basic cases are:

R U R'
R U R' U R U R'
R U' R' U' R U R'

R U2 R' U2 R U' R'

R U2 R' U R U' R'
R U' R' U2 R U R'
L U R U R' L'

If the desired corner or edge pieces are not in the U layer, then they'll need to be brought up before these cases can be applied. If the required pieces are already in the U-layer, but connected incorrectly they'll need to be separated before they can be solved.

### Algorithms for Special Cases

The core blockbuilding techniques introduced above are the minimum requirement for completing F2L intuitively. As familiarity with F2L improves it may be desirable to optimise some of the more difficult cases, for example where the desired cubies are connected incorrectly. It's recommended that intuitive blockbuilding is fully understood before moving onto the F2L algorithms below.

The algorithms solve these cases optimally (unless stated otherwise), without affecting edge orientation. They are applicable to all F2L slots when reflected accordingly.

### D-layer 1x1x2s

Pieces separated

R U R'

R2 U R2

U2 R' U2

U R U'

U' R

R2 U R' U
U' R U' R2

R U

R U2 R U'

Pieces connected

U' R' U R' U'
R U' R U R'

U' R' U R U'
U R2 U' R' U R

R U' R' U2

R U2 R2 U'
U' R2 U2 R

(U') R U R2
U2 R U R'

R U R' U' R
R' U' R U R2 U'
U' R' U2 R U R'

U' R U R' U
R U R' U R

R U2 R' U2 R U R'
U R U R' U' R U R'

L F2 U F2 U' F2 L'
L D F2 D' L2 U L
F' R U R' U' R' F R(sub opt)
U2 R' U' R' U' R' U R U R(sub opt)

R U' R' U R U' R'

R U R' U2 R U R'
U2 R U2 R' U R U R'

R U' R' U2 R U' R'

R2 U R2 U R2 U2 R2
R U R' U' R U R' U' R U R' U'
(sub opt)

### Connected Cubies

Each of the connected cases are split into three groups

1. Connected cubies in U layer, above their slot
2. As 1, but with the opposite slot free
3. Connected cubies occupying their slot

The initial moves in brackets position the block before the insertion algorithm, so may not be necessary:

1. SAME COLOUR TOP

Above slot
F2 L D' L D L2 F2
R U' R U2' R2' U' R2 U' R2
U' R' U2 R' U R' U' R U2 R
R U R' U2 R U' R' U R U' R'
R U2 R' U R U R' U R U' R'
Using free slot
R U' R U R2 (D edge in FR)
In slot
L D' L' U L D L'
U' R U2 R' U R U R' (sub opt)
R U' R' U2 R U' R' (sub opt)

2. OPPOSITE COLOURS TOP, COLUMN CASE

Above slot
R' U2 R2 U R2 U R
Using free slot
R' U2 R2 U R' (D edge placed)
R2 U2 R' U R' (D edge in UL)
In slot
See edge placed case #3...

3. OPPOSITE COLOURS TOP, L CASE

Above slot
(U') R U' R' U R U R'
Using free slot
U' R2 U R U' R2 (D edge placed)
U' R' U R U2 R2 (D edge in UL)
In slot
R U2 R U R' U R U2 R2
R U R' U2 R U' R' U R U R' (sub opt)

4. D-COLOUR TOP, SAME COLOURS SIDE

Above slot
(U2) R2 U2 R' U' R U' R2
R U R' U2 R U R' U' R U R' (sub opt)
U R U' R\' U' R U' R' U R U' R' (sub opt)
R U2 R' U2 R U R' U R U R' (sub opt)
Using free slot
R' U' R U' R2 (D edge in UL)
In slot
L' D2 L U2 L' D2 L
U' R U' R' U' R U2 R' (sub opt)

5. D-COLOUR TOP, OPPOSITE COLOURS SIDE

Above slot
R U2 R' U' R U R'
Using free slot
As above
In slot
R2 U2 R' U' R U' R' U2 R'
R U R' U' R U2 R' U' R U R'

1. Bad connection of block and D-face edge

Solutions
R' U' R U R2 U' R'
R' U2 R U R' U' R2 U2 R
R' U R U2 R' U2 R' U R' U2 R'
R' U2 R' U2 R U R
L' U R' U' L U2 R' U R' U2 R
Avoidance
R U2 R2 U' R'
U R' D' L F2 L' D
R' U2 R' D R' U R D'
U R2 U' R2 U' R2

2. Bad connection of block and mid-slice edge
Solutions
R2 D' R U R' D
R U2 R' U' R U R2
R U R' U' R2 U R2
R U' R' U2 R U2 R2
(U2) L U' R U L' U2 R2
Avoidance
U2 R U2 R' U' R2

### Multiblocking

Sometimes a situation arises where multiple 1x1x2 blocks appear in the U-layer. If both L an R slices are still free it's fairly easy to temporarily 'store' a block in one side while dealing with the other. However, if one of the slices is already complete there is much less room to manipulate the completed blocks without breaking them up. The algs below show some optimal solutions to these cases. If a completed block is already 'stored' in its L/R slice then rotate the side, bringing the block into the U-layer to match one of the cases below.

### Two parallel F2L blocks

DF edge free
R U R2 U2 R'

DF edge wedged between them
(U') R' U2 R U R' U' R2 U R

DF edge in mid-slice
U' R' U2 R U R' U' R2 U R

DF edge placed
R U' R' U' R' U R

DF edge in U-layer
U' R' U' R U2 R2 U2 R'

### Adjacent F2L and D-layer blocks: D-layer block free

mid-slice edge in R-slice
R' U' R' U' R'

mid-slice edge in U-layer
U R' U2 R2 U2 R U R'
U' R U R2 U2 R2 U' R

### Adjacent F2L and D-layer blocks: F2L block free

mid-slice edge in R-slice
U' R2 U D R' U2 R D' R
R' U' R' U R U2 R' U2 R'
R U' R2' U' R2 U R U' R'

mid-slice edge in U-layer
(U2) R' U R' D R' U2 R D'
(U') R' U' R U R2 U' R2 U' R
(U) R' U2 R' U2 R U R' U' R'
L' U R2 U' L U' R U' R2

### Diagonally opposite F2L and D-layer blocks: edge in U-layer

mid-slice edge next to F2L block
(U) L' U R' U' R' L U2 R'
(U') R2 U' D R' U' R D' R
R' U R' U2 R' U R' U2 R
R' U' R' U2 R U R2 U' R'

mid-slice edge next to D-layer block
R' U2 L U' R' U L' U R'
(U) R' U' R U R2 U' R' U' R'
(U') R' U2 R U R2 U' R2 U' R
(U) R2 U R2 U2 R' U2 R' U R'

### Diagonally opposite F2L and D-layer blocks: edge in R-slice

edge in FR
(U) R' U2 R'

edge in DR
(U') R2 D R' U2 R D' R
(U) L' U R U' R' L U2 R'
(U) R' U' R U R U' R' U' R'

edge in BR
(U') R2 U2 R2' U R U' R'

### Openslotting

'Openslotting' is when a completed 1x2x2 block is placed so that it occupies the alternative F2L position. This leaves the slot receiving the adjoining 1x1x2 in an 'open' position. Deliberately leaving a slot open can improve efficiency and is a useful technique for improving lookahead. If 1x2x2's which belong in the front are moved to the rear of the F2L, it fills the hidden BL and BR edge positions, as well as the DBL and DRB corner positions, improving visibility of pieces.

### Basic Cases

(U) L' U R U' L
R U2 R' U' R

(U) R' U L U' R2 U L'
(U) R2 D R' U2 R D' R'
(U') R U2 R' U' R U R' U' R

R2 U2 R2 U' R2 U' R'

R U R' U' R U' R' U' R
R U2 R' U R U R' U' R
R B2 U L U' L' B2

(U') R U2 R' U R U' R' U R
(U) R' U2 R2 U R2 U R2

(U') R U' R' U R U' R' U R
R U R' U2 R U2 R' U R
R B2 U2 R B2 R' U2 B2

### Corner Trapped

R U2 R' U R

R U' R' U' R

R U L' U R' U' L R
L R U' R' U L' U R
R U R' U' R U' R' U R

### Edge Trapped

(U2) R U R' U' R

R U' R' U R

R U R' U R U' R' U' R
(U') L' U2 L F2 R' F2 R2
(U') L' U2 R U2 R' U2 L R

### Both Trapped

R' U2 R' U R U' R U2 R2
R2 U2 R U' R U R' U2 R'
F2 U' F2 R' D R' D' R'
R' D' R' D R' B2 U' B2

R U' R U2 R2 U' R2 U' R'
R' U' R2 U' R2 U2 R U' R

R U R2 U2 R U R' U R2
R2 U R' U R U2 R2 U R

### Connected Cases

R U' R' U' L' U R U' L
R U R' U2 R U' R' U' R
F R B R' F' R B'
F' R B R' F R B'

(U') R U R' U' R U R' U' R
R' U' R2 U' R2 U2 R2

R U' R' U2 R U' R' U R
(U) R' U' R U' R' U2 R2

(U) R' U2 R U R' U R2

(U) L' U2 L U L' U L R
R U R' U' R U R' U2 R
(U2) R U R' U2 R U R' U' R
R B2 L U L' U' B2

## ZZF2L Lookahead / General Tips

At the beginning of ZZF2L there are four partially hidden edge locations. Because no rotations are used, it is not possible to check these pieces directly - this creates a challenge for lookahead. The following tips are suggested for good ZZF2L lookahead:

• Partially Hidden Edges: Learn to identify partially hidden edges through elimination. Because edges are already oriented, there are at most four possibilities for any F2L edge. If three of these four are visible/known, then the fourth can be worked out.

• Partially Hidden Corners: If familiar with the colour scheme, then any corner with only two stickers visible can be worked out. This means that six of the eight corners can be identified by looking at only the R/L/F/U sides. The coracle corner lookahead drill can help with this.

• EOLine-F2L Transition: During EOLine execution be sure to focus on searching for F2L pieces. Try to avoid the temptation to 'check' that the line edges have been placed correctly.

• Flexible 1x2x2 Building: When starting a 1x2x2 block, be willing to use either a D-layer or E-slice edge. Avoid a strong bias for one or the other.

• Flexible 1x2x2 Placement: If initial 1x2x2 blocks occupy the rear F2L slots then lookahead becomes much easier. If an initial 1x2x2 normally belongs to the front, it can temporarily be placed in the back (using an R' or L move) while other blocks are built. See openslotting.

• Avoid Scanning D/B: Looking at these faces interrupts the flow and makes it difficult to keep track of what is happening around the cube. When unable to find anything use R/L moves rather than rotations. Adopting this approach will encourage development in the lookahead skills highlighted above.

### General Tips

Where there is a strong preference for one hand, cube rotations such as z for left-hand blocks can sometimes make algorithm execution easier.

As a final note, it is possible to apply a subset of the ZBF2L algorithms for the last two 1x1x2 blocks. Only the ZBF2L cases with LL edges already oriented apply.

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Last updated: 7th August 2016