adventures in cubing

It’s been a little while since I felt like I’ve accomplished much in terms of cubing, especially after plateauing at about 30-35 seconds on 3×3 solves. So, I decided to revisit PLL time attacks, and, after a few days of practice, got a good outcome: an on-camera 72-second PLL attack that started and ended with a solved cube:

By way of brief background, PLL is the last step in CFOP — once you have a solved bottom face, solved bottom two layers, and solved top face. All that’s left is to get those four edges and four corners in the top layer rejiggered into their proper position. There are 21 PLL cases (22 if you count solved), each named after a letter that somewhat resembles the pattern of the edge and corner swaps. More detailed background and the PLL algorithms can be found on the speedsolving.com wiki.

A PLL time attack is the performance of each of the 21 PLLs in a stream without stopping. Completing it in a minute is respectable, but not amazing; forty-five seconds is really good; and better than that is truly impressive. When I first learned PLLs, I did a quasi time attack — quasi because it was truncated (I did the Gs separately), because I did each PLL individually (not in a single stream), and because I used my best of three attempts per PLL. The sum of the 21 parts was 66 seconds.

As I recognized then, 66 seconds was totally unrealistic and misleading:

First, these times represent my best of three attempts. Second, I would not be able to keep up that flow for over a minute and without confusing the algorithms as I went. There’s a big difference between doing them seriatim with breaks to think about each, and just racing through them seamlessly in a real attack.

Normalized, that effort surely would have been over two minutes (if I could have completed it at all). So, my complete time attack is a dramatic improvement and accomplishment.

Much of the fun of this effort was finding a way to start and end with a solved cube. That’s not necessary for a time attack to be “genuine,” but I thought there was an enviable tidiness to it. It also served as an objective way of confirming that the PLLs were performed accurately. Taking bits and pieces of different folks’ PLL orders from the speedsolving.com forum — and adjusting them for my algorithms (after all, there are many ways of approaching each PLL) — I struck on an order that not only flowed relatively smoothly but also returned to a solve state 7½ times (the ½ was a solved but not AUF'd position). Chunking the algorithms into sections also made it a lot easier to memorize the order. Here it is in detail, exactly as executed, and annotated with turns-per-second (TPS) notes and even an animated reconstruction:

total time: 1:12 (72 seconds)
total moves: 266 (based on ETM)
overall TPS: 3.7
reconstruction: web applet

// yellow up, green front

R U R’ y’ R2 u’ R U’ R’ U R’ u R2   // Gd [12]
R2′ u’ R U’ R U R’ u R2 y R U’ R’   // Gc [12] [solved]
R’ U’ R y R2 u R’ U R U’ R u’ R2   // Gb [12]
R2′ u R’ U R’ U’ R u’ R2 y’ R’ U R   // Ga [12]
// solved [48 moves; 14 seconds; 3.4 TPS]

R’ U2 R U R’ z R2 U R’ D R U’ z’   // Ja [11]
U   // AUF [1]
R’ U2 R’ D’ R U’ R’ D R U R U’ R’ U’ R   // Rb [15]
x’ R U’ R’ D R U R’ D’ R U R’ D R U’ R’ D’ x   // E [16]
// solved (not AUF’d) [43 moves; 11 seconds; 3.9 TPS]

R U2′ R’ U’ R U2′ L’ U R’ U’ L   // Jb [11]
U   // AUF [1]
R U2 R D R’ U R D’ R’ U’ R’ U R U R’   // Ra [15]
M2 U M2 U M’ U2 M2 U2 M’   // Z [11]
// solved [38 moves; 11 seconds; 3.5 TPS]

M2 U M2 U2 M2 U M2   // H [8]
R’ U’ F’ R U R’ U’ R’ F R2 U’ R’ U’ R U R’ U R   // F [18]
R U R’ U’ R’ F R2 U’ R’ U’ R U R’ F’   // T [14]
// solved [40 moves; 10 seconds; 4 TPS]

z D’ R2′ D R2 U R’ D’ R U’ R U R’ D R U’   // V [15]
D’ R U’ R2′ D R’ U D’ R U’ R2′ D R’ U R    // Nb [15]
D R’ U R2 D’ R D U’ R’ U R2 D’ R U’ R’ z’   // Na [15]
y’   // rotation [0]
F R U’ R’ U’ R U R’ F’ R U R’ U’ R’ F R   // Y [17]
// solved [62 moves; 14 seconds; 4.4 TPS]

l’ U R’ D2 R U’ R’ D2 R l   // Aa [10]
l’ R’ D2 R U R’ D2 R U’ l   // Ab [10]
// solved [20 moves; 6 seconds; 3.3 TPS]

M2 U M U2 M’ U M2   // Ua [8]
M2 U’ M U2 M’ U’ M2   // Ub [7]
// solved [15 moves; 4 seconds; 3.8 TPS]

Besides chunking into self-solving sets, I also ordered these from hardest to easiest. I often screw up Gs, so leading with them gave me the ability to start over a few times before I was too far in. The J and R combo sections are not hard to execute, but I did stutter and hesitate a few times — remembering to AUF (to get solved states) and keeping the order straight. Then it picks up steam with the easy H, F, T section at 4 TPS, peaking at 4.4 for V through Y (the most technically challenging but smoothest section for me). That just left the As and Us — both easy, but with some delays in their execution here.

I would have liked to have finished in under a minute, shaving 12 seconds (or 16%). With some practice, I think I’ll be there soon. Certainly, a few stutters as I struggled to remember where I was in the sequence account for a few seconds that I can shave. And if I can relax a little — I always tense up with the timer running and camera on!?! — the layers will fall into place more smoothly and I can pick a few more seconds; a lubed and well-tensioned Zhanchi shouldn’t have snagged that much (and doesn’t when I practice). Right there is about half of the time I’d need to shave to get sub-60....