7x7 help: I thought I had it but I don't

[rasiel]

I managed to solve the 7x7x7 for the first time (took me forever) but then I'm drawing a blank on the 2nd solve. Building the inner 3x3 and the corners is very easy but how does one get these guys in their right places without messing anything else up?
View attachment 7

 

[lerenard]

never solved a 7x7, but that looks like it would require a commutator to solve. If you don't how to do those, look it up.

 

[AlphaSheep]

This video help me when I had the same problem

Spoiler

 

[Dene]

Use niklas on the inner slice.

 

[rasiel]

I've seen that video like 84 times but the dude goes way too fast for me and I end up getting frustrated because I have three unsolved sides, not two. The thing everyone keeps saying is that only the last two centers are difficult. Not so. Building the first two is easy enough but the other four faces you lose your working area so you constantly have to be aware of not messing up the completed sides.

What's most frustrating is that on the first solve at one point it "all clicked" in my head and I was able to complete the centers but now I lost that mental clarity. I'll get it eventually but wish there was an idiot-proof tutorial or even notation for dealing with these commutators.

 

[Dene]

The reason having three centres is easy and only the last two is harder is because when you have three left you only have to turn those three sides. Don't focus on commutators, build blocks! Just build 1x5 rows and slot them all in together.

 

[AlphaSheep]

Talking about the last two centres is misleading because you're really just solving the one and the last one gets solved automatically because there are no centre pieces left. Because of this, you can use any technique for the last two centres on the 3rd last, or even 4th last centre. Just focus on one centre at a time.

There is a notation for dealing with this. Say, R refers to a clockwise turn of the outer layer, r is a clockwise turn of the 2 outer layers from the right, 3r is a clockwise turn of the three layers from the right.

To solve the situation in your picture, you can do:

• Line up the missing red block to with where it needs to go: F
• Move the red block into position: 3r r'
• Move the newly solved red line out of the way: U' r
• Bring back the red pieces that you moved out of position: U 3r' r
• Bring back the red line that was moved out of the way: U' r'

Watch this animation if you're having trouble with the notation

 

[rasiel]

After many, many hours I think I finally have it down. I wanted to say thanks to everyone who responded here. If I can figure out a way to hold the phone in a stand I'll post a video so I can help others who are in this rut I've been in!

Many thanks again.