Last 2 centers are killing me.

[Hadley4000]

On the 7x7x7, it is taking me sometimes up to an HOUR JUST to get the last TWO centers. I know zero algs for stuff like that. I want to be able to get decent times on the 7x7x7, but need something aside from the hope-for-the-best method.

 

[joey]

Learn commutators.

 

[mrCage]

On the 7x7x7, it is taking me sometimes up to an HOUR JUST to get the last TWO centers. I know zero algs for stuff like that. I want to be able to get decent times on the 7x7x7, but need something aside from the hope-for-the-best method.

Hi

This what i have predicted. Knowledge from 4x4x4 and 5x5x5 is not really always enough to solve even larger cubes, if you use a reduction approach. I foresaw the trouble with the centers.

And yes, easy commutators is a (the) cure for that.

- Per

 

[Leviticus]

I have the same problem, it takes me about 5-6 minutes for the first 4 centers and then another 5-6 for the last 2. I just get as far as possible, say i center wrong on each, and then just play around with slices trying to make that 1x6 bar, its not consistant but its fun

 

[CharlieCooper]

and that is exactly why i got so incredibly angry with a 7x7 on gabbasoft

 

[Jason Baum]

Here are a couple of basic moves that should help you out:

r U r' U r U2 r' (just a Sune with slice turns)

r' d r U' r' d' r'

Try messing around with these algs a bit to see how they work. You can also do the same moves on the inner layers to solve different pieces. Obviously, you want to build as many center pieces as possible before having to use these algs.

 

[masterofthebass]

When I do my last 2 centers, I do half of one face first. Then, I work my way out, and I'm left with either 1 or 2 oblique centers left to do w/ commutators. For 7x7, think of the inner 9 as 5x5 edges, and then attach the outer ones to that 1x3 block. I find it much easier to think this way.

 

[fanwuq]

I spent a really long time trying to figure that out on gabbasoft too! Except I figured it out in about 5-15 min. I don't remember what I did, but it was all intuition. I just tried some weird commutators and tried to pair things. I did double layer PLL parity, H perm, U perm, etc.
It's quite a bit different from the 4x4.

 

[Harry]

So, if I don't use reduction,is it the same case if I use cage? Or I suppose to learn commutators

 

[rjohnson_8ball]

Hmm, I used to do huge cube centers (on a computer) in a different way. By huge cubes, I mean like really big. I did 31x31.

First, I would solve 4 out of 6 faces, with 2 faces left.

Then I would use (r f r' f ') (U?) (f r f ' r') (U?').The U? would be U or U' or U2... a U turn of your choice. The r and f indicate the slice that isolates the bad center cubie. The result after the sequence would be the bad U center cubie swapped with a center cubie on the F face. EVERYTHING else stays undisturbed. After that, you can swap 2 more, again, and again until you have the centers correct.

I have not hardly read any sites on big cubing, but my methods worked okay for me. Caution, what I recommend might not be suitable for speed, but it makes solving managable.

My method can be slower than just starting the last 2 centers as 2x3, expanding to 3x3, then appending rows and corners, building them up. See http://www.speedsolving.com/forum/showthread.php?t=4930

 

[mrCage]

So, if I don't use reduction,is it the same case if I use cage? Or I suppose to learn commutators

Hi

Cage is very heavily relying on commutators in nature. Block handling is used to speed things up. The fact that there are many centers on same orbital with same colour makes centers commutators quite powerful. When "swapping 2 centers" on a cube don't make the common mistake of filling in the missing tile with the first part of a ABA'B' commutator. The missing tile is coming from another spot on same layer most of the time.

Example:

AAB >>> BAA

This looks appearantly like a swap not a 3-cycle. So actually it's better written like so

A1,A2,B >>> B,A1,A2

I'm too lazy right now to make proper diagrams or explaining exhaustive in any way ....

- Per

 

[rachmaninovian]

well harry since sgcubers is up again you can always approach me about centre commutators..haha.
If you understand how the commutator you are using works, while switching some centres you can actually deliberately pair up blocks to switch later.

 

[Harry]

well harry since sgcubers is up again you can always approach me about centre commutators..haha.
If you understand how the commutator you are using works, while switching some centres you can actually deliberately pair up blocks to switch later.

hmmm, how do you know I am in the sgcubers?

@mrCage, how the commutators are supposed to help me in solving big cubes. The one that I have only got R, L, U and D...... There is no r, l, u and d.....

Do I must modify the 3x3x3 commutators myself or what?

Thanks........

 

[rachmaninovian]

I don't think they work the same. maybe try niklas? and change the R and L to r and l respectively. I personally do not use that. I use (y) l' d l U2 l' d' l U2 (y').
faster for me somehow.

 

[mrCage]

well harry since sgcubers is up again you can always approach me about centre commutators..haha.
If you understand how the commutator you are using works, while switching some centres you can actually deliberately pair up blocks to switch later.

hmmm, how do you know I am in the sgcubers?

@mrCage, how the commutators are supposed to help me in solving big cubes. The one that I have only got R, L, U and D...... There is no r, l, u and d.....

Do I must modify the 3x3x3 commutators myself or what?

Thanks........

Hi

I will get some (Gabbasoft) vidcaps done. But not while im at work of course :rolleyes:

- Per