# Notice to big cube BLD beginners.



## Zane_C (Jun 4, 2011)

This may seem obvious, but it's important to address.
It's a mistake many cubers (including myself) have made when starting big cubes BLD. Maybe you still do it. 

I'm talking about memorising your centers perfectly, executing your memo perfectly, then taking off your blindfold with 100% confidence... to reveal UNSOLVED centers!

*This is because after solving other pieces, the centers have been arranged differently to how you memorised them!*

*This error can be easily eliminated by solving centers FIRST.
If you solve pieces before the centers (ie. wings, midges, corners), make certain that the algorithms you use do not disturb the centers!* 

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*Example: *
Solving the corners first is popular for any sized cube. If you're using Old Pochmann, the U center/s are offset by a U' for every Y-perm!

_Solution:_
The most obvious solution would be to either switch to a center-friendly corner method, or execute them after the centers.
If you really don't want to switch solving method or execution order:
You can do a U, U' or U2 set-up to rotate the centers to where they were when you memorised them. Then undo the set-up after the centers are solved. Cornelius Dieckmann does this. 
Other solutions are stated in posts within this thread.

For M2 uses, M U2 M U2 and its inverse are NOT center-friendly.

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*Parity algorithms:*
The common parity algs are NOT center-friendly, so execute parity algs AFTER the centers are solved.

*Choose your parity/flipping algs wisely:*
Even after the centers are solved on a 5x5, a midge flipping or parity alg swapping UF and UB wings may still affect the centers.

Eg. 
r2 U2 r2 Uw2 r2 u2 will disturb the centers if they are already solved.

Rw2 F2 U2 r2 U2 F2 Rw2 will NOT disturb the centers if they are already solved.


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## EMI (Jun 4, 2011)

In all the tutorials I have seen, this problem was mentioned. I usually momorize centers, then memorize edges and corners, and solve it the same way.
Another way to do mind the problem is using algoritms that do not rotate the centers. I prefer the first way. That's what it was explained like in all the tutorials...


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## rubiksarlen (Jun 4, 2011)

one more thing if you use old pochamnn corners 1st and centers after:

if you have corner parity (t-perm+pll parity fix to fix it), do it AFTER u solve the centers because if u do it right after corners the centers will be off by some U turns, as a t-perm has an odd number of U's.


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## Zane_C (Jun 4, 2011)

You can do a Y-perm, then a J-perm.

There's a lot of things you can do, I was only giving people the gist of it.


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## cmhardw (Jun 4, 2011)

Awesome thread idea! I too have made this mistake multiple times before I finally realized it! My solution was to solve centers first, just as you say in the top part of your post.

I only found one error:



Zane_C said:


> Rw2 F2 U2 r2 U2 F2 Rw2 will NOT disturb the centers.


 
On my 5x5x5 supercube this swaps the 1x3 center block on the U and l faces with the one on the U and r faces by rotating each 180 degrees around the central most U face center. It also rotates the 1x3 block on the l and F faces with the r and F faces by rotating them 180 degrees around the F face central most center.

I use a similar alg for this case: Rw2 Fw2 U2 r2 U2 Fw2 Rw2 and it has the same effect.

Awesome thread idea! I think it will help many people out!


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## DavidWoner (Jun 4, 2011)

Zane_C said:


> You can do a U, U' or U2 set-up to rotate the centers to where they were when you memorised them. Then undo the set-up after the centers are solved. Cornelius Dieckmann does this. However, this can take a bit of thinking and isn't highly recommended.


 
I highly recommend it.

What I don't recommend is learning a new corners method (either exec or memo) solely for the purpose of bigBLD, when this simple trick will suffice. If I had thought I would have to learn a centers-safe corner method or redo my corner memo so it was strong enough to last through center exec I would have never attempted 4BLD.

Learning edges and centers is daunting enough, I would never tell a beginner they need to relearn corners when it is totally not necessary.


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## Zane_C (Jun 5, 2011)

@ Chris, what I meant to say was Rw2 F2 U2 r2 U2 F2 Rw2 won't scramble 5x5 centers if they are already solved.
I get the feeling that I'm not responding to your post correctly...

@ David, thanks, very good point.


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## Yes We Can! (Jun 5, 2011)

Zane_C said:


> *Example: *
> Solving the corners first is popular for any sized cube. If you're using Old Pochmann, the U center/s are offset by a U' for every Y-perm!
> 
> _Solution:_
> ...


 
I actually do something different (less efficient):
If I have e.g. 6 targets, I do another 2 y-perms to have the centers restored again.
If I have 5, I do another 3. If I have 3 --> 1 more y-perm.
So basically I add as many y-perms needed to have a multiple of 4.

Regarding parity - example: 7 targets; what I'd do:
Execute all 7 targets, do another y-perm (this way I'd have done 8 y-perms in total), solve parity at the end of the solve (you can use (F R U' R' U' R U R') (U r2 U2 r2 Uw2 r2 Uw2 U) ( R U R' U' R' F R F') for that).

(sorry if that was badly worded)

Another thing you can do:
If you have let's say 5 targets, just leave out the 5th (because then you have done 4, which is a multiple of 4) and do the 5th one at the end of the solve.
Obviously, you can leave out as many targets as you want to, as long as your amount of done y-perms is a multiple of 4.

tl;dr: Use what Zane_C said 

PS: I did the y-perm mistake too on my first few solves. Yay! I'm ****ing retarded


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## Zane_C (Jun 5, 2011)

Yes said:


> PS: I did the y-perm mistake too on my first few solves. Yay! I'm ****ing retarded


Haha, there's no need to say that, as it's not common knowledge that a Y-perm rotates the U center 90 degrees ccw.

When I used to count the Y-perms, the most annoying thing was shooting to the wrong corner/s. Then having to undo, while still keeping track of the Y-perms.


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## TMOY (Jun 5, 2011)

Yes said:


> Another thing you can do:
> If you have let's say 5 targets, just leave out the 5th (because then you have done 4, which is a multiple of 4) and do the 5th one at the end of the solve.
> Obviously, you can leave out as many targets as you want to, as long as your amount of done y-perms is a multiple of 4.
> )



Another idea: the inverse of the Y perm happens to also be a Y-perm, and rotates the U center in the opposite direction. So just alternate between them, that way in non-parity solves the U center will always be back in place at the end.


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## JonnyWhoopes (Jun 6, 2011)

TMOY said:


> Another idea: the inverse of the Y perm happens to also be a Y-perm, and rotates the U center in the opposite direction. So just alternate between them, that way in non-parity solves the U center will always be back in place at the end.


 
Ooh, I like that. Is there anybody who actually uses this in solve?


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## TMOY (Jun 8, 2011)

No idea, I don't use Pochmann corners myself. But for someone having trouble to keep track of the number of Y-perms he has performed it's IMHO a possiblity to consider.


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## Jakube (Jun 8, 2011)

JonnyWhoopes said:


> Ooh, I like that. Is there anybody who actually uses this in solve?


 
I don´t. But I solve the centers first, and after that the edges, so I don´t have to worry about messing up the U centers.


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## rubiksarlen (Aug 24, 2011)

anyone know where i can learn 5x5 BLD from?


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## riffz (Aug 24, 2011)

rubiksarlen said:


> anyone know where i can learn 5x5 BLD from?


 
I'm not sure that there's a comprehensive source that will walk you through all of it, since it's basically a combination of 3BLD and 4BLD piece types and some extra stuff involving parity. +centers are really the only new thing in 5BLD, and I find them to be way easier than x-centers.


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