• Welcome to the Speedsolving.com, home of the web's largest puzzle community!
    You are currently viewing our forum as a guest which gives you limited access to join discussions and access our other features.

    Registration is fast, simple and absolutely free so please, join our community of 35,000+ people from around the world today!

    If you are already a member, simply login to hide this message and begin participating in the community!

Notice to big cube BLD beginners.

Zane_C

Premium Member
Joined
Oct 12, 2009
Messages
2,757
Location
~100km W of Melbourne, Australia
WCA
2010CARN01
YouTube
Visit Channel
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!


---------------------------------------------------

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.

---------------------------------------------------

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.
 
Last edited:

EMI

Member
Joined
Apr 23, 2011
Messages
849
Location
Germany
WCA
2011RHEI01
YouTube
Visit Channel
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...
 

rubiksarlen

Member
Joined
Feb 3, 2011
Messages
563
Location
Malaysia
WCA
2011TANA02
YouTube
Visit Channel
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.
 

cmhardw

Premium Member
Joined
Apr 5, 2006
Messages
4,106
Location
Atlanta, Georgia
WCA
2003HARD01
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:

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!
 

DavidWoner

The Punchmaster
Joined
May 7, 2008
Messages
3,937
Location
Kansas City, MO, USA
WCA
2008WONE01
YouTube
Visit Channel
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.
 

Yes We Can!

Member
Joined
Jan 27, 2009
Messages
2,312
Location
Berlin, Germany
WCA
2009DIEC01
YouTube
Visit Channel
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.
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 :p

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

Zane_C

Premium Member
Joined
Oct 12, 2009
Messages
2,757
Location
~100km W of Melbourne, Australia
WCA
2010CARN01
YouTube
Visit Channel
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.
 

TMOY

Member
Joined
Jun 29, 2008
Messages
1,802
WCA
2008COUR01
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.
 

TMOY

Member
Joined
Jun 29, 2008
Messages
1,802
WCA
2008COUR01
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.
 
Top