How to find a sabotaged piece?

[olekosun]

So my brother likes to sabotage my cube when I'm not around, and take an edge or corner out and put it back in the wrong way, and then scramble up the cube.

The F2L is then solvable, but I get stuck trying to complete the last layer. I then have to take the whole cube apart and reassemble it the correct way. Is there a trick to spot the wrong piece right away without needing to fully disassemble and reassemble it?

 

[EnterPseudonym]

instead of reassembling the whole cube, just flip/twist the piece that is wrong.

 

[aronpm]

Tell your brother to **** off.

Also, you can flip an edge or twist a corner without reassembling the entire puzzle.

 

[DcF1337]

Why do you need to take whole cube apart when you can just disassemble and reassemble the top layer?

Usually turning around one edge piece works. If you still can't solve it just rearrange the necessary corner pieces.

 

[EnterPseudonym]

Or tell him if he wants to make it really unsolvable to flip an even number of edges.

 

[Deleted member 2864]

Or tell him if he wants to make it really unsolvable to flip an even number of edges.

This.

Or you could tell him to stop twisting the corners because those are the hardest to fix. Most cubes can have the corners twisted without taking any pieces out at all.

 

[Ranzha]

Whenever someone who I know has messed with my cube before scrambles the puzzle, I immediately check for corner orientation and edge orientation.
At that point, I wouldn't try looking for permutation parity--I'd have to do a BLD memo thing, which I am not in favour of.

EDGE ORIENTATION:
Look at the edge in UF.
If a U/D-face sticker is on the U-face, it is oriented.
If a U/D-face sticker is on the F-face, it is NOT oriented.
Assume now that there is no U/D-face sticker on the edge.
If a F/B-face sticker is on the U-face, it is oriented.
If else, it is NOT oriented.

Apply for spots:
UL, FL, DL, BL, UB, UF, DF, DB, UR, FR, DR, BR.
The way to check the orientation is to look at the sticker of the edge that is named first: for an edge BL, you'd check the sticker on the back, and not the left, since in BL, B was indicated before L.

Corner orientation:
Look at the U-layer. More specifically, the UFR corner.
Which way is the U/D-face sticker on the corner facing?
If it's up, call it a "0".
If it's to the right, call it a "2".
If it's to the left, call it a "4".
Repeat process for the U layer. Then, repeat with the D layer. Do an x2 rotation and find the values.
Add all of the values you get. If it is divisible by 6, the cube has no corner orientation parity. If you have a remaining indivisible value of 2, flip any corner anticlockwise. If it's 4, flip any corner clockwise.

 

[FatBoyXPC]

I just solve f2l then solve OLL via 2LOLL method. If you have 3 edges oriented you know which one to flip. If you have all 4 edges oriented check to see which corner is wrong. If you have a cross shaped OLL, there are only two ways the corners will be oriented. Just look up the 4 edges oriented section of the OLL section of the wiki (which is only 7 OLLs). When you see what you are closest to, flip the incorrect corner to the position it should be in.

FYI, this does not mean he flipped that piece. That's just how it worked out if you already "solved" the piece that he flipped incorrectly. A lot of people will try this to cubers, and after you get experienced enough you can just solve, pop the piece out, fix it, finish the solve, like it's no big deal. It really upsets those people when you solve it like that and still break 30 seconds, 20 seconds, whatever.

 

[stinkocheeze]

Learn full OLL and make it into a case you know.

 

[jiggy]

Is your brother a cuber? If not, I think it's most likely that the only way he knows how to sabotage your cube is because you told him how. Tut tut tut, what have we learned?

Just solve F2L and you'll either see an impossible OLL or an impossible PLL.

ie/
Only one or three edges orientated - invalid state
A 2LOLL case you don't recognise - invalid state
(If you don't know 2 look OLL, shame. on. you.)
A PLL you don't recognise - invalid state.

and then fix the piece that's wrong.

 

[Matt S]

Fixing the Cube never requires rearranging more than one row (on edge plus two corners), and it doesn't matter which row you choose, although you'll obviously choose one that isn't yet solved. If an odd number of edges are correctly oriented, flip the edge. If the permutation is odd, swap the corner position. And, orient the corners such that the total twist of all corners is divisible by three. Then solve the last layer as normal.

After you've had enough pops, recognizing all this becomes second nature.

 

[cubedude7]

Solve the cross/f2l, and try to do OLL/PLL, and you will see the flipped pieces.

 

[blah]

Corner orientation:
Look at the U-layer. More specifically, the UFR corner.
Which way is the U/D-face sticker on the corner facing?
If it's up, call it a "0".
If it's to the right, call it a "2".
If it's to the left, call it a "4".
Repeat process for the U layer. Then, repeat with the D layer. Do an x2 rotation and find the values.
Add all of the values you get. If it is divisible by 6, the cube has no corner orientation parity. If you have a remaining indivisible value of 2, flip any corner anticlockwise. If it's 4, flip any corner clockwise.

lol

If it's up, call it a "0".
If it's to the right, call it a "572639".
If it's to the left, call it a "1145278".

...

If it is divisible by 1717917, the cube has no corner orientation parity.

1717917 - that's really easy to remember!

 

[RealDeal]

Well at least he removes the piece and flips it around. I've had some people truly **** me off by "flipping" an edge by removing the stickers and putting them the wrong way.

and as for solving this, on the last layer just look at how many edges are orientated correctly. All oll cases have either 0, 2 or 4 edges orientated, if you have either 1 or 3 orientated just flip the one that is not orientated.