Petrus Help

[VoltageX]

hey, I just switched to to the Petrus method since my LBL solves got down to about a minute and i need help to cut down my times. The main thing i need to loose time on is checking bad edges (It takes about 20 seconds). Can someone please give me hints on how to reduce my check bad edges time and overall Petrus solve time?

- Thanks in advance

 

[Kyle™]

The only thing I can think of is when you see a pair of bad edges, remember you do not need to watch yourself do the algorithm to ensure you complete it correctly. Right as you locate a pair of bad edges, you need to continue looking as you begin to flip them. A large portion of time can be saved by continuously scanning the remaining edges as you flip pairs. Also, try to locate bad edges on whichever face is most visible after your previous step. So, as you are completing your 2x2x3 phase, start looking ahead. Teach yourself to look for other things "as" you complete steps, not "after" you complete steps.

 

[immortalcube]

Flipping bad edges is the easiest step in the Petrus method. However, it's also the hardest to wrap your mind around at first. All you need to do is look at the 7 edges that are not part of the 2x2x3. If you put them in their correct position using only the two free layers (without breaking up the 2x2x3 block in any way for any reason), would they be correctly twisted, or would they be incorrectly twisted?

When you become more advanced, you can look at this step thusly: If our two free faces are the U and F faces...
Any edge on the U face that has the U face color facing up is good. Any edge on the U face that has the F color facing up is bad.
Any edge on the F face that has the F color facing forwards is good. Any edge on the F face that has the U color facing forwards is bad.

This might seem complicated now, but it will be very easy once you get the hang of it, and you won't even think about it. Now that you can recognize bad edges, fix them!

As for the rest of your solve time here is some good general advice:
Look ahead! Even if it means you have to go a bit slower, find the pieces you are going to use before you need them. I've found that setting a metronome to a slow pace, and doing one turn per beat forces me to look ahead. (use http://www.metronomeonline.com/ if you don't own one).
Practice, Practice, Practice!! That is the key. Switching to a faster method does not guarantee immediate improvement. In fact, your times will probably be really high for the first week or so. However, they will never improve if don't practice enough.

Sorry if I ran a bit long there. All of the information you need on the Petrus method can be found at his site: http://lar5.com/cube/ . If you need any more help, PM me and I will try to help you as well as I can.

 

[CharlieCooper]

as someone has just said, i can only really suggest looking for one pair as you get rid of another (or spot the first pair as you place the last pieces of your 2x2x3) you can also eliminate some bad edges while you complete the 2x2x3 (there is a good youtube video... but i can't remember who did it and where it is!) which means you at least won't be in a situation with 6 bad edges (unless 6 bad edge algs are your bag, of course!)

i think you just need to practice a lot, you will soon be able to spot them very very quickly and that obviously makes getting rid of them far simpler.

 

[ubervern]

When you become more advanced, you can look at this step thusly: If our two free faces are the U and F faces...
Any edge on the U face that has the U face color facing up is good. Any edge on the U face that has the F color facing up is bad.
Any edge on the F face that has the F color facing forwards is good. Any edge on the F face that has the U color facing forwards is bad.

um.. any edge on the U face without the U face color facing up is bad as well, it does not have to have the F color facing up. same for the F face.

I never look for good edges.
In learning this I always named aloud the U and F face colors so that when turning the cube in my hand I could remember what I was looking for. But with practice it does become second nature, I sometimes find myself fixing edges without having consciously identified which ones were wrong.

 

[immortalcube]

When you become more advanced, you can look at this step thusly: If our two free faces are the U and F faces...
Any edge on the U face that has the U face color facing up is good. Any edge on the U face that has the F color facing up is bad.
Any edge on the F face that has the F color facing forwards is good. Any edge on the F face that has the U color facing forwards is bad.

um.. any edge on the U face without the U face color facing up is bad as well, it does not have to have the F color facing up. same for the F face.

I never look for good edges.
In learning this I always named aloud the U and F face colors so that when turning the cube in my hand I could remember what I was looking for. But with practice it does become second nature, I sometimes find myself fixing edges without having consciously identified which ones were wrong.

I was just showing an example of how you could make a set of rules to define good and bad edges, without fully giving him the answer. I never have to think about if an edge is bad or not anymore. After enough practice you just subconsciously know which ones are and are not.

 

[Statical]

just a question what really is the use of switching the bad edges?

 

[Johannes91]

what really is the use of switching the bad edges?

It's a trivial step that takes barely any time at all, and makes the rest of the solve a lot easier. How would you continue the solve if you didn't fix them?

 

[Swordsman Kirby]

just a question what really is the use of switching the bad edges?

Do you like <R,U> or <R,F,U> more?

 

[Statical]

just a question what really is the use of switching the bad edges?

Do you like <R,U> or <R,F,U> more?

R,U of course but im was just asking coz i really never understood this concept of switching bad edges im a fridrich user anyway

 

[immortalcube]

if you switch bad edges after making a 2x2x3 block, you can finish the rest of the F2L in 2-gen, and you always get cross OLLs, so you only have to learn 7 algs to have 1 look OLL.

 

[Speedy McFastfast]

just a question what really is the use of switching the bad edges?

Do you like <R,U> or <R,F,U> more?

R,U of course but im was just asking coz i really never understood this concept of switching bad edges im a fridrich user anyway

To build on what SK was saying, when you flip bad edges the rest of the F2L is done completely with RU turns. After that you only have 7 OLLs to know, and then PLL.

 

[Statical]

ok i finally get thiis concept after months thx alot