Rubik's Cube (3x3x3) Cross Optimization (Fridrich Method):
Rubik's Cube (3x3x3) Cross Optimization for the Fridrich Method:
by: Caleb Lau
Introduction:
I always tell people that the cross is the easiest step in solving the Rubik's Cube with a Fridrich-style approach. However, I also believe that the cross is one of the hardest steps of the Fridrich method to master. This is because it is the most intuitive part of the solution and it does require some amount of thought and creativity. The problem then is not solving the cross, but solving it effectively and optimally. Mastering a step that involves such, requires the solver to understand and apply various techniques that can be attained with in depth practice and study of the cross.
In this article, I want to help you start out with some simple techniques that I have adopted while solving the cross. This guide is written for you to save you the time and effort that it would take you to realize these techniques. However, as I will always say, it is imperative that you fully understand exactly what you are doing in each of these cases, so that you can apply them masterfully during an actual solve. You know that you have mastered cross optimization when you can solve it everytime in no more than 8 turns.
As a prerequisite for this article, it is recommended that you already understand how to solve a cross on the Rubik's Cube. Whether or not you are solving effectively is not important. This is what we will discuss here in this article. Also, basic knowledge of standard notation is recommended.
Basics:
One of the most important aspects of the Rubik's Cube that must be taken in thought when solving the cross is the overall color scheme. It is imperative that you know your color scheme. You should be able tell what colors are on R, L, D, and B just by looking at U and F. In this guide, I will be using standard American color scheme, that is: Red-Orange, Green-Blue, and White-Yellow with a BOY corner. Examples will be shown solved on White.
When solving the cross, many novices will not have a regular cube position, always making whole cube turns. However, this can prove to be ineffective because it takes more time to look for pieces on a moving cube than on a static one. Idealy, in the Fridrich method, one should be looking ahead on the Rubik's Cube for F2L pairs as they are solving the cross. It should not be nessecary to look at for cross pieces because that is done during inspection time. Now that we have established a need to solve the cross in a consitant location, the question remains: where?
I, personally, would recommend learning to solve the cross on the D face of the Rubik's Cube. This is because the rest of the cube can be seen with cross on the bottom. As I stated above, all your thought should be directed towards looking ahead, so you should not need to look at what you are solving. By putting the cross on the bottom, you are able to see what you have yet to solve, and you don't have to be distracted by what you have already solved. Although most beginners find it easier to learn to solve the cross on the top, in the end it would be better to solve it where it will be less prominant. Aside from using the B face, many cubers use either the L or R face, depending on what specific hands they use to solve. Although I recommend solving on the bottom, solving on the sides is still better than solving on U or F. All examples in this guide will work with solving on the bottom, however in the applet you can turn the cross to say, the L face, and watch from there.
Let's get started with some techniques!
Technique #1: Using 'Helping' Moves to 'Help' Other Edges
This first technique is just a technique that can help you to lower the total number of turns needed to put the edges on the B face.
When putting in edge pieces to form the cross, many cubers tend to put one piece at a time. Of course, you can only put one edge piece in its spot at a time, but you can use the moves that it takes to put the edge in its spot to setup another edge(s) to be put in easily. Yes, that was a complicated explaination, so I'll say it again; this time try to see what I'm saying: You can only put one edge piece in its spot at a time, but you can use the moves that it takes to put the edge in its spot to setup another edge(s) to be put in easily. I'll use the applets below to explain.
In this example, we are solving the Blue and the Orange pieces. The first two turns, R' U, set up the Blue piece to be put into the B face. The third turn puts the the Orange into its spot, placing the Blue piece right it needs to be to put it in the B face as well.
In this example, we solve for all the pieces. Take you time and try to understand how this works. Go step by step and try to identify the 'helping' moves and the pieces that they 'help.' When you fully understand this, you will be able to combine this technique with the next.
BEWARE: Only combine this technique with the next if you want your Cross time to drop dramitcally.
Technique #2: Relative Placement of Edge Pieces
The edge pieces on the Cross must be in position with their respective center pieces for it to be considered "solved." However, this does not mean that the edge pieces must be solved into their correct position. Because the center pieces do not move in relation to one another (this is not physically possible), they can be used as reference points. This is why it is imperative to know your color scheme by heart. If you can solve the edges in relation to one another, then sometimes it can save you time. After solving the edges into their relative position, you can do either a D, D', or D2 to get the pieces into their right spot. See the applets below for examples and assistance. (Hint: as you are looking out for these cases, try looking for opposites. In my opinions, these are the easiest to work with.)
This is an easy example. Watch as the pieces are solved on the B layer, then turned to match their centers. It might be easier to track if you watch it step by step.
This is an example in which the relative positions are a D2 away from the right positions. Once again, it may be easier to follow the applet if you take it step by step.
This technique, although relatively easy to follow and execute, can dramatically decrease your cross solving times by not restricting where you can place the edge pieces.
Using Inspection Time Wisely
Inspection time is the time for you to look at whatever you want to look at on the cube before the actual solve. Most people tend to look for the optimal cross solution, but other, more skilled Fridrich-users, can sometimes even look ahead to the point of F2L pairs. I would recommend just sticking with looking for the cross. This is mainly because you don't want to over-cram your mind with information before you solve. During a solve, it is essential that your brain be active, but relaxed. If you cram too much information into your head, you will stress yourself out before the solve.
With that said, it is important that, while practicing, you practice using your inspection time. If you are just starting out with cross optimization, I would recommend that for a couple days, you just focus on optimization and not on the time it takes you to solve the cross. Then after more practice, slowly time your inspection time and practice to get the time down to 15 seconds, the official alotted inspection time. After becoming more consistant at that, practice memorizing your cross solution. You should be able to solve a cross behind your back after 15 seconds of inspection.
Optimization vs. Speed
A big debate among Fridrich users is whether or not a fast cross time is important. Some say that with a fast cross, you save time (obviously), while others say that while taking your time on the cross, you can look ahead for F2L. Which one is more effective?
This is one of those cases where I would say it is up to personal preference. It all depends on your personal cubing style. For me, I try to find a middle ground. I try to look ahead for F2L pairs, but I don't let that slow my overall tempo down. If I can't find any pieces, I don't slow down and look, I just continue on and look for pairs later.
Conclusion
I find my conclusions to articles becoming more and more alike. This time I'll keep it short: Practice!!
If you have questions or comments, please feel free to contact me
Happy Cubing!
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