When Dr. Dave posted about close combinations, I immediately saw the huge benefit these concepts could have when applied to opening clusters in straight pool. If you haven't seen it, look here:
http://forums.azbilliards.com/showthread.php?t=467238
The long and short of it is that for a 3/8" gap, which is just under a shaft diameter, you can shoot either left or right as much as a half ball hit and the ob will still go straight forward (line of centers). If you are interested you really should read Dave's thread first.
In the first photo below I've illustrated a combination that just misses to the left point. So how do we know if this shot can be made? Well, most of us know that if the two balls (5 and 15) are frozen or close to frozen, then the 15 can be thrown in if you can hit the 5 from the left side. Pretty basic. Now the interesting part. If the gap is close to 3/8" as easily measured by comparing to your shaft diameter (typically 13 mm or 1/2 inch) then you have to be very careful. Dave's analysis shows that in this situation you cannot alter the straight path of the 15 ball into the left point almost no matter what you do with the 5 ball (except for large angles beyond a half ball hit). Yes, you can throw balls some with english, but in many clusters you can't do that because there are too many balls in between. The english wears off before it gets to the ob.
So if the combo balls are close we can throw them to the right, if they are close to a shaft diameter apart, you can't throw them. If they are farther apart than that, like a full shaft diameter, then you can overcut the ball in the other direction.
What happens in this scenario? Refer to the second photo close up. In a cluster like this, everything is determined for you. Either the shot will go or it won't. About the only thing you can alter is the speed of the shot. Can the combo be thrown to the right in order to pocket the ball? Well in this case the cb is up table, to I'll be hitting the 4 ball. The 9/14 tangent line is in the direction of the yellow line. This shows that we'll be hitting less than a half ball hit, putting the shot within the parameters of Dave's analysis (plus or minus a half ball hit). So we'll be pushing the 5 to the right of the red line of centers. With a gap smaller than 3/8" we know that this will also throw the 15 ball in that same direction. Conclusion: the shot is dead on.
Given that I had a whole pocket to work with, I shot with less speed rather than more. This increases the amount of throw, assuring enough to move the 15 away from that point. Sure enough the 15 went just left of center pocket.
Now in this example I could have made it more interesting to separate the two balls a little and make the gap bigger. I'm sure many of you would say that you know it will throw right because of the small gap. But (be honest now!) how many of you knew that this shot would turn into impossible if the gap were just a little wider at 3/8"? It became clear to me that this kind of analysis was lacking in my game because when I went through this thought process with this particular shot I kept thinking it didn't look like it could go.
I hope Dave's great discovery opens up some avenues for helping you get through straight pool racks. I know it has been an eye-opener for me.
http://forums.azbilliards.com/showthread.php?t=467238
The long and short of it is that for a 3/8" gap, which is just under a shaft diameter, you can shoot either left or right as much as a half ball hit and the ob will still go straight forward (line of centers). If you are interested you really should read Dave's thread first.
In the first photo below I've illustrated a combination that just misses to the left point. So how do we know if this shot can be made? Well, most of us know that if the two balls (5 and 15) are frozen or close to frozen, then the 15 can be thrown in if you can hit the 5 from the left side. Pretty basic. Now the interesting part. If the gap is close to 3/8" as easily measured by comparing to your shaft diameter (typically 13 mm or 1/2 inch) then you have to be very careful. Dave's analysis shows that in this situation you cannot alter the straight path of the 15 ball into the left point almost no matter what you do with the 5 ball (except for large angles beyond a half ball hit). Yes, you can throw balls some with english, but in many clusters you can't do that because there are too many balls in between. The english wears off before it gets to the ob.
So if the combo balls are close we can throw them to the right, if they are close to a shaft diameter apart, you can't throw them. If they are farther apart than that, like a full shaft diameter, then you can overcut the ball in the other direction.
What happens in this scenario? Refer to the second photo close up. In a cluster like this, everything is determined for you. Either the shot will go or it won't. About the only thing you can alter is the speed of the shot. Can the combo be thrown to the right in order to pocket the ball? Well in this case the cb is up table, to I'll be hitting the 4 ball. The 9/14 tangent line is in the direction of the yellow line. This shows that we'll be hitting less than a half ball hit, putting the shot within the parameters of Dave's analysis (plus or minus a half ball hit). So we'll be pushing the 5 to the right of the red line of centers. With a gap smaller than 3/8" we know that this will also throw the 15 ball in that same direction. Conclusion: the shot is dead on.
Given that I had a whole pocket to work with, I shot with less speed rather than more. This increases the amount of throw, assuring enough to move the 15 away from that point. Sure enough the 15 went just left of center pocket.
Now in this example I could have made it more interesting to separate the two balls a little and make the gap bigger. I'm sure many of you would say that you know it will throw right because of the small gap. But (be honest now!) how many of you knew that this shot would turn into impossible if the gap were just a little wider at 3/8"? It became clear to me that this kind of analysis was lacking in my game because when I went through this thought process with this particular shot I kept thinking it didn't look like it could go.
I hope Dave's great discovery opens up some avenues for helping you get through straight pool racks. I know it has been an eye-opener for me.
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