Poolology: Zone A missing alignment values

[BC21]

Here's the table setup:

View attachment 706158

The target pocket for the object balls is the top left corner pocket. First, examine the 8-ball. It has a position value of 40, and an alignment value of 40 (the bottom left corner pocket diamond). So, the overhang is 40/40, which is equivalent to 100/100, which makes the overlap 0/100, but the 8-ball can be cut into the target pocket, as Bob Jewett pointed out below, so what's up with the Poolology numbers for that shot? Next, examine the 1-ball. The position value is 50, and the alignment value is once again 40, so the overhang is 40/50, or 80/100, which makes the overlap 20/100, which is slightly thinner than a 1/4 ball hit = 25/100. Obviously, the CB could be placed so that the 1-ball required a thinner cut than a 20/100 to make it in the target pocket.

Therefore, imagine moving the CB upwards towards the top long rail. That would cause the line of centers through the 1-ball and the CB to hit somewhere on the bottom long rail---an area where there are no alignment values specified in the Poolology book. Does that mean a 1/8 ball cut = 12.5/100 is outside the geometry of the Poolology system for such a back cut into the top left corner pocket?

The Poolology book is not that complicated. It's a simple tool that works very well for the vast majority of shots that come up on a pool table. But the system has its limitations.

For the 8ball shot, the system does not work. This has been addressed here and on YouTube. As the alignment value gets closer to the object ball position value, the shot begins to creep outside the system's parameters. That doesn't mean it can't be made. It just means the Poolology system can't give you an accurate aiming solution. The numbers work very well up to a 1/4 ball cut, and also very well for most shots up to a 1/8 cut.
But there are shots where the system begins to become less accurate as the shot nears a 1/8 cut.

The 1 ball shot works just fine using the system. It shows to be between a 1/4 and a 1/8 aim/overlap. OB ball on 50, alignment value of 40, gives an overlap of 1/5, which is slightly thinner than a quarter ball aim. A 1/4 aim would be a little thick, causing the ob to hit the end rail about 2 or 3 inches from the pocket. A 1/8 aim would send the ob to the long rail about a diamond up from the pocket. The exact shot angle (around 52°) isn't important. But it shows that the system is correct, because a 1/4 hit produces a 48° cut and a 1/8 produces a 61° cut. Factoring in throw, based on normal shot speed, these angles are closer to 46° and 60°.

Aiming a fourth of a ferrule (about 3mm) thinner than a 1/4 aim will produce the correct cut angle to pocket the 1 ball.

No 100th fractional math is needed.

 

[BC21]

I don't have access to a pool table right now, but the next time I do, I will try Dr. Dave's angle template and compare to some of the Poolology numbers. Thanks for the suggestion.

Keep in mind that the exact angle to the pocket is NOT the angle you get when you actually cut the call, due to collision-induced throw.

The Poolology system provides a slight overcut to compensate for throw, but the system is not perfect. There are limitations, as shown in this video...

 

[Poolmanis]

Here's the table setup:

View attachment 706158

Hard to see exact placement of balls from little screen of phone. But i would estimate 1 ball is 55-56 degree cut and 8 ball 59-60 degree cut. Very little difference in aiming.

 

[scratchandrun]

I still have not incorporated poolology 100% in my game due to my slow calculations but for the times the fraction is easy to calculate it gives me some peace of mind.

after having a physical point I should aim to i am more focused on my pre shot routine than trying to remember when I saw the contact point or where the ghost ball center is.

the more I use it the easier it is to identify fractions before calculating them so I hope that soonish I will not be needing it for most of my shots

what makes it a bit tricky is finding which positional values to use for 40+ in zone A and zone C.

I think the book could use some more examples from those zones

 

[7stud]

what makes it a bit tricky is finding which positional values to use for 40+ in zone A and zone C.

Yes, I had that problem, too--especially when the position lines change by 20 in Zone C. This is what I am doing now: I lay my cue stick on one position line (don't let go of it!), then I move my body and sight down the other position line. That allows me to more easily estimate where the OB lies between the two position lines.