Parallel Shift Banking System

[Petros Andrikop]

I would describe the Grady rule as "x to 0.375x," which is the same as Eckert's "2x to 3/4x" rule. My rule, which measures across from the diamonds in the rail grooves, instead of through the diamonds on the rail, is the "(2x+1/3) to x" rule.


Per the diagrams in my July '13 BD article, the lines of aim from the "(2x+1/3) to x" rule actually agree with the through-diamond "2x to 3/4x" rule fairly well over the range of typical bank shots. When I get some time, I'll do some experiments at home and check the comparisons carefully.


The systems definitely differ for large-angle banks like this. I look forward to testing these out too.

Thanks,
Dave

I'm not sure if Grady's approach is actually x to 0.375x or Eckerts 2x to 3/4x, Eckert is just taking off 1/8 for every diamond distance, to reach the same spot as Grady.
I still believe Grady's approach is the most simple, for it's very easy from every position to estimate 50%, 75% and 62.5% which is in between. No need to find an extra point at cushion contact and seems very reliable. I haven't measured exactly the differences between that and 2x+1/3 but seems they should have significant variations as the angle opens.
Anyway, this is good food for thought, thanks for the responces.
Best,
Petros

 

[dr_dave]

... unless the OB is far enough from the rail to where it will be rolling when it hits the cushion. With these types of banks, the through-diamond 2-to-1 rolling-ball system is fairly reliable.

True, it's the in-between shots that are tough. You sometimes need to worry about side spin on the object ball even at slow speed.

Agreed. Even if you know every system for every type of shot, you still need to be able to use experience-based judgment and intuition to adjust for the "in between" shots and the bank shot physics effects.

Regards,
Dave

 

[renard]

True, it's the in-between shots that are tough. You sometimes need to worry about side spin on the object ball even at slow speed.

Thanks Bob!

 

[dr_dave]

I'm not sure if Grady's approach is actually x to 0.375x or Eckerts 2x to 3/4x, Eckert is just taking off 1/8 for every diamond distance, to reach the same spot as Grady.
I still believe Grady's approach is the most simple, for it's very easy from every position to estimate 50%, 75% and 62.5% which is in between.

Most kick and bank systems measure distances on both rails from the target pocket. If I understand your description of the Grady system, the distance from the pocket to the aim point on the banking rail is between 25% and 50% (37.5% or 3/8) of the distance from the pocket on the opposite rail.

That's why I prefer to call it the "x to 3/8x" system. If you double the numbers, this can be written as "2x to 3/4x" or just "2 to 3/4." This is how Eckert does it; but the results are identical. I think "2 to 3/4" is a good way to think about it because people can more easily relate it to the common "2 to 1" system used for slow, rolling-ball kicks or banks. The aim point with fast-speed banks is closer to the pocket (3/4) than with slow-roll kicks or banks (1).

Regards,
Dave

 

[Petros Andrikop]

Most kick and bank systems measure distances on both rails from the target pocket. If I understand your description of the Grady system, the distance from the pocket to the aim point on the banking rail is between 25% and 50% (37.5% or 3/8) of the distance from the pocket on the opposite rail.

That's why I prefer to call it the "x to 3/8x" system. If you double the numbers, this can be written as "2x to 3/4x" or just "2 to 3/4." This is how Eckert does it; but the results are identical. I think "2 to 3/4" is a good way to think about it because people can more easily relate it to the common "2 to 1" system used for slow, rolling-ball kicks or banks. The aim point with fast-speed banks is closer to the pocket (3/4) than with slow-roll kicks or banks (1).

Regards,
Dave

Unfortunately I can't find the video of Grady to describe it better, Eckert says in his video he's taking off/adding 1/4 diamond for every 2 diamonds distance, so when he's banking from middle pocket to a corner pocket (4 diamonds distance between pockets) he's taking off/adding 2x1/4=1/2 diamond.
Grady measured the distances in percentages, so when he came from the same position (middle pocket to corner pocket, 4 diamonds distance between pockets) he discribes that distance as 100%, so 50% is 2 diamonds away (where someone banks at normal rolling speed with no english to get to the pocket), 75% is 3 diamonds away and 62.5% is between 2(50%) and 3(75%) diamonds, so 2.5 diamonds away from his starting point at the opposite rail or 1.5 diamond away from the corner pocket. Quite easy, no formula needed.
I'll try to come back with some visual description.
Thanks,
Petros