# Rolling-Cue-Ball CAROM ANGLE Systems

#### dr_dave

##### Instructional Author
Gold Member
Silver Member
Just one more comment and then I'm out of the discussion.
Again I'm not arguing the merits of Dr. D's system. I believe it works.

BTW, it is not "my system" (except for the peace-sign stuff and the 0.281 marked-cue RCA stuff). Coriolis discovered the 2/7 RCA system in the early 1800s, Bob Jewett came up with the cue approach, and Patrick Johnson came up with the CB-tangent-line-drop approach.

I'm not saying the method in Hoppe's book is better or worse.

In terms of giving an accurate carom direction, the "back of the ball" system is most definitely worse.

I do think, with any system, (disregarding fundamentals errors) practice and experimentation is needed to perfect, if perfection is even possible.
I'm confident the math is accurate. Dr. D wouldn't publish it unless this is so.

Agreed. With enough practice and "adjustments," any system can be made to be very effective.

That said, the method in Hoppe's book works within certain range of attack angles. Other angles requires practice. Some angles, ?? Well ya gotta go with another method, or game strategy. I know this and this topic has nothing to do with my original question.

The "back of the ball" system does give the correct line at one angle (close to a 3/4-ball hit), and comes close with fairly full hits (close to and thicker than 3/4-ball hits), but it is not as good as other systems, unless you "practice" enough to develop "intuition" for how to correct for the inaccuracies when necessary.

#### CapnCarom

##### New member
FYI, I just posted a new video that demonstrates several useful systems to accurately predict carom direction for rolling-CB shots. The carom angle is the amount the CB deflects off the OB. Being able to predict this is useful to detect a possible scratch, to plan break-out and carom shots, and to visualize position-play paths through “traffic.” Check it out:

0:00 – Intro
0:22 – 1 - 30˚ Rule Peace Sign
1:01 – 2 - Full and Thin Hits
1:39 – 3 - Rolling Carom Angle (RCA) System
3:18 – 4 - CB Line RCA
4:20 – 5 - Marked-Cue RCA
5:45 – 6 - Perpendicular RCA
6:29 – 7 - Speed Effects
7:31 – 8 - Easy Example
9:15 – 9 - Tough Example
10:37 – Wrap Up
11:32 – ---- system montage

As always, I look forward to your feedback, comments, questions, complaints, and requests.

Enjoy!
Dr Dave!!! Great video! As usual, I learned something new from ya today! Man, that Coriollis dude was a real genius, eh? Thanks for the refinement of the 2/7 estimate... that's really spot on!

#### dr_dave

##### Instructional Author
Gold Member
Silver Member
Dr Dave!!! Great video!

I'm glad you liked it because this is not the case with everybody. This video is getting viewed on YouTube at a much lower rate than my normal instructional videos. I guess some people don't like seeing or hearing about the math/physics stuff, and maybe some people are turned off by using the cue with several seemingly-difficult aiming steps at the table.

As usual, I learned something new from ya today!

Man, that Coriolis dude was a real genius, eh?

Most definitely. FYI, I wrote up a bunch of his contributions in a series of Billiards Digest articles many years ago. If you or others are interested, see:
Coriolis Pool Physics Contributions

Thanks for the refinement of the 2/7 estimate... that's really spot on!

You're welcome. I aim to swerve.

#### Poolmanis

##### AzB Silver Member
Silver Member
I'm glad you liked it because this is not the case with everybody. This video is getting viewed on YouTube at a much lower rate than my normal instructional videos. I guess some people don't like seeing or hearing about the math/physics stuff, and maybe some people are turned off by using the cue with several seemingly-difficult aiming steps at the table.

Most definitely. FYI, I wrote up a bunch of his contributions in a series of Billiards Digest articles many years ago. If you or others are interested, see:
Coriolis Pool Physics Contributions

You're welcome. I aim to swerve.
Don´t be too concerned about views. You cannot always tell how viewers gonna react. Do your own stuff. Your viewers watch you because you make content that differs from others. Some videos will not reach/interest viewers. If you wanna get more subs/views check these videos:

#### dr_dave

##### Instructional Author
Gold Member
Silver Member
Don´t be too concerned about views. You cannot always tell how viewers gonna react. Do your own stuff. Your viewers watch you because you make content that differs from others. Some videos will not reach/interest viewers.

Thanks for that, which is a good attitude for me to have. But at the same time, I like to cater to what I think people want and need.

If you wanna get more subs/views check these videos:

Thanks for those. I will watch them when I get on the spin bike later today.

FYI, I tried your Draw Challenge yesterday. I am working on a video to promote your Challenge, and I'll include my best attempts in that. I should post it by tomorrow. I suspect people will like it more than my recent "Pool vs. Cats" video. People obviously didn't "want" or "need" that one.

#### bb9ball

##### Registered
Is there a quick way to use the new RCA method to determine where to set the CB with BIH for a desired path? I thought about it a couple of times while practicing today and none of the methods seemed to lead to an easy way to do this. Your peace sign is probably the easiest method to do this, but it doesn't work with all angles.

#### dr_dave

##### Instructional Author
Gold Member
Silver Member
Is there a quick way to use the new RCA method to determine where to set the CB with BIH for a desired path? I thought about it a couple of times while practicing today and none of the methods seemed to lead to an easy way to do this.

With the marked-cue RCA approach, for a given OB direction and desired carom direction, move the butt end along the tangent line until the marked spot points at the carom target, and then place the CB anywhere along the line from the GB to the joint. For a given CB position and desired carom direction, place the joint along the CB-GB line and rotate the butt until the marked spot points at the carom target. Then a line through the butt end and GB gives you the required tangent line for the shot. Aim for a line of centers perpendicular to that.

Your peace sign is probably the easiest method to do this, but it doesn't work with all angles.

The peace sign is much easier. It works for all angles between 1/4-ball and 3/4 ball hits. If you want to be accurate, you can adjust your peace sign slightly based on the cut. See the videos here for more info on how to do that:

For hits fuller than 3/4-ball, you can use the 3-times-times-the-angle system in reverse by visualizing 1/3 of the total desired carom angle.

For examples of how to use the peace sign and other techniques to plan ball-in-hand carom shots, see:

Enjoy!

#### eg9327

##### Active member
Great article, as always! I tried it and it works perfectly! Due to time involed i think the 75% aproach is close enough and works faster. Will definately incorporate into my game. A question for the next level. I see top one pocket players make the cue ball come off at any angle they want and arrive at amazingly small target zones. Can you elaborate on develoing this skill?

#### dr_dave

##### Instructional Author
Gold Member
Silver Member
A question for the next level. I see top one pocket players make the cue ball come off at any angle they want and arrive at amazingly small target zones. Can you elaborate on develoing this skill?

Simple: Develop strong intuition through countless hours of smart practice and experience, always paying attention to where the CB heads and learning to make adjustments in the future.

#### eg9327

##### Active member
Simple: Develop strong intuition through countless hours of smart practice and experience, always paying attention to where the CB heads and learning to make adjustments in the future.
I was hoping for another magic pill. But fortunately I do love spending hours at this!

#### bb9ball

##### Registered
With the marked-cue RCA approach, for a given OB direction and desired carom direction, move the butt end along the tangent line until the marked spot points at the carom target, and then place the CB anywhere along the line from the GB to the joint. For a given CB position and desired carom direction, place the joint along the CB-GB line and rotate the butt until the marked spot points at the carom target. Then a line through the butt end and GB gives you the required tangent line for the shot. Aim for a line of centers perpendicular to that.

The peace sign is much easier. It works for all angles between 1/4-ball and 3/4 ball hits. If you want to be accurate, you can adjust your peace sign slightly based on the cut. See the videos here for more info on how to do that:

For hits fuller than 3/4-ball, you can use the 3-times-times-the-angle system in reverse by visualizing 1/3 of the total desired carom angle.

For examples of how to use the peace sign and other techniques to plan ball-in-hand carom shots, see:

Enjoy!

Thanks, I have just experimented with Patrick Johnson's method which can't be used with BIH.

After posting, I thought I might get a "some exercises are left to the reader".

#### Bob Jewett

##### AZB Osmium Member
Staff member
Gold Member
Silver Member
Thanks, I have just experimented with Patrick Johnson's method which can't be used with BIH.
Actually, something very much like PJ's approach can be used for BIH. Take any convenient point on the cue ball's side of the shot that is on the line between the carom target and the center of the ghost ball. For example, one that is about a foot from the tangent line. Drop a perpendicular from that point to the tangent line, and note the distance. Come back from the point by about 3 (or 2.5) times the distance. That new point is on the CB line to the ghost ball.

#### bb9ball

##### Registered
Actually, something very much like PJ's approach can be used for BIH. Take any convenient point on the cue ball's side of the shot that is on the line between the carom target and the center of the ghost ball. For example, one that is about a foot from the tangent line. Drop a perpendicular from that point to the tangent line, and note the distance. Come back from the point by about 3 (or 2.5) times the distance. That new point is on the CB line to the ghost ball.

Thanks for helping come up with this new system for all rolling cue ball angles. And, thanks for helping find a method without needing a mark on the cue. I was hoping to avoid possibly getting a complaint from a hillbilly.

#### Patrick Johnson

##### Fish of the Day
Silver Member
Actually, something very much like PJ's approach can be used for BIH. Take any convenient point on the cue ball's side of the shot that is on the line between the carom target and the center of the ghost ball. For example, one that is about a foot from the tangent line. Drop a perpendicular from that point to the tangent line, and note the distance. Come back from the point by about 3 (or 2.5) times the distance. That new point is on the CB line to the ghost ball.
You can measure in front of or behind the OB, and find the carom angle for an existing aim line or find the aim line you need with ball-in-hand.

pj
chgo

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