Reference points for 90 degree angle Elbow-Cue?

hsbilliards

hsbilliards

AzB Silver Member
Silver Member
Fellow BCA instructors exactly where do you reference to check the 90 degree angle when reviewing side angle video of a students elbow/forearm to cue stick?

1. Center of elbow to middle hand knuckle OOIOO________>cueball?
2. Center of elbow to middle of first knuckle of pointer finger OOOI_______>cueball?
3. Outside elbow to center knuckle?

Hopefully this makes sense. Please explain why.

To me this seems some what important to reference in order to make sure fore arm is at true 90 degrees to cue stick.

My thought is middle elbow to center of pointer finger knuckle.

Thanks for responding
Earl Munson
 
I'm not a BCA instructor, but...

Why does this matter at all? Once a you get close enough to 90 degrees that you need these reference points, you are at 90 degrees. It seems to me that as long as the player isn't a long way from this the really important thing is that they do it the same way every time, not that it is within 2 degrees of "perfect".

On the other hand, I haven't answered your question, have I? I guess I would use the rearmost edge of the forearm, from the outside edge of the elbow to the wrist on the pinky side, but our bodies are so different that no one standard is going to be adequate for everyone.
 
Mark Wilson told me that the way I was setting up with my hand about two inches forward of 90 degrees was more accurate that with the forearm perpendicular to the cue, but that power was sacrificed as a result.

He suggested that I move my grip hand back on the cue to achieve 90 degrees and thus more power without effort.

Helped me a lot.

Flex
 
hsbilliards said:
Fellow BCA instructors exactly where do you reference to check the 90 degree angle when reviewing side angle video of a students elbow/forearm to cue stick?

1. Center of elbow to middle hand knuckle OOIOO________>cueball?
2. Center of elbow to middle of first knuckle of pointer finger OOOI_______>cueball?
3. Outside elbow to center knuckle?

Hopefully this makes sense. Please explain why.

To me this seems some what important to reference in order to make sure fore arm is at true 90 degrees to cue stick.

My thought is middle elbow to center of pointer finger knuckle.

Thanks for responding
Earl Munson
Click to expand...
I don't take quite that precise an approach. If I see that the student is half a hand ahead of vertical, I point out the orthodox teaching, and that many great players hold the stick exactly where he does, and that if he has any trouble getting power on some shots, he might consider gripping a little farther back, like Buddy Hall and (insert your favorite perpendicular player). The vast majority of students I've seen have other problems that are far more important to work on -- if in fact being half a hand ahead of perpendicular is a problem.
 
whoa

Longhair said it.
This will vary from player to player because of muscle/bone structure
and the most comfortable grip for each.
-cOOp


hsbilliards said:
Fellow BCA instructors exactly where do you reference to check the 90 degree angle when reviewing side angle video of a students elbow/forearm to cue stick?

1. Center of elbow to middle hand knuckle OOIOO________>cueball?
2. Center of elbow to middle of first knuckle of pointer finger OOOI_______>cueball?
3. Outside elbow to center knuckle?

Hopefully this makes sense. Please explain why.

To me this seems some what important to reference in order to make sure fore arm is at true 90 degrees to cue stick.

My thought is middle elbow to center of pointer finger knuckle.

Thanks for responding
Earl Munson
Click to expand...
 
Bob Jewett said:
I don't take quite that precise an approach. If I see that the student is half a hand ahead of vertical, I point out the orthodox teaching, and that many great players hold the stick exactly where he does, and that if he has any trouble getting power on some shots, he might consider gripping a little farther back, like Buddy Hall and (insert your favorite perpendicular player). The vast majority of students I've seen have other problems that are far more important to work on -- if in fact being half a hand ahead of perpendicular is a problem.
Click to expand...

What he said...with the addition that if the inside angle leads to a shoulder drop BEFORE cb contact then the tip will hit the CB higher than intended.

Regards,
Jim
 
I just try and set up to the CB (before taking any practice strokes) so that my grip arm is perpendicular and my middle and ring finger are directly hanging below the center of my arm...

I try to set up farily close to the CB and then begin my "practice" stroke..

This of course puts me "just forward" of perpendicular "at impact".

If I try and set up so that at impact my arm is perpendicular, I have to set up behind perpendicular .......If I do this, two things happen....My timing and stroke go haywire....and I usually foul by hitting the CB during my practice stroke...

People also have different arms just like different legs...Some people can hyper extend there arms past straight......I can not totally straighten my arm...(never have been able to)...I think a have what is a kin to bowed legs...I have bowed arms...I think I have a little "forward curvature" of the forearm...which may create an illusion of "forward of perpendicular".......

What amazes me is how Bustamante hits the ball...It appears as if he is setting up almost a foot away from the CB......I can't see how his arm would ever be perpendicular at impact.
 
BRKNRUN said:
What amazes me is how Bustamante hits the ball...It appears as if he is setting up almost a foot away from the CB......I can't see how his arm would ever be perpendicular at impact.
Click to expand...

It's not, but that's not to say that he doesn't hit the ball where he wants.
 
When I have a student that looks obviously out of 90 degrees I set there arm visually at 90 and then put a rubber band on there cue so that they can feel it with their thumb and pointer finger as a reference.

When I use video analysis in a side view I will also put white sticky ring binder (looks like doughnut) on their elbow (center) and was putting another ring binder in the center of the hand.

using analysis software I can check the exact angle (see atttached photo).

What looked visually at 90 degrees was actually more. In the case of the photo it was 99 degrees.

My question is ...Am I referencing the hand wrong (ring binder in wrong place) and will that extra 9 degrees make a difference? It does in my opinion.

For myself one or two fingers off makes a difference in my accuracy.

Thanks guys for all your input.
 

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hsbilliards said:
When I have a student that looks obviously out of 90 degrees I set there arm visually at 90 and then put a rubber band on there cue so that they can feel it with their thumb and pointer finger as a reference.

When I use video analysis in a side view I will also put white sticky ring binder (looks like doughnut) on their elbow (center) and was putting another ring binder in the center of the hand.

using analysis software I can check the exact angle (see atttached photo).

What looked visually at 90 degrees was actually more. In the case of the photo it was 99 degrees.

My question is ...Am I referencing the hand wrong (ring binder in wrong place) and will that extra 9 degrees make a difference? It does in my opinion.

For myself one or two fingers off makes a difference in my accuracy.

Thanks guys for all your input.
Click to expand...


What I notice is your knuckles on your fist...I would think they should be level in this position instead of facing upward like they are.
 
hsbilliards said:
... My question is ...Am I referencing the hand wrong (ring binder in wrong place) and will that extra 9 degrees make a difference? It does in my opinion.

For myself one or two fingers off makes a difference in my accuracy....
Click to expand...
Geometrically the correct point in the hand to reference to is the finger that actually grips the stick, which is either the index or middle finger for most people.

For the student pictured, I'd be much more inclined to work on his back leg than his grip location, unless he was having trouble with power shots.
 
Bob, that is what I was thinking as well. The reference should be where he holds the cue (thumb/pointer finger).

Curious why you mentioned back leg? He seems to be balanced and equal weight on both feet but I really cannot tell. He would have to know that. What do you see in the picture that indicates a problem? Thats interesting. Stance in my opinion is so important.
 
hsbilliards said:
.. Curious why you mentioned back leg? He seems to be balanced and equal weight on both feet but I really cannot tell. He would have to know that. What do you see in the picture that indicates a problem? Thats interesting. Stance in my opinion is so important.
Click to expand...
His back leg is bent. Unless he has a physical problem that prevents it, I would recommend that he keep the back leg straight for stability and repeatability. Just as the anchored straight left arm anchors the upper body, the straight back leg anchors the lower body. In my view, this is more important than half a hand of grip position.

For people who don't much care for discussions of fundamentals:

Yes, some players have their own unique stances. The idea is to find things that have a good chance to help the long-term improvement of the player. One of those is to find a way to make the stance more solid.
 
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Bob that makes sense about anchoring the back leg and keeping it straight. I really never thought about that. I try to teach things where a student will stay consistent in as many points as possible ie the straight bridge arm. On the stance I teach keeping the forward foot pointing in the same direction and parallel to the cue a shoulder width wide (foot slightly outside shoulder). This allows consistency. Many of my beginner students tend to crowd the cue and there grip arm incant s toward their body.

The reason I am looking for precise answers on correct training techniques is because I train 12 high school billiard teams in the Dallas area (had over 100 students this school year) and I want to give them the best instruction as possible. I personally like hard answers and can back it up with the whys. Thanks.
 
I think you should measure the 90-degrees this way:

The line from the hinge point of the elbow through the center of mass of the lower arm (forearm + hand) should be at a 90-degree angle to the floor (assuming a level floor).

Here's why:

The most effortless stroke is generally considered the most desirable for multiple reasons. If you exerted zero muscle force in the forward stroke, the maximum velocity would be at the point where the 90-degree rule I defined above is met, or in other words, the gravitational bottom of the pendulum.

Now you do exert force with the bicep during the stroke, because gravity alone really won't give you much stroke power, but if you contact the CB at 90-degrees at defined above, the least amount of effort is required to achieve a given cue velocity at impact.

Also, this will be the point when the grip hand is moving parallel to the floor. Just before this point, the hand is moving forward and slightly down, and just after this point, the hand is moving forward and slightly up. Only at this point is the momentum of the cue directly parallel with the table bed, meaning you'll see maximum efficiency (not wasting energy by directing it down into the table or up into the air).

So that's my answer. The center of mass of the lower arm should be plumb with the hinge point of the elbow at contact.

-Andrew
 
Andrew Manning said:
I think you should measure the 90-degrees this way:

The line from the hinge point of the elbow through the center of mass of the lower arm (forearm + hand) should be at a 90-degree angle to the floor (assuming a level floor).

Here's why:

The most effortless stroke is generally considered the most desirable for multiple reasons. If you exerted zero muscle force in the forward stroke, the maximum velocity would be at the point where the 90-degree rule I defined above is met, or in other words, the gravitational bottom of the pendulum.

Now you do exert force with the bicep during the stroke, because gravity alone really won't give you much stroke power, but if you contact the CB at 90-degrees at defined above, the least amount of effort is required to achieve a given cue velocity at impact.

Also, this will be the point when the grip hand is moving parallel to the floor. Just before this point, the hand is moving forward and slightly down, and just after this point, the hand is moving forward and slightly up. Only at this point is the momentum of the cue directly parallel with the table bed, meaning you'll see maximum efficiency (not wasting energy by directing it down into the table or up into the air).

So that's my answer. The center of mass of the lower arm should be plumb with the hinge point of the elbow at contact.

-Andrew
Click to expand...
I think Andrew is right one here. If we were designing a machine to hit a cueball using a human-like arm, we would want the forearm 90 degrees to the floor at impact, not 90 degrees to the cue. However, since I'm picky, the cue is probably still not parallel to the floor at this point, if only to clear the rail.

I have seen many more players with problems keeping the forearm perpendicular to the floor as seen from behind that I have as seen from the side. I am talking about curling under the shoulder, mostly, sometimes so far that a free, straight stroke is impossible.
 
While many players will be more stable and comfortable with the back leg bent, there is nothing inherently wrong with playing with both legs bent. The only potential problem might be that the player will tire more easily. The stance only requires that the player be balanced, comfortable, a tripod, and allow free movement of the cue (with a pendulum swing) to a natural finish.

To Earl Munson...the student in your Pro Video diagram is ahead of perpendicular too much. This will likely result in the cuetip being forced slightly down (before contacting the CB), and results in not striking the CB exactly where the player wants to. Have him move his hand backwards slightly, and don't worry about the back leg. To check perpendicular with your video software more accurately, get more to the sideview of the player (where the elbow is mostly in the center of the frame), and have them touch the CB with their tip.

Scott Lee
www.poolknowledge.com

Bob Jewett said:
His back leg is bent. Unless he has a physical problem that prevents it, I would recommend that he keep the back leg straight for stability and repeatability. Just as the anchored straight left arm anchors the upper body, the straight back leg anchors the lower body. In my view, this is more important than half a hand of grip position.

For people who don't much care for discussions of fundamentals:

Yes, some players have their own unique stances. The idea is to find things that have a good chance to help the long-term improvement of the player. One of those is to find a way to make the stance more solid.
Click to expand...
 
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