Draw shot cue elevation effects

dr_dave said:
As I promised in my previous threads dealing with draw shot physics, I finally got around to studying the effects of cue elevation. For people who like the math and physics, it can be found here:

For people who don't like the math and physics, here are the bottom-line conclusions:

  1. Elevating the cue reduces the amount of CB spin at OB contact, resulting in less draw distance (see TP B.8 for more info). The loss in spin is small for small cue elevations, but increases with more elevation (for a given cue speed and tip offset).
  2. Modest cue elevations (about 0-15 degrees) reduce the spin-to-speed ratio of the CB at OB contact, resulting in "slower" draw (see TP B.9 for more info).
  3. As you increase cue elevation above about 20 degrees, the spin-to-forward-speed ratio increases, allowing for "quicker" draw (see TP B.9 for more info). An extreme example is a highly elevated masse draw (pique) shot, where you create lots of backspin with very little forward speed.
Sometimes cue elevation is required to clear over an obstacle ball, or to prevent a double hit when there is a small gap between the CB and OB. And as noted above, with larger cue elevations, better "quick draw" action can result. However, for maximum draw distance, a level cue (or as close to level is possible) appears to be best.

The math and physics is fairly involved, but here's the basic concept:
With an elevated cue, the CB doesn't lose any speed or spin while it is airborne (between the bounces); however, more speed and spin is lost during the bounces (including the first bounce off the tip, based on HSV B.44) than with a near-level-cue drag shot.​

I look forward to any comments, suggestions, disagreements, or questions you might have.

Regards,
Dave

PS: FYI, the conclusions from all of my draw analyses can be found here:
Click to expand...

Dr Dave, have you considered squirt in the vertical plane?

When I was a beginning player, I heard and read to keep the cue as level as possible. So I figured that setting up a shot where the cue would clear the rails (I'm talkin' a really level cue here!) would yield the maximum amount of draw. This mostly resulted in scooping up the cue ball and miscues.

I contend that some elevation is required so that the initial velocity of the cue ball is absolutely horizontal (Vy0 = 0). Less elevation for an LD shaft, a bit more elevation for regular shafts. Past this point, we actually perform a jump shot, with Vy0 < 0.

As a corollary, I submit that your demonstration of a follow-shot jumping over dimes is caused by a similar vertical squirt phenomenon, only, in the downward direction.


* I know the thread is 6-years old, but I'm right on topic... I think ;-)
 
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dr_dave said:
As I promised in my previous threads dealing with draw shot physics, I finally got around to studying the effects of cue elevation. For people who like the math and physics, it can be found here:

For people who don't like the math and physics, here are the bottom-line conclusions:

  1. Elevating the cue reduces the amount of CB spin at OB contact, resulting in less draw distance (see TP B.8 for more info). The loss in spin is small for small cue elevations, but increases with more elevation (for a given cue speed and tip offset).
  2. Modest cue elevations (about 0-15 degrees) reduce the spin-to-speed ratio of the CB at OB contact, resulting in "slower" draw (see TP B.9 for more info).
  3. As you increase cue elevation above about 20 degrees, the spin-to-forward-speed ratio increases, allowing for "quicker" draw (see TP B.9 for more info). An extreme example is a highly elevated masse draw (pique) shot, where you create lots of backspin with very little forward speed.
Sometimes cue elevation is required to clear over an obstacle ball, or to prevent a double hit when there is a small gap between the CB and OB. And as noted above, with larger cue elevations, better "quick draw" action can result. However, for maximum draw distance, a level cue (or as close to level is possible) appears to be best.

The math and physics is fairly involved, but here's the basic concept:
With an elevated cue, the CB doesn't lose any speed or spin while it is airborne (between the bounces); however, more speed and spin is lost during the bounces (including the first bounce off the tip, based on HSV B.44) than with a near-level-cue drag shot.​

I look forward to any comments, suggestions, disagreements, or questions you might have.

Regards,
Dave

PS: FYI, the conclusions from all of my draw analyses can be found here:
Click to expand...

Thanks, Dave.
Your contributions are outstanding!
Will Prout
 
dr_dave said:
I know there are people out there who are convinced that you can get more straight-back draw distance by jacking up the cue, even when jacking up is not required (e.g., to clear an obstacle ball). I was hoping some of those people would get involved in the discussion and try to explain how jacking up helps. Is it possible that some people can create more cue speed (e.g., by dropping the elbow and involving the shoulder) with a jacked up cue, while still controlling the tip contact point?

Regards,
Dave
Click to expand...
While doing the BU Draw Shot exercise, I also found that, mechanically, asking my brain to pin the cue ball a little bit (within a reasonable slight elevation) made my elbow stay a bit higher, by blocking my shoulder joint. I don't necessarily suffer from elbow drop during the forward stroke. Rather I had a tendency to have too long of a backstroke combined with a piston stroke (which I once thought was ideal): my elbow had to come down to keep the back-swing level. Call it a premature elbow-drop.

IOW, intentionally hitting the cue ball with a slightly elevated cue helps me keep good form.
 
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martind2112 said:
IOW, intentionally hitting the cue ball with a slightly elevated cue helps me keep good form.
Click to expand...

I agree. Controlling draw is a lot more critical than getting the maximum draw. I never try to get the maximum draw anymore. I guess all those cue balls flying across the pool hall and miscues cured me. Controlling the draw distance is the most important aspect. A consistent stroke and consistent tip placement are the keys.
 
dr_dave said:
As I promised in my previous threads dealing with draw shot physics, I finally got around to studying the effects of cue elevation. For people who like the math and physics, it can be found here:

For people who don't like the math and physics, here are the bottom-line conclusions:

  1. Elevating the cue reduces the amount of CB spin at OB contact, resulting in less draw distance (see TP B.8 for more info). The loss in spin is small for small cue elevations, but increases with more elevation (for a given cue speed and tip offset).
  2. Modest cue elevations (about 0-15 degrees) reduce the spin-to-speed ratio of the CB at OB contact, resulting in "slower" draw (see TP B.9 for more info).
  3. As you increase cue elevation above about 20 degrees, the spin-to-forward-speed ratio increases, allowing for "quicker" draw (see TP B.9 for more info). An extreme example is a highly elevated masse draw (pique) shot, where you create lots of backspin with very little forward speed.
Sometimes cue elevation is required to clear over an obstacle ball, or to prevent a double hit when there is a small gap between the CB and OB. And as noted above, with larger cue elevations, better "quick draw" action can result. However, for maximum draw distance, a level cue (or as close to level is possible) appears to be best.

The math and physics is fairly involved, but here's the basic concept:
With an elevated cue, the CB doesn't lose any speed or spin while it is airborne (between the bounces); however, more speed and spin is lost during the bounces (including the first bounce off the tip, based on HSV B.44) than with a near-level-cue drag shot.​

I look forward to any comments, suggestions, disagreements, or questions you might have.

Regards,
Dave

PS: FYI, the conclusions from all of my draw analyses can be found here:
Click to expand...


Its hard to explain why, but if I am up close to an object ball(2-3 balls distance) I feel I can draw more accurately if I am jacked up a bit. Maybe its just me, but I especially feel this way when playing with a bigger, heavier cue ball.
 
martind2112 said:
Dr Dave, have you considered squirt in the vertical plane?
Click to expand...
Yes, it's been discussed many times, for instance as the reason that follow shots swerve more (sooner).

I contend that some elevation is required so that the initial velocity of the cue ball is absolutely horizontal (Vy0 = 0). Less elevation for an LD shaft, a bit more elevation for regular shafts. Past this point, we actually perform a jump shot, with Vy0 < 0.
Click to expand...
"Scoop" jumps are caused by hitting too low and miscueing.

As a corollary, I submit that your demonstration of a follow-shot jumping over dimes is caused by a similar vertical squirt phenomenon, only, in the downward direction.
Click to expand...
Virtually every shot hops a little because the cue is always at least a little elevated (as you allude to). Vertical squirt probably plays a small role.

Your thoughts make sense but overlook key factors.

pj
chgo
 
I wonder why so many old-time players would elevate on draw-shots?I don't do it myself, but then again I only play on lightening fast Simonis pool cloths and match snooker cloths and the tendency is to get too much draw, rather than too little. Perhaps there was some sort of factor with the different equipment of the "olden days" that the elevation fixed..Here is a clip from the pool stone-age, where apparently people did everything wrong:rolleyes: (I'm not underestimating anybody, but in the interest of minimizing angry posts about me being a nobody compared to David Howard etc, I'd like to point out that I joking in the last sentence)
https://www.youtube.com/watch?v=RjZq0HN82Os
 
Straightpool_99 said:
I wonder why so many old-time players would elevate on draw-shots?I don't do it myself, but then again I only play on lightening fast Simonis pool cloths and match snooker cloths and the tendency is to get too much draw, rather than too little. Perhaps there was some sort of factor with the different equipment of the "olden days" that the elevation fixed..Here is a clip from the pool stone-age, where apparently people did everything wrong:rolleyes: (I'm not underestimating anybody, but in the interest of minimizing angry posts about me being a nobody compared to David Howard etc, I'd like to point out that I joking in the last sentence)
https://www.youtube.com/watch?v=RjZq0HN82Os
Click to expand...

They came up playing on slow cloth, where you couldnt easily keep backspin on the ball over a distance. Jacking up slightly, jumps the ball off the surface a bit reducing some of the loss of spin due to the friction of the cloth. It used to be referred to as "skipping" the ball across the cloth where I grew up.
Onto Simonis, its not needed as often, but is still a useful shot depending on your ability and the distance between the balls. Jacking up makes the shot harder in several ways, and that is why its usually discouraged, especially for newer players.
 
Moosehead Bridge

dr_dave said:
As I promised in my previous threads dealing with draw shot physics, I finally got around to studying the effects of cue elevation. For people who like the math and physics, it can be found here:

For people who don't like the math and physics, here are the bottom-line conclusions:

  1. Elevating the cue reduces the amount of CB spin at OB contact, resulting in less draw distance (see TP B.8 for more info). The loss in spin is small for small cue elevations, but increases with more elevation (for a given cue speed and tip offset).
  2. Modest cue elevations (about 0-15 degrees) reduce the spin-to-speed ratio of the CB at OB contact, resulting in "slower" draw (see TP B.9 for more info).
  3. As you increase cue elevation above about 20 degrees, the spin-to-forward-speed ratio increases, allowing for "quicker" draw (see TP B.9 for more info). An extreme example is a highly elevated masse draw (pique) shot, where you create lots of backspin with very little forward speed.
Sometimes cue elevation is required to clear over an obstacle ball, or to prevent a double hit when there is a small gap between the CB and OB. And as noted above, with larger cue elevations, better "quick draw" action can result. However, for maximum draw distance, a level cue (or as close to level is possible) appears to be best.

The math and physics is fairly involved, but here's the basic concept:
With an elevated cue, the CB doesn't lose any speed or spin while it is airborne (between the bounces); however, more speed and spin is lost during the bounces (including the first bounce off the tip, based on HSV B.44) than with a near-level-cue drag shot.​

I look forward to any comments, suggestions, disagreements, or questions you might have.

Regards,
Dave

PS: FYI, the conclusions from all of my draw analyses can be found here:
Click to expand...

Forgive me I haven't had the advanced Math but one thing I have noticed in regular play.

Using a bridge at a higher elevation using draw will easily produce an airborne cue ball and summarily leaves the table. The Moosehead bridge can easily be put into many cue cases and affixed to a break cue and it has a notch to one side that is particularly designed..... one might think for the extended draw shot.

So in keeping with mathematical calculations how would one show this.

ElevatedDraw + CueBall = DeepDoDo

ElevatedDraw + RightMooseheadNotch= :smile:

I apologize to the academic community.
 
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dr_dave said:
I know there are people out there who are convinced that you can get more straight-back draw distance by jacking up the cue, even when jacking up is not required (e.g., to clear an obstacle ball). I was hoping some of those people would get involved in the discussion and try to explain how jacking up helps. Is it possible that some people can create more cue speed (e.g., by dropping the elbow and involving the shoulder) with a jacked up cue, while still controlling the tip contact point?

Regards,
Dave
Click to expand...

Dr. Dave,

I would fall into a category of people that would prefer to "SLIGHTLY" raise the butt of the cue when executing a power draw shot. I think bridge height is related to this. For me, where I form a very solid bridge that will give me confidence to stroke through the bottom of the cue ball without a miscue--this bridge is slightly elevated...the elevated bridge forces a slightly elevated butt, so the tip can contact the bottom of the cue ball. This also helps in freeing the butt of the cue from the chance of an impact with the table as I follow through, so I think the very slightly elevated bridge and butt help me perform a smooth powerful stroke that accelerates through the bottom of the cue ball.

I feel like, for most shots, I can get all the draw I need with this method. It does add a bit of "quick" draw to the cue ball, and when I hit it good, the cue ball looks like it starts to draw and then after about a foot, it looks like it accelerates! I think this sometimes intimidates opponents.

kollegedave
 
Patrick Johnson said:
What does that mean?

pj
chgo
Click to expand...
Yeah, I know... clear as mud. :embarrassed2:

It's just that I make a conscious effort to follow through along the (slightly elevated) line of the cue. I feel like I'm trying to drill a hole through the cue ball and make the tip touch the cloth. I used the word "pin" because it feels I'm actually compressing the cue ball against the slate, like a jump shot feels but to a lesser extent, obviously.

It's just a mental picture I establish in order not to drop my elbow, which would make me hit higher on the CB than I intend.
 
martind2112 said:
Yeah, I know... clear as mud. :embarrassed2:

It's just that I make a conscious effort to follow through along the (slightly elevated) line of the cue. I feel like I'm trying to drill a hole through the cue ball and make the tip touch the cloth. I used the word "pin" because it feels I'm actually compressing the cue ball against the slate, like a jump shot feels but to a lesser extent, obviously.

It's just a mental picture I establish in order not to drop my elbow, which would make me hit higher on the CB than I intend.
Click to expand...
Oh, OK - thanks.

pj
chgo
 
Patrick Johnson said:
Yes, it's been discussed many times, for instance as the reason that follow shots swerve more (sooner).


"Scoop" jumps are caused by hitting too low and miscueing.


Virtually every shot hops a little because the cue is always at least a little elevated (as you allude to). Vertical squirt probably plays a small role.

Your thoughts make sense but overlook key factors.

pj
chgo
Click to expand...

What I'm suggesting is that, even hitting only half-a-tip of bottom spin with a cue that's perfectly level, the cue ball would hop from squirt. To impart momentum that's totally horizontal, one would need to use the same type of pivot used to compensate for lateral squirt.

Cue perfectly level: cue ball squirts upwards (Vy0 > 0)
Exagerated butt elevation: equates a minute jump shot (Vy0 < 0) -> cue ball jumps.
Just the right amount of elevation: Vy0 = 0
 
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martind2112 said:
What I'm suggesting is that, even hitting only half-a-tip of bottom spin with a cue that's perfectly level, the cue ball would hop from squirt. To impart momentum that's totally horizontal, one would need to use the same type of pivot used to compensate for lateral squirt.
Click to expand...
That's a sensible thought in theory, but in most cases you'd need to reduce the downward angle needed for draw (not increase it) in order to make it small enough to just compensate for upward squirt.

pj
chgo
 
I suspect the main reason some players get more draw when jacking up is that they struggle to hit the CB low enough with their standard bridge and the jacking up tends to allow them to hit closer to the miscue limit, without the feel that they are going to miscue.

Another thought refers to alignment perception. I've observed that myself and some others, tend to perceive the shot line a little more to the left (for right handers), when elevated. As draw largely eliminates the capacity to swoop / swipe on shots, which many intuitively do, to create the required pot line, they may have more success with potting accuracy on draw shots when elevated during alignment.

I know this sounds a bit convoluted, but it could be part of what helps some players have success with jacking up on draw shots.

Colin <-- Hates jacking up!
 
Colin Colenso said:
I suspect the main reason some players get more draw when jacking up is that they struggle to hit the CB low enough with their standard bridge and the jacking up tends to allow them to hit closer to the miscue limit, without the feel that they are going to miscue.
Another thought refers to alignment perception. I've observed that myself and some others, tend to perceive the shot line a little more to the left (for right handers), when elevated. As draw largely eliminates the capacity to swoop / swipe on shots, which many intuitively do, to create the required pot line, they may have more success with potting accuracy on draw shots when elevated during alignment.
I know this sounds a bit convoluted, but it could be part of what helps some players have success with jacking up on draw shots.
Colin <-- Hates jacking up!
Click to expand...
I saw an old video once ,maybe 20 years, ago by an instructor named Don Feeney. In that video he demonstrated (how in his determination) that a slightly elevated cue really helped reduce collision induced throw. Even with various side CB hits, but especially when hitting straight low with that old 'drag stroke' and letting the CB roll pure.
I'm not so sure about ALL of that, but I do know that it is helpful to me on those long cuts where the guy has you wedged up in a corner pocket and you can't stroke clean.
What is your opinion of his analysis?
TY.
 
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GoldenFlash said:
I saw an old video once ,maybe 20 years, ago by an instructor named Don Feeney. In that video he demonstrated (how in his determination) that a slightly elevated cue really helped reduce collision induced throw. Even with various side CB hits, but especially when hitting straight low with that old 'drag stroke' and letting the CB roll pure.
I'm not so sure about ALL of that, but I do know that it is helpful to me on those long cuts where the guy has you wedged up in a corner pocket and you can't stroke clean.
What is your opinion of his analysis?
TY.
Click to expand...
Don "Preacher" Feeney usually knows what he's talking about, but I think he's off base here. Any forward or backward rotation on the cue ball (even too much side spin) reduces throw, but of course either of those can be added without jacking up.

Drag draw is also just another way of adding forward rotation.

pj
chgo
 
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