Draw shot cue elevation effects

dr_dave

dr_dave

Instructional Author
Gold Member
Silver Member
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:
 
Thanks Dr. Dave. You always give great information based on fact while the rest of us use a lot of intuition. Very refreshing.
 
TX Poolnut said:
That link gave me a headache, so it must be true. Thanks Doc! :)
Click to expand...
I assure you that the headache it gave me is probably a lot worse than the headache it gave you. :banghead:

Also, you had the option to just read the conclusions and not look at the monstrous math and physics. You must like pain. :eek:

Regards,
Dave
 
Tennesseejoe said:
Thanks Dr. Dave. You always give great information based on fact while the rest of us use a lot of intuition. Very refreshing.
Click to expand...
Thanks.

I know a lot of people think they get more draw "juice" or "snap" with elevation, so I am hoping we can figure out what they really mean and what's really behind the beliefs.

Regards,
Dave
 
Nice to see some real science confirming what should be a given. If anyone tries to claim they get better draw by jacking up, I can just show them this page and watch their eyes cross.
 
What I found fascinating is in TP B.8 where maximum draw occurs significantly before the cue tip is near the miscue limit.
 
CreeDo said:
Nice to see some real science confirming what should be a given. If anyone tries to claim they get better draw by jacking up, I can just show them this page and watch their eyes cross.
Click to expand...
I've been trying to think of reasons some people might get more draw with a jacked up cue. This is all I could come up with:
  1. If you hit the same contact point on the CB, there will be a greater "tip offset" from center with an elevated cue.
  2. What they mean by "more draw" is "more draw for the amount of speed given to the OB."
  3. Maybe they tighten their grip with the jacked up cue, causing them to hit the CB lower than they think.

Anybody have any other ideas (other than "Maybe they are delusional")?

Regards,
Dave
 
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 again, Dave, for your tireless efforts to confuse us with the facts. Does the difference vary with the distance between CB/OB?

This information, coupled with the well known fact that jacking up plays hell with accuracy, suggests pretty clearly that jacking up is to be avoided. However, the "quick draw" benefit is not to be overlooked. When the OB is relatively nearby (so you won't miss the shot because of being jacked up) it can make sense to jack up in order to get the CB to draw at a steeper angle.

pj
chgo
 
Last edited:
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...


wait. are you saying that if i want to increase the amount of draw i can apply to the cue ball i should use a level cue?

now i'll have something else to practice in my second week of learning to play pool
 
Patrick Johnson said:
Thanks again, Dave, for your tireless efforts to confuse us with the facts.
Click to expand...
You're welcome. I aim to squerve.

Patrick Johnson said:
Does the difference vary with the distance between CB/OB?
Click to expand...
... not really. See the graphs on pages 7 and 8 of TP B.10.

Patrick Johnson said:
This information, coupled with the well known fact that jacking up plays hell with accuracy, suggests pretty clearly that jacking up is to be avoided. However, the "quick draw" benefit is not to be overlooked. When the OB is relatively nearby (so you won't miss the shot because of being jacked up) it can make sense to jack up in order to get the CB to draw at a steeper angle.
Click to expand...
Good summary. Well stated.

Regards,
Dave
 
Could it be that many players think they get more draw with a jacked up cue because the draw takes effect quicker?
 
There are draw shots that you can execute with an elevated shaft that cannot be done with a level stroke. Play some one pocket and you will really notice how many different draw angles you can produce.
 
dr_dave said:
Thanks.

I know a lot of people think they get more draw "juice" or "snap" with elevation, so I am hoping we can figure out what they really mean and what's really behind the beliefs.

Regards,
Dave
Click to expand...

I agree 110% that a level cue is best when doing a draw shot but since I've done table length draw shots with the OB being near the one end pocket and the cue ball pretty much near the other end cushion and have drawn it all the way back, I have to assume that the loss isn't all that much. I would say this information should be pointed to people that are still learning to draw a ball and think jacking up is the way it should be done.
MULLY
 
poolplayer2093 said:
wait. are you saying that if i want to increase the amount of draw i can apply to the cue ball i should use a level cue?

now i'll have something else to practice in my second week of learning to play pool
Click to expand...

Most definitely. And not only improve your draw but it will improve your accuracy. Even though my previous post seemed like I was going against what Dave was saying, I honestly wasn't. I totally agree that you shouldn't jack up your cue to try to "improve" your draw because you'll definitely be doing just the opposite. Especially if you're at the level you stated above. Keep that cue as level as you can and stroke through the ball.
MULLY
 
Tennesseejoe said:
Could it be that many players think they get more draw with a jacked up cue because the draw takes effect quicker?
Click to expand...
That's conclusion "3" in my original post. Maybe that's one of the things people think.

Regards,
Dave
 
TheMadScientist said:
There are draw shots that you can execute with an elevated shaft that cannot be done with a level stroke. Play some one pocket and you will really notice how many different draw angles you can produce.
Click to expand...
Agreed. That's what I mean by "quick draw" (which you get with a higher spin-to-speed ratio).

Regards,
Dave
 
poolplayer2093 said:
wait. are you saying that if i want to increase the amount of draw i can apply to the cue ball i should use a level cue?
Click to expand...
A small amount of cue elevation doesn't hurt much, but a near-level cue is better (unless there is a cut angle and you want "quick" draw, in which case cue elevation can help, provided you can still maintain enough accuracy, which can be tougher with an elevated cue).

Regards,
Dave
 
dr_dave said:
...for maximum draw distance, a level cue (or as close to level is possible) appears to be best...
Click to expand...
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
 
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