What does pool physics offer for advice on draw shots?
Here’s the list of conclusion, which can be found at the end of TP B.8 (all of the graphs referenced below are clearly labeled in the analysis if you want to check them out):
- Generally, to get more draw, you must hit the cue ball harder and lower (see graphs A and G). No big surprise here!
- More tip offset does not produce significantly more draw as you approach the miscue limit; so, generally, it is advisable to not hit too close to the miscue limit (see graphs A and G).
- With larger drag distances, and for a given maximum cue speed, max draw occurs at less than maximum tip offset (at about 70%-80% tip offset). In other words, you don’t get more power draw by hitting closer to the miscue limit. However, 80% is still fairly close to the miscue limit (see Graphs G, Q, S, and U, and see the data on the previous page).
- In general, with a draw shot with a medium desired draw distance, a slower cue speed with more tip offset will result in better draw distance control than a faster cue speed with less offset (see the slopes of the curves in Graphs A and G at a given draw distance).
- Stop shots are much less sensitive to tip offset position than draw shots are. In other words, CB position is much easier to control with a stop shot, as compared to a draw shot (see Graphs G, H, I, N, and O).
- For a short stop shot, slower speed offers slightly better control (see the overall slopes of the curves in Graph I). For longer stop shots, faster speed appears to offer slightly better stop control (see Graphs N and O); although, with more speed, the CB will drift sideways more if the OB isn’t hit perfectly squarely.
- For stun-through (small controlled follow) and stun-back (small controlled draw), a firmer hit closer to center offers better CB distance control (see Graphs L and M).
- It is much easier to control draw distance on a new, slick cloth than it is on a “sticky” cloth, especially with lower-speed shots (see Graph T). The statement assumes the player is equally well “adjusted” to each cloth condition. Any player will need to adjust when playing under different cloth conditions.
- It is easier to draw the ball on slick cloth, and faster cloth allows for greater draw distances.
For more info and illustrations, see “Draw Shot Physics – Part I: basics” (BD, April, 2009) and “Draw Shot Physics – Part II: examples” (BD, May, 2009) and “How High or Low Should You Hit the Cue Ball?” (BD, September, 2011).
With a straight draw shot (with no cut angle), the amount of draw is determined solely by the amount of CB spin at contact with the OB. This is the topic of TP B.8. In TP B.9, I look at both spin and the spin-to-speed ratio. Examples where spin-to-speed ratio is more important than spin are when …
- … you don’t want to hit the OB too hard (e.g., to leave the OB by a pocket if you can’t or don’t want to pocket it, to increase the effective size of the pocket, or with some one-pocket shots), while still maximizing draw (e.g., to achieve position for the next shot or to play a safety).
- … you want to keep the draw angle as narrow as possible when there is a cut angle (e.g., to avoid a ball or a pocket, or to get straight up or down the table better).
Here are the results of the analysis:
- Generally, to get more spin at contact with the OB, you must hit the CB harder and lower. However, as you approach the miscue limit, you get a smaller gain in spin. And for longer drag distance shots, the amount of spin actually decreases as you approach the miscue limit (see Graphs A and I). See TP B.8 for more info and results.
- More tip offset results in a greater spin-to-speed ratio at OB contact (except for long drag shots, especially if conditions are “sticky” (see Graphs B and J). So to get a better spin-to-speed ratio, hit as low as you can on the CB without being at too high a risk of miscuing.
TP B.10 – Draw shot cue elevation effects, looks at the effects of cue elevation. Here are the conclusions from the analysis:
- 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).
- Modest cue elevations (about 0-15°) reduce the spin-to-speed ratio of the CB at OB contact, resulting in “slower” draw (see quick draw for more info).
- As you increase cue elevation above about 20°, the spin-to-forward-speed ratio increases, allowing for “quicker” draw (see quick draw for more info). An extreme example is a highly elevated massé 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 as possible) appears to be best. For more info, illustrations, and examples, see “Draw Shot Physics – Part IV: cue elevation effects” (BD, July, 2009).
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.
Some people claim they get better draw when they elevate the cue some. Possible explanations for this can be found in the draw-shot cue-elevation effects resource page.