Summary: David Alciatore ("Dr. Dave") ILLUSTRATED PRINCIPLES
"Draw Shot Primer Part I: physics"
Note: Supporting narrated video (NV) demonstrations, high-speed video (HSV) clips, and
technical proofs (TP) can be accessed and viewed online at billiards.colostate.edu. The
reference numbers used in the article (e.g., NV 3.8) help you locate the resources on the
website. If you have a slow or inconvenient Internet connection, you might want to view
the resources offline using a CD-ROM. See the website for details.
Over the next few months, I will be presenting a series of articles dealing with draw shot
principles. The goal is for the reader to come away with some useful information and systems for
becoming more effective at planning and executing draw shots. In my January-July, 2004 articles
(available on my website), I showed how the 90° and 30° rules are extremely useful tools in
planning stun and follow shots. Therefore, the natural question is: "Well, what about draw shots
... is there a similar rule for them?" Well, let's start by exploring some basic physics so we can try
to come away with some useful tools.
Unlike with the 30° rule for a natural roll follow shot, where the cue ball deflects close to 30°
over a wide range of cut angles (see NV 3.8 and my past articles), the deflected angle for a draw
shot varies quite a bit as the cut angle changes. The physics and math details to show this can
be found in TP A.20, and the results, which are probably more interesting to most people, are
shown in Diagram 1. The graph shows how much the cue ball deflects away from its original
direction for various ball-hit fractions. Diagram 2 illustrates the deflected angle for 1/4-ball, 1/2-