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View Full Version : Aiming carom shots using the 30 & 90 degree rules



dr_dave
12-23-2004, 05:20 PM
<blockquote><font class="small">Quote hookster52:</font><hr>
what i am wanting too know is how to calculate a carom shot if the cueball and the first object ball are not lined up in a 30 degree path. i know that the cueball follows a 30 degree path if the line of aim is in a 30 degree angle but what if the cueball and the first ball you are hitting to make cueball hit the ball your trying to make is not in a 30 degree angle deflection path. how do you calculate for cueball path ??<hr /></blockquote>
If the object ball is not in the 30 degree path, one option is the try to line up the shot for a 90 degree cue ball carom. Normal videos NV 7.2-7.4 (http://www.engr.colostate.edu/~dga/pool/normal_videos/index.html) and my March and June, 2004 instructional articles (http://www.engr.colostate.edu/~dga/pool/bd_articles/index.html) explain how to use the 90 and 30 degree rules to aim carom shots.

If you need to plan a carom shot that cannot be conveniently set up in the 90 or 30 degree directions, the 90 and 30 degree rules still give you good points of reference. The amount of cue ball vertical spin (follow, stun, draw) will determine where it goes relative to the 90 and 30 degree directions. With full stun, the cue ball will head exactly in the tangent line direction. With complete roll, the ball will deflect in the 30 degree direction. For other shots, it is difficult to reliably know exactly where the cue ball will go, so it is best to not attempt caroms in these cases unless you have no other options. Like many things in pool, all you can do is practice a bunch and develop intuition for how much the cue ball deflects with various amounts of vertical spin. Also, as described in my March, 2005 instructional article (http://www.engr.colostate.edu/~dga/pool/bd_articles/index.html), shot speed also affects the exact cue ball trajectory. However, the 90 and 30 degree directions are still good to know to have some definite points of reference.

dr_dave
12-23-2004, 05:37 PM
For the benefit of others, here's another reply from the original thread (http://www.billiardsdigest.com/ccboard/showthreaded.php?Cat=&amp;Board=ccb&amp;Number=167746&amp;page =0&amp;view=collapsed&amp;sb=5&amp;o=&amp;fpart=1):
<blockquote><font class="small">Quote Stretch:</font><hr>This might help.....when i'm looking at a carom of less than 30% your basically hitting "throught" the carom ball to get to the ob. OR you can cut the carom ball real thin and make the ob. I find that hitting through the ob much more dependable. What i do is draw a line from the ob's contact point to the carom ball. Where that line touches the carom ball is your target. It will be on the oposite side of where your standing behind the cue ball, but just aim for that point anyway as if the rest of the carom ball wasn't there. Use half a tip high and get natural roll or a little follow, remember it's a follow stroke. It dosn't take long to get the hang of it.<hr /></blockquote>