cue
tip Dr.
Dave's answers to frequently-asked questions (FAQs),
mostly from the BD
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maintained for the book: The
Illustrated Principles of Pool and Billiards
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Digest "Illustrated Principles"
instructional articles
How much does the tip deform during contact with the cue ball?
Here's an image from some high-speed video filmed by a group from Austria a couple of years ago:
The full video clip can be viewed at HSV A.76 (it is the third clip in the sequence). The video was shot at 2000 frames per sec with a high-resolution color camera. An isolated clip of the close-up of the tip contact can be found at HSV A.76a.
I've collected a sequence of images from the video clip and have made them available in MS Word and PDF formats. The MS Word file is large (1.7 MB), but it is very useful. If you page down through the file to load all of the images, you can then use the scroll bar to simulate a flip-book animation. The faster you scroll, the faster the simulated "video" plays. The images are 1/2000 second (0.0005 or 5 ten-thousandths of a second) apart.
Here are some observations, insights, and questions from the collection of stills:
- The tip is probably relatively soft based on the contact time and amount of deformation. Contact lasts about 4 frames (over frames 3-6), which corresponds to about two thousandths (0.002) of a second.
- The cue tip seems to stay in contact with the ball as the ball starts to rotate, which might contribute to the amount of cue stick deflection.
- The cue tip had an excessive amount of chalk on it (as evidenced by the pre-impact chalk trail through the air and by the huge chalk cloud after impact).
Is it important to remove the mushroomed edges of a tip?
If your tip is properly shaped tip and you are hitting the cueball within the non-miscue zone, the extreme edge of the tip doesn't come into play (e.g., see the diagrams in my July '06 instructional article dealing with "tips" of English).
However, removing the mushroomed edges does:
How long is the tip in contact with the cue ball?
Clips HSV A.77-A.81 show close-ups of cue tip impact for various hardness tips and various speeds. Here are some conclusions:
Does the tip hardness affect how much Enlgish can be applied?
Here are some relevant factors:
For the effects of tip hardness on squirt, see my August '08 article.
from Bob_Jewett:
One issue is which harness of
tip will allow the farther-from-center hit. Some believe that a soft tip takes
chalk better so it can hit the ball farther from center.
There is a counter theory, and that is because a softer tip will have a longer contact time than a hard tip. During contact, the tip rides around the side of the ball some, so the final eccentricity as the tip leaves the ball is larger than when the tip first hits the ball. A softer tip, with the longer contact time will be farther off center at the end than a harder tip with the same starting offset. If both tips can only hold to a certain point of offset, and you start your shot so the miscue point is barely reached at the end of contact, the average offset will be larger for the harder tip. This means that the harder tip can create more spin for a given ball speed.
Which dominates? Holding chalk better or starting farther off-center? I don't know of any experiment that has tested this.
What brands of tip are commonly recommended?
Morri, Sniper, and Triangle.
Does the tip and shaft size make a difference?
For applying English, in general a smaller and rounder tip is better. My July '06 article explains and illustrates one reason: more table clearance, especially for larger offset shots. Another reason is that the smaller, rounder shape allows for a more uniform contact area as the tip offset is increased. (If you have a copy of my book, this is illustrated in Figure 2.2 on pg. 18). A final reason is that, for shots with English, the impact is more centralized to the core of the stick for a smaller, rounder tip. (Some people, for example Predator's marketing personnel, claim that this helps reduce squirt. I'm not sure about this, but I have no evidence to suggest otherwise.)
One advantage of a larger, flatter tip is that a center-ball hit, with some tip placement inaccuracy, will generally have less unintentional English (and unexpected throw). In other words, a larger, flatter tip is more "forgiving" with center-ball hits.
A disadvantage of a larger tip and shaft is that the shaft will typically have more endmass and result in more squirt. Also, a smaller tip might make it easier for some people to visualize and pinpoint the desired tip contact point on the cue ball.
Another concern related to shaft diameter is bridge comfort. With a closed bridge, some shaft sizes and tapers will be morecomfortable than others to different individuals. This is less of a concern with an open bridge.