How long is the tip in contact with the cue ball?
Clips HSV A.77-A.81 and A.147-A.151 show close-ups of cue tip impact for various hardness tips and various speeds. The Jacksonville Project, also did some measurements of tip contact time. Here’s a newer video showing how contact time varies with cue speed:
Here is a summary of the results of these videos:
- most contact times (i.e., for most tips and most speeds) are in the millisecond range (about 0.001-0.002 sec).
- a soft tip at slow speed has a longer contact time (as high as 0.002-0.003 sec), but still extremely small.
- a very hard tip (e.g., phenolic) at fast speed has a shorter contact time (as low as 0.0008 sec).
- the contact time increases for slower speeds and decreases slightly for faster speeds, but not by much (still in the millisecond range).
- chalk does not stay on tips (especially hard tips) very well at impact (see the blue clouds that separate from the tips in the videos).
Some people think that what they do with their grip hand or follow through can change the tip contact time, but this is not the case (i.e., it is not possible to get a significant effect). Also, some people think a softer tip, which has a slightly longer contact time, can create more CB “reaction.” This is not the case. The peak force isn’t as large with a longer contact time (i.e., the force is spread out over a longer time). Therefore, the “hit” might “feel” slightly different to the player. However, the momentum effects (cue and ball speed changes) will still be the same, assuming the tips being compared have the same efficiency. Another thing that might be different is that a shorter contact time is usually associated with a harder tip, and a harder tip might have better efficiency, so the CB might have slightly more speed (with a given stroke) with a harder tip for a given cue mass and speed. And with more speed, less spin will be lost on the way to the OB or cushion, giving the impression that the hit created more spin.
With an increase in tip contact time, the effective tip offset will be slightly greater (because the tip will rotate out with the CB during contact), but this will also result in more squirt, which will diminish the effectiveness of the slightly larger tip offset. For more info, see cue tip hardness effects and getting more spin with an LD shaft.
Some people think cue acceleration at impact with the CB has an important effect on cue tip contact time, but this is not the case. For more info, see stroke acceleration.
For more info and resources on related topics, see:
- tip hardness effects
- cue tip efficiency
- cue “hit,” “feel” and “playability
- effects of light vs. tight grip
- stroke acceleration
- follow through
- stroke timing
Over what distance is the cue tip in contact with the cue ball on a typical shot?
The contact distance is much smaller than most people think. For example, with a break shot with a very hard tip, a typical contact distance (per TP B.20) is only about 1/10 inch (3 mm). With softer tips, the contact time and distance is longer. With slower speed shots, the contact distance is shorter.
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