Where can I find information on experimental results from squirt-testing robots?
See published data for some cue-comparison results from Platinum Billiards resulting from cue tests with “Iron Willie” (a cue-testing machine developed in 1994). The Jacksonville Project also did some work with “Iron Willie.” Meucci has also done some tests with their “Myth Destroyer” machine introduced in 1998 (see the original Meucci video and other videos available on their website); although, due to the violations of the “Rules of CB Deflection (Squirt) Testing” below. Meucci’s setup should probably be called the “Myth Creator” instead.
The following articles document work with a cue-testing machine developed at Colorado State University (CSU) in 2007, for CueStix International:
- “Squirt – Part VII: cue test machine results” (BD, February, 2008)
- “Return of the squirt robot” (BD, August, 2008)
The CSU machine used a spring stretched to various indexed and latched lengths to create repeatable cue speeds. The cue was supported by an adjustable-height V-bridge and a rubber-lined grip which slid on linear bearings. When a cue was loaded, both the grip and bridge heights were adjusted to ensure the tip was on the horizontal centerline of the CB, with the cue level. The squirt angle was measured both manually by observing where the CB struck at the end of the test table, and electronically with two crossing IR beams that detected the CB speed components in two directions. Before going with the spring-loaded linear system, we had considered the three prototype design concepts demonstrated in the following videos:
- Pneumatic cue-stick tester prototype
- Spring-loaded cue-stick tester prototype
- Motorized cue-stick tester prototype
The final machine built and used for testing was of much better quality than the prototypes. Results from lots of testing done with the final machine are available in the BD instructionial article links above.
NOTE – When using a machine to test cues, the “grip” needs to be flexible, like the flesh in a human hand (e.g., by lining the mechanical “grip: with silicone rubber).
The problem with a non-human, extremely-firm robot grip is that it can add significant effective weight to the cue. If the grip is totally rigid, the weight of the machine’s “hand” and “arm” completely add to the weight of the cue. For example, if you put an 18 oz cue in a rigid machine grip, and the weight of the machine’s “grip” is 20 oz, the cue will act like a 38 oz cue! The result of this is that the CB will not leave fast enough to clear the tip with an off-center hit. The tip will either remain in contact with the CB or catch up after initial contact, creating either a push or double hit. The hit will look and sound normal, but the CB will have more squirt (CB deflection) … sometimes a lot more (as if there where a miscue). For more info, see the maximum sidespin resource page. Lot’s of care must be taken when using a machine to test and characterize cues that will be used by non-machine humans.
If you don’t have access to a robotic squirt-testing machine, decent results can be obtained with careful experiments with human shooters. The following videos recommend procedures for how to do this:
For more info, see: “Cue Tip Squirt Testing” (BD, June, 2014) and “The Carbon Fiber Shaft Craze” (BD, December, 2019). The best way to test and compare cues or shafts is to measure the natural pivot length.
Rules for CB Deflection (Squirt) Testing
Things one must be aware of when testing a shaft or tip for cue ball deflection (squirt), using either a robot or a person, include the following:
- Tip size, shape, hardness, and weight should be the same for all shafts tested; otherwise results will be affected (for more info, see tip hardness effects, tip size and shape effects).
- The cue should be perfectly level during the tests; otherwise, swerve will be a factor, and it will vary with cue elevation and shot speed, which varies with cue weight (this is where the butt can have an effect) and tip efficiency. Swerve also varies with cloth conditions, which can change over time with dirtiness, temperature, and humidity.
- The cue ball squirt angle should be measured directly. Measurements should not be made based on the motion of an object ball that the cue ball hits. The use of an object ball introduces the variable of throw, which can vary with ball surface conditions at the point of contact and with ball speed, which can vary with cue weight and tip efficiency.
- The tip should be consistently on the horizontal centerline of the cue ball; if not, tip contact height effects will come into play.
- The total cue weight should be the same with each test. As pointed out in “2” above, cue weight can affect the speed of the shot; and if the cue is not level this can affect swerve and net CB deflection. Also, the cue weigth could affect tip contact time, which would change the amount of squirt (see the endmass resource page).
- The bridge length should be long enough (8 inches or more) to safely prevent any possible squirt bridge-length effects.
- Robot testing should be done by an independent “laboratory,” not a cue manufacturer, because the manufacturer might not be impartial if the tests involve the manufacturer’s cues or shafts.
- measuring the natural pivot length of a shaft.
from Cornerman (in AZB post):
Meucci’s system starts with a false condition: too tight a grip, a grip that human couldn’t possibly have, so when it strokes the cueball, the cuestick tip and cueball are in longer contact than the 0.001s measured contact time of a human stroke.
Contact time x speed of transverse wave propagation down the shaft = length of shaft “in effect” of the collision.
A normal human stroke will have something in the order of 6″ of the front end of the shaft “in effect;” the Myth Destroyer, due to its overly tight grip, has a much longer length of shaft “in effect.”
More shaft length in effect = more mass in effect = more squirt.
Meucci’s ferrule design [see below] was meant to partially delay or de-couple the ferrule from the shaft (there’s some space between the top of the ferrule to the top of the tenon), so it does well for the Myth Destroyer. Predator’s design is significantly reducing the overall mass in the first 6″, and it wasn’t meant to beat a non-real robot situation. So Predator does worse on the Myth Destroyer (because the Myth Destroyer wants to add mass that’s beyond the 6″ if the ferrule isn’t decoupled).
And that’s just the robot grip problem.
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