L.S. Dennis
Well-known member
Given what I just read, I totally agree
The best video of a Carbon Fiber shafts deflection testing with a robot arm
- Thread starter Mirza
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Versions used were the 12.9mm Revo and the 12.5mm Cynergy. The Ignite only comes in 1 diameter (12.2mm).
This is a very good point. Shaft diameter and length need to be EXACTLY the same or there will be a variiance. There is a calculus to deflection which I will not expand upon b/c I could write a book here and someone would likely refute it anyway. I appreciated the scientific approach, but w/o the constant of shaft diameter and length, I presume the results could have variance.
The differences in impact on the centerball hits are due to refraction from slight angle differences from the holder of the camera recording. That aside, there is a 1mm advantage with both the Cuetec and the SMO shafts at the centerball hit.
I also agree with others that the piece holding the CB is not attached to the mainframe. Even though it was aligned by laser, a1mm variance would disrupt the end results.
The final results are in the video @10:02 for LEFT English showing deflections of 7-9mm given a (near) perfect 7ft shot.
Bottom line,(to me), is to consider if a 1mm advantage is worth the expense of a CF shaft??
Since the SMO only comes in 1 diameter, they should've compared it to the smallest diameter offering from Predator and Cuetec. Even if they wanted to do a "pound for pound" comparison, that would still imply testing the SMO against the 12.4mm Revo (since the SMO is 12.5mm).
Agreed, it's extremely questionable. It's commonly known most players use way more english than needed.
It is 70 mm to 93 mm, not 7 - 9 mm.
My bad! Ya right. When I was typing that I had shaft diameters on the brain. my apology.
Pool & Firearms have a lot in common......
One is horizontal deflection; the other is vertical.
On the vertical side, this guy knows his poopy....
Gun deflection
he gets to the meat of it @13:20
Member of the over English club?? Guilty!
That shot went into the rail at 19 and should have hit 38 2 tenths short of the pocket.
Even with Center Ball that was a little short indeed.
So I have been saying ever since the Revo and the others came out that many of the CF cues add more action to the cueball at the same stroke, about 15%, seems I was correct
I think "more action" in pool typically means higher spin/speed ratio. I assume you're talking about more efficient energy transfer (more force), which doesn't affect spin/speed ratio?So I have been saying ever since the Revo and the others came out that many of the CF cues add more action to the cueball at the same stroke, about 15%, seems I was correct
pj
chgo
It would affect it all, 15% more power should equal 15% more spin, unless physics fail at the pool table LOL. You hit the cueball at X speed, you get Y revolutions/second. You hit it at X speed +15%, you get Y + 15% revolutions/second. I can't think of any reason why that would not be the case.
That allows you to hit the same shot softer with CF and everything will seem easier. Pat is right though in that the "quality" of the spin won't change. Both the spin and the speed will increase with CF for a given stick speed.
I really wish the experimenters had measured RPMs but that's not so easy. I think you have to count revolutions on the slo-mo video manually unless you have a very smart analysis system.
That's the case, alright, but more RPMs doesn't mean greater "spin effect" (which usually means greater angle change off a rail) - for that you need higher spin-to-speed ratio, which isn't increased with a harder hit on the same CB spot.
It's a semantic difference, but important to understanding/communicating the dynamics of CB spin.
pj
chgo
P.S. Oops - I see Bob beat me to it (dammit, Bob!).
It may not affect the maximum angle change you can theoretically get due to things like how the rails grip and the friction, physical limitations of reality, but you can get the same effect with 15% less force which is always a good thing for accuracy and touch. And for draw and follow, more action would equal more distance traveled, or again, less effort needed to do the same thing as you did with another shaft. All good things. While we may not be able to equate 15% less effort as a 15% improvement in ball pocketing or position, there has to be some benefit, even if it's much smaller like 5%, that is a huge thing to overall win chances over a match or a night.
Say you go from making 19 balls to making 20, which can be the difference between a break and run and a break and sell out the last ball or two every other game. In a race to 9 or 11, or even 7, this can mean an extra game win. Imagine you are up 2-0 and your extra win happens then due to 15% better position on some 3-4 rails shot, now it's 3-0 and not 2-1, which is a world of difference in the match, not just in score but in the mental state of the opponent (assuming you are not playing Shaw or SVB LOL). In addition to this, your mental confidence in the stoke and ability to move the ball as needed is increased, so you have that extra bonus to the skill and outcome of the game or shot. I always tell people that get nervous or play scared that you need to think like you will make every shot and every position even though you won't be able to; with good equipment behind you, this feeling increases. Imagine going parachuting KNOWING your chute will not fail you instead of just hoping it won't, or that it will fail 15% more, that's the difference in feel as you approach the table with some harder shot.
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I watched the video, thanks for sharing.
@Bob Jewett @dr_dave @Cornerman @nataddrho
Every squirt testing machine I've seen pictures/video/text descriptions of has been roughly the same. An arm holding a cue stick on a real table, with real cloth, striking a cue ball, and measuring how far the ball moved off center on the end rail. Provisions (on some setups) are made to minimize the swerve effects, such as shooting very hard, and removing the end rail to make the cue perfectly level.
Thinking outside the box, what if the whole idea was redesigned to eliminate cloth friction entirely, and eliminate the large and somewhat permanent fixture on the tester's pool table.
How about something like a 4" PVC pipe that slips over the test cue. The cue and PVC pipe would be perfectly vertical. It would have internal provisions to center the test cue (and allow some compliance like a bridge hand does). A CB could be dropped from the top of the pipe so it hits the tip, then bounces off. There could be a hole in the top of the pipe that the CB just fits though, and that hole could slide to adjust how much "spin" is on the ball. There would be some measuring device to see how much the dropped ball "deflected" sideways off of the tip. The measuring device could be some sort of vision system (nowadays an iPhone in slow motion might work), or maybe even the DigiBall could be the test ball, and use its built in accelerometer to measure how far the CB deflected.
Pros are this could be a very compact setup compared to a robot setup that takes up the whole table. More compact means less materials, and usually a lower cost. It could even be offered for sale as a self contained product. No swerve since no friction.
Cons off the top of my head would be since its dependent on gravity, it would be very important the tube is leveled vertically. Another con is this a new concept, so it would need to be developed and find out its flaws. Thoughts?
@Bob Jewett @dr_dave @Cornerman @nataddrho
Every squirt testing machine I've seen pictures/video/text descriptions of has been roughly the same. An arm holding a cue stick on a real table, with real cloth, striking a cue ball, and measuring how far the ball moved off center on the end rail. Provisions (on some setups) are made to minimize the swerve effects, such as shooting very hard, and removing the end rail to make the cue perfectly level.
Thinking outside the box, what if the whole idea was redesigned to eliminate cloth friction entirely, and eliminate the large and somewhat permanent fixture on the tester's pool table.
How about something like a 4" PVC pipe that slips over the test cue. The cue and PVC pipe would be perfectly vertical. It would have internal provisions to center the test cue (and allow some compliance like a bridge hand does). A CB could be dropped from the top of the pipe so it hits the tip, then bounces off. There could be a hole in the top of the pipe that the CB just fits though, and that hole could slide to adjust how much "spin" is on the ball. There would be some measuring device to see how much the dropped ball "deflected" sideways off of the tip. The measuring device could be some sort of vision system (nowadays an iPhone in slow motion might work), or maybe even the DigiBall could be the test ball, and use its built in accelerometer to measure how far the CB deflected.
Pros are this could be a very compact setup compared to a robot setup that takes up the whole table. More compact means less materials, and usually a lower cost. It could even be offered for sale as a self contained product. No swerve since no friction.
Cons off the top of my head would be since its dependent on gravity, it would be very important the tube is leveled vertically. Another con is this a new concept, so it would need to be developed and find out its flaws. Thoughts?
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It would probably have some validity but I think that the results wouldn't be absorbed easily by the masses. It is too abstract for pool players to feel "apples to apples".
I like the cloth-less frictionless idea. It eliminates swerve. My robot was built on top of my Husky wood workbench, which has extremely low friction compared to cloth. The final angle was mostly unmodified from the exit angle by rotational effects of the cue ball.
Agreed. Although, I like the “thinking outside the box” with a vertical setup instead of horizontal.
If the cue is level, cloth friction is of no practical concern. The “table” doesn’t need to be a pool table with rails (requiring cue elevation). It can be any table (or floor) with a green of blue cloth to make people think the testing looks like pool.
Love the thinking out of the box and thinking simplicity (and inexpensively).
The shaft being vertical must be supported by something that gives. Any of these test robots that inappropriately grips the stick too tight will give misleading results. I know some people will say that if it’s the same for every cue, it shouldn’t matter. This is incorrect. This would be like testing to see who the fastest runner is, but having them run on snow. The guy that can deal with the snow (snow shoes, for example) will win, but the test was supposed to be looking at fastest runner.
In this case, an overly firm grip will falsely affect the tip/ball collision, so the shaft that can deal with that will perform better. But that wouldn’t be the actual user scenario. The Jacksonville Experiment showed this nearly 25 years ago.
As a career-long automation and robotics engineer, designing a “robot” isn’t an issue. Time, money and ROI are. IMNSHO, we don’t need to build a robot to tests shafts for ourselves. But I applaud anyone who gives the effort. I just wish everyone who does build a robot consults with Bob Jewett first for Lessons Learned from previous work he and The Jacksonville Experiment already uncovered.
Good post Freddie.
For those interested, lots of "Lessons Learned" from several past efforts to do machine-based CB deflection (squirt) testing can be found here:
IMO, careful human testing of CB deflection can be much more accurate than many past machine-testing results.
And for those interested in more info on the "Jacksonville Experiment," everything available can be found here:
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Neat idea.
I think you will need to measure the speed and direction of the ball off the tip very accurately. I think you also need to measure the spin.
A good tip (bouncy, efficient) will tend to make the ball bounce up from the tip more than a dead tip. The shaft and butt also change the efficiency as mentioned for the wood shaft results above.
If the measurement problem can be solved I think you will get more info than just squirt since you will also be measuring tip/cue efficiency and maybe some other things.
Maybe the setup can be turned horizontal and put on a table -- shoot the ball at the stick. The problem is how to control the speed of the incoming ball.