Deflection question, explain how a stiffer CF shaft has less deflection.

VarmintKong said:
I am not knowing the answer to your question. However you bring up something I’ve wondered about myself:

Deflection isn’t just squirt. It is the sum total of squirt and swerve.
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I call this “Effective Squirt,” a term I started using 30+ years ago where squirt dominated the spin compensation. So squirt is squirt, and effective squirt is the result of all spin effects I add up squirt effect, swerve effect, and throw effects to determine my compensation.
 
Cornerman said:
I call this “Effective Squirt,” a term I started using 30+ years ago where squirt dominated the spin compensation. So squirt is squirt, and effective squirt is the result of all spin effects I add up squirt effect, swerve effect, and throw effects to determine my compensation.
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To avoid confusion, I like to use "net CB deflection" or just "CB deflection" or "squerve" for the net effects of squirt and swerve. When most people say "deflection" or "CB deflection," I think this is what they mean (even though some people just mean "squirt" when they say "deflection"):

squirt_swerve_CB-deflection.jpg
 
Jaden said:
Because CF is stronger and therefore can remain stable and strong with more hollowness and thinner walls, they are capable of being lower deflection than wood. I've created a hybrid shaft that plays better than pretty much anything else I've played with that is a kielwood shaft that has been cut down and fused with a carbon fiber tube for the final 10 inches.

It can be larger diameter giving better consistency and forgiveness of hit, yet still have relatively low deflection and with that good feeling and feedback of a wood to wood joint.
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Interesting ❗️
 
Stiffness does matter. The original 11.8 mm Revo was flexible and deflected a lot. The newer version is much stiffer and has close to zero deflection.

My theory is that because as shaft flexes it will push the cue ball offline in the opposite direction before it completely leaves the tip. If you've ever hit with an old graphite shaft you can really feel this flexing and increase in deflection

If you have an original 11.8 mm Revo. Try grabbing it at the joint and tip and flexing it. Very flexy vs 12.9 or newer 11.8 revo
 
dr_dave said:
Stiffness matter a little, but the mass of the part of the shaft closest to the tip is by far the main factor causing CB deflection or squirt. This is covered in detail with explanations, analysis, and demonstrations here:

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You're wrong. It matters a lot

2 reasons why people don't feel it. One they aren't good enough at pool to notice. Two they didn't use enough sidespin. This goes for testing as well. Really need to get closer to 2 tips of side with a smooth firm stroke to generate max deflection
 
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dr_dave said:
If you think all my analyses, testing results, and demonstrations are wrong, please provide proof.
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To be fair, sometimes it is difficult to separate the effects of stiffness and endmass. If you make a shaft bigger without taking measures to reduce the endmass, the end of the shaft will be stiffer and have more endmass, so you might think it is the increased stiffness that is causing more CB deflection, but it is actually the extra endmass primarily responsible.
 
poolscholar said:
Find an old and new 11.8 revo and you'll have proof. You're not always correct
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I don’t have an old and new 11.8 Revo, but if the CB deflection is different, it is because one has more endmass than the other. It might also have more stiffness as a result (e.g., if the carbon fiber wall thickness is greater, making it stronger, stiffer, and heavier).
 
dr_dave said:
I don’t have an old and new 11.8 Revo, but if the CB deflection is different, it is because one has more endmass than the other. It might also have more stiffness as a result (e.g., if the carbon fiber wall thickness is greater, making it stronger, stiffer, and heavier).
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That's a theory but you need sophisticated experiments to prove this
 
dr_dave said:
I don’t have an old and new 11.8 Revo, but if the CB deflection is different, it is because one has more endmass than the other. It might also have more stiffness as a result (e.g., if the carbon fiber wall thickness is greater, making it stronger, stiffer, and heavier).
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Your reputation proceeds you, your testing videos speak for themselves, I for one thank you for all the FREE information you have given to the pool playing community, it has helped me tremendously, Thank You, you can't please everyone......
 
SSP said:
Your reputation proceeds you, your testing videos speak for themselves, I for one thank you for all the FREE information you have given to the pool playing community, it has helped me tremendously, Thank You, you can't please everyone......
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Thank you for the supportive comment. You're welcome.

FYI, speaking of testing videos, people might find the one below interesting. It compares CB deflection for a wide range of shafts including Revos of all three sizes (11.8, 12.4, and 12.9 mm). The video also shows an easy way for anybody to do accurate testing on their own. The video also discusses how carbon-fiber shafts can be made to have less endmass. Enjoy:

 
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poolscholar said:
Yes if you have two shafts which are similar build but vary in flexibility. Then you can learn something potentially

Hopefully with more than 2 but it's tough. Science is hard
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You're barking up the wrong tree. Stiffness affecting CB squirt is as big a myth as pro's don't drop their elbows.

There is even one guy on these forums years ago that took a shaft and whittled it away in the bridge area so it looked like a dog chewed on it. It made a localized area very thin, so the shaft would have a lot of flex, without affecting the mass near the tip much. It squirted the same. I forget who did it now, it was probably 20 years ago. There might have even been a youtube video. Pat was around then, he might remember.

I'd wager if you cut a shaft in two pieces 1 foot from the tip, and put a joint at the cut made of a spring, the deflection would be the almost identical.
 
iusedtoberich said:
You're barking up the wrong tree. Stiffness affecting CB squirt is as big a myth as pro's don't drop their elbows.

There is even one guy on these forums years ago that took a shaft and whittled it away in the bridge area so it looked like a dog chewed on it. It made a localized area very thin, so the shaft would have a lot of flex, without affecting the mass near the tip much. It squirted the same. I forget who did it now, it was probably 20 years ago. There might have even been a youtube video. Pat was around then, he might remember.

I'd wager if you cut a shaft in two pieces 1 foot from the tip, and put a joint at the cut made of a spring, the deflection would be the almost identical.
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The "Beaver Cue" experiment was done by Mike Page. I also recreated it with careful measurements, as documented in this article:

“Return of the squirt robot” (BD, August, 2008)
​
The experimental results in this article might also be of interest:

“Squirt – Part VII: cue test machine results” (BD, February, 2008)​
 
dr_dave said:
The "Beaver Cue" experiment was done by Mike Page. I also recreated it with careful measurements, as documented in this article:

“Return of the squirt robot” (BD, August, 2008)
​
The experimental results in this article might also be of interest:

“Squirt – Part VII: cue test machine results” (BD, February, 2008)​
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You admit flex affects deflection but nobody understands how much.

Posting old articles doesn't prove anything, nor does making one video or having a phd. We need carbon fiber shafts of various flexibility and a robot. Testing anything with a human shooting is suspect and definitely not science
 
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