Cue Tip Contact Myth-Busting Truths in Super Slow Motion

buckshotshoey said:
Tell me if I'm describing this correctly....

Let's say you strike a cue ball with a 100% exact aim point with both tips. The hard tip won't compress as much as a soft so the actual contact point is relatively small and concentrated.

Say the soft tip aim point is EXACTLY the same, but as the tip contacts and compresses, it is actually is producing rotation at a point closer to the center of the ball?

If I am seeing this right, this could be why a hard tip produces more rotation then a soft. The longer "lever" (or moment arm) produces more torque (as minimal as that might be).
Click to expand...

Regardless of the size of the contact patch, there is an "effective tip offset" (or center of pressure) corresponding to the hit (close to the center of the contact patch). That's what determines the amount of spin. If a soft tip and hard tip both hit the CB with the exact same effective tip offset from the center of the CB, they will both generate the same spin/speed ratio; and if the CB speed is the same for both shots, the spin will also be the same. For more info and explanations, see the "Can a softer tip put more spin on the ball?" section on the cue tip hardness effects resource page.
 
dr_dave said:
The spin (rotation) is directly related to the speed (translation) based solely on the tip offset (lever or moment arm) from the center of the ball. Math, physics, common sense, and experience at the table all agree on this point. If you want to see the math and physics, it is here:

Click to expand...

Is this how you communicate with other mechanical engineers at conferences? Is this how you teach?

What’s your point? You said some sentences, but what message are you trying to communicate?


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DynoDan said:
A bit off-topic, but has anyone ever tried playing with rosin instead of chalk?
BTW: I’ve decided that the safe solution to this ‘tip-hardness’ controversy issue is to just use a medium tip 😁.
Click to expand...

Something sticky does just like chalk except taking a little longer. Eventually, it gets on everything around. No way to keep it from migrating. Much nastier than chalk, a ball rolling can make a tearing sound as the sticky material grabs and rips loose.

Short version, not something to try at home or on a pool table that isn't due to be recovered!


jollyrodger said:
Ooooh I want to get in on who’s credentials are biggest lmao

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Click to expand...

I had about a paragraph of initials I could string behind my name a few decades back. As a representative for a business I listed them on a business card. I wanted a much plainer card too but when setting up with a new supplier all I had was the cluttered up card with me.

"What do all those initials behind your name mean?

"They mean I get to charge more an hour for my services than someone that doesn't have those initials behind their name."

"That's what I thought they meant!"

In truth because much of our fees were based on manhours we billed at a rate two or three times higher than many of our competitors and were cheaper! We had the knowledge to take care of business a lot faster. Add that we did things right the first time and it added up to saving people a lot of money. Maybe the initials meant something after all!

Hu
 
pvc lou said:
How has my argument changed?

Excuse me Fred, but your use of the terminology of mechanics is incoherent.

Are you really an engineer?


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Click to expand...
Seriously? You’ve transitioned through :

Softer tips create more spin

to

Tip hardness makes a difference somehow since Dave said to be more delicate with a hard tip vs soft speeds.

to

There is a difference in tip efficiency.




Am I really an engineer? Let’s add you to that other guy who didn’t understand the basic ideal gas law that questioned if I was a mechanical engineer (who actually focused on thermodynamics). He lost on that one as well, and to his credit gave a video of his apology.

I clearly understand mechanical physics. You’ve already insulted two other guys whose careers based on the study physics have been very successful. I guess you insulting me as you did them should make me feel privileged.
 
I thought we were measuring by paper size. I have an entire poster with letters on it. Some call it an eye chart but I like to call it my creds!


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I've always liked this quote. Seems somehow appropriate here.

pj
chgo

education.jpg
 
Cornerman said:
Seriously? You’ve transitioned through :

Softer tips create more spin

to

Tip hardness makes a difference somehow since Dave said to be more delicate with a hard tip vs soft speeds.

to

There is a difference in tip efficiency.




Am I really an engineer? Let’s add you to that other guy who didn’t understand the basic ideal gas law that questioned if I was a mechanical engineer (who actually focused on thermodynamics). He lost on that one as well, and to his credit gave a video of his apology.

I clearly understand mechanical physics. You’ve already insulted two other guys whose careers based on the study physics have been very successful. I guess you insulting me as you did them should make me feel privileged.
Click to expand...

You’re all tangled up amigo.


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DynoDan said:
A bit off-topic, but has anyone ever tried playing with rosin instead of chalk?
BTW: I’ve decided that the safe solution to this ‘tip-hardness’ controversy issue is to just use a medium tip 😁.
Click to expand...
I'm with you dude! Best of both worlds.

Now that my hair hurts and I am going to be thinking about alllll of this information that I didn't ever think about before, I am going to skip my practice session and start drinking.
 
Cornerman said:
Seriously? You’ve transitioned through :

Softer tips create more spin

to

Tip hardness makes a difference somehow since Dave said to be more delicate with a hard tip vs soft speeds.

to

There is a difference in tip efficiency.

Am I really an engineer? Let’s add you to that other guy who didn’t understand the basic ideal gas law that questioned if I was a mechanical engineer (who actually focused on thermodynamics). He lost on that one as well, and to his credit gave a video of his apology.

I clearly understand mechanical physics. You’ve already insulted two other guys whose careers based on the study physics have been very successful. I guess you insulting me as you did them should make me feel privileged.
Click to expand...
Alright Fred, I'll try to be more explicit since you (and others) don't appear to see the common thread connecting what you consider to be disjoint thoughts aimed at what they call "moving the goalposts" these days.

What is in dispute is "Myth 3" in Doctor Dave's video: "Tip Hardness Effects."

At 3:06, Dr. Dave says: "Some people think that because a soft tip stays in contact longer with the cueball, it can impart more or less spin than a harder tip. But this is not true. For an explanation why see the tip hardness effects resource page linked in the video description."

This claim is made after showing that the measured contact times for a phenolic and a soft-leather tip are 0.8ms and 1.9ms, respectively. A difference of a factor of 2.

Ok. So, double the contact time, and the "imparted spin" in the words of Dr. Dave, are effectively the same. Contact time has no effect.

What does it mean for a thing to have no effect. Let's consider a simple example:

Whether I wear socks to bed has no effect on whether the sun rises tomorrow morning. Therefore, if I wear socks to bed, or I don't, the sun will rise. I won't have to pull one sock off my foot or add an extra sock to the other foot to compensate anything. The sun will rise no matter what.

Now let us return to the question of tip hardness and imparted spin. Dr. Dave said earlier in this thread that to get the same imparted spin with a hard tip, a more delicate stroke is required. Therefore, the hardness of the tip is not independent of the imparted spin.

This is already a lot to digest, Engineer Fred. We can return to the so-called tip-efficiency later, when we sort out this first piece.
 
Cornerman said:
So… vector math wasn’t part of your studies? Amazing. Do you argue with Russians on how to speak Russian? I wouldn’t think so. There are some fundamental parts of this discussion that you don’t seem to be familiar with, so nothing said will ever make sense to you. I believe Mr Jewett had already addressed this, I presume with you. You might have responded with, “ouch.”

I’m not here to convince you. I’d only request that you do more study on Physics fundamentals so we can have meaningful conversations. As it is, we’re not there.
Click to expand...

Change a few words here and there and this response could have been written by a CTEr in the Aming Forum.

Lou Figueroa
just sayin’
 
dr_dave said:
FYI, I just posted a new video that busts many common myths concerning what happens when a cue tip hits a cue ball. Everything is supported by super-slow-motion high-speed-camera footage. Check it out:


Contents:
0:00 - Intro
0:10 - Myth 1 – Tip Contact Time
0:48 - Myth 2 – Control During Contact
2:07 - Myth 3 – Tip Hardness Effects
3:16 - Myth 4 – Shot Speed Effects
4:23 - Myth 5 – Miscues
5:42 - Myth 6 – Sliding Contact
6:29 - Wrap Up
6:45 - ---- clip montage

As always, I look forward to your feedback, comments, questions, complaints, and requests.

Enjoy!
Click to expand...
Doc ? Does this mean that we can't push a cb unless the cb is against something like solid... ? Guy
 
lfigueroa said:
Change a few words here and there and this response could have been written by a CTEr in the Aming Forum.

Lou Figueroa
just sayin’
Click to expand...
Except...

Freddie's post comes after this thread is filled with detailed explanations repeated over and over (including by Freddie) of what pvc lou and others can't seem to grasp. Where's the CTE thread that even comes close to that?

pj
chgo
 
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