setting cue ball in motion

[Cornerman]

Actually, you could be right about this. I thought that effective end mass was highly influenced by the last 1/3rd of the shaft, where the other 2/3rds are negligable. I would think that by introducing your bridge hand to the last 1/3rd, you would be modifying the end mass slightly via changing the resonant frequency of the end of the shaft. Dr. Dave showed that squirt changes as you move the pivot point.
.

I think you are misreading what Dr. Dave is saying about the pivot point.

Be that as it may, unless your bridge hand is supremely rigid (like made of metal, then the bridge hand has little influence on the effective mass in the collision. (bridge length is not the same thing as the pivot point, no matter how many people try to redefine the terms).

The human hand has too much compliance to add mass to the collision.

The effective end mass is a result of tip/ball contact time and rate of transverse wave propagation down the shaft, as well as real world losses.

Freddie

 

[nrhoades]

I think you are misreading what Dr. Dave is saying about the pivot point.

Be that as it may, unless your bridge hand is supremely rigid (like made of metal, then the bridge hand has little influence on the effective mass in the collision. (bridge length is not the same thing as the pivot point, no matter how many people try to redefine the terms).

The human hand has too much compliance to add mass to the collision.

The effective end mass is a result of tip/ball contact time and rate of transverse wave propagation down the shaft, as well as real world losses.

Freddie

Perfect! Thanks for clairfying.

 

[Cdryden]

What are the other factors?

Haven't they already been stated? Force and friction. Or rather the balance of the two in my opinion. Everything else either adds to or detracts from these two factors. I consider the mass of the ball to be a constant (sure some are heavier than others but WTH)

You could argue that the amount of dust in the air adds to drag to the ball but what does it really matter in the big picture. Maybe if you explained what it is that you are fishing for people could be of more help. You are coming off a little vague to me, but I quit caffeine today so maybe it's just me!

 

[nrhoades]

Haven't they already been stated? Force and friction. Or rather the balance of the two in my opinion. Everything else either adds to or detracts from these two factors. I consider the mass of the ball to be a constant (sure some are heavier than others but WTH)

You could argue that the amount of dust in the air adds to drag to the ball but what does it really matter in the big picture. Maybe if you explained what it is that you are fishing for people could be of more help. You are coming off a little vague to me, but I quit caffeine today so maybe it's just me!

Cdryden, maybe you're right in that I've approached my question backwards, so I'll ask it like this:

---

You have to make a shot in pool.
You look at the table, and use your brain to figure out the solution.
You set yourself up, take a stance, take practice strokes, and get ready.
But when it comes down to that split second that the cue tip hits the cue ball, the only pertubation that you are making in the world is:

-transfer of momentum between cue stick and cue ball at a specific point in space, in a specific direction. Nothing more, nothing less.

All of the physical factors, experience, and feel contribute in calculating the SOLUTION. But the solution is ALWAYS, AND ONLY
-tip position
-angle/pitch
-speed

everytime, and can never be more, or less.

THEREFORE, the effort of coming up with the SOLUTION, and the effort in HITTING THE CUEBALL, should be mutually exclusive operations. I.e. the mental aspect shouldn't overlap the physical aspect, i.e. don't need to think about the shot once the solution is found.

My question to those who don't agree with this, is WHY?

 

[Cdryden]

Cdryden, maybe you're right in that I've approached my question backwards, so I'll ask it like this:

---

You have to make a shot in pool.
You look at the table, and use your brain to figure out the solution.
You set yourself up, take a stance, take practice strokes, and get ready.
But when it comes down to that split second that the cue tip hits the cue ball, the only pertubation that you are making in the world is:

-transfer of momentum between cue stick and cue ball at a specific point in space, in a specific direction. Nothing more, nothing less.

All of the physical factors, experience, and feel contribute in calculating the SOLUTION. But the solution is ALWAYS, AND ONLY
-tip position
-angle/pitch
-speed

everytime, and can never be more, or less.

THEREFORE, the effort of coming up with the SOLUTION, and the effort in HITTING THE CUEBALL, should be mutually exclusive operations. I.e. the mental aspect shouldn't overlap the physical aspect, i.e. don't need to think about the shot once the solution is found.

My question to those who don't agree with this, is WHY?

Now I get ya, sorry if I seem a little slow. I picked the wrong day to quit sniffin glue! (couldn't help it, I had to throw in another airplane quote.)

I guess I am on the same thought process as you. Once I have my mind set on what I am going to do (from a standing position) I get down on the shot and let muscle memory do its job.

 

[Cornerman]

Cdryden, maybe you're right in that I've approached my question backwards, so I'll ask it like this:

---

You have to make a shot in pool.
You look at the table, and use your brain to figure out the solution.
You set yourself up, take a stance, take practice strokes, and get ready.
But when it comes down to that split second that the cue tip hits the cue ball, the only pertubation that you are making in the world is:

-transfer of momentum between cue stick and cue ball at a specific point in space, in a specific direction. Nothing more, nothing less.

All of the physical factors, experience, and feel contribute in calculating the SOLUTION. But the solution is ALWAYS, AND ONLY
-tip position
-angle/pitch
-speed

everytime, and can never be more, or less.


My question to those who don't agree with this, is WHY?

My answer is that from the contact point of view, there are only two things that influence: Velocity and position (velocity encompasses the angle including pitch as well as the speed scalar ) considering you can't change the mass and you're not heating the balls up to change the energy.

So, you're still correct, but if the conversation ends there then it's way short-sighted. How to get the solution is as important as the solution itself if not more so.

 

[nrhoades]

Now I get ya, sorry if I seem a little slow. I picked the wrong day to quit sniffin glue! (couldn't help it, I had to throw in another airplane quote.)

I guess I am on the same thought process as you. Once I have my mind set on what I am going to do (from a standing position) I get down on the shot and let muscle memory do its job.

Good.

Now, getting feedback from stroke speed is easy. You... can either feel it in your hand, and/or see how far the balls roll, and make a mental note.

How do you get feedback from where the tip touched the cue? Well, you can look at. But then if you are looking there, you're not looking at the object ball. If you look at the object ball, you can't get information of where the tip landed. I suppose you can feel for that too, and maybe watch how the cue ball reacts. But how much does that tell you of EXACTLY where you hit the cue ball?

This is actually a hard problem to solve. A high-speed camera is the only way I know of.

My ultimate question (lol), is if someone came up with an afordable tool that told you exactly where you hit the cue ball, would it be of interest to the general public? Would people buy it?

 

[Andrew Manning]

My ultimate question (lol), is if someone came up with an afordable tool that told you exactly where you hit the cue ball, would it be of interest to the general public? Would people buy it?

You seem to forget that a freshly-chalked tip will leave a very clear mark on a freshly-wiped ball, making it pretty trivial to tell where you struck the ball. Of course, using an all-white ball makes it impossible to tell where the mark is in relation to the original orientation of the ball, so you'd use a ball with a number on it for this purpose. Use a striped ball for even more reference points.

So, I don't think anyone would pay much for such a device since every set of balls includes many of them.

-Andrew

 

[Cdryden]

Good.

Now, getting feedback from stroke speed is easy. You... can either feel it in your hand, and/or see how far the balls roll, and make a mental note.

How do you get feedback from where the tip touched the cue? Well, you can look at. But then if you are looking there, you're not looking at the object ball. If you look at the object ball, you can't get information of where the tip landed. I suppose you can feel for that too, and maybe watch how the cue ball reacts. But how much does that tell you of EXACTLY where you hit the cue ball?

This is actually a hard problem to solve. A high-speed camera is the only way I know of.

My ultimate question (lol), is if someone came up with an afordable tool that told you exactly where you hit the cue ball, would it be of interest to the general public? Would people buy it?

I believe Scott Lee does something similar to this. He video records a persons stroke and uses that as a tool to correct a persons stroke. A great idea if you ask me. I also believe that he has mentioned that most people he has worked with were not hitting the cue ball where they thought they were.

As far as a tool for this, there is one. A cue ball with no finish that allows you to see the chalk mark from the impact on the cue ball. May not be techy enough for some but it is simple, affordable and reliable.

 

[Cornerman]

You seem to forget that a freshly-chalked tip will leave a very clear mark on a freshly-wiped ball, making it pretty trivial to tell where you struck the ball. Of course, using an all-white ball makes it impossible to tell where the mark is in relation to the original orientation of the ball, so you'd use a ball with a number on it for this purpose. Use a striped ball for even more reference points.

So, I don't think anyone would pay much for such a device since every set of balls includes many of them.

-Andrew

^^^This^^^

Add to that the Rempe training ball has these convenient target lines on it that in conjunction with the aforementioned fresh chalk mark....

 

[nrhoades]

Hmmm, OK.

I could definately see how just looking at the remaining chalk mark on a ball would be enough for most people.

Not that I'm over-thinking; I have a few hair-brained ideas for alternative solutions (some higher-tech), but if there's no verification for a need of the basic idea then I don't need to think about them further, lol!

 

[Cdryden]

Hmmm, OK.

I could definately see how just looking at the remaining chalk mark on a ball would be enough for most people.

Not that I'm over-thinking; I have a few hair-brained ideas for alternative solutions, but if there's no verification for a need of the basic idea then I don't need to think about them further, lol!

There's nothing wrong with trying to improve on a old idea, what was your plan?

 

[Sloppy Pockets]

The human hand has too much compliance to add mass to the collision.

The effective end mass is a result of tip/ball contact time and rate of transverse wave propagation down the shaft, as well as real world losses.

There was a recent thread where the idea of using a 1oz cue to achieve great break speed was brought up. Someone with an engineering background made the point that the cue speed would have to be about 50 MPH in order to move the CB at 20 MPH.

I'm not an engineer, so I don't know exactly how to calculate such things, buy I thought that even 50 MPH was too slow for the 1oz cue to be moving. So, I decided to make my own lightweight "cue" from the 2oz butt section of one of my ultralight fly rods with a temporary tip from the remnants of an old Le Pro I was replacing.

It took a bit of time to figure out how stroke with it, but the results were pretty amusing. If I just let go of the "cue", it bounced back in my hand and the CB barely trickled past mid-table, even though the test cue was twice the mass of the 1oz cue used in the theoretical calculation. However, if I grasped it firmly and powered through the shot, I was able to get almost three table lengths of CB travel with a power stroke.

As an engineer yourself, I am curious to hear your opinion as to why this would happen if the hand contributes nothing to the energy of the collision.

BTW if anybody tries this, make damn sure that the Loctite gel is completely cured before you test hit the ball. After several power strokes the tip popped off, splattering cyano glue all over my new measles ball. Lucky for me it didn't get all over the cloth, but it was a PITA getting it off the ball.:embarrassed2:

 

[nrhoades]

There's nothing wrong with trying to improve on a old idea, what was your plan?

The high-tech ones include:

- mounting 6-axis gyro/accelerometer chip inside the cue ball, and using optical infrared modulation to get the information out. Or wirelessly. Therefore you can have a computer screen or tv that shows exactly where the ball was struck (based on some math), and you can compare it to where you THINK you struck it.

VERY hard to make, very hard to calculate counter balances, maybe impossible for perfect balance.

Low-tech idea:

-I figured that it was hard to see the chalkmark on the ball after you hit it. Maybe it isn't. Anyway, drill a tiny hole (1/16th") in a cue ball about 1/16th deep, and before each shot, rub red chalk into the hole. Then place the cue ball down and orient it to the red dot is exactly where you want to hit it. After you hit the cue ball, there should be a tiny red chalk mark on your tip. if you missed the spot, no red mark on your tip.

I have a few other ideas, but if just using a Rempe ball works for everyone then the problem has already been solved :grin:

 

[fastone371]

1. Point on the surface of the cue ball.
2. Angle and pitch of impact vector.
3. Velocity of impact vector.

Curious... does anybody believe that there is anything OTHER than these three responsible for setting the cue ball in motion?

What are they? What is YOUR opinion?

EDIT:

Thanks guys... from the discussion so far we've identified the four dominant components that a player can modulate (at shot time) that have the most influence on cue ball trajectory. These are:

1) tip position
2) tip angle/pitch
3) velocity
4) bridge length

If you shoot the same shot, with the same bridge length and similar velocity, it is the tip position and angle/pitch that will most influence the cue ball trajectory.

So, would you agree that precision of #1 and #2 is the absolute most important part of pool shotmaking consistency, above all else? Would you agree that all the effort of good fundementals leads to simply, precise spatial delivery of the tip?

If you don't agree, why?

I am not trying to be a smartass here, but how would bridge length have an effect?

 

[Cornerman]

As an engineer yourself, I am curious to hear your opinion as to why this would happen if the hand contributes nothing to the energy of the collision.

I think you're asking a different question to what I was saying (and I might not have been crystal clear, thought I think the discussion context made it fairly clear... as mud). I was saying the bridge hand doesn't add mass to the effective end mass in the squirt equation.

For forward motion:

When you're talking about cueball speed in the same direction of the cue stroke, then the important considerations for mass is the speed of sound through the cuestick. And during contact with the cueball, the speed of sound wave does runs through the length of the axis of the cue and then some. So not only is the whole cue mass involved, but there is an effective mass contribution from your body to the forward motion.

 

[Sloppy Pockets]

-I figured that it was hard to see the chalkmark on the ball after you hit it. Maybe it isn't. Anyway, drill a tiny hole (1/16th") in a cue ball about 1/16th deep, and before each shot, rub red chalk into the hole. Then place the cue ball down and orient it to the red dot is exactly where you want to hit it. After you hit the cue ball, there should be a tiny red chalk mark on your tip. if you missed the spot, no red mark on your tip.

Maybe somebody will invent a CB with a single red dot or maybe even a red circle on it.

EDIT: Oops! Sorry, I re-read your post and see you meant something different than what I thought.

 

[swest]

Someone may have pointed this out already, but, of course, just looking at the chalk spot on the cue ball doesn't tell you 'where you hit it', because you've lost the original orientation of the ball... Every shot would look the same, if that's all you had to go on.

The cue ball must have some markings (a' la the Rempe ball) in order for the chalk mark to be useful.

 

[Cdryden]

The high-tech ones include:

- mounting 6-axis gyro/accelerometer chip inside the cue ball, and using optical infrared modulation to get the information out. Or wirelessly. Therefore you can have a computer screen or tv that shows exactly where the ball was struck (based on some math), and you can compare it to where you THINK you struck it.

VERY hard to make, very hard to calculate counter balances, maybe impossible for perfect balance.

Low-tech idea:

-I figured that it was hard to see the chalkmark on the ball after you hit it. Maybe it isn't. Anyway, drill a tiny hole (1/16th") in a cue ball about 1/16th deep, and before each shot, rub red chalk into the hole. Then place the cue ball down and orient it to the red dot is exactly where you want to hit it. After you hit the cue ball, there should be a tiny red chalk mark on your tip. if you missed the spot, no red mark on your tip.

I have a few other ideas, but if just using a Rempe ball works for everyone then the problem has already been solved :grin:

I gotta ask because of previous experience, are you an engineer? I worked as a machinist for years and we had a few engineers that meant well but had a tendency to over engineer everything! It got to where it became a bit of a problem. I got a kick out of it, but the boss got a bit angry when the budgets got out of whack from needless spending.

I once had a engineer who was designing a clean air system for our building ask me how much air was in the clean room. I looked at him and said "All of it?" He was not amused. I eventually got to where I answered all his questions with one standard answer, 4.
He would ask me something like "how did you figure the circular interpolation for milling that sphere?" and I would answer "I divided it by 4". He would walk away and work on it for a few hours and be completely confused. Another time he asked me how much Carbon is in 316 Stainless steel, I said "4".
After a while he quit asking me to do his work. He didn't last long after that.


I think you had a neat idea but it was maybe a bit over engineered, but you never know. It's people like you that sometimes come up with the best stuff. Without people thinking out of the box and improving on existing ideas we would still be in the dark ages.

 

[Sloppy Pockets]

I think you're asking a different question to what I was saying. I was saying the bridge hand doesn't add mass to the effective end mass in the squirt equation.

For forward motion:

When you're talking about cueball speed in the same direction of the cue stroke, then the important considerations for mass is the speed of sound through the cuestick. And during contact with the cueball, the speed of sound wave does runs through the length of the axis of the cue and then some. So not only is the whole cue mass involved, but there is an effective mass contribution from your body to the forward motion.

No, I understood what you meant, I just wanted your opinion on the mass at the grip end. What you say is what I figured, although I've seen the opposite argument coming from many learned pool experts.

However, regarding the speed of sound, it travels through maple at about 4000 FPS, so a hard tip coupled with a fast stroke speed that created only a 1/1000th second impulse would not allow for much or any contribution from hand mass if the cue is more than four feet from the tip. Is that correct?