Break cue science

[Bob Callahan]

I've been working my way through Marlow's "The Physics of Pocket Billiards", and found some very interesting statements about break cues.

On page iv of the preface he says, "An analysis is provided in Chapter 8 Break Shots to show that the optimum Break Cue is a light weight Cue Stick whose effective mass is equal to the Cue Ball mass."

On page 221 of chapter 8 he says, "This, in turn, implies choosing a light weight construction, maybe with a hollow shaft and a sound absorber on the Butt end of the Cue Stick, and a Cue Tip with a very high speed of sound."

What do you think?

 

[WoodyJ]

U-m-m-m, I don't know much, but my cue ball weighs under 6 oz. and I can't imagine trying to break with a (normal) cue that light.

 

[ridewiththewind]

The secret to a great break is the proper form and technique, not the equipment.

Lisa

 

[mosconiac]

U-m-m-m, I don't know much, but my cue ball weighs under 6 oz. and I can't imagine trying to break with a (normal) cue that light.

I don't think he's referencing the at-rest, scale weight of the cue, but the "effective mass" of the cue as it lies in hand. How that is determined, I do not know, but have you ever noticed how the balance of a cue can make a "heavy" cue feel light in your hands & a "light" cue can feel heavy?

 

[dr_dave]

I've been working my way through Marlow's "The Physics of Pocket Billiards", and found some very interesting statements about break cues.

On page iv of the preface he says, "An analysis is provided in Chapter 8 Break Shots to show that the optimum Break Cue is a light weight Cue Stick whose effective mass is equal to the Cue Ball mass."

That's not true. The optimal break cue weight will vary quite a bit from one individual to another. For more info, see:

http://billiards.colostate.edu/threads/cue.html#weight​

On page 221 of chapter 8 he says, "This, in turn, implies choosing a light weight construction, maybe with a hollow shaft and a sound absorber on the Butt end of the Cue Stick, and a Cue Tip with a very high speed of sound."

A hard tip is a good idea, and low-squirt is also good to better match the natural pivot length to a long break bridge length. For more info, see:

http://billiards.colostate.edu/threads/cue_tip.html#hardness
http://billiards.colostate.edu/threads/cue.html#pivot​

Regards,
Dave

 

[Bob Callahan]

The optimal break cue weight will vary quite a bit from one individual to another.

I'll go you one farther--I think the optimum break cue weight can vary for a single individual. Training can make a difference. I hit the cue ball faster when I was practicing martial arts than I do now as a rock climber. I also think a change in breaking technique can change optimal weight. But, I really don't think there's a huge difference--no matter what--if you are already relatively skilled.

I think the optimal break cue weight lies on a pretty flat curve.

Are there any pros who use a light-weight break cue? Anyone on this forum?

 

[Bob Callahan]

The secret to a great break is the proper form and technique, not the equipment.

Lisa

Sure, but better form/technique and equipment would be even nicer, wouldn't it? *grin*

 

[jdxprs]

I've been working my way through Marlow's "The Physics of Pocket Billiards", and found some very interesting statements about break cues.

On page iv of the preface he says, "An analysis is provided in Chapter 8 Break Shots to show that the optimum Break Cue is a light weight Cue Stick whose effective mass is equal to the Cue Ball mass."

On page 221 of chapter 8 he says, "This, in turn, implies choosing a light weight construction, maybe with a hollow shaft and a sound absorber on the Butt end of the Cue Stick, and a Cue Tip with a very high speed of sound."

What do you think?

i think this makes me feel dumb, because i have no idea what it's talking about!

 

[Bob Callahan]

i think this makes me feel dumb, because i have no idea what it's talking about!

Don't feel too bad, I'm a math/physics guy, and I still don't think the book is easy reading...I doubt many people have worked their way through it. What it's basically saying is that a break cue should only weigh slightly more a cue ball (6 oz) if you want the best break speed. Tips should be hard. Useless vibrations need to be controlled.

 

[3RAILKICK]

Work to do

I've been working my way through Marlow's "The Physics of Pocket Billiards", and found some very interesting statements about break cues.

On page iv of the preface he says, "An analysis is provided in Chapter 8 Break Shots to show that the optimum Break Cue is a light weight Cue Stick whose effective mass is equal to the Cue Ball mass."

On page 221 of chapter 8 he says, "This, in turn, implies choosing a light weight construction, maybe with a hollow shaft and a sound absorber on the Butt end of the Cue Stick, and a Cue Tip with a very high speed of sound."What do you think?

My break cue is 17.5 oz. I'm old and have bad knees. I can't and don't use much body or legs to break. The 17.5 allows a bit more snap from a relatively stationary position.

What is a 'speed of sound cue tip'? I would like to try one. What speed is phenolic? I'm looking for an edge.

My playing cue is 19.5. So is 17.5 light? Sometimes-a couple of oz's can seem like a lot.

Then again-I've seen guys break with 22-23 oz cues and just crush em! Go figure. Timing and technique? It seems-loose muscles and quick acceleration combine to make power.

I am neither loose nor quick-I just try not to hurt myself while breaking.

I think Bustamante threw his elbow out a couple of years ago. No wonder!

Be safe.

3railkick

I chose/choose not to comment on the vibration dampner.

 

[Bob Callahan]

My break cue is 17.5 oz. I'm old and have bad knees. I can't and don't use much body or legs to break. The 17.5 allows a bit more snap from a relatively stationary position.

What is a 'speed of sound cue tip'? I would like to try one. What speed is phenolic? I'm looking for an edge.

My playing cue is 19.5. So is 17.5 light? Sometimes-a couple of oz's can seem like a lot.

Then again-I've seen guys break with 22-23 oz cues and just crush em! Go figure. Timing and technique? It seems-loose muscles and quick acceleration combine to make power.

I am neither loose nor quick-I just try not to hurt myself while breaking.

I think Bustamante threw his elbow out a couple of years ago. No wonder!

Be safe.

3railkick

I chose/choose not to comment on the vibration dampner.

Having the best possible break cue really makes sense for someone like you. You want the most bang for your buck, so to speak. An efficient cue would let you play longer before tiring, and make it less likely that you'd mess up your elbow. *smile*

 

[Bob Jewett]

... What do you think?

I think there are several problems with his analysis. I think the speed of sound in the tip is irrelevant since its length is short, but he worries a lot about it. I think it is better to model the tip as a spring of negligible length. The speed of sound in the wood is important.

I think the statement, "No pushing of the Cue Ball by accelerating the Cue Stick during the period of contact is allowed in a legal pool shot. This rule is generally ignored during play, but it will be strictly heeded in the following analysis," ignores what we have learned since 1995 about tip-ball interaction.

I think that it is much easier to write a 1-D simulation (finite element model) of the stick striking the ball and plug in known values and see how the system works than to work out the physics from equations that are based on uncertain assumptions.

I think that the surface of the tip almost certainly does not oscillate as shown in Fig. 86, p. 211, and that there is time for "a few" round trips of compression down the stick and back during most shots.

I think for finding the best break cue weight, it is important to include the mass of the hand and arm that the player must accelerate along with the stick during the shot. A crude first-principles guess would be that the mass of the stick should be the geometric mean of the masses of the arm and the ball (within a factor of 6.28).

There is much that is interesting in Marlow's book, but I think some of the analyses needed more data and pay too much attention to details that are likely unimportant. If anyone here would like to get a copy of his book, I have some copies available for $30 including shipping.

 

[LWW]

"An analysis is provided in Chapter 8 Break Shots to show that the optimum Break Cue is a light weight Cue Stick whose effective mass is equal to the Cue Ball mass." ... "This, in turn, implies choosing a light weight construction, maybe with a hollow shaft and a sound absorber on the Butt end of the Cue Stick, and a Cue Tip with a very high speed of sound."

What do you think?

I think these 2 statements by the author are at the best very poorly worded.

To make sense of "EFFECTIVE MASS" I'm assuming they mean the amount of mass contained in the portion of the shaft which bends/flexes from the impact with the CB. This would be the first several inches of the shaft and in most cases would be less than the mass of the CB. Perhaps he is meaning the mass of the shaft being roughly equal to the mass of the CB? That would make more sense.

Also, their is no such thing as a "very high speed of sound" in any sensible definition. The SOS can vary depending on altitude ... but at any given altitude and atmospheric condition the SOS is a constant, and I can't imagine anyone with a break shot approaching the SOS. Some firearm ammunition doesn't break the SOS.

LWW

 

[Bob Callahan]

I'm sure as we all get lost in this sea of technical jargon, there are people who are wondering, "What's the fuss about...I just grab a house cue and bust 'em." What we're all interested in is a better house cue. One that takes less work to do the same job, and with a little extra umph for when you need it. Just like cars that can go 150 MPH, even though that is illegal most places.

Please bear with us.

Bob, it's been about 20 years since you, George Onoda, and I used to exchange calls and papers on this stuff. A lot has happened since then. 17 years of that during which I never thought about or played pool. I'll address some of your comments later today. G'nite.

 

[Bob Jewett]

... Also, their is no such thing as a "very high speed of sound" in any sensible definition. The SOS can vary depending on altitude ... but at any given altitude and atmospheric condition the SOS is a constant, and I can't imagine anyone with a break shot approaching the SOS. Some firearm ammunition doesn't break the SOS. ...

Marlow mentions the speed of sound of the materials because that is the speed with which compression waves travel through the materials (leather, ferrule, wood, metal joint) during the time that the tip is on the cue ball. It is by these compression waves that the energy of the stick is transferred to the cue ball.

No physical object approaches the speed of sound during the shot.

 

[TheBook]

What makes a good break is form, speed, and accuracy plus a tight rack that is line up. Also good cloth with no indentations under the head ball. Good balls also are required.

 

[MitchAlsup]

On page iv of the preface he says, "An analysis is provided in Chapter 8 Break Shots to show that the optimum Break Cue is a light weight Cue Stick whose effective mass is equal to the Cue Ball mass."
<snip>
What do you think?

While there may be a modicum of truth to the statement, when you add that that cue needs to be operated by a real live human being, I think the physics changes. In particular, I think that the muscle physiology of the human arm will operate better with a cue weighing more like that of the play cue than anything really different than the play cue.

A cue which is too light is hard to stroke dead straight, and while it may hit the CB is great speed, the CB may not go where you want it to go. The converse is true with overly heave cue, the cue hits the CB straight and accurate but so slow the rack hardly busts open (think 50 oz cues, here).

The break is more about precision than about power. Use the tool with greatest precisioin, and your break will improve.

 

[Andrew Manning]

I think these 2 statements by the author are at the best very poorly worded.

To make sense of "EFFECTIVE MASS" I'm assuming they mean the amount of mass contained in the portion of the shaft which bends/flexes from the impact with the CB. This would be the first several inches of the shaft and in most cases would be less than the mass of the CB. Perhaps he is meaning the mass of the shaft being roughly equal to the mass of the CB? That would make more sense.

Also, their is no such thing as a "very high speed of sound" in any sensible definition. The SOS can vary depending on altitude ... but at any given altitude and atmospheric condition the SOS is a constant, and I can't imagine anyone with a break shot approaching the SOS. Some firearm ammunition doesn't break the SOS.

LWW

The speed of sound is only constant within a single medium at a given temperature and pressure.

From medium to medium, however, it can vary greatly. In this case the speed of sound through air (the one your post is talking about), is actually totally irrelevant. The speed through the tip, ferrule, shaft wood, etc., however, is both relevant and dependent on the cue stick in question.

-Andrew

 

[3RAILKICK]

Having the best possible break cue really makes sense for someone like you. You want the most bang for your buck, so to speak. An efficient cue would let you play longer before tiring, and make it less likely that you'd mess up your elbow. *smile*[/QUOTE]


Thank you for your concern and kind words. All of us here at the 'home' appreciate it.

3rails-used to be four

 

[TATE]

I think there are several problems with his analysis. I think the speed of sound in the tip is irrelevant since its length is short, but he worries a lot about it. I think it is better to model the tip as a spring of negligible length. The speed of sound in the wood is important.

I think the statement, "No pushing of the Cue Ball by accelerating the Cue Stick during the period of contact is allowed in a legal pool shot. This rule is generally ignored during play, but it will be strictly heeded in the following analysis," ignores what we have learned since 1995 about tip-ball interaction.

I think that it is much easier to write a 1-D simulation (finite element model) of the stick striking the ball and plug in known values and see how the system works than to work out the physics from equations that are based on uncertain assumptions.

I think that the surface of the tip almost certainly does not oscillate as shown in Fig. 86, p. 211, and that there is time for "a few" round trips of compression down the stick and back during most shots.

I think for finding the best break cue weight, it is important to include the mass of the hand and arm that the player must accelerate along with the stick during the shot. A crude first-principles guess would be that the mass of the stick should be the geometric mean of the masses of the arm and the ball (within a factor of 6.28).

There is much that is interesting in Marlow's book, but I think some of the analyses needed more data and pay too much attention to details that are likely unimportant. If anyone here would like to get a copy of his book, I have some copies available for $30 including shipping.

One of the details in break cues that I think many cue makers have got pretty wrong is how stiff the shaft of a break cue needs to be. Some I've used have been way too stiff on the shaft and not stiff enough at the joint.

Recently I replaced a really stiff shaft on my break cue with a lighter, more pliable laminated shaft. I started getting more action on the balls plus better control. The difference with a more lively shaft was pretty obvious.



Chris