Effect of break cue weight

M

mnShooter

AzB Silver Member
Silver Member
I was watch a documentary today that got me thinking. They had this Shao Lin martial artist punch a bag. He punched it at 27mph. I don't think any pool player can move their arm that fast especially with a cue in their hand.

Some advocates say speed is more important in a hard break. So why don't we break with a 6 oz cue?

What I'm really wondering is what is the relationship between cue speed, cue weight and cueball speed ? I'm thinking the cueball travels faster than the cue otherwise no one could achieve speeds of 35 mph. Let say the cue is three times as heavy as the cueball. Does that mean the cueball goes three times as fast as the cue?

Has there ever been a study on this where the cue speed stays the same and the weight is changed with a robot?
 
Too technical for me!?

Hey,

I think this is an excellent question. I don't know the answer :eek: but, I've read somewhere that a lighter cue does allow for a faster stroke which equates to more velocity which may equal to a more powerful break :rolleyes:

However, my experience tells me that a heavier cue IME allows me to break the balls better :confused: perhaps because my stroke is more controlled and therefore, I'm focusing better on the point of impact -- the cue does the work instead of my speed/stroke!? :cool:

I'm sure there are some folks here that can help us figure this out ;)
 
krbsailing said:
Hey,

I think this is an excellent question. I don't know the answer :eek: but, I've read somewhere that a lighter cue does allow for a faster stroke which equates to more velocity which may equal to a more powerful break :rolleyes:

However, my experience tells me that a heavier cue IME allows me to break the balls better :confused: perhaps because my stroke is more controlled and therefore, I'm focusing better on the point of impact -- the cue does the work instead of my speed/stroke!? :cool:

I'm sure there are some folks here that can help us figure this out ;)
Click to expand...

There's a thread entitled "Choosing a break cue" in which various members, including myself, duked it out on that question. Check it out. I hope you'll find it helpful. In general, however, most people achieve greater cueball velocity with a cue in the 18-19 oz. range. Of course, velocity is not the only factor in a quality break, so in the final analysis, you've got to use what works for you.
 
mnShooter said:
What I'm really wondering is what is the relationship between cue speed, cue weight and cueball speed ?
Click to expand...
There was also another thread a couple months ago debating this same subject.

If you want to get into the nitty-gritty physics, then check out Chapter 3 of Ron Shepard's paper.

However, take note of Shepard's loose skin approximation in the second paragraph of Chapter 3. If you don't totally drop out the mass of the hand/forearm like Shepard does in his calculations, you'll only end up with a lighter "optimum" cue weight. In my opinion, I still believe lighter is better, at least if your sole goal is maximizing CB speed.
 
Best break cue I ever tried was with maple forearm and purpleheart handle.
Less than 19 oz.
 
Personally, I love the feel of a heavier break cue. Right now the cue i am using is a 21oz and I can just break a rack open, with a nice and easy break.

When breaking on a 7ft table and playing 8ball, i can break from the box and Rarely do i ever break HARD, I generally use a med break and still get the rack to explode.

And even on a 9ft I dont break hard and still get the same effect. I just let the weight of the cue do the work for me.
 
mnShooter said:
...What I'm really wondering is what is the relationship between cue speed, cue weight and cueball speed ? I'm thinking the cueball travels faster than the cue otherwise no one could achieve speeds of 35 mph. Let say the cue is three times as heavy as the cueball. Does that mean the cueball goes three times as fast as the cue?
Click to expand...
You're right about the cueball moving faster than the stick. Ideally, without energy loss, it should take off at 1.5 times the stick's speed when the stick is three times its weight. In reality, the number is about 1.3. If the stick's mass was infinite, it would take off at only two times the stick's speed in a perfectly elastic collision. So you tend to get diminishing returns by increasing mass.

On the other hand, if the stick is extremely light, you can't get up enough speed to make up for its small mass because you have to accelerate your hand/arm too, which limits the speed.

If you knew not only the mass of an individual's hand/arm, but how the mass is distributed throughout its length, you could use physics to come up with an optimum cue weight for that particular individual. Although hand/arm mass plays essentially no role in the collision itself, you would need to know it in order to figure out how much resistance it offers to accelerating it. I don't know of any easy way to get these measurements.

So as a practical matter, the easiest thing to do is to try cues of various weights and see which one works best...but I guess nobody needed to tell you that. It will definitely be different for different individuals. Using robots will not help for obvious reasons.

Jim
 
I tried one for months that was approx 17oz (I play w/ a 19oz cue) and felt like I lost a bit of power with it. If I were buying one, it would be the same or a little heavier than my player.
 
Jal said:
You're right about the cueball moving faster than the stick. Ideally, without energy loss, it should take off at 1.5 times the stick's speed when the stick is three times its weight. In reality, the number is about 1.3. If the stick's mass was infinite, it would take off at only two times the stick's speed in a perfectly elastic collision. So you tend to get diminishing returns by increasing mass.

On the other hand, if the stick is extremely light, you can't get up enough speed to make up for its small mass because you have to accelerate your hand/arm too, which limits the speed.

If you knew not only the mass of an individual's hand/arm, but how the mass is distributed throughout its length, you could use physics to come up with an optimum cue weight for that particular individual. Although hand/arm mass plays essentially no role in the collision itself, you would need to know it in order to figure out how much resistance it offers to accelerating it. I don't know of any easy way to get these measurements.

So as a practical matter, the easiest thing to do is to try cues of various weights and see which one works best...but I guess nobody needed to tell you that. It will definitely be different for different individuals. Using robots will not help for obvious reasons.

Jim
Click to expand...

Very good post... good description.

I suggest that a player purchase a Break Cue, with a removable "weight bolt", so that adjusting the cue's weight to the nominal best for the player, can be done easily, over time.

My next Break Cue design will have a weight bolt in the shaft, so I can adjust the weight forward or aft. It's just a trial design. I like the shorter Break Cues too... they feel different, but they hit a ton.

I also suggest that a player purchase a cue with a Break Cue shaft, one that has a real Stiff SPINE.... maybe 13.5mm to 14mm in size. The laminated shafts are superb for this application. A Break Cue taper helps out too.

I don't believe a player can make a snap judgement, about a particular weight, because the optimal situation can only be determined by a pure hit on the cueball & a great hit on the rack. Anything less than a pure hit on the Cue Ball is wasted energy & anything less than a great hit on the rack is also energy loss. True judgement is made with experience, over time.

Some of us are not able to break at 30 MPH, but we are capable of a great break, because of our accuracy of hit, which helps out in the consistancy department....

Since the Break Shot is altogether different than the play shot, methodical practice is necessary. The Professionals got a real "eye opener" during the IPT tournaments. Having to break from the box & hit the lead ball gave them a real test. It became very obvious that a dry break & anything less than top play would eliminate you very quickly.

Good Luck...
 
The actual equation for momentum is;

momentum= Mass X Speed(squared) thus making the speed of the cue more important than the weight. That being said, there are limitations to the actual speed you can move you arm (rotational inertia) so there is a magical weight specific to your arm.

In English: You can only stroke a cue so fast but the weight will factor in. A lighter cue will break harder but there is a cut-off to that weight.
 
Jal said:
You're right about the cueball moving faster than the stick. Ideally, without energy loss, it should take off at 1.5 times the stick's speed when the stick is three times its weight. In reality, the number is about 1.3. If the stick's mass was infinite, it would take off at only two times the stick's speed in a perfectly elastic collision. So you tend to get diminishing returns by increasing mass.

On the other hand, if the stick is extremely light, you can't get up enough speed to make up for its small mass because you have to accelerate your hand/arm too, which limits the speed.

If you knew not only the mass of an individual's hand/arm, but how the mass is distributed throughout its length, you could use physics to come up with an optimum cue weight for that particular individual. Although hand/arm mass plays essentially no role in the collision itself, you would need to know it in order to figure out how much resistance it offers to accelerating it. I don't know of any easy way to get these measurements.

So as a practical matter, the easiest thing to do is to try cues of various weights and see which one works best...but I guess nobody needed to tell you that. It will definitely be different for different individuals. Using robots will not help for obvious reasons.

Jim
Click to expand...
Great post, as usual Jim. And I hope more people read this post rather than some of the "lighter is better" posts. The optimum break weight is very much individual depending on how the person breaks. The final optimum weight could be lighter or could be heavier than his own shooting cue or the next guy's break cue.

Fred
 
ratcues said:
The actual equation for momentum is;

momentum= Mass X Speed(squared) thus making the speed of the cue more important than the weight. .
Click to expand...

Momentum is mass * velocity. Kinetic energy is 1/2* mass* velocity^2.

You're mixing your physifors.

Fred
 
mnShooter said:
What I'm really wondering is what is the relationship between cue speed, cue weight and cueball speed ?
Click to expand...
The simple answer is that the cue weight does contribute a healthy amount to the speed of the cueball, but only to a certain limit.

People put out the 1/2*m*v^2 kinetic energy equation all the time, and then assume that since the velocity is squared, that velocity is "more important." But it's not. Not really. The equation is an equation. And the final result (kinetic energy) is the most important, all other things being equal. If you put in X amount of kinetic energy into the stick, it comes out with about X amount kinetic energy. If the cuestick is lighter, the velocity goes up proportionally per the equation. If the cuestick is heavier, the velocity goes down proportionally per the equation. The kinetic energy is virtually the same. The differences in the actual collision are other things like energy transfer efficiency (which favors the lighter cue down to 6 oz) and the energy associated with the cue (which favors the heavier cues up until... I don't know what the limit is, but there's a limit). It shoud be no surpise that the "optimum" therefore is somewhere down between.

What am I trying to say???? The weight has an effect. You can't break with a 6 oz cue (which is supposed to have the highest transfer efficiency for 6 oz balls). Don't bother with a 30 oz cue, because it simply becomes too difficult to get your maximum force and energy into the cuestick because of its mass. It should be no surprise that anything within a couple of ounces of 18 oz works pretty well (see JAL's post) which happens to coincide with halfway between the two numbers. Being able to use a cue, stroke it fast, and hit the center seems to be what optimizes the break.

Fred
 
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