Break cue science

mikepage said:
Bob -

Given that the speed of sound in maple is 4100 m/s, I'm wondering if break cue manufacturers are barking up the wrong tree going to harder and harder tips.

Presumably the motivation for going to hard tips--phenolic or whatever--is a belief that they are more efficient in the way you describe above.

Do you--or anybody--know whether this is true?

An unintended comsequence, though, of these hard tips may be that because the contact time is shorter, there may not be enough time for the ball to "see" the full mass of the stick.

4100 meters/sec is 4 meters per milsecond. A round trip for the compression wave is about 3 meters (two stick lengths). So it takes about three quarters of a milisecond for the cueball to even have a chance of knowing about the back of the stick.

My guess is the contact time for break tips is in that range.

Why not try an efficient soft tip? Maybe get the contact time up to 1.2 ms or more ?

What do you tink?
Click to expand...

The sos in CarbonFibre is about 16800 M/S . I have Aluminium ferrules and joint but a steel pin, ali is about 5270 M/S and steel is about 5032 M/S.
My question is , does the sound accelerate after passing through the tip and the ferrule as it gets to the carbon shaft?
It may explain the solid hit from the carbon shaft.These shafts do not have wood cores.
We have noticed with a phenolic tip a very high pitch sound from the cue ball strike, which is not there with a med layered tip.
Any thoughts Mike or Dave?
 
conetip said:
The sos in CarbonFibre is about 16800 M/S . I have Aluminium ferrules and joint but a steel pin, ali is about 5270 M/S and steel is about 5032 M/S.
My question is , does the sound accelerate after passing through the tip and the ferrule as it gets to the carbon shaft?
Click to expand...
The speed of the elastic waves do change as they propagate into different materials, based on the material properties.

conetip said:
It may explain the solid hit from the carbon shaft.These shafts do not have wood cores.
We have noticed with a phenolic tip a very high pitch sound from the cue ball strike, which is not there with a med layered tip.
Click to expand...
The phenolic tip generates a higher-pitched sound with any cue because of the sharper (faster) impact it creates. Also, because the carbon-fiber shaft has higher natural frequencies than a wood shaft, the higher frequencies from the tip can ring stronger.

Regards,
Dave
 
conetip said:
The sos in CarbonFibre is about 16800 M/S . I have Aluminium ferrules and joint but a steel pin, ali is about 5270 M/S and steel is about 5032 M/S.
My question is , does the sound accelerate after passing through the tip and the ferrule as it gets to the carbon shaft?
It may explain the solid hit from the carbon shaft.These shafts do not have wood cores.
We have noticed with a phenolic tip a very high pitch sound from the cue ball strike, which is not there with a med layered tip.
Any thoughts Mike or Dave?
Click to expand...

I don't have time to fully address this right now, but this may help:

http://www.ndt-ed.org/EducationResources/CommunityCollege/Ultrasonics/Physics/acousticimpedance.htm
 
Thanks Bob,
It seems then that in my case, very little is reflected.
I guess that must be right as otherwise there would be 4 strong relections in .001 second.
It also explains why we only see in high speed camera shots the effects of the cues resonance as the sound effects are just too quick.
Thanks for the input and info.
Neil
 
Speed kills--accuracy, that is.

From http://www.technologyreview.com/blog/arxiv/25621/ :

"The most interesting result is that there is a clear trade off between speed and accuracy: slower throws are better. That will agree with most people's experience of throwing and also with the mountain of measured data that already exists on this topic." (For true science geeks, here's the link to the original paper: http://arxiv.org/pdf/1008.1442v1 )

What does this have to do with breaking? Well, breaking is basically an underarm throw requiring accuracy, and that means that heavier and slower is probably better than lighter and faster.

I've done a bunch of what we'll loosely call "experiments" the last couple of months. A 10-oz Predator Air averaged just as many balls as a homemade 30-oz monster. Things were pretty much the same for everything in between, statistically speaking. Phenolic and hard leather tips were about the same. Especially the leather ones soaked in glue for a few days before pressing them. Homemade metal ferrules seemed no better than run-of-the-mill ones.

But there was one thing that did standout: heavier cues were easier to control.

So far, I haven't found a magic break cue, but if I do, I'll be sure to tell...no...wait a minute...
(Don't hold your breath.)

In the meantime, it looks like the semi-scientific evidence is leaning toward using heavier cues to keep your stroke truer.
 
That is the first thing in this whole interesting thread that made sense! Given a 19oz cue, a consistent 22mph break and a samsara break tip - Do I have the ideal break tip? I assume there are other factors that might be needed?

Chris

Bob Jewett said:
,,, and probably the most important: the ability to give back the energy stored during compression. In an ideal contact, half of the speed of the cue ball comes from the decompression of the tip.
Click to expand...
 
Springy/Whippy Break shaft

Alright, since we seem to have some of the greatest minds of our time weighing in on this subject, let me present a question, or perhaps a dilema.

I have heard that you want a break cue with a whippy/springy shaft because that would allow the springiness/whippiness of that shaft to further accelerate the cue ball upon the spring straightening out after the initial hit (the pole vaulters pole used as an analogy). This is also part of the theory behind Willee Cue's Texas Jackhammer ferrule (http://willeecue.com/Breakferrule.html)

Versus the traditional 'shaft like a tree trunk' break cue.

I'd be most interested to hear the arguments on both sides.

Thanks in advance.
 
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In my search for the perfect break cue, I'm committing pool room heresy--I'm trying a ramin wood break shaft. It's probably illegal, too, since ramin is an endangered species (like the niobium SQUID). Maybe illegal in another way, since the guy I bought it from (actually two of them) wasn't the kind of person I'd like to meet in a dark alley--but that might be said about a lot of people I've played pool with.

One of the things I've come across in my ever-continuing-search-for-the-perfect-break-cue is this excellent US government publication about the mechanical properties of wood:

http://www.fpl.fs.fed.us/documnts/fplgtr/fplgtr190/chapter_05.pdf

Probably only of use to the severely perfectionistic cue maker, or the nerdiest of pool players.
 
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The Best break tip shape? poll shows that players use several tip shapes for breaking.

So what's the best shape?

You won't find the definitive answer here, but at least it's a start. First, there's a lot of approximating in what follows. That's probably ok, since measurements in pool are approximate, anyway. Heck, even cloth from the same roll will play differently because of the way it's stretched. Ever seen a perfect 14mm tip? Also, the graphics below aren't perfect either. That's partially because the software used to generate them, while wonderful, requires more time than I'm willing to spend to get all the measurements perfect. :o It's Geometer's Sketchpad, the same software used for A proof without words: Why elevating a cue slightly may increase draw:. Lastly, probably all the information presented is available either in Bob Jewett's stuff, or David Alciatore's stuff. Another case of my laziness, and because--like pool--it's a lot more fun to do math than watch someone do math. What follows is a just a little high school geometry.

(How's that for a preamble with lots of excuses?)

14mm seems to be a common choice for break tips, particularly on break/jump sticks. It's often praised because it gives more striking surface than 13mm. How much more?

If the tips are flat, the area of the larger can be divided by the area of the smaller, and then multiplied by 100 to get a percentage:

break-1.gif

In this 5X enlarged view, you can see that there's very little difference when you lay a 13mm tip over a 14mm tip. The potential striking area of the 14mm is only about 16 percent larger than the 13mm.

14mm feels fat to me, and 13mm doesn't, so after doing this calculation, it doesn't seem like such a big deal to use 13mm. Especially since you're supposed to break near center ball, anyway. 14mm is only a little more forgiving of stroke flaws.

If you want to do this for other sizes, there's a shortcut: divide the squares of their diameters, and multiply by 100:

13^2 /12^2 X 100 = 117.36, or about 17 percent.

Wonder what happens to the striking area if tip isn't flat? That's for later in the week, after enough people have checked this and pointed out any stupid errors I've made. :grin:
 
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ridewiththewind said:
The secret to a great break is the proper form and technique, not the equipment.

Lisa
Click to expand...

Lisa,

While most people don't have great form or technique on the break, there are those who do. Among those people, are you implying that different break cues make no difference?

KMRUNOUT
 
By the way, as a footnote to the earlier post, comparing "sweet spots" of tips is probably not the best way to do things. What you really want to know is how badly can you miss the center of the ball and get away with it. Forgetting about the miscue limit, and the slight elevation of the cue, it's calculated by just comparing the radii of the two tips. For 14mm and 13mm we have:

7/6.5 x 100 = 107.69, or about 7 1/2 percent.

Even less than was found by comparing areas. Not surprising when you realize there's only a .5 millimeter difference.
 
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