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dr_dave
01-28-2008, 04:57 PM
FYI, my February '08 article (http://billiards.colostate.edu/bd_articles/2008/feb08.pdf) shows a bunch of interesting results from a squirt-testing machine some students and I designed and built recently. The article contains illustrations and graphs showing data for:

- how squirt varies (or doesn't vary) with speed.

- how squirt varies (or doesn't vary) with twist angle of a laminated shaft.

- how squirt varies as end-mass of different amounts is added at different distances from the tip.

Check out the article and let me know if you have any feedback, comments, or questions.

Thanks,
Dave

mikepage
01-28-2008, 05:45 PM
<blockquote><font class="small">Quote dr_dave:</font><hr> [...]
- how squirt varies (or doesn't vary) with speed.

- how squirt varies (or doesn't vary) with twist angle of a laminated shaft.

- how squirt varies as end-mass of different amounts is added at different distances from the tip.

[...]<hr /></blockquote>

Very nice Dave.

This should put these issues to rest --or at least throw the ball clearly in the court of anyone who makes a claim at odds with these results.

If you take requests, I would like sometime to see the extra-endmass versus distance curves for the same cue with a soft tip and a hard tip --and maybe even for a soft shot and a hard shot.

dr_dave
01-28-2008, 06:02 PM
<blockquote><font class="small">Quote mikepage:</font><hr> <blockquote><font class="small">Quote dr_dave:</font><hr> [...]
- how squirt varies (or doesn't vary) with speed.

- how squirt varies (or doesn't vary) with twist angle of a laminated shaft.

- how squirt varies as end-mass of different amounts is added at different distances from the tip.

[...]<hr /></blockquote>

Very nice Dave.<hr /></blockquote>Thanks. Thank you also for your YouTube video to which I refer the readers.

<blockquote><font class="small">Quote mikepage:</font><hr>This should put these issues to rest --or at least throw the ball clearly in the court of anyone who makes a claim at odds with these results.<hr /></blockquote>Agreed.

<blockquote><font class="small">Quote mikepage:</font><hr>If you take requests, I would like sometime to see the extra-endmass versus distance curves for the same cue with a soft tip and a hard tip --and maybe even for a soft shot and a hard shot.<hr /></blockquote>Good suggestion. I'll add this to my students' "list" for this semester.

Regards,
Dave

Bob_Jewett
01-28-2008, 06:38 PM
<blockquote><font class="small">Quote dr_dave:</font><hr> FYI, my February '08 article (http://billiards.colostate.edu/bd_articles/2008/feb08.pdf) shows a bunch of interesting results from a squirt-testing machine some students and I designed and built recently. ... <hr /></blockquote>
For me the most surprising result was how much the squirt increased for an addition of only one gram of weight near the tip. (Is that right?) If so, it sort of gives you how much mass is active for normal squirt (2.5 degrees). How well does that correspond to the actual mass of the last 4 or 7 inches of the shaft? Also, it's not perfectly clear that squirt is a linear function of the mass added to near the tip, but it looks close.

dr_dave
01-28-2008, 10:55 PM
<blockquote><font class="small">Quote Bob_Jewett:</font><hr> <blockquote><font class="small">Quote dr_dave:</font><hr> FYI, my February '08 article (http://billiards.colostate.edu/bd_articles/2008/feb08.pdf) shows a bunch of interesting results from a squirt-testing machine some students and I designed and built recently. ... <hr /></blockquote>
For me the most surprising result was how much the squirt increased for an addition of only one gram of weight near the tip. (Is that right?)<hr /></blockquote>That's right. The small binder clip weighs only about 1/3 gram, and the larger binder clip weighs about 1 gram.

<blockquote><font class="small">Quote Bob_Jewett:</font><hr>If so, it sort of gives you how much mass is active for normal squirt (2.5 degrees). How well does that correspond to the actual mass of the last 4 or 7 inches of the shaft?<hr /></blockquote>The actual "effective endmass" of the shaft is tricky to calculate; although, it can be indirectly measured from squirt measurements. The graphs at the end of TP A.31 (http://billiards.colostate.edu/technical_proofs/new/TP_A-31.pdf) suggests typical "effective endmass" might be in the 1/3 ounce (8 gram) range (corresponding to a mass ratio of about 20). But adding mass at different distances from the tip affects the "endmass" with different degrees.

<blockquote><font class="small">Quote Bob_Jewett:</font><hr>Also, it's not perfectly clear that squirt is a linear function of the mass added to near the tip, but it looks close.<hr /></blockquote>Theory doesn't predict a linear relationship between endmass and squirt (see TP A.31 (http://billiards.colostate.edu/technical_proofs/new/TP_A-31.pdf)); but even if it did, my experiment looked at the amount of added mass (at different distances), not the total "endmass." To me, the results just show the expected result that squirt increases with added endmass. Also, the results show that mass added closer to the tip has a dramatic effect. I was also surprised by the strength of this effect. Its no surprise why a lighter ferrule and a hollow shaft-end can make a big difference.

Regards,
Dave

av84fun
01-29-2008, 12:52 AM
GREAT work Dave...as usual. One TINY, insignificant issue but one that could win a prop bet. Your studies showed the squirt effect at other than VERY slow speeds.

Often, however, the "no variation with speed" proponents use the word "no" in its literal sense and I THINK you would agree that is not correct.

I have demonstrated "zero squirt" in the following experiment.

1. Freeze 3 balls in a line near the center of the table.
2. Move one of the balls the thickness of a dime to create a TINY "window" for another ball to pass through.
3. Remove the middle ball and place its center behind the centers of the other two balls.
4. Cue as level as possible and using a 1.5 tip offset, shoot very softly and the CB will pass through the gap.

You will see that the cue stick might glance over to strike an OB but the CB can pass through the gap.

The total CB travel through the gap is less than an inch..(if the center passes, the whole ball passes) and so there couldn't possibly be any offsetting swerve...and likely no swerve at all since by positioning the balls at center table, a truly level stroke can be effected.

I suppose that sensitive equipment might show that there actually IS squirt but an amount less than .5 the thickness of a dime but the prop bet still wins if it is worded that squirt does NOT vary with speed.

Again, I can't imagine any practical application of the theory that squirt does vary at extremely slow speeds...except winning prop bets which is a noble enough endeavor.

(-:

Regards,
Jim

cushioncrawler
01-29-2008, 03:17 AM
Dr Dave -- Good stuff. I think that the red line for stiffness karnt be dismissed so eezyly. One would havta actually do some tests with cues of different stiffness (and the same endmass) to be able to say that with authority.

I still think that non-endmass haz effekt. If one looks at a vibrating cue (after a stroke with sidespin) the null might be perhaps over 12" from the tip, and i suspekt that (extra) wt at say 18" would tell. Just this week i found that i could get more slowspeed sidespin by uzing a very loose grip. This seems to suggest that the wt (or something) of the hand affekts spin (and hencely possibly squirt).

Just last nite a billiardz mate of mine reported how some of hiz cues have identical leftwards and rightwards deflection (testing with a dead wt), but that one of hiz cues had a "bad" test, and he said that this cue had allwayz given him "trouble". Inspection showed that the grain had a twist in places.

I am thinking that it would be good to do theze tests to the left and to the right. Not to get a more accurate average, but to check whether there iz some sort of bias.

It would be interesting if some sort of tests could compare soft tips and hard tips. madMac.

mikepage
01-29-2008, 06:56 AM
<blockquote><font class="small">Quote cushioncrawler:</font><hr> Dr Dave -- Good stuff. I think that the red line for stiffness karnt be dismissed so eezyly. One would havta actually do some tests with cues of different stiffness (and the same endmass) to be able to say that with authority.

I still think that non-endmass haz effekt. If one looks at a vibrating cue (after a stroke with sidespin) the null might be perhaps over 12" from the tip, and i suspekt that (extra) wt at say 18" would tell. Just this week i found that i could get more slowspeed sidespin by uzing a very loose grip. This seems to suggest that the wt (or something) of the hand affekts spin (and hencely possibly squirt).

Just last nite a billiardz mate of mine reported how some of hiz cues have identical leftwards and rightwards deflection (testing with a dead wt), but that one of hiz cues had a "bad" test, and he said that this cue had allwayz given him "trouble". Inspection showed that the grain had a twist in places.

I am thinking that it would be good to do theze tests to the left and to the right. Not to get a more accurate average, but to check whether there iz some sort of bias.

It would be interesting if some sort of tests could compare soft tips and hard tips. madMac. <hr /></blockquote>


OK, but bear in mind I measured no directional difference in squirt for this cue either after the first (farthest) notch was cut or after I hired the beaver to make the second one.

http://myweb.cableone.net/fargopage/wmcfh3.jpg

jingle
01-29-2008, 09:48 AM
Dave, do you have any plans to test similar maple shafts with varying degrees of stiffness against each other? I'd be very curious to see if the stiffer=more squirt theory holds true.

dr_dave
01-29-2008, 10:06 AM
<blockquote><font class="small">Quote av84fun:</font><hr> GREAT work Dave...as usual.<hr /></blockquote>Thanks.
<blockquote><font class="small">Quote av84fun:</font><hr>One TINY, insignificant issue but one that could win a prop bet. Your studies showed the squirt effect at other than VERY slow speeds.<hr /></blockquote>I'm not sure what you mean here. Could you explain further or be more specific?
<blockquote><font class="small">Quote av84fun:</font><hr>Often, however, the "no variation with speed" proponents use the word "no" in its literal sense and I THINK you would agree that is not correct.<hr /></blockquote>A better way to say it might be: for all practical purposes, and with typical equipment, there is no variation in squirt with speed. But now we're starting to sound like contract attorneys.

<blockquote><font class="small">Quote av84fun:</font><hr>I have demonstrated "zero squirt" in the following experiment.

1. Freeze 3 balls in a line near the center of the table.
2. Move one of the balls the thickness of a dime to create a TINY "window" for another ball to pass through.
3. Remove the middle ball and place its center behind the centers of the other two balls.
4. Cue as level as possible and using a 1.5 tip offset, shoot very softly and the CB will pass through the gap.

You will see that the cue stick might glance over to strike an OB but the CB can pass through the gap.

The total CB travel through the gap is less than an inch..(if the center passes, the whole ball passes) and so there couldn't possibly be any offsetting swerve...and likely no swerve at all since by positioning the balls at center table, a truly level stroke can be effected.

I suppose that sensitive equipment might show that there actually IS squirt but an amount less than .5 the thickness of a dime but the prop bet still wins if it is worded that squirt does NOT vary with speed.

Again, I can't imagine any practical application of the theory that squirt does vary at extremely slow speeds...except winning prop bets which is a noble enough endeavor.<hr /></blockquote>At slow speeds, swerve occurs almost immediately, so if your cue elevation and amount of English creates enough swerve to exactly cancel the amount of squirt for your cue, there will be no apparent squerve (the combination of squirt and swerve) for a slow speed shot.

Regards,
Dave

Jal
01-29-2008, 10:22 AM
<blockquote><font class="small">Quote av84fun:</font><hr> GREAT work Dave...as usual.<hr /></blockquote>I'll second that.

<blockquote><font class="small">Quote av84fun:</font><hr>One TINY, insignificant issue but one that could win a prop bet. Your studies showed the squirt effect at other than VERY slow speeds.

Often, however, the "no variation with speed" proponents use the word "no" in its literal sense and I THINK you would agree that is not correct.

I have demonstrated "zero squirt" in the following experiment.

1. Freeze 3 balls in a line near the center of the table.
2. Move one of the balls the thickness of a dime to create a TINY "window" for another ball to pass through.
3. Remove the middle ball and place its center behind the centers of the other two balls.
4. Cue as level as possible and using a 1.5 tip offset, shoot very softly and the CB will pass through the gap.

You will see that the cue stick might glance over to strike an OB but the CB can pass through the gap.

The total CB travel through the gap is less than an inch..(if the center passes, the whole ball passes) and so there couldn't possibly be any offsetting swerve...and likely no swerve at all since by positioning the balls at center table, a truly level stroke can be effected.<hr /></blockquote>Jim, I don't think this test really demonstrates less squirt. A dime is almost 1/16" thick - let's say 1/20". If you managed set up the middle ball in the exact center of the gap, you would then have about 1/40" clearance on either side.

If the middle ball was set back by 1", then it could move sideways 1/40" in 1" of forward travel. That's an angle of 1.4 degrees. This is roughly at the lower end of the range of squirt angles at large tip offsets.

Even with the balls at center table, and presuming that little or no follow was used, the cue cannot be made level unless it's considerably shorter than usual. So the cueball will swerve. If it was hit softly enough to only travel two diamonds (about 1 mph), then it could very well have completed its swerving in just that 1" of travel.

If the cueball was closer than 1", say 1/2", then less swerve would take place, but a greater squirt angle of 2.9 deg would be tolerated. If 1/4" back, then 5.7 degrees would be allowed.

And all of this presumes that the stick was pointed perpendicular to the gate, say within some fraction of a degree. That shouldn't be too hard to do though. However, setting up the cueball so that it's centered in the gap would be difficult, I would think.

So I just can't see how this test really proves anything, but maybe you took some special precautions not described?

Jim

dr_dave
01-29-2008, 10:31 AM
<blockquote><font class="small">Quote cushioncrawler:</font><hr> Dr Dave -- Good stuff. I think that the red line for stiffness karnt be dismissed so eezyly.<hr /></blockquote>I assume you are referring to Diagram 4 in the article (http://billiards.colostate.edu/bd_articles/2008/feb08.pdf). My only claim here is that people who think extra stiffness is required to produce more squirt are incorrect. Added endmass alone (without added stiffness) produces significant increases in squirt. This supports the theory in TP A.31 (http://billiards.colostate.edu/technical_proofs/new/TP_A-31.pdf).

<blockquote><font class="small">Quote cushioncrawler:</font><hr>One would havta actually do some tests with cues of different stiffness (and the same endmass) to be able to say that with authority.<hr /></blockquote>The difficulty here is that "endmass" is related to stiffness. A stiffer shaft will typically be thicker and heavier at the end. Also, transverse shock waves will travel faster in a stiffer shaft, effectively increasing the "endmass." See the paragraph after Equation 4 in TP A.31 (http://billiards.colostate.edu/technical_proofs/new/TP_A-31.pdf).

<blockquote><font class="small">Quote cushioncrawler:</font><hr>I still think that non-endmass haz effekt.<hr /></blockquote>I'm not sure what you mean here. If you mean that an increase in endmass without an increase in stiffness does not increase squirt, then I strongly disagree.

<blockquote><font class="small">Quote cushioncrawler:</font><hr>Just last nite a billiardz mate of mine reported how some of hiz cues have identical leftwards and rightwards deflection (testing with a dead wt)<hr /></blockquote>Just to be clear, this "deflection" is a measure of stiffness, not squirt. This is one reason I and others prefer the term "squirt" over "deflection." In the context of dead-weight stiffnes tests, less cue "deflection" (i.e., more stiffness) would generally imply more "squirt" (i.e., more cue ball deflection).

<blockquote><font class="small">Quote cushioncrawler:</font><hr>but that one of hiz cues had a "bad" test, and he said that this cue had allwayz given him "trouble". Inspection showed that the grain had a twist in places.<hr /></blockquote>I would expect this "bad" cue to have consistent squirt at all twist angles, because the endmass would not be orientation dependent, for all practical purposes (e.g., see Diagram 3 in the article).

<blockquote><font class="small">Quote cushioncrawler:</font><hr>I am thinking that it would be good to do theze tests to the left and to the right. Not to get a more accurate average, but to check whether there iz some sort of bias.<hr /></blockquote>Good point. With the Diagram 3 data, we simulated this by varying the twist angle of the cue.

<blockquote><font class="small">Quote cushioncrawler:</font><hr>It would be interesting if some sort of tests could compare soft tips and hard tips.<hr /></blockquote>Agreed. This is high on our list of things to do.

Regards,
Dave

dr_dave
01-29-2008, 10:46 AM
<blockquote><font class="small">Quote jingle:</font><hr> Dave, do you have any plans to test similar maple shafts with varying degrees of stiffness against each other? I'd be very curious to see if the stiffer=more squirt theory holds true. <hr /></blockquote>See my reply to cushioncrawler (http://www.billiardsdigest.com/ccboard/showthreaded.php?Cat=&amp;Board=ccb&amp;Number=273473&amp;page =&amp;view=&amp;sb=&amp;o=&amp;vc=1). It is difficult (if not impossible) to easily change the stiffness without changing the endmass, unless you do something like Mike Page's beaver-cue demo (see his posting about this (http://www.billiardsdigest.com/ccboard/showthreaded.php?Cat=&amp;Board=ccb&amp;Number=273428&amp;page =0&amp;view=collapsed&amp;sb=5&amp;o=&amp;vc=1)). I would prefer not do this to my cues, but the beaver-cue-test does seem to show that squirt does not depend directly on shaft stiffness. What do the stiffness believers out there think of this demo?

Regards,
Dave

Billy_Bob
01-29-2008, 10:50 AM
So far as how much squirt for a particular type of cue such as laminated vs low deflection... And that laminated seems to have no less squirt than a solid wood cue... Well this is consistent with my "non-robot" personal testing.

FYI - I did my testing with the testing methods discussed in Ron Shepard's paper on squirt (link below).

I don't know if your robot can do this or not, but I would like to see what pivot point length the robot would come up with for a cue with a Predator 314 shaft.

Shepard paper...
http://www.sfbilliards.com/Shepard_squirt.pdf

dr_dave
01-29-2008, 11:15 AM
<blockquote><font class="small">Quote Billy_Bob:</font><hr> So far as how much squirt for a particular type of cue such as laminated vs low deflection... And that laminated seems to have no less squirt than a solid wood cue... Well this is consistent with my "non-robot" personal testing.

FYI - I did my testing with the testing methods discussed in Ron Shepard's paper on squirt (link below).

I don't know if your robot can do this or not, but I would like to see what pivot point length the robot would come up with for a cue with a Predator 314 shaft.

Shepard paper...
http://www.sfbilliards.com/Shepard_squirt.pdf<hr /></blockquote>
My November '07 article (http://billiards.colostate.edu/bd_articles/2007/nov07.pdf) illustrates and expands on the Shepard techniques. I have pivot length results for various cues in the middle paragraph on page 4 of the article. In TP B.1 (http://billiards.colostate.edu/technical_proofs/new/TP_B-1.pdf), I show how the natural pivot length of a cue can be determined with a single measurement. I also have lots of useful and interesting conclusions in TP B.1. Check it out (if you don't mind skipping over a bunch of silly math and physics). Per the paragraph at the bottom of page 3, my pivot length numbers seem much smaller than Shepard's predicted values. I'm not sure why. My numbers are larger than Platinum Billiards' numbers (see a previous posting on this topic (http://www.billiardsdigest.com/ccboard/showthreaded.php?Cat=&amp;Board=ccb&amp;Number=252507&amp;page =0&amp;view=&amp;sb=&amp;o=&amp;fpart=&amp;vc=) for details). Mine are in the middle, so they must be right. /ccboard/images/graemlins/wink.gif

Regards,
Dave

av84fun
01-29-2008, 11:57 AM
dr_Dave [ QUOTE ]
At slow speeds, swerve occurs almost immediately, so if your cue elevation and amount of English creates enough swerve to exactly cancel the amount of squirt for your cue, there will be no apparent squerve (the combination of squirt and swerve) for a slow speed shot.<hr /></blockquote>

Just use a jump cue or the shaft of your regular cue so you can stroke dead level...so there is no swerve and therefore, no squirt to cancel out. The CB still passes through showing that there is virtally no squirt on extremely slow shots.

But PLEASE don't change the descriptive language to "for all practical purposes" or similar language. That would just ruin my prop bet!!! (-:

Just keep it that "squirt does not vary with speed" and I can pick up a lot of extra gas money!!!
(-:

Jim

dr_dave
01-29-2008, 12:11 PM
<blockquote><font class="small">Quote av84fun:</font><hr><blockquote><font class="small">Quote dr_dave:</font><hr>At slow speeds, swerve occurs almost immediately, so if your cue elevation and amount of English creates enough swerve to exactly cancel the amount of squirt for your cue, there will be no apparent squerve (the combination of squirt and swerve) for a slow speed shot.<hr /></blockquote>
Just use a jump cue or the shaft of your regular cue so you can stroke dead level...so there is no swerve and therefore, no squirt to cancel out. The CB still passes through showing that there is virtally no squirt on extremely slow shots.<hr /></blockquote>Based on Jal's reply (http://www.billiardsdigest.com/ccboard/showthreaded.php?Cat=&amp;Board=ccb&amp;Number=273470&amp;page =&amp;view=&amp;sb=&amp;o=&amp;vc=1), there can still be squirt (virtually and practically).

<blockquote><font class="small">Quote av84fun:</font><hr>But PLEASE don't change the descriptive language to "for all practical purposes" or similar language. That would just ruin my prop bet!!! (-:<hr /></blockquote>I like "virtually" better. Good idea. Still sound like a lawyer though. /ccboard/images/graemlins/crazy.gif

<blockquote><font class="small">Quote av84fun:</font><hr>Just keep it that "swerve does not vary with speed" and I can pick up a lot of extra gas money!!!<hr /></blockquote>The effect of swerve varies a lot with speed, distance, conditions, type and amount of English, and cue elevation. That's easy money. /ccboard/images/graemlins/cool.gif

Did you mean "squirt" here? If so, I can neither confirm nor deny that squirt virtually varies with speed in a practical sense. /ccboard/images/graemlins/wink.gif

Regards,
Dave

dr_dave
01-29-2008, 02:41 PM
<blockquote><font class="small">Quote Bob_Jewett:</font><hr>...it's not perfectly clear that squirt is a linear function of the mass added to near the tip, but it looks close.<hr /></blockquote>Bob,

FYI, I just added two pages to TP A.31 (http://billiards.colostate.edu/technical_proofs/new/TP_A-31.pdf) (see pages 5 and 6), showing the theoretical predications of how squirt varies with mass ratio and endmass. The theory backs up your claim that squirt should vary fairly linearly with endmass.

Regards,
Dave

av84fun
01-29-2008, 04:31 PM
Dr_Dave..."Did you mean "squirt" here? "

Yes...brain cramp on my part.
(-:

av84fun
01-29-2008, 04:42 PM
JAL..."If the middle ball was set back by 1", then it could move sideways 1/40" in 1" of forward travel. That's an angle of 1.4 degrees. This is roughly at the lower end of the range of squirt angles at large tip offsets."

Gotcha...but you don't get the FULL width of the gate because at the extremes, there would be contact with the gate balls.

Re: the length of the cue, in another post I suggested using a jump cue or cue shaft so that zero swerve could be assured.

As far as such minute ball movements due to swerve or squirt as such slow speeds I am just enough of a "show me" kind of guy to want to see plots of scientific studies before I would accept that there is ANY swerve produced even by a slightly downwardly inclined cue on a 1 mph shot over the distance of 1 inch.

I am sure all scientific minds will appreciate my need to see evidence rather than to accept theories.

Regards,
Jim

Jal
01-29-2008, 06:26 PM
<blockquote><font class="small">Quote av84fun:</font><hr> JAL..."If the middle ball was set back by 1", then it could move sideways 1/40" in 1" of forward travel. That's an angle of 1.4 degrees. This is roughly at the lower end of the range of squirt angles at large tip offsets."

Gotcha...but you don't get the FULL width of the gate because at the extremes, there would be contact with the gate balls.<hr /></blockquote>Yes, that true Jim, but I think it might be hard to detect a barely grazing contact. We're talking a "cut angle" of maybe 89 degrees and some considerable fraction of that remaining degree. And, depending on where you set up the cueball, you could have most of that 1/20" as clearance.

<blockquote><font class="small">Quote av84fun:</font><hr>Re: the length of the cue, in another post I suggested using a jump cue or cue shaft so that zero swerve could be assured.<hr /></blockquote>Yes, I didn't think of that. But you have to be pretty careful to assure that it's level.

<blockquote><font class="small">Quote av84fun:</font><hr>As far as such minute ball movements due to swerve or squirt as such slow speeds I am just enough of a "show me" kind of guy to want to see plots of scientific studies before I would accept that there is ANY swerve produced even by a slightly downwardly inclined cue on a 1 mph shot over the distance of 1 inch.

I am sure all scientific minds will appreciate my need to see evidence rather than to accept theories.<hr /></blockquote>I appreciate your skepticism. In my mind though, predicting the amount a ball will curve is about as reliable as anything you could attempt to predict on the table.

Jim

av84fun
01-29-2008, 09:15 PM
JAL..."I appreciate your skepticism. In my mind though, predicting the amount a ball will curve is about as reliable as anything you could attempt to predict on the table. "

All your commnents are understood and appreciated. But I'm not going to worry about predicting swerve on a nearly level shot.

I am going to be concerned with squirt on medium pace shots and up and CIT on ALL cuts because those issues are were the greatest error factors lie.

I think we need to "pick our battles" and not get caught up in paralysis by analysis.

One fairly stone-headed gentleman on another forum was passing the ridiculous notion that swerve meaningfully canceled out squirt ON A BREAK SHOT with english which, of course, is a preposterous notion given that the CB is in the air a goodly portion of the time on its way to the rack!

Maybe the "swerve" he was talking about was caused by wind currents while the CB was airborne!!

(-:

cushioncrawler
01-30-2008, 05:58 PM
<blockquote><font class="small">Quote dr_dave:</font><hr> <blockquote><font class="small">Quote cushioncrawler:</font><hr> Dr Dave -- Good stuff. I think that the red line for stiffness karnt be dismissed so eezyly.<hr /></blockquote>I assume you are referring to Diagram 4 in the article (http://billiards.colostate.edu/bd_articles/2008/feb08.pdf). My only claim here is that people who think extra stiffness is required to produce more squirt are incorrect. Added endmass alone (without added stiffness) produces significant increases in squirt. This supports the theory in TP A.31 (http://billiards.colostate.edu/technical_proofs/new/TP_A-31.pdf).<blockquote><font class="small">Quote cushioncrawler:</font><hr>One would havta actually do some tests with cues of different stiffness (and the same endmass) to be able to say that with authority.<hr /></blockquote>The difficulty here is that "endmass" is related to stiffness. A stiffer shaft will typically be thicker and heavier at the end. Also, transverse shock waves will travel faster in a stiffer shaft, effectively increasing the "endmass." See the paragraph after Equation 4 in TP A.31 (http://billiards.colostate.edu/technical_proofs/new/TP_A-31.pdf).<blockquote><font class="small">Quote cushioncrawler:</font><hr>I still think that non-endmass haz effekt.<hr /></blockquote>I'm not sure what you mean here. If you mean that an increase in endmass without an increase in stiffness does not increase squirt, then I strongly disagree.<blockquote><font class="small">Quote cushioncrawler:</font><hr>Just last nite a billiardz mate of mine reported how some of hiz cues have identical leftwards and rightwards deflection (testing with a dead wt)<hr /></blockquote>Just to be clear, this "deflection" is a measure of stiffness, not squirt. This is one reason I and others prefer the term "squirt" over "deflection." In the context of dead-weight stiffnes tests, less cue "deflection" (i.e., more stiffness) would generally imply more "squirt" (i.e., more cue ball deflection).<blockquote><font class="small">Quote cushioncrawler:</font><hr>but that one of hiz cues had a "bad" test, and he said that this cue had allwayz given him "trouble". Inspection showed that the grain had a twist in places.<hr /></blockquote>I would expect this "bad" cue to have consistent squirt at all twist angles, because the endmass would not be orientation dependent, for all practical purposes (e.g., see Diagram 3 in the article).<blockquote><font class="small">Quote cushioncrawler:</font><hr>I am thinking that it would be good to do theze tests to the left and to the right. Not to get a more accurate average, but to check whether there iz some sort of bias.<hr /></blockquote>Good point. With the Diagram 3 data, we simulated this by varying the twist angle of the cue.<blockquote><font class="small">Quote cushioncrawler:</font><hr>It would be interesting if some sort of tests could compare soft tips and hard tips.<hr /></blockquote>Agreed. This is high on our list of things to do. Regards, Dave.<hr /></blockquote>Dr Dave -- Yes my mate's "deflection" woz simply a measure of the end-bend (by hanging a dead wt) uzing a micrometer(?). But hiz assertion about the "bad" cue related (i think) to the difference in squirt (left and right). Here perhaps he had trouble judging squirt, or trouble getting (or judging) sidespin. Koz, its not just about endmass and stiffness, all cues will (i think, and he thinks) "buck" on every shot. If a cue iz bent (ie haz a permanent bend) then it will want to buck "that way". This buck might inkreec sidespin (and/or squirt) or it might dekreec it (if held the wrong "way"). We know about bends and how they (their buck) might affekt our shot (ie we sometimes hold the cue such that the bendnbuck helps the skrew etc). Likewize we know that the grain affects stiffness in varyus directions (angles), and that the stiffness iz greatest parallel to the grain, but there are 2 parallel directions, and few of us know which of theze iz stiffest. My mate knows, koz he haz tested (meazured) hiz cues.

However, a cue's natural buck-direction iznt necessaryly linked direktly to stiffness-direction (i didnt have the heart to tell him this) -- eg the cue might have a bend which affekts buck more than duz grain. Perhaps one could find a cue's natural buck-direction if one hit a qball dead-center -- but here it kood be affekted by the shape of the tip (eg if u replace a badly worn tip with a nice new tip the buck-direction kood change). Such buck kood be a source of bias in squirt tests.

Anyhow, my mate's tale suggests that end-mass iz not the only term in the equation.

At the risk of repeating Mike Page's tests, there iz a way of finding the effekt of stiffness. U get a (cheap) cue, and u do squirt tests at say 8 angles. Then, u make 2 (small) saw cuts into the shaft say 9" from the tip, ie an identikal cut on each side, to take stiffness out of thoze 2 directions, then repeat the (8) tests. Then make the cuts deeper, etc etc. madMac.

dr_dave
01-30-2008, 06:16 PM
<blockquote><font class="small">Quote cushioncrawler:</font><hr>At the risk of repeating Mike Page's tests, there iz a way of finding the effekt of stiffness. U get a (cheap) cue, and u do squirt tests at say 8 angles. Then, u make 2 (small) saw cuts into the shaft say 9" from the tip, ie an identikal cut on each side, to take stiffness out of thoze 2 directions, then repeat the (8) tests. Then make the cuts deeper, etc etc. madMac.<hr /></blockquote>Mac,

See my posting concerning Mike's beaver cue (http://www.billiardsdigest.com/ccboard/showthreaded.php?Cat=&amp;Board=ccb&amp;Number=273475&amp;Foru m=ccb&amp;Words=beaver&amp;Match=Entire%20Phrase&amp;Searchpag e=0&amp;Limit=25&amp;Old=1week&amp;Main=273349&amp;Search=true#Pos t273475). Isn't the whole point of this test to show that this type of stiffness change has no affect on the amount of squirt?

Regards,
Dave

cushioncrawler
01-30-2008, 06:37 PM
<blockquote><font class="small">Quote mikepage:</font><hr> <blockquote><font class="small">Quote cushioncrawler:</font><hr> Dr Dave -- Good stuff. I think that the red line for stiffness karnt be dismissed so eezyly. One would havta actually do some tests with cues of different stiffness (and the same endmass) to be able to say that with authority. I still think that non-endmass haz effekt. If one looks at a vibrating cue (after a stroke with sidespin) the null might be perhaps over 12" from the tip, and i suspekt that (extra) wt at say 18" would tell. Just this week i found that i could get more slowspeed sidespin by uzing a very loose grip. This seems to suggest that the wt (or something) of the hand affekts spin (and hencely possibly squirt). Just last nite a billiardz mate of mine reported how some of hiz cues have identical leftwards and rightwards deflection (testing with a dead wt), but that one of hiz cues had a "bad" test, and he said that this cue had allwayz given him "trouble". Inspection showed that the grain had a twist in places. I am thinking that it would be good to do theze tests to the left and to the right. Not to get a more accurate average, but to check whether there iz some sort of bias. It would be interesting if some sort of tests could compare soft tips and hard tips...<hr /></blockquote>OK, but bear in mind I measured no directional difference in squirt for this cue either after the first (farthest) notch was cut or after I hired the beaver to make the second one. http://myweb.cableone.net/fargopage/wmcfh3.jpg <hr /></blockquote>Mike -- Very interesting --could u describe your tests in more detail?? I notice that the notches were at about 45dg to the grain (probably not important).

Woz the squirt equal across the notches, compared to parallel (etc) to the notches. madMac.

cushioncrawler
01-30-2008, 07:05 PM
<blockquote><font class="small">Quote dr_dave:</font><hr> <blockquote><font class="small">Quote cushioncrawler:</font><hr>At the risk of repeating Mike Page's tests, there iz a way of finding the effekt of stiffness. U get a (cheap) cue, and u do squirt tests at say 8 angles. Then, u make 2 (small) saw cuts into the shaft say 9" from the tip, ie an identikal cut on each side, to take stiffness out of thoze 2 directions, then repeat the (8) tests. Then make the cuts deeper, etc etc. madMac.<hr /></blockquote>Mac, See my posting concerning Mike's beaver cue (http://www.billiardsdigest.com/ccboard/showthreaded.php?Cat=&amp;Board=ccb&amp;Number=273475&amp;Foru m=ccb&amp;Words=beaver&amp;Match=Entire%20Phrase&amp;Searchpag e=0&amp;Limit=25&amp;Old=1week&amp;Main=273349&amp;Search=true#Pos t273475). Isn't the whole point of this test to show that this type of stiffness change has no affect on the amount of squirt? Regards, Dave<hr /></blockquote>Dr Dave -- Yes the "cuts" test(s) would show the effekt of stiffness.

But i am not sure of Mike's methodology (see my posting to Mike). Lets say that i am correct and that stiffness counts -- in which case Mike's tests shood show less squirt az the notches grew in size and number -- how then could Mike's test(s) show that stiffness duznt count?? The answer to that question could be that Mike choze to hit the qball harder after the notches were cut (or swung harder, ie to hit the qball "the same"). Hitting the qball "harder" would allmost certainly here involve a dirty big push, rather than a nice stroke. A dirty big push would involve a longer contact time, and, it would involve the wt etc of the hand getting into the equation. In the past i have mentioned 2 effekts. One woz that the wt of the hand can effekt squirt (unless u had a very loose grip). The other woz the speed of the shot, i said that squirt woz greater at slow speed -- here my real meaning woz that the qtip-qball contact time woz greater, hence more squirt. Here i havnt explained why, nor have i explained why Dr Dave's student's tests show otherwize (but i think that i can). Anyhow, thoze are 2 possible reezonz why Mike's tests might have missled.

Dr Dave, how would u describe the robot-grip of the butt, and the robot bridge (ie at the shaft) in your tests?? Here i am thinking about your tests. But i am allso thinking about something new, we would expekt that the robot-bridge had little effekt on squirt, what with it being at about the 9" null point on the shaft, but varying (somehow) the firmness (or something) of the robot-bridge kood be a good possible test. madMac.

dr_dave
01-31-2008, 09:44 AM
<blockquote><font class="small">Quote cushioncrawler:</font><hr> <blockquote><font class="small">Quote dr_dave:</font><hr><blockquote><font class="small">Quote cushioncrawler:</font><hr>At the risk of repeating Mike Page's tests, there iz a way of finding the effekt of stiffness. U get a (cheap) cue, and u do squirt tests at say 8 angles. Then, u make 2 (small) saw cuts into the shaft say 9" from the tip, ie an identikal cut on each side, to take stiffness out of thoze 2 directions, then repeat the (8) tests. Then make the cuts deeper, etc etc. madMac.<hr /></blockquote>Mac, See my posting concerning Mike's beaver cue (http://www.billiardsdigest.com/ccboard/showthreaded.php?Cat=&amp;Board=ccb&amp;Number=273475&amp;Foru m=ccb&amp;Words=beaver&amp;Match=Entire%20Phrase&amp;Searchpag e=0&amp;Limit=25&amp;Old=1week&amp;Main=273349&amp;Search=true#Pos t273475). Isn't the whole point of this test to show that this type of stiffness change has no affect on the amount of squirt? Regards, Dave<hr /></blockquote>Dr Dave -- Yes the "cuts" test(s) would show the effekt of stiffness.<hr /></blockquote>Isn't the point of the test to show the lack of effect of this type of stiffness change on squirt? Have you tried Mike's beaver-cue test? I haven't, but I trust Mike's claims until I see hard data proving otherwise. Now, if the cuts were made much closer to the tip, I would expect a change in squirt, because the effective "endmass" would be changed.

<blockquote><font class="small">Quote cushioncrawler:</font><hr>But i am not sure of Mike's methodology (see my posting to Mike). Lets say that i am correct and that stiffness counts -- in which case Mike's tests shood show less squirt az the notches grew in size and number -- how then could Mike's test(s) show that stiffness duznt count?? The answer to that question could be that Mike choze to hit the qball harder after the notches were cut (or swung harder, ie to hit the qball "the same"). Hitting the qball "harder" would allmost certainly here involve a dirty big push, rather than a nice stroke. A dirty big push would involve a longer contact time, and, it would involve the wt etc of the hand getting into the equation.<hr /></blockquote>I can't imagine Mike would be this careless, but I guess it is possible.

<blockquote><font class="small">Quote cushioncrawler:</font><hr>Dr Dave, how would u describe the robot-grip of the butt, and the robot bridge (ie at the shaft) in your tests?? Here i am thinking about your tests. But i am allso thinking about something new, we would expekt that the robot-bridge had little effekt on squirt, what with it being at about the 9" null point on the shaft, but varying (somehow) the firmness (or something) of the robot-bridge kood be a good possible test.<hr /></blockquote>I seriously doubt the bridge or grip could have any effect on squirt measurements unless the grip were very tight and heavy and caused a double hit. We have used high-speed video to show that this is not occurring. The bridge is well back from the point where the added mass began to have no effect on squirt, so I don't see how the bridge could be a factor. I'm pretty sure the ball is long gone before the shock waves even reach the bridge. If this is true, the bridge couldn't possibly have an effect. Having said this, I still might try different materials in our bridge and grip to see if it has any effect. If it does, I owe you a beer.

Regards,
Dave

mikepage
01-31-2008, 11:46 AM
<blockquote><font class="small">Quote Dr. Dave:</font><hr>
<blockquote><font class="small">Quote cushioncrawler:</font><hr>But i am not sure of Mike's methodology (see my posting to Mike). Lets say that i am correct and that stiffness counts -- in which case Mike's tests shood show less squirt az the notches grew in size and number -- how then could Mike's test(s) show that stiffness duznt count?? The answer to that question could be that Mike choze to hit the qball harder after the notches were cut (or swung harder, ie to hit the qball "the same"). Hitting the qball "harder" would allmost certainly here involve a dirty big push, rather than a nice stroke. A dirty big push would involve a longer contact time, and, it would involve the wt etc of the hand getting into the equation.<hr /></blockquote>I can't imagine Mike would be this careless, but I guess it is possible.

<hr /></blockquote>

Sorry Dave, but "dirty big push" is probably about right ;-)

But to CC, the comparison wasn't just pre-notch to post-notch, it was notch vertical (ultra whippy) to notch horizontal (normal stiffness).

dr_dave
01-31-2008, 11:55 AM
<blockquote><font class="small">Quote mikepage:</font><hr> <blockquote><font class="small">Quote Dr. Dave:</font><hr>
<blockquote><font class="small">Quote cushioncrawler:</font><hr>But i am not sure of Mike's methodology (see my posting to Mike). Lets say that i am correct and that stiffness counts -- in which case Mike's tests shood show less squirt az the notches grew in size and number -- how then could Mike's test(s) show that stiffness duznt count?? The answer to that question could be that Mike choze to hit the qball harder after the notches were cut (or swung harder, ie to hit the qball "the same"). Hitting the qball "harder" would allmost certainly here involve a dirty big push, rather than a nice stroke. A dirty big push would involve a longer contact time, and, it would involve the wt etc of the hand getting into the equation.<hr /></blockquote>I can't imagine Mike would be this careless, but I guess it is possible.<hr /></blockquote>

Sorry Dave, but "dirty big push" is probably about right ;-)<hr /></blockquote>How could you? /ccboard/images/graemlins/confused.gif /ccboard/images/graemlins/grin.gif

For a while there, you were my hero. /ccboard/images/graemlins/wink.gif

Now I want to pull out my Dremmel Tool and an old cue and try out the "beaver-cue" experiment myself.

Regards,
Dave

PS: Thanks for suggesting the "beaver-cue" experiment. Great idea!

cushioncrawler
02-03-2008, 01:42 AM
<blockquote><font class="small">Quote dr_dave:</font><hr>....Isn't the point of the test to show the lack of effect of this type of stiffness change on squirt? Have you tried Mike's beaver-cue test? I haven't, but I trust Mike's claims until I see hard data proving otherwise. Now, if the cuts were made much closer to the tip, I would expect a change in squirt, because the effective "endmass" would be changed.....<hr /></blockquote>Dr Dave -- I must admit that i have 2 cues that i have cut big scallops out of the shafts, to make them flexy in one direction (2 directionz actually, ie at 180dg), and i have uzed them in matches. Here the end 8" woznt touched, the scallops being in the next say 8". I noticed that squirt woz lesserer normal to the scallop, and soft skrew woz eezyr normal to the scallop.

And i have 2 cues that i have cut lots of sawcuts into, to make them flexy in one direction -- theze cues were for masse' shots. In one cue i allso cut out the shaft near the tip to half depth, and added a half cylinder of lead, to inkreec the tip wt, to help the masse action (to help masse control aktually). Plus i have messed around with 2 or 3 other cues, eg made them shorter and heavyr etc, for masse' shots.

At prezent, my favorit cue for masse's (and for nursery cannonz) iz a solid fibreglass cue (this stuff iz heavy). I put a 9mm tip on one end, and an 11mm tip on the other. Both endz are great. I havnt measured the squirt(s) but i will when i get back up the hill to my new joint (in a few minutes time). Funny thing, this cue only weighs 11oz (it iznt very long, and iz only about 13mm at the thick end), and it outplayz all of my heavyr (masse') cues.

Last night i woz laying in bed thinking about squirt etc. When u think about it, for most such shots (ie shots with english), i think that we try to uze a certain amount of sidespin, coupled with a certain amount of pace. Hencely, to be striktly correct (in our tests etc) we shood compare cues (squirt) on that basis, ie being able to give a certain amount of english at a certain speed (and the corresponding squirt). Here i feel that stiff and/or heavy-tipped cues would suffer in theze squirt tests even more-so (than they do in the standard "squirt at a certain tip-offset and certain pace" tests), at least they would at soft or medium pace. But, if u factor-in control (ie repeatability), the stiffer and/or heavyr cues might come out on top at all speedz (at least at medium or low spin-rates) ( at least for some playerz)??? madMac.

dr_dave
02-04-2008, 11:28 AM
<blockquote><font class="small">Quote cushioncrawler:</font><hr> <blockquote><font class="small">Quote dr_dave:</font><hr>....Isn't the point of the test to show the lack of effect of this type of stiffness change on squirt? Have you tried Mike's beaver-cue test? I haven't, but I trust Mike's claims until I see hard data proving otherwise. Now, if the cuts were made much closer to the tip, I would expect a change in squirt, because the effective "endmass" would be changed.....<hr /></blockquote>Dr Dave -- I must admit that i have 2 cues that i have cut big scallops out of the shafts, to make them flexy in one direction (2 directionz actually, ie at 180dg), and i have uzed them in matches. Here the end 8" woznt touched, the scallops being in the next say 8". I noticed that squirt woz lesserer normal to the scallop, and soft skrew woz eezyr normal to the scallop.<hr /></blockquote>I plan to do a series of experiments with cuts made in different positions and with various hardness tips. I am very curious to see some "machine" results. I'll be sure to share the data when it is available.

<blockquote><font class="small">Quote cushioncrawler:</font><hr>Last night i woz laying in bed thinking about squirt etc. When u think about it, for most such shots (ie shots with english), i think that we try to uze a certain amount of sidespin, coupled with a certain amount of pace. Hencely, to be striktly correct (in our tests etc) we shood compare cues (squirt) on that basis, ie being able to give a certain amount of english at a certain speed (and the corresponding squirt). Here i feel that stiff and/or heavy-tipped cues would suffer in theze squirt tests even more-so (than they do in the standard "squirt at a certain tip-offset and certain pace" tests), at least they would at soft or medium pace. But, if u factor-in control (ie repeatability), the stiffer and/or heavyr cues might come out on top at all speedz (at least at medium or low spin-rates) ( at least for some playerz)??? madMac. <hr /></blockquote>As with all of the tests we do with our machine, we will do them at several repeatable speeds. Concerning the amount of English, I don't think it will vary much with speed (for a given tip offset). We have shown that squirt doesn't appear to vary with shot speed. For more info, see Diagram 2 and the related paragraph in my February '08 article (http://billiards.colostate.edu/bd_articles/2008/feb08.pdf) and Diagram 3 and the related paragraph in my December '07 article (http://billiards.colostate.edu/bd_articles/2007/dec07.pdf). The physics and discussion in TP A.31 (http://billiards.colostate.edu/technical_proofs/new/TP_A-31.pdf) also support the experimental data and claims in my articles so far.

Regards,
Dave

wolfdancer
02-04-2008, 11:32 AM
"beaver cues, stiffness"....must i remind you that this is a family site?
We have young impressionable Republicans reading these posts