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View Full Version : low deflection cue VS non-low deflection (BHE/FHE)



jondrums
02-16-2007, 04:41 PM
This is my first thread here. I post a little here and at AZbilliards but I wanted to put this question up here first because I believe I have a good chance to get a well informed and thorough answer on this forum.

I started playing only several months ago, and naturally decided to chose a low-deflection OB-1 shaft based on many people's recomendations.

After learning about Back Hand English and Front Hand English (BHE, FHE) I've started to wonder if for beginners it actually might be easier to work with a NON-low-deflection shaft. Let me explain:

For a given shot strength (soft, medium, firm, hard), each shaft has a given pivot point right? It would seem that a shaft which has deflection properties such that the pivot point allows you to conviniently use BHE for most shots that require english would be very forgiving. If you aim up the shot with center ball (using the correct bridge length), and apply english with the back hand, a little variation in how much english is applied should have very little effect on the path of the CB.

However, with FHE (and a low deflection cue) one must first be have a smooth stroke and strike the CB with exactly the right amount of english. In addition, it seems harder to me to figure out how to deal with such long pivot points. Platinum Billiards OB-1 shaft test says that it has a 12" pivot point for a 15mph shot (hard?). I am assuming that for most medium and soft shots that I tend to shoot a lot of, the pivot point is something like 30-50 ". I think that for very soft shots where the pivot point is 50" or so, then FHE should work very well. For very hard shots BHE english with a 12" bridge should be good. What about medium shots??? these seem to be very hard for me!

I am beginning to think that it might be easier and more forgiving to have a cue whose pivot point ranges from like 8"-20" or something like that so that I could use BHE all the time and just vary my bridge length.

So what do you all think?

Jal
02-16-2007, 11:50 PM
<blockquote><font class="small">Quote jondrums:</font><hr> This is my first thread here. I post a little here and at AZbilliards but I wanted to put this question up here first because I believe I have a good chance to get a well informed and thorough answer on this forum.<hr /></blockquote>You'll get an answer here, whether well informed or thorough remains to be seen. In that vein, and since nobody else has responded, let me start it off by questioning some of your assumptions.

<blockquote><font class="small">Quote jondrums:</font><hr>...For a given shot strength (soft, medium, firm, hard), each shaft has a given pivot point right?<hr /></blockquote>Apparently not. Tests done by Platinum indicate that there is very, very little change in squirt (deflection) with shot speed. Their measured dependency is not that far off (in the ballpark anyway), from what simple physics predicts.

<blockquote><font class="small">Quote jondrums:</font><hr> It would seem that a shaft which has deflection properties such that the pivot point allows you to conviniently use BHE for most shots that require english would be very forgiving. If you aim up the shot with center ball (using the correct bridge length), and apply english with the back hand, a little variation in how much english is applied should have very little effect on the path of the CB.<hr /></blockquote>Agreed.

<blockquote><font class="small">Quote jondrums:</font><hr>...I am assuming that for most medium and soft shots that I tend to shoot a lot of, the pivot point is something like 30-50 ".<hr /></blockquote>The pivot point should still be around 12" if in fact that is the pivot point at the faster speeds. People have measured this for the Predator line, using different methods, and have obtained wildly varying results. After about ten quadzillion posts on squirt over the years, there's still some question as to what the actual pivot point distance is for any cue. (For what it's worth, I believe the Platinum results which seem less prone to error.)

<blockquote><font class="small">Quote jondrums:</font><hr>I think that for very soft shots where the pivot point is 50" or so, then FHE should work very well. these seem to be very hard for me!<hr /></blockquote>You're probably mixing the effects of squirt and swerve together. On soft shots, swerve, which is the curving of the cueball after it's struck with english, tends to cancel squirt, giving the appearence of less squirt.

<blockquote><font class="small">Quote jondrums:</font><hr>For very hard shots BHE english with a 12" bridge should be good. What about medium shots???<hr /></blockquote>Again, what you're really adjusting for is swerve if you're pivoting at the cue's physical pivot point. There is no easy answer. You'll just have to learn to compensate from experience. There is a formula but it's unlikely you'll be using it at the table.

<blockquote><font class="small">Quote jondrums:</font><hr>I am beginning to think that it might be easier and more forgiving to have a cue whose pivot point ranges from like 8"-20" or something like that so that I could use BHE all the time and just vary my bridge length.<hr /></blockquote>Bridging at the cue's pivot point does pretty much eliminate the squirt variable. But there's still swerve (have I mentioned throw?) to deal with. Sorry, but there's no magic formula that removes judgement from all of this. But if you know what you're up against (squirt, swerve, and throw), at least you have a rational basis for making adjustments. And really, when the object ball isn't too far from the pocket, such as a diamond or so, and the cueball isn't too far away from it, using english successfully isn't that tough. It requires judgement, but isn't as difficult as all of the above may suggest. At greater distances, it gets harder.

Colin Colenso, a strong advocate of backhand english, has a nice video on it here (http://www.youtube.com/watch?v=ERFTM8dbat0).

Jim

Billy_Bob
02-17-2007, 07:12 AM
The following is *the* paper on squirt, deflection, pivot points, etc. See page 10 "Squirt Measurements:" for how to test a cue for its pivot point.

Everything You Always Wanted to Know About Cue Ball
Squirt, But Were Afraid to Ask..
http://www.sfbilliards.com/Shepard_squirt.pdf

dr_dave
02-17-2007, 08:06 AM
As Jal has pointed out, squirt compensation isn't as simple as many people think. The simple BHE and FHE techniques don't take into account swerve and throw effects. Shot speed, cue stick elevation, cue tip offset, and cue stick/tip selection can affect all three effects. It helps to understand all of the effects and how they vary with shot parameters, but at some point, you need to practice lots of shots to add an intuitive feel to your level of understanding. For more understanding, see:<ul type="square"> online video demonstrations (http://www.engr.colostate.edu/~dga/pool/normal_videos/index.html) NV 4.13-4.16 and NV A.17-A.21
instructional articles dealing with throw (August '06 - June '07) (http://www.engr.colostate.edu/~dga/pool/bd_articles/index.html)
Shepard and other articles and books linked to here (http://www.engr.colostate.edu/~dga/pool/physics/index.html).
links to thread discussion highlights under "English" here (http://www.engr.colostate.edu/~dga/pool/threads.html)
[/list]
Happy viewing, reading, and learning,
Dr. Dave

jondrums
02-17-2007, 09:51 PM
<blockquote><font class="small">Quote Jal:</font><hr> Apparently not. Tests done by Platinum indicate that there is very, very little change in squirt (deflection) with shot speed. Their measured dependency is not that far off (in the ballpark anyway), from what simple physics predicts. <hr /></blockquote>

VERY interesting! I will carefully read the resources mentioned here on squirt, but I was going on something I studied quite a bit about in Phil Capelle's book "play your best pool". On page 96, he has a published chart of CB deflection for various shots. His chart shows that the deflection is dependant on speed (ex: soft .4deg, med .78deg, hard 1.25deg). He explains that this is his test. He does not talk about swerve at all here, so perhaps he has built in the swerve numbers to this chart without talking about it (NOT FAIR!). Perhaps his chart has been discussed before here?

<blockquote><font class="small">Quote Jal:</font><hr>You're probably mixing the effects of squirt and swerve together. On soft shots, swerve, which is the curving of the cueball after it's struck with english, tends to cancel squirt, giving the appearence of less squirt. <hr /></blockquote>

Thanks, this is a good explaination. I do have a pretty good understanding of squirt versus swerve, but it would be very easy to confuse them on the table!

Thanks for the info so far guys. I'm off to do some more reading, and on-table testing.

Jon

Jal
02-18-2007, 12:17 AM
<blockquote><font class="small">Quote jondrums:</font><hr> <blockquote><font class="small">Quote Jal:</font><hr> Apparently not. Tests done by Platinum indicate that there is very, very little change in squirt (deflection) with shot speed. Their measured dependency is not that far off (in the ballpark anyway), from what simple physics predicts. <hr /></blockquote>

VERY interesting! I will carefully read the resources mentioned here on squirt, but I was going on something I studied quite a bit about in Phil Capelle's book "play your best pool". On page 96, he has a published chart of CB deflection for various shots. His chart shows that the deflection is dependant on speed (ex: soft .4deg, med .78deg, hard 1.25deg). He explains that this is his test. He does not talk about swerve at all here, so perhaps he has built in the swerve numbers to this chart without talking about it (NOT FAIR!). Perhaps his chart has been discussed before here?<hr /></blockquote>I can't claim any expertise myself but am going mainly by a post from Steve Titus of Platinum Billiards on the RSB (rec.sport.billiard) usenet group. It's a very brief post just about 8/10 of the way down this page (http://groups.google.com/group/rec.sport.billiard/browse_thread/thread/f1528d496a9cbaae/25f8344254370e28?q=squirt+platinum+steve+.3%25&amp;lnk =ol&amp;hl=en&amp;).

He says:

"Really accurate testing of speed vs squirt is a tricky business - it
takes a great many shots and the tip takes a beating, and squirt is
very sensitive to the shape of the tip. What I have seen so far is
that, for a pretty good variety of shafts, squirt tends to increase
with speed at the rate of .2% to .3% per mph, over the range of 9mph
to 21mph."

I've figured it should be about 1% per mph based on a somewhat rough calculation. Whatever it is, the indications are that it's small. However, if upon further consideration, you feel that Phil Capelle's test and results are valid, please let us know and we can hash it over. I'll believe just about anything about squirt at this point. /ccboard/images/graemlins/smile.gif





<blockquote><font class="small">Quote jondrums:</font><hr><blockquote><font class="small">Quote Jal:</font><hr>You're probably mixing the effects of squirt and swerve together. On soft shots, swerve, which is the curving of the cueball after it's struck with english, tends to cancel squirt, giving the appearence of less squirt. <hr /></blockquote>

Thanks, this is a good explaination. I do have a pretty good understanding of squirt versus swerve, but it would be very easy to confuse them on the table!

Thanks for the info so far guys. I'm off to do some more reading, and on-table testing.<hr /></blockquote>You're welcome and thank you. Perhaps you'll be able to shed some more light on this for the rest of us. Good luck with your research.

Jim

colincolenso
02-18-2007, 08:37 AM
I never fully accepted the Platinum tests, not that I have any deep knowdlege about the reliability or lack there of in their procedure.

I also wonder about the incentive of their tests confirming the proposed theory of squirt being independent of speed.

After all, haven't we seen several cue makers undertake similar tests that have found their own cues to be lower squirt? hmmmm /ccboard/images/graemlins/confused.gif

My own testing has pretty much convinced me that speed increases squirt, though I must admit, that I've also found that swerve seems to play much more significant role than I had initially estimated.

It may be useful to talk in terms of "Net CB Deflection" rather than trying to separate out squirt and swerve. After all, what we really need to know is what bridge length we need at various speeds in order to contact the CB at the aim point on the OB.

Then all we have to do is worry about throw /ccboard/images/graemlins/tongue.gif

I've been doing some work on this and will hopefully have some articles and videos with further ideas / insights in the next few months.

Colin

Billy_Bob
02-18-2007, 11:53 AM
The important thing to me is being able to shoot a shot using english and get the cue ball to go where I am aiming. (Then factor in throw.)

So a cue and a method of using that cue which will do this.

Then if my cue gets damaged or stolen, being able to replace that cue with the exact same thing.

The "pivot point", "back hand english", "front hand english" thing has really helped me to shoot these shots accurately.

But I don't see cue makers manufacturing cues with the pivot point in mind. Seems to me they should manufacture a cue with the pivot point in a specific useful place. Where your bridge hand is or where you place your hand on the butt of the cue.

Or for back hand english players, maybe a cue to use when the cue ball is near a rail and you need to use a shorter bridge. Say a 4 inch pivot point.

And then mark the pivot point on the shaft. Include instructions with the cue on how to shoot using the pivot point, etc.

Maybe sort of like golf. Use this club for this shot, use another for another shot.

jondrums
02-18-2007, 12:29 PM
Billy_Bob:
I think you may be onto something here with marking the shaft. However, a playing cue may just be subject to too many variations in shot types to really benefit from this kind of thing. I was thinking more along the lines of break cues! Most people try to have a very consistant break CB location as well as a consistant bridge length. I would bet that there is also not a lot of variation in stroke speed for a given player. With this in mind it would make sense to make sure and bridge exactly at the appropriate pivot point (or get a cue with the right pivot point for your break style). This would give maximum forgiveness for any slightly off-center hits.

Jon

canadan
02-18-2007, 12:43 PM
if you goto page101 of play your best pool " if the cb is stuck with a downward blow wile using side spin , will cause the ball to curve the dirction of the spin" and curve will not be a factor with a level stick. thats why most ppl try not to use draw on long shots.

cushioncrawler
02-18-2007, 02:27 PM
<blockquote><font class="small">Quote colincolenso:</font><hr> ....I also wonder about the incentive of their tests confirming the proposed theory of squirt being independent of speed. After all, haven't we seen several cue makers undertake similar tests that have found their own cues to be lower squirt? hmmmm /ccboard/images/graemlins/confused.gif

My own testing has pretty much convinced me that speed increases squirt, though I must admit, that I've also found that swerve seems to play much more significant role than I had initially estimated. It may be useful to talk in terms of "Net CB Deflection" rather than trying to separate out squirt and swerve. After all, what we really need to know is what bridge length we need at various speeds in order to contact the CB at the aim point on the OB. Colin <hr /></blockquote> Hi Colin -- I agree re your "nett squirt" comments. But, there is no doubt in my mind that squirt inkreecez with speed. Here is what i said a while back....

"....But i disagree with Dr Dave (and Bob??) re the effect of speed -- my tests (uzing a qball on a pendulum) show that pure-squirt is less the harder u hit the qball -- but Dr Dave is usually talking about impure-squirt (ie real squirt on a real table), this is less (or can be less) depending on how much u (naturally) jack-up....." madMac.

ljmoss
02-19-2007, 02:18 AM
shall i see you on tuesday night?
-i see you made it to the forum of the guru's. you will be in good company now!
we have had squirt and deflection around for quite awhile, as i said a few weeks ago.

ljmoss

dr_dave
02-19-2007, 09:18 AM
<blockquote><font class="small">Quote Jal:</font><hr> <blockquote><font class="small">Quote jondrums:</font><hr> <blockquote><font class="small">Quote Jal:</font><hr> Apparently not. Tests done by Platinum indicate that there is very, very little change in squirt (deflection) with shot speed. Their measured dependency is not that far off (in the ballpark anyway), from what simple physics predicts. <hr /></blockquote>

VERY interesting! I will carefully read the resources mentioned here on squirt, but I was going on something I studied quite a bit about in Phil Capelle's book "play your best pool". On page 96, he has a published chart of CB deflection for various shots. His chart shows that the deflection is dependant on speed (ex: soft .4deg, med .78deg, hard 1.25deg). He explains that this is his test. He does not talk about swerve at all here, so perhaps he has built in the swerve numbers to this chart without talking about it (NOT FAIR!). Perhaps his chart has been discussed before here?<hr /></blockquote>I can't claim any expertise myself but am going mainly by a post from Steve Titus of Platinum Billiards on the RSB (rec.sport.billiard) usenet group. It's a very brief post just about 8/10 of the way down this page (http://groups.google.com/group/rec.sport.billiard/browse_thread/thread/f1528d496a9cbaae/25f8344254370e28?q=squirt+platinum+steve+.3%25&amp;lnk =ol&amp;hl=en&amp;).

He says:

"Really accurate testing of speed vs squirt is a tricky business - it
takes a great many shots and the tip takes a beating, and squirt is
very sensitive to the shape of the tip. What I have seen so far is
that, for a pretty good variety of shafts, squirt tends to increase
with speed at the rate of .2% to .3% per mph, over the range of 9mph
to 21mph."

I've figured it should be about 1% per mph based on a somewhat rough calculation. Whatever it is, the indications are that it's small. However, if upon further consideration, you feel that Phil Capelle's test and results are valid, please let us know and we can hash it over. I'll believe just about anything about squirt at this point. /ccboard/images/graemlins/smile.gif





<blockquote><font class="small">Quote jondrums:</font><hr><blockquote><font class="small">Quote Jal:</font><hr>You're probably mixing the effects of squirt and swerve together. On soft shots, swerve, which is the curving of the cueball after it's struck with english, tends to cancel squirt, giving the appearence of less squirt. <hr /></blockquote>

Thanks, this is a good explaination. I do have a pretty good understanding of squirt versus swerve, but it would be very easy to confuse them on the table!

Thanks for the info so far guys. I'm off to do some more reading, and on-table testing.<hr /></blockquote>You're welcome and thank you. Perhaps you'll be able to shed some more light on this for the rest of us. Good luck with your research.<hr /></blockquote>I also did a crude experiment trying to characterize how much squirt varies with speed; but, like others, I wasn't able to eliminate swerve as a factor (although, I minimized the effect by keeping the cue stick as horizontal as possible). See NV A.17 (http://www.engr.colostate.edu/~dga/pool/normal_videos/new/NVA-17.htm) to view the experiment and results.

Regards,
Dave

dr_dave
02-19-2007, 10:18 AM
<blockquote><font class="small">Quote canadan:</font><hr> if you goto page101 of play your best pool " if the cb is stuck with a downward blow wile using side spin , will cause the ball to curve the dirction of the spin" and curve will not be a factor with a level stick. thats why most ppl try not to use draw on long shots.<hr /></blockquote>One problem here is that the cue stick is never perfectly horizontal ... it is always elevated at least a little over the rails (see TP A.3 (http://www.engr.colostate.edu/~dga/pool/technical_proofs/new/TP_A-3.pdf)). Every shot with English can exhibit squirt, swerve, and throw. The amounts you need to compensate vary with shot speed, cut angle, amount of English, and cue stick elevation. See my recent series of articles on throw and English effects (http://www.engr.colostate.edu/~dga/pool/bd_articles/index.html) and the links under "English" here (http://www.engr.colostate.edu/~dga/pool/threads.html) for more information.

Regards,
Dave

wolfdancer
02-19-2007, 10:47 AM
I was shown an interesting shot recently...where both the CB and OB are frozen to the long rail...and for the next shot, the CB needs to be on the other side of the table.
You lay the butt of the cue on the cloth, hitting the CB with an upward angle, and enough OE to get position.
It looks good when it works....great for winning a beer bet.

colincolenso
02-19-2007, 07:30 PM
<blockquote><font class="small">Quote cushioncrawler:</font><hr> Hi Colin -- I agree re your "nett squirt" comments. But, there is no doubt in my mind that squirt inkreecez with speed. Here is what i said a while back....

"....But i disagree with Dr Dave (and Bob??) re the effect of speed -- my tests (uzing a qball on a pendulum) show that pure-squirt is less the harder u hit the qball -- but Dr Dave is usually talking about impure-squirt (ie real squirt on a real table), this is less (or can be less) depending on how much u (naturally) jack-up....." madMac. <hr /></blockquote>

Hi madMac,
Didn't you mean to say that pure squirt is MORE the harder you hit the CB above?

btw: We'll have to get together for a hit somewhere soon, now that I'm back in town.

Col

colincolenso
02-19-2007, 07:42 PM
<blockquote><font class="small">Quote dr_dave:</font><hr>
He says:

"Really accurate testing of speed vs squirt is a tricky business - it
takes a great many shots and the tip takes a beating, and squirt is
very sensitive to the shape of the tip. What I have seen so far is
that, for a pretty good variety of shafts, squirt tends to increase
with speed at the rate of .2% to .3% per mph, over the range of 9mph
to 21mph."

I've figured it should be about 1% per mph based on a somewhat rough calculation. Whatever it is, the indications are that it's small. However, if upon further consideration, you feel that Phil Capelle's test and results are valid, please let us know and we can hash it over. I'll believe just about anything about squirt at this point. /ccboard/images/graemlins/smile.gif

Regards,
Dave <hr /></blockquote>

That's interesting info Dave!

The tip shape affects squirt comment is especially interesting as I have suggested in the past that a possible contributing mechanism to squirt is partial slip at the tip-CB interface, and this would explain why speed and tip shape are variables in squirt.

The accepted mechanism, what I call rotation induced deflection, would tend to conclude that speed and tip shape are quite independent.

Anyway, on the issue of rate of change of squirt with speed, I would guess this kind of range:

1-3mph: 5% per mph
3-7mph: 3% per mph
7-10mph: 2% per mph
10mph+: 1% per mph

This would result in a doubling of squirt from 1mph to 20mph, or something in that range.

Now this is total specu-guestimation based on experience of playing around with BHE, but that cannot filter out all variables. I'd love to see some conclusive experimentation.

Colin

cushioncrawler
02-20-2007, 12:24 AM
<blockquote><font class="small">Quote colincolenso:</font><hr> <blockquote><font class="small">Quote cushioncrawler:</font><hr> Hi Colin -- I agree re your "nett squirt" comments. But, there is no doubt in my mind that squirt inkreecez with speed. Here is what i said a while back....

"....But i disagree with Dr Dave (and Bob??) re the effect of speed -- my tests (uzing a qball on a pendulum) show that pure-squirt is less the harder u hit the qball -- but Dr Dave is usually talking about impure-squirt (ie real squirt on a real table), this is less (or can be less) depending on how much u (naturally) jack-up....." madMac. <hr /></blockquote> Hi madMac, Didn't you mean to say that pure squirt is MORE the harder you hit the CB above? btw: We'll have to get together for a hit somewhere soon, now that I'm back in town. Col <hr /></blockquote> Yes -- The first bit shood have said "dekreecez". This is for pure squirt -- i hit a ball hanging on a pendulum.

Real squirt on a real table for a real (jacked-up) cue would depend on swerve, and could even be negative for some players and/or some cues i reckon.

Yeah, we shood get together, bit difficult at present as i have started building a house at Garibaldi, about 60 minutes from Geelong, will be finished in time for the billiards season. And i wont be playing in the snooker competition this season, but i will next year, alltho it might be in the Ballarat league instead of Geelong. I will give u a call, u shood come out and have a beer and see my plans for my billiard room (for my Duke). I heard that Neil Robertson won the snooker -- i will havta have a look on the snooker websites. madMac.

dr_dave
02-20-2007, 08:00 AM
<blockquote><font class="small">Quote colincolenso:</font><hr> <blockquote><font class="small">Quote dr_dave:</font><hr>
He says:

"Really accurate testing of speed vs squirt is a tricky business - it
takes a great many shots and the tip takes a beating, and squirt is
very sensitive to the shape of the tip. What I have seen so far is
that, for a pretty good variety of shafts, squirt tends to increase
with speed at the rate of .2% to .3% per mph, over the range of 9mph
to 21mph."

I've figured it should be about 1% per mph based on a somewhat rough calculation. Whatever it is, the indications are that it's small. However, if upon further consideration, you feel that Phil Capelle's test and results are valid, please let us know and we can hash it over. I'll believe just about anything about squirt at this point. /ccboard/images/graemlins/smile.gif

Regards,
Dave <hr /></blockquote>

That's interesting info Dave!<hr /></blockquote>Just to be clear, that was not a quote from me. It was from one of my posts, but the text is a quote from Jal, who was quoting somebody from Platinum Billiards. Although, I agree that it is interesting information.

<blockquote><font class="small">Quote colincolenso:</font><hr>The tip shape affects squirt comment is especially interesting as I have suggested in the past that a possible contributing mechanism to squirt is partial slip at the tip-CB interface, and this would explain why speed and tip shape are variables in squirt.<hr /></blockquote>I have also suggested this in the past. I guess great minds think alike. /ccboard/images/graemlins/wink.gif

<blockquote><font class="small">Quote colincolenso:</font><hr>Anyway, on the issue of rate of change of squirt with speed, I would guess this kind of range:

1-3mph: 5% per mph
3-7mph: 3% per mph
7-10mph: 2% per mph
10mph+: 1% per mph

This would result in a doubling of squirt from 1mph to 20mph, or something in that range.

Now this is total specu-guestimation based on experience of playing around with BHE, but that cannot filter out all variables.<hr /></blockquote>Obviously, swerve is the most important variable. At higher speeds, swerve is much less of a factor and the "effective squirt" is much more.

<blockquote><font class="small">Quote colincolenso:</font><hr>I'd love to see some conclusive experimentation.<hr /></blockquote>Funny you should mention that. I have a set of experiments planned with high-speed video and some equipment I have some students working on. I also plan to write a series of articles on squirt and swerve after I finish my series on throw.

Regards,
Dave

cushioncrawler
02-20-2007, 03:19 PM
<blockquote><font class="small">Quote dr_dave:</font><hr> <blockquote><font class="small">Quote colincolenso:</font><hr>I'd love to see some conclusive experimentation.<hr /></blockquote>Funny you should mention that. I have a set of experiments planned with high-speed video and some equipment I have some students working on. I also plan to write a series of articles on squirt and swerve after I finish my series on throw... <hr /></blockquote> Dr Dave -- Dont forget to test for "pure throw" allso. And, perhaps repeat Bob's experiments with a wt at varyus points of the shaft -- i think that there might be a nodal point at work here. madMac.

dr_dave
02-20-2007, 03:25 PM
<blockquote><font class="small">Quote cushioncrawler:</font><hr> <blockquote><font class="small">Quote dr_dave:</font><hr> <blockquote><font class="small">Quote colincolenso:</font><hr>I'd love to see some conclusive experimentation.<hr /></blockquote>Funny you should mention that. I have a set of experiments planned with high-speed video and some equipment I have some students working on. I also plan to write a series of articles on squirt and swerve after I finish my series on throw... <hr /></blockquote> Dr Dave -- Dont forget to test for "pure throw" allso. And, perhaps repeat Bob's experiments with a wt at varyus points of the shaft -- i think that there might be a nodal point at work here. madMac. <hr /></blockquote>Did you mean "pure squirt" instead of "pure throw" (i.e., prevent swerve corruption of results)? If so, I have that covered. If not, please let me know what you mean by "pure throw."

Thanks,
Dave

wolfdancer
02-20-2007, 03:43 PM
I have carefully avoided this thread because as Ajax once said "It's all Greek to me" and we all know that Ajax went crazy in the end.
No one else here though, has the resources to set up these experiments, nor that expensive "Brownie" camera to film it, and then share it....so I'd think that folks would appreciate your efforts....and not try to use your pool skills( or lack thereof, lol) to denigrate your quest for, and sharing of, pool info
Myself, I don't want to see squirt, swerve, throw...explained.
They are great excuses for when I miss.....
Good luck with the experiment!!

BRussell
02-20-2007, 05:16 PM
I need some more basic context here: Are certain cues marketed as or known as having low deflection? What makes them low in deflection? And can someone give some examples of specific cues with low deflection, and maybe some with high deflection? TIA.

dr_dave
02-20-2007, 05:51 PM
<blockquote><font class="small">Quote BRussell:</font><hr> I need some more basic context here: Are certain cues marketed as or known as having low deflection? What makes them low in deflection? And can someone give some examples of specific cues with low deflection, and maybe some with high deflection? TIA. <hr /></blockquote>
FYI, "low squirt" = "low cue ball deflection" (not to be confused with cue stick deflection, which can be quite large for low squirt cues).

Some cues exhibit less squirt than others. You can see a comparison here (https://www.platinumbilliards.com/rating_deflect.php).

Predator seems to offer the best selection of low squirt cues. OB-1 is another popular selection.

For more background information, see the links under "cue stick," "English," and "squirt" here (http://www.engr.colostate.edu/~dga/pool/threads.html).

Regards,
Dave

cushioncrawler
02-20-2007, 07:18 PM
<blockquote><font class="small">Quote dr_dave:</font><hr> ....Did you mean "pure squirt" instead of "pure throw" (i.e., prevent swerve corruption of results)? If so, I have that covered. If not, please let me know what you mean by "pure throw." Thanks,Dave <hr /></blockquote> Yes, "pure squirt". I put the qball on the end of some string hanging from the roof of the garage, and stroked directly towards the edge of a doorway, hitting the qball off-center, the qball swinging throo the doorway, just missing the edge. I did this hitting softly, and hitting hard, trying to do the same things each time, and measuring (guessing) the gap between qball and door. Karnt remember exactly, but soft gave say 150mm and hard gave say 100mm, the ratio might even have been 2:1, i wrote it down in a diary, but it was all very rough anyhow. I probably used a 2-finger (ie light) grip of the cue, to keep the wt of the hand out of it. Its difficult to judge qtip offset on the qball accurately (or consistently), but i am expert at that sort of thing. madMac.

Stretch
02-20-2007, 08:10 PM
<blockquote><font class="small">Quote cushioncrawler:</font><hr> <blockquote><font class="small">Quote dr_dave:</font><hr> ....Did you mean "pure squirt" instead of "pure throw" (i.e., prevent swerve corruption of results)? If so, I have that covered. If not, please let me know what you mean by "pure throw." Thanks,Dave <hr /></blockquote> Yes, "pure squirt". I put the qball on the end of some string hanging from the roof of the garage, and stroked directly towards the edge of a doorway, hitting the qball off-center, the qball swinging throo the doorway, just missing the edge. I did this hitting softly, and hitting hard, trying to do the same things each time, and measuring (guessing) the gap between qball and door. Karnt remember exactly, but soft gave say 150mm and hard gave say 100mm, the ratio might even have been 2:1, i wrote it down in a diary, but it was all very rough anyhow. I probably used a 2-finger (ie light) grip of the cue, to keep the wt of the hand out of it. Its difficult to judge qtip offset on the qball accurately (or consistently), but i am expert at that sort of thing. madMac. <hr /></blockquote>

Does the weight of your hand make a difference? St.

dr_dave
02-20-2007, 10:07 PM
<blockquote><font class="small">Quote cushioncrawler:</font><hr> <blockquote><font class="small">Quote dr_dave:</font><hr> ....Did you mean "pure squirt" instead of "pure throw" (i.e., prevent swerve corruption of results)? If so, I have that covered. If not, please let me know what you mean by "pure throw." Thanks,Dave <hr /></blockquote> Yes, "pure squirt". I put the qball on the end of some string hanging from the roof of the garage, and stroked directly towards the edge of a doorway, hitting the qball off-center, the qball swinging throo the doorway, just missing the edge. I did this hitting softly, and hitting hard, trying to do the same things each time, and measuring (guessing) the gap between qball and door. Karnt remember exactly, but soft gave say 150mm and hard gave say 100mm, the ratio might even have been 2:1, i wrote it down in a diary, but it was all very rough anyhow. I probably used a 2-finger (ie light) grip of the cue, to keep the wt of the hand out of it. Its difficult to judge qtip offset on the qball accurately (or consistently), but i am expert at that sort of thing. madMac. <hr /></blockquote>I look forward to getting my own results for comparison. I find it very difficult to believe that squirt would decrease at higher speeds, if everything else (e.g., tip offset) is kept constant. Are you sure that is what you measured ... less squirt at higher speeds???

Regards,
Dave

cushioncrawler
02-21-2007, 02:45 AM
<blockquote><font class="small">Quote dr_dave:</font><hr> ....I look forward to getting my own results for comparison. I find it very difficult to believe that squirt would decrease at higher speeds, if everything else (e.g., tip offset) is kept constant. Are you sure that is what you measured ... less squirt at higher speeds??? Regards,Dave <hr /></blockquote> Dr Dave -- Yes, less, for pure-squirt. I wont bother looking for my diary notes for the tests (packed away), but i remember i had my diary in front of me a few months ago when i wrote....
<blockquote><font class="small">Quote jingle:</font><hr> ...Is this generally accepted as true? (soft tips produce more squirt than harder tips) It seems to me to be the case, just curious if it has actually been tested before?<hr /></blockquote> <blockquote><font class="small">Quote cushioncrawler:</font><hr> In english-billiards (12' table) the acid-test of squirt is the long-jenny -- i used to uze very hard (brown) leather tips, made extra hard by hammering or viceing -- when i tried to wean myself onto ordinary elk tips (softish) , i found that i had to stroke towards the door of the lady's toilets to get the same contact on the object ball -- it is as Dr Dave suspects, the extra tip-ball contact time brings more of the wt of the cue into the equation, hence extra squirt.

But i disagree with Dr Dave (and Bob??) re the effect of speed -- my tests (uzing a qball on a pendulum) show that pure-squirt is less the harder u hit the qball -- but Dr Dave is usually talking about impure-squirt (ie real squirt on a real table), this is less (or can be less) depending on how much u (naturally) jack-up. madMac.<hr /></blockquote>

cushioncrawler
02-21-2007, 03:03 AM
<blockquote><font class="small">Quote Stretch:</font><hr> ....Does the weight of your hand make a difference? St. <hr /></blockquote> Yes, the wt of the cue makes a difference, ie a heavy cue squirts more. But, re the stuff about less pure-squirt at hi-speed, no, this would apply to all cues, but this would be of allmost zero interest to the play of pool etc, but iz the sort of thing i am eager to point out to fizzyks-players.

But, re cue wt, here i know that Dr Dave and Shepard and Bob all disagree with me. They say that the wt of the tip plus say 200mm (only) affect squirt, but i say the whole wt of the cue duz, and here i know that Bob haz dunn tests with a wt fixed near the tip, but i think that Bob found a nodal point and shood have mooved the wt further.

And, i say (koz i know) that how u grip the cue affects squirt, ie a light 2-finger grip or a solid full-palm grip (like kids uze when they are turning japanese), but here i am on my own again.

And, i know that a hard tip dekreecez squirt, but again i am on my own here. madMac.

jondrums
02-21-2007, 07:45 AM
regarding testing for pure squirt:

MadMac has done some testing with a hanging cue ball, this seems like a very good method to get rid of cloth effects - provided the string is suitably long. It seems like it would be VERY hard to get the cue ball to sit still enough while trying to stroke at it. I would suggest the addition of a backstop with an aiming target and carbon paper (ala platinum billiards tests) for measuring the impact location.

Has anyone tried a surface other than cloth - like perhaps placing teflon sheet on top of a pool table. I might be able to get ahold of a piece of teflon sheet long enough to be of use. Of course it will be of utmost importance to get the sheet perfectly flat and level.

Just brainstorming here, but does anyone out there have access to an optical benchtop? - that's stainless steel, but could be made very flat and level. A little crisco and a test would be good-to-go. How about a good size granite measuring table?

Of course now we would need our own stroke robot...

Jon

dr_dave
02-21-2007, 08:06 AM
<blockquote><font class="small">Quote jondrums:</font><hr>Of course now we would need our own stroke robot...<hr /></blockquote>I have three different student groups working on the design and construction of three radically different cue testers, as part of a course project. I have some limited funding from a cue manufacturer. The testers are being designed to have the ability to stroke the cue stick horizontally without cue stick elevation (to eliminate swerve as a factor). They will also have precise control over cue speed and tip offset (left/right and up/down from center-ball). We will also have automatic, precision sensing of both ball speeds and squirt angle. We are attempting to overcome some of the limitations identified with existing cue testers (e.g., Predator's Iron Willy and Meucci's Myth Destroyer). I'll be sure to share video demos and experimental results when they become available. Our goal is to do some tests in the May/June timeframe.

Regards,
Dave

Billy_Bob
02-21-2007, 08:58 AM
FYI - Suggestions for future testing...

As you have probably read, Predator says...

"Predator research has clearly shown that a dime radius (or shape of a dime) will produce 5 percent to 10 percent less cue ball deflection than the more commonly used nickel shape. The cue ball deflection is reduced because the dime radius centralizes the hit to the center, or strong part, of the shaft."

Above from...
http://www.predatorcues.com/predator_cues_tech_tips.html

So I would be interested in research done on tips. Tip hardness, tip shape. For example: Does a certain tip and tip shape get more draw than another?

And if you really want to get into "tip-ology", there is also "oval" or egg shaped!

Also there is disagreement as to the pivot point on a Predator cue with a 314 shaft. I'm not a robot, but it seems to me the pivot point is much further back.

dr_dave
02-21-2007, 09:06 AM
Good suggestions. That's already on my list.

Anybody else have any other suggestions, recommendations, requests, or cautions?

Thanks,
Dave

<blockquote><font class="small">Quote Billy_Bob:</font><hr> FYI - Suggestions for future testing...

As you have probably read, Predator says...

"Predator research has clearly shown that a dime radius (or shape of a dime) will produce 5 percent to 10 percent less cue ball deflection than the more commonly used nickel shape. The cue ball deflection is reduced because the dime radius centralizes the hit to the center, or strong part, of the shaft."

Above from...
http://www.predatorcues.com/predator_cues_tech_tips.html

So I would be interested in research done on tips. Tip hardness, tip shape. For example: Does a certain tip and tip shape get more draw than another?

And if you really want to get into "tip-ology", there is also "oval" or egg shaped!

Also there is disagreement as to the pivot point on a Predator cue with a 314 shaft. I'm not a robot, but it seems to me the pivot point is much further back.<hr /></blockquote>

cushioncrawler
02-21-2007, 02:16 PM
<blockquote><font class="small">Quote jondrums:</font><hr> regarding testing for pure squirt: MadMac has done some testing with a hanging cue ball, this seems like a very good method to get rid of cloth effects - provided the string is suitably long. It seems like it would be VERY hard to get the cue ball to sit still enough while trying to stroke at it. I would suggest the addition of a backstop with an aiming target and carbon paper (ala platinum billiards tests) for measuring the impact location.

Has anyone tried a surface other than cloth - like perhaps placing teflon sheet on top of a pool table. I might be able to get ahold of a piece of teflon sheet long enough to be of use. Of course it will be of utmost importance to get the sheet perfectly flat and level.

Just brainstorming here, but does anyone out there have access to an optical benchtop? - that's stainless steel, but could be made very flat and level. A little crisco and a test would be good-to-go. How about a good size granite measuring table? Of course now we would need our own stroke robot... Jon <hr /></blockquote> Hi Jon -- My lab must look like thoze old photos of old Nobel winners sitting in an old lab with gadgets made of fencing wire and pipe. My most valued bit of equipment is toilet paper over bluetack over a bit of lumber -- saves having an assistant.

A robot would havtahav a "soft" bridge, and a "light" grip.

I think that there are 2 allmost seperate factors affecting the effect of cue wt. Firstly, the natural way(s) a cue bends, ie due to a simple compression-impulse, and due to a sideways-impulse. Where is the effective shaft nodal-point??, ie where u could add wt without much affecting squirt.

Secondly, due to the pozzy of the main wt in the butt. Where is the effective (butt) nodal point, ie where u could add wt without much affecting squirt. I seem to remember hanging a cue horizontally on 2 strings, and tapping the tip sideways, and trying to guess which bit of the cue didnt moov sideways (at first) -- this was at about the 1/3 point i think. Ucan allmost do the same thing by simply laying the cue along a line, and poking the tip sideways, seeing which bit of the cue stays on the line, but this method would be fraught.

If it were possible, u could make a cue with zero wt, except that u add wt at the butt nodal point. U couldnt do better than this if u wanted to minimize something or other, depending too on how much "out of balance" u could personally tolerate. But, i dont think like this, i would maximize the rotational inertia of my cue -- i would add wt at the end of the butt and allso down towards the say halfpoint -- koz this sort of wt distribution helps with feel and consistency and accuracy i think, and is not appreciated enuff by anyone, even if it duz make squirt greater, and even if it makes draw lesserer, but control is paramount i reckon, but everyone iz different. madMac.

Billy_Bob
02-22-2007, 09:15 AM
I have several more suggestions for testing (I do a lot of "wondering" how things work sometimes)...

For different tip shapes, you can use electrical PVC pipe cut in half, then sandpaper held to the inside curve of the PVC. (Sandpaper tip shapers)

Now the neat thing about this (so far as research goes) is the PVC comes in all sorts of different sizes. In addition to the dime and nickel shapes (or thereabouts), you can also get quarter shape and larger. Even "billiard ball" shape with larger size PVC.

And that is an interesting question. Would a tip shaped to the same radius as a billiard ball work the best? You would think so. But I think a dime shape works best myself.

I wonder why?

Maybe because the tip is "squishing" in at impact? Maybe the dime shape turns into a billiard ball shape at impact?

Then the next thing I wonder about....

(I don't know if there is any way to test this...) A tip "gripping" the cue ball when it is hitting the cue ball off-center. Do different shapes of tips, hardness of tips have more "surface area" of the tip contacting the cue ball at time of impact?

What would get the most friction between the cue tip and cue ball at time of impact? Least amount of friction?

Everybody knows a "flat tip" will not work very well. There is not much area of the tip coming in contact with the cue ball when hitting it off-center. A curved tip works better. But what is the best radius which will have the most "surface area contact" between tip and cue ball at time of impact?

Using a robot for stroke and different tip shapes and measuring cue ball spin after hit or whatever...

Maybe a radius between quarter shaped and dime shaped works equally well?

Maybe a billiard ball tip shape works best?

Maybe there is a range of shapes which get about the same results?

Maybe a soft, medium, and hard tip works just as well? Maybe not.

Perhaps certain tips work better at slower speeds and other tips work better at faster speeds?

So what is this thing about the tip "gripping" the cue ball? What actually is happening to cause more or less "gripping" or action on the cue ball?

And then the materials cue tips are made of. Many feel pig skin works better than leather. Is this true or "just in our heads"?

And then cue balls. Seems to me new shiny cue balls get more action than on old (20 year old) dull finish pitted cue balls. Then there is the trick on applying silicone to a cue ball. (This cue ball can do amazing things!) But you would think a tip would grip the dull looking cue ball better than a shiny slick cue ball? (More friction?) And of course there is the friction of the ball on the cloth to consider along with all this.

I read you are designing your robot to shoot level and to be able to hit off-center...

With draw shots, many say you should shoot level. What happens when you jack up the stick a bit and shoot downwards? What happens when you jack up the stick a bit more? What happens if you were to shoot slightly upwards?

dr_dave
02-22-2007, 09:28 AM
<blockquote><font class="small">Quote Billy_Bob:</font><hr> I have several more suggestions for testing (I do a lot of "wondering" how things work sometimes)...

For different tip shapes, you can use electrical PVC pipe cut in half, then sandpaper held to the inside curve of the PVC. (Sandpaper tip shapers)

Now the neat thing about this (so far as research goes) is the PVC comes in all sorts of different sizes. In addition to the dime and nickel shapes (or thereabouts), you can also get quarter shape and larger. Even "billiard ball" shape with larger size PVC.

And that is an interesting question. Would a tip shaped to the same radius as a billiard ball work the best? You would think so. But I think a dime shape works best myself.

I wonder why?

Maybe because the tip is "squishing" in at impact? Maybe the dime shape turns into a billiard ball shape at impact?

Then the next thing I wonder about....

(I don't know if there is any way to test this...) A tip "gripping" the cue ball when it is hitting the cue ball off-center. Do different shapes of tips, hardness of tips have more "surface area" of the tip contacting the cue ball at time of impact?

What would get the most friction between the cue tip and cue ball at time of impact? Least amount of friction?

Everybody knows a "flat tip" will not work very well. There is not much area of the tip coming in contact with the cue ball when hitting it off-center. A curved tip works better. But what is the best radius which will have the most "surface area contact" between tip and cue ball at time of impact?

Using a robot for stroke and different tip shapes and measuring cue ball spin after hit or whatever...

Maybe a radius between quarter shaped and dime shaped works equally well?

Maybe a billiard ball tip shape works best?

Maybe there is a range of shapes which get about the same results?

Maybe a soft, medium, and hard tip works just as well? Maybe not.

Perhaps certain tips work better at slower speeds and other tips work better at faster speeds?

So what is this thing about the tip "gripping" the cue ball? What actually is happening to cause more or less "gripping" or action on the cue ball?

And then the materials cue tips are made of. Many feel pig skin works better than leather. Is this true or "just in our heads"?

And then cue balls. Seems to me new shiny cue balls get more action than on old (20 year old) dull finish pitted cue balls. Then there is the trick on applying silicone to a cue ball. (This cue ball can do amazing things!) But you would think a tip would grip the dull looking cue ball better than a shiny slick cue ball? (More friction?) And of course there is the friction of the ball on the cloth to consider along with all this.<hr /></blockquote>Thank you for the suggestions. I will look at as much as I can find time to look at. I agree that there is much to be learned about tip shape, deformation, friction properties, and alternative materials.

<blockquote><font class="small">Quote Billy_Bob:</font><hr>I read you are designing your robot to shoot level and to be able to hit off-center...

With draw shots, many say you should shoot level. What happens when you jack up the stick a bit and shoot downwards? What happens when you jack up the stick a bit more? What happens if you were to shoot slightly upwards?<hr /></blockquote>The main purpose for the testing machines will be to characterize squirt. We don't plan to build in cue elevation adjustment (although maybe we can set up for this later). Sorry.

Catch you later,
Dave

BRussell
02-22-2007, 10:34 AM
<blockquote><font class="small">Quote dr_dave:</font><hr>I have three different student groups working on the design and construction of three radically different cue testers, as part of a course project. <hr /></blockquote> I have to say, I'm concerned about your career. Do the rank and tenure committees consider your pool work part of your scholarship? /ccboard/images/graemlins/grin.gif

dr_dave
02-22-2007, 10:49 AM
<blockquote><font class="small">Quote BRussell:</font><hr> <blockquote><font class="small">Quote dr_dave:</font><hr> <blockquote><font class="small">Quote jondrums:</font><hr>Of course now we would need our own stroke robot...<hr /></blockquote>I have three different student groups working on the design and construction of three radically different cue testers, as part of a course project. <hr /></blockquote> I have to say, I'm concerned about your career. Do the rank and tenure committees consider your pool work part of your scholarship? /ccboard/images/graemlins/grin.gif <hr /></blockquote>Actually, that is a serious question. At first my superiors didn't like how much time I spent on this stuff, but now they are starting to come around a little. It helps that I am starting to receive some professional recognition for some of my pool work:

- Several companies have approached me and have funded some work for my students and me.

- The American Society of Mechanical Engineers (ASME) has me listed in their "Distinguished Lecturers" program for my seminar: "The Illustrated Principles of Pool and Billiards." This a technical, but fun, multimedia talk geared towards engineers.

- I recently got elected as a Fellow of ASME, and my pool contributions played a part in that process.

- In the near future, I will have an article about the physics of billiards appear in Scientific American magazine.

My department is now starting to see a little value in the work. But I still do it because I am passionate about it, and because I feel like I still have a lot more to contribute ... not because my bosses like it.

Regards,
Dave

Billy_Bob
02-22-2007, 11:18 AM
Actually it is amazing how research in the area of "games" can be quite helpful to private industry and of course defense related things.

"Bell Labs" paid researchers there to research game playing...
http://cm.bell-labs.com/cm/cs/who/dmr/ken-games.html

IBM also sees the value of such research...
http://www.research.ibm.com/deepblue/learn/html/e.html

DARPA...
http://www.hollywoodreporter.com/hr/search/article_display.jsp?vnu_content_id=1000674193

Here is some "pool related" research being done at other universities...

http://cpk.auc.dk/education/IMM/pooltrainer/

http://www.theglobeandmail.com/servlet/ArticleNews/TPStory/LAC/20040724/ROBOT24/TPScience/

http://post.queensu.ca/~greensm/

BRussell
02-22-2007, 11:27 AM
<blockquote><font class="small">Quote dr_dave:</font><hr>Actually, that is a serious question. <hr /></blockquote> Yeah, I'm quite familiar with the issues involved in academic promotion and tenure, and looking at your website, I suspected it might be an issue. /ccboard/images/graemlins/grin.gif

But I think it's absolutely appropriate that you get credit for it. The standard for valuable scholarly contributions shouldn't be how few people read your papers, but in some fields that seems to be the case.

dr_dave
02-22-2007, 11:30 AM
<blockquote><font class="small">Quote BRussell:</font><hr> <blockquote><font class="small">Quote dr_dave:</font><hr>Actually, that is a serious question. <hr /></blockquote> Yeah, I'm quite familiar with the issues involved in academic promotion and tenure, and looking at your website, I suspected it might be an issue. /ccboard/images/graemlins/grin.gif <hr /></blockquote>To which website are you referring ... I have many, not all pool related.

BTW, I got tenure about 10 years ago; so theoretically, I can do whatever the hell I please, almost. /ccboard/images/graemlins/wink.gif

Thank you for the concern,
Dave

canadan
02-22-2007, 06:07 PM
when I got my predator it came with a nickle shaped tip not a dime.

dr_dave
02-22-2007, 07:20 PM
<blockquote><font class="small">Quote canadan:</font><hr> when I got my predator it came with a nickle shaped tip not a dime.<hr /></blockquote>Mine did too, but I shaped it down to dime radius.

Dave

canadan
02-23-2007, 12:39 PM
which one do you like more ? i was thinking of getting a dime shaper?

canadan
02-23-2007, 12:43 PM
but I was playing with my buddies Z2 that had a dime shape and i had no cb control at all try for a little draw and the cue ball would come back to the other side of the table. or give a little english of a rail and it would catch and run like a mother. thats why im worried abot a smaller tip.

GeorgeV
02-23-2007, 01:16 PM
Forgive me for the tangent, but I thought this might be a good place to get your attention about this.

I just bought a Predator 314-2 shaft for my Viking. I've never had a problem with "scooping" the cue ball before with a regular shaft when applying extreme low, but I was "scooping" a lot right after I started using the Predator. Seems to me that the same shaft characteristics (hollow end) that cause it to deflect off a cue ball when using side would cause it to deflect downward and cause "scooping" when using low. As a result, I'm not able to hit as low as I used to (not necessarily a bad thing). Still trying to adjust.

Do you think my understanding is correct (i.e. that the Predator shaft is deflecting downward and causing more scooping than a "normal" shaft)?

Thanks,
George in VA

dr_dave
02-23-2007, 01:22 PM
<blockquote><font class="small">Quote canadan:</font><hr> which one do you like more ? i was thinking of getting a dime shaper?<hr /></blockquote>I like the dime shape better (see my July '06 instructional article (http://www.engr.colostate.edu/~dga/pool/bd_articles/2006/july06.pdf) for some of my reasons).

Regards,
Dave

dr_dave
02-23-2007, 01:32 PM
<blockquote><font class="small">Quote GeorgeV:</font><hr> Forgive me for the tangent, but I thought this might be a good place to get your attention about this.

I just bought a Predator 314-2 shaft for my Viking. I've never had a problem with "scooping" the cue ball before with a regular shaft when applying extreme low, but I was "scooping" a lot right after I started using the Predator. Seems to me that the same shaft characteristics (hollow end) that cause it to deflect off a cue ball when using side would cause it to deflect downward and cause "scooping" when using low. As a result, I'm not able to hit as low as I used to (not necessarily a bad thing). Still trying to adjust.

Do you think my understanding is correct (i.e. that the Predator shaft is deflecting downward and causing more scooping than a "normal" shaft)?<hr /></blockquote>I don't think a low squirt cue should, by itself, cause more scoop shots. Scoop shots are usually the result of a miscue (e.g., see the 2nd shot in HSV A.1 (http://www.engr.colostate.edu/~dga/pool/high_speed_videos/new/HSVA-1.htm)). A low squirt cue does experience a lot of cue stick deflection after impact, but the ball is long gone by then (e.g., see HSV A.38 (http://www.engr.colostate.edu/~dga/pool/high_speed_videos/new/HSVA-38.htm) and HSV A.109 (http://www.engr.colostate.edu/~dga/pool/high_speed_videos/new/HSVA-109.htm)).

Don't lose faith in your cue ... just hit the ball right (and make sure the tip is well textured and chalked).

Regards,
Dave

dr_dave
02-23-2007, 01:36 PM
<blockquote><font class="small">Quote canadan:</font><hr> but I was playing with my buddies Z2 that had a dime shape and i had no cb control at all try for a little draw and the cue ball would come back to the other side of the table. or give a little english of a rail and it would catch and run like a mother. thats why im worried abot a smaller tip. <hr /></blockquote>Check out my July '06 instructional article (http://www.engr.colostate.edu/~dga/pool/bd_articles/2006/july06.pdf). I discuss and illustrate the advantages and disadvanteges of tips of different sizes and shapes.

Regards,
Dave

Fran Crimi
02-23-2007, 02:13 PM
You've got two ways to look at this, canadan. You can take Dave's advice or you can mimic the majority of the pro players and use a nickel shaped tip. They tend to agree with you in that they don't necessarily want the cue ball to run all over the place on them.

Fran

wolfdancer
02-23-2007, 02:26 PM
"- Several companies have approached me and have funded some work for my students and me.

- The American Society of Mechanical Engineers (ASME) has me listed in their "Distinguished Lecturers" program for my seminar: "The Illustrated Principles of Pool and Billiards." This a technical, but fun, multimedia talk geared towards engineers.

- I recently got elected as a Fellow of ASME, and my pool contributions played a part in that process.

- In the near future, I will have an article about the physics of billiards appear in Scientific American magazine."
xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx

I thought this would merit a little "peer recognition" around here as well, but...
So let me be the first here to congratulate you!!!!!!!
It may be time to move away from pool, and on to a study of Golf's realtionship to physics....like moving from plane geometry to solid geometry. I could start your studies off with my copy of the out of print "Quantum Golf"..and the Homer Jones book, virtually unreadable without an M.E. degree,
"G.O.L.F. (geometrically oriented linear force)

Fran Crimi
02-23-2007, 02:28 PM
<blockquote><font class="small">Quote GeorgeV:</font><hr> Forgive me for the tangent, but I thought this might be a good place to get your attention about this.

I just bought a Predator 314-2 shaft for my Viking. I've never had a problem with "scooping" the cue ball before with a regular shaft when applying extreme low, but I was "scooping" a lot right after I started using the Predator. Seems to me that the same shaft characteristics (hollow end) that cause it to deflect off a cue ball when using side would cause it to deflect downward and cause "scooping" when using low. As a result, I'm not able to hit as low as I used to (not necessarily a bad thing). Still trying to adjust.

Do you think my understanding is correct (i.e. that the Predator shaft is deflecting downward and causing more scooping than a "normal" shaft)?

Thanks,
George in VA
<hr /></blockquote>

Hi George,

Hope you don't mind my interjecting with my opinion here. Maybe I can help. It sounds to me like one of two things may be happening. First, do you know what the tip is on your new shaft? Is is extremely hard? That might cause you a problem or two, especially if it's not roughed. That's one possibility.

The second is your stroke. You might have been getting away with a stroke flaw that you can no longer get away with using the Predator shaft.

I didn't see this listed in Dave's article that he referred you to, but I think the main reason for miscueing while drawing the ball is because the player changes his angle of attack during the stroke. If you start to level off your cue or flatten it out right at impact, this will cause the miscue or scoop. Sometimes this is caused by grabbing the cue with your back hand really tightly at impact or dropping your upper arm too soon. You may have been getting away with the stroke flaw with your old shaft but the new one may not. Just focus on bringing the cue in and out on the same angle and don't change it all through the stroke. That should help. It's hard to explain without my showing you, so if you aren't clear, please feel free to ask me to clarify.

Fran

canadan
02-23-2007, 02:50 PM
i have to agree here my first 2 preators had a softer tip (fresher?) the last shaft I got had a realy hard tip (aired out?) and I was miss cueing like crazy, draw would jump off the table. first time playing with it was league night too (ouch) so i used my shaper and sanded it down alot now its like the rest of the tips. you will be able to use as much draw as you can. make sure you use a shape so you tip is nice all the way around and not lop sided.

cushioncrawler
02-23-2007, 04:03 PM
<blockquote><font class="small">Quote dr_dave:</font><hr> .... In the near future, I will have an article about the physics of billiards appear in Scientific American magazine..... <hr /></blockquote> Dr Dave -- I think that no-one haz ever looked (photographed) a ball throo a microscope. I think that balltoball impact-marks, qtip-marks, cling-marks, polishing etc need to be looked into properly (close-up). What causes (affects) balltoball friction??

Same with cloth(s). We have burning bits of ball, burning bits of cloth, residues. A very close-up look might reveal something.

We (cue-sports) need more theoryz regarding how and why things happen. Much of what we know and read, good az it is, is really just math and dynamics. Much of it can rightly be called a "Law" of whatever, but karnt rightly be called "Theory", in my opinion. For instance Newton invented or discovered some good "laws" re gravitation, but i dont think that he ever had any "theorys" trying to explain what caused gravitation.

Why do (did) ivoryz have a sharper louder "click" of impact than any other ball, even tho ivory is perhaps the softest ball ever made (grown), ignoring wooden balls. This might have something to do with the "poor" thermal and accoustic (sonic) propertyz of ivory -- the impact noise (ringing) duznt last long, hence ivory sounds az if it iz the hardest ball. I dont know where this sort of thing might lead. But, it duz lead us back to the soft n light n hi-polish kraps that have been foisted on us poor players. Perhaps a statistical analysis (alah Dr Onoda) of the size(s) of the krap flatspot(s), and their rate of "decay", and the chances of getting a qtip chalk-mark, or a balltoball impact-mark within the flatspot during any one impact, based on the size(s) of the flatspot and based on the population and vigor of the marks, and thusly why the kraps cling twice more often and allso more powerfully than the good old oldenday balls, that would be interesting allso. Hmmmmmm -- i think i felt like Fast Larry must often feel just then. madMac.

dr_dave
02-23-2007, 05:25 PM
<blockquote><font class="small">Quote wolfdancer:</font><hr> "- Several companies have approached me and have funded some work for my students and me.

- The American Society of Mechanical Engineers (ASME) has me listed in their "Distinguished Lecturers" program for my seminar: "The Illustrated Principles of Pool and Billiards." This a technical, but fun, multimedia talk geared towards engineers.

- I recently got elected as a Fellow of ASME, and my pool contributions played a part in that process.

- In the near future, I will have an article about the physics of billiards appear in Scientific American magazine."
xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx

I thought this would merit a little "peer recognition" around here as well, but...
So let me be the first here to congratulate you!!!!!!!
It may be time to move away from pool, and on to a study of Golf's realtionship to physics....like moving from plane geometry to solid geometry. I could start your studies off with my copy of the out of print "Quantum Golf"..and the Homer Jones book, virtually unreadable without an M.E. degree,
"G.O.L.F. (geometrically oriented linear force)
<hr /></blockquote>Thank you for your kind comments.

Concerning golf vs. pool physics, pool is much easier to analyze: horizontal surface, nearly perfect spheres, no aerodynamics to consider, basic collision mechanics, etc. I'll need to save golf for a future life. Pool is challenging enough for me for now ... my list of things I want to do is already ten times longer than I could ever hope to accomplish.

Dave

GeorgeV
02-23-2007, 09:44 PM
<hr /></blockquote>I don't think a low squirt cue should, by itself, cause more scoop shots. Scoop shots are usually the result of a miscue (e.g., see the 2nd shot in HSV A.1 (http://www.engr.colostate.edu/~dga/pool/high_speed_videos/new/HSVA-1.htm)). A low squirt cue does experience a lot of cue stick deflection after impact, but the ball is long gone by then (e.g., see HSV A.38 (http://www.engr.colostate.edu/~dga/pool/high_speed_videos/new/HSVA-38.htm) and HSV A.109 (http://www.engr.colostate.edu/~dga/pool/high_speed_videos/new/HSVA-109.htm)).

Don't lose faith in your cue ... just hit the ball right (and make sure the tip is well textured and chalked).

Regards,
Dave <hr /></blockquote>

I'm hangin in there with my Predator. I figure that if so many great players are using it, that it must be me! It just surprised me so much when I kept scooping the cue ball when I very, very rarely ever did before. I've only had it about a week, and I'm getting better control of it.

Thanks for your reply.

George in VA

GeorgeV
02-23-2007, 09:59 PM
<blockquote><font class="small">Quote Fran Crimi:</font><hr>

Hi George,

Hope you don't mind my interjecting with my opinion here. Maybe I can help. It sounds to me like one of two things may be happening. First, do you know what the tip is on your new shaft? Is is extremely hard? That might cause you a problem or two, especially if it's not roughed. That's one possibility.

The second is your stroke. You might have been getting away with a stroke flaw that you can no longer get away with using the Predator shaft.

I didn't see this listed in Dave's article that he referred you to, but I think the main reason for miscueing while drawing the ball is because the player changes his angle of attack during the stroke. If you start to level off your cue or flatten it out right at impact, this will cause the miscue or scoop. Sometimes this is caused by grabbing the cue with your back hand really tightly at impact or dropping your upper arm too soon. You may have been getting away with the stroke flaw with your old shaft but the new one may not. Just focus on bringing the cue in and out on the same angle and don't change it all through the stroke. That should help. It's hard to explain without my showing you, so if you aren't clear, please feel free to ask me to clarify.

Fran <hr /></blockquote>

Thanks for your advice, Fran.

I am definitely inconsistent with my stroke. Haven't played much recently. Played a lot back when I was a teenager, then didn't play for over 25 yrs. Got back into the game a couple of years ago, but I haven't been playing much lately.

I prefer a soft tip, and the one on the Predator is a layered tip. Not sure if it's hard or medium, but it's definitely not soft. I chalk often, and I keep the tip plenty rough, I think. I think maybe I was expecting some "magic" from it and was trying to do too much with it. I've calmed down now and am noticing an improvement in my stroke. I don't think I'm changing the angle of my cue at impact. I learned about keeping the cue level when hitting low way back when, and I always do. I'm not sure whether I'm otherwise experiencing any benefit from the Predator. I've also always been a mostly back-hand english player (even before I knew what BHE was!) and think I've always unconsciously compensated for whatever squirt I've experienced. I'm hangin in there with the Predator, though. I figure some of the best players in the world are using it, so it's worth giving a shot.

Reading these forums might be causing me to think too much. Gotta watch that!

Thanks again.

George in VA

Fran Crimi
02-24-2007, 07:57 AM
I know what you mean about too much information, George. If we had to think of all the stuff that's discussed here every time we take a shot, we'd be basket cases. Yeeikes!

Just one more thing...there's a difference between level and straight. It's an old wives tale to think that you can keep your cue level. We're always shooting at some sort of downward angle, mostly due to the rails of the table being in the way. Just keep that angle consistent in and out and don't level off the last minute. Go straight through with your cue. A good gauge to determine if you did that is if you scraped the cloth with your cue tip in your follow through while drawing the ball. If your tip doesn't finish into the cloth, you may have leveled off your stroke. For the most part, you don't want to do that when you draw the ball.

Fran

dr_dave
02-24-2007, 08:47 AM
George,

Fran suggested some good advice for some things to watch for. You might want to also check out my May '06 instructional article (http://www.engr.colostate.edu/~dga/pool/bd_articles/2006/may06.pdf). It has some good check lists of things to be aware of and consider.

Regards,
Dave

<blockquote><font class="small">Quote GeorgeV:</font><hr> <blockquote><font class="small">Quote Fran Crimi:</font><hr>

Hi George,

Hope you don't mind my interjecting with my opinion here. Maybe I can help. It sounds to me like one of two things may be happening. First, do you know what the tip is on your new shaft? Is is extremely hard? That might cause you a problem or two, especially if it's not roughed. That's one possibility.

The second is your stroke. You might have been getting away with a stroke flaw that you can no longer get away with using the Predator shaft.

I didn't see this listed in Dave's article that he referred you to, but I think the main reason for miscueing while drawing the ball is because the player changes his angle of attack during the stroke. If you start to level off your cue or flatten it out right at impact, this will cause the miscue or scoop. Sometimes this is caused by grabbing the cue with your back hand really tightly at impact or dropping your upper arm too soon. You may have been getting away with the stroke flaw with your old shaft but the new one may not. Just focus on bringing the cue in and out on the same angle and don't change it all through the stroke. That should help. It's hard to explain without my showing you, so if you aren't clear, please feel free to ask me to clarify.

Fran <hr /></blockquote>

Thanks for your advice, Fran.

I am definitely inconsistent with my stroke. Haven't played much recently. Played a lot back when I was a teenager, then didn't play for over 25 yrs. Got back into the game a couple of years ago, but I haven't been playing much lately.

I prefer a soft tip, and the one on the Predator is a layered tip. Not sure if it's hard or medium, but it's definitely not soft. I chalk often, and I keep the tip plenty rough, I think. I think maybe I was expecting some "magic" from it and was trying to do too much with it. I've calmed down now and am noticing an improvement in my stroke. I don't think I'm changing the angle of my cue at impact. I learned about keeping the cue level when hitting low way back when, and I always do. I'm not sure whether I'm otherwise experiencing any benefit from the Predator. I've also always been a mostly back-hand english player (even before I knew what BHE was!) and think I've always unconsciously compensated for whatever squirt I've experienced. I'm hangin in there with the Predator, though. I figure some of the best players in the world are using it, so it's worth giving a shot.

Reading these forums might be causing me to think too much. Gotta watch that!

Thanks again.

George in VA
<hr /></blockquote>

SPetty
02-25-2007, 07:53 PM
<blockquote><font class="small">Quote Fran Crimi:</font><hr> Just keep that angle consistent in and out and don't level off the last minute. Go straight through with your cue. A good gauge to determine if you did that is if you scraped the cloth with your cue tip in your follow through while drawing the ball. <hr /></blockquote>That's new to me, Fran. I'm going to have to pay attention to what's going on with my stroke on the draw shot. I've been miscuing the draw a little lately, and it's driving me nuts! I think I'm always trying to go through the ball "level", so what you describe here may be part if not all of my problem. Thanks.