Predator shaft question

[av84fun]

Cornerman...<<If you're going to do a test to compare squirt, you need to make sure that swerve is out of the test as much as possible.>>

English or "side" does NOT in and of itself, cause swerve (see Science of Pocket Billiards, Koehler, p.76)

So in testing for squirt a level cue must be used and if so, there will be no swerve...only squirt.

Also, I don't think that shooting 2 foot shots is an optimal test. The reason being that with a rather firm shot, it would be nearly impossible to SEE whether the ball went in DEAD CENTER...or was off...say 1/8 inch to one side or the other.

So, double the distance to 4 feet and you can get a miss of 1/4 inch which will cause you to miss by as much as a full diamond on a long shot.

Finally, squirt affects shots of ALL lengths so it should be tested at ALL lengths.

Regards,
Jim

 

[Cornerman]

Cornerman...<<If you're going to do a test to compare squirt, you need to make sure that swerve is out of the test as much as possible.>>

English or "side" does NOT in and of itself, cause swerve (see Science of Pocket Billiards, Koehler, p.76)

Of course. What makes you believe I think otherwise???

So in testing for squirt a level cue must be used and if so, there will be no swerve...only squirt.

It's almost impossible... no, it's impossible to shoot that length of shot shown with a level cue. Hence, if you're going to test for squirt and squirt only, you must shoot a shot that minimizes the possibility of swerve. There are only a handful of angles that allow a person to shoot a truly level shot with any practicality. The shot shown wasn't one of them.

Also, I don't think that shooting 2 foot shots is an optimal test.

There's a big surprise.

The reason being that with a rather firm shot, it would be nearly impossible to SEE whether the ball went in DEAD CENTER...or was off...say 1/8 inch to one side or the other

So, double the distance to 4 feet and you can get a miss of 1/4 inch which will cause you to miss by as much as a full diamond on a long shot.

Finally, squirt affects shots of ALL lengths so it should be tested at ALL lengths.

Regards,
Jim

I think you misunderstand the meaning of the test. The test is to compare the squirt of one shaft vs. the squirt of the other shaft. All of these other wonderful things you are talking about are all useful, but not relevant in terms of comparing one to another in squirt terms only. Not effective squirt, blended squirt, or long-range squirt. All of those have a swerve component (something you haven't embraced, but maybe you will)

What is useful is that the input (pivot point) compared to the output (cueball left dead spinning in place) with a shot that has the least amount of swerve as reasonably possible (short distance, firm controllable shot). If on this one setup you see a difference in pivot points, then the original question is answered. End of story.

Truth be told, I have no intention in trying to describe in words why this a hugely affective test for squirt compensation, and why it's been put into the FAQ, and why it is by far the best practical test written on paper for squirt comparison. If you need more information on it, it's best to show on a table. Aside from that, once again, you and I are obviously on different pages. And that's going to lead to a very fruitless discussion. As this post is.

Fred

 

[cuejoey]

Predators have less cue ball deflection. The shaft has a great amount of deflection at the tip end because it is hollow. The shaft deflects to the side letting the cueball move straight, whereas a solid shaft pushes the cue ball to the side.

The whole shaft does not deflect a lot, only that few inches (5?) in the very front that is hollow.

whenever i read about these shafts i wonder what Willie and Fats would think of them today..

 

[Cornerman]

whenever i read about these shafts i wonder what Willie and Fats would think of them today..

Fats would have loved them. He would have figured out a way to make money marketing them.

Fred

 

[inthezone]

<<I'm going to try to test the deflection as best I can to compare the Varney modified 314 to the other shafts I have. I think setting up the shot as shown below using two stripped balls would help with aiming and consistant tip position. I thought I would aim the center of the cue tip through the right edge of the stripe on the 15 ball and also pick a spot to aim the center of the tip on the 11 ball (using the stripe on the 11 ball to help with aiming at different parts of the OB). I'll try to use a level cue and pretty firm speed on a fast table to help minimize swerve.>>


I think this is an excellent way to test - much better than the pivot test later described which is hugely flawed due to the throw effect which is why it yields such high numbers. The PB site #'s are correct because they are calculated from the squirt directly.

Steve

 

[Jal]

<<I'm going to try to test the deflection as best I can to compare the Varney modified 314 to the other shafts I have. I think setting up the shot as shown below using two stripped balls would help with aiming and consistant tip position. I thought I would aim the center of the cue tip through the right edge of the stripe on the 15 ball and also pick a spot to aim the center of the tip on the 11 ball (using the stripe on the 11 ball to help with aiming at different parts of the OB). I'll try to use a level cue and pretty firm speed on a fast table to help minimize swerve.>>


I think this is an excellent way to test - much better than the pivot test later described which is hugely flawed due to the throw effect which is why it yields such high numbers. The PB site #'s are correct because they are calculated from the squirt directly.

Steve

Throw only introduces a slight error into the pivot test results. A potentially larger error can be due to post-impact swerving of the cueball, or to be more exact, the adjustment made to minimize it when mistaking it for an off-center hit. It depends on speed and cue inclination. Some rough calculations indicate that when performing the test correctly, the cueball should move about two to four inches over to the english side after impact. More like two inches if the cue is inclined four degrees with a ball speed of 8 mph, but four inches if the cue is inclined five degrees with a ball speed of 10 mph. These figures may be severely modified by vertical spin interaction with the cloth, I don't know at this point. Ignoring this, an adjustment for it still isn't enough to explain the discrepancy between the Predator/Platinum data and the pivot results, which often differ by a factor of 3-4.

I think the best way to perform the pivot test is to wet the contact area and forget about what the cueball does afterwards. Simply adjust the pivot point until the object ball moves along the line of centers. That way you eliminate errors introduced by throw, post-impact cueball swerve, post-impact object ball swerve (if hit above center), cloth/v-spin interaction, and maybe a few other things nobody's thought of. And the nature of the test pretty much eliminates pre-impact swerve if the balls are not much more than a diamond apart with a firm hit.

If Platinum's results are wrong, it's not easy to explain why either. I don't think added mass due to the robot's grip can account for it. Possibly there's some partial miscuing going on. But Platinum's data agrees with Predator's data very closely and you wouldn't think this would be so if miscues were taking place.

Jim

 

[Cornerman]

I think the best way to perform the pivot test is to wet the contact area and forget about what the cueball does afterwards. Simply adjust the pivot point until the object ball moves along the line of centers. That way you eliminate errors introduced by throw, post-impact cueball swerve, post-impact object ball swerve (if hit above center), cloth/v-spin interaction, and maybe a few other things nobody's thought of. And the nature of the test pretty much eliminates pre-impact swerve if the balls are not much more than a diamond apart with a firm hit.

I like it.

With wetted contact area and spin-induced throw minimized, the pivot points do get lower compared to without wetting, if the desired result for a straight in shot is with the cueball left spinning in place. I think. Is it a factor of 3 or 4 lower? I wouldn't think so. What kind of numbers have you been getting?

Fred

 

[inthezone]

quote Jal: If Platinum's results are wrong, it's not easy to explain why either.


Jal, the pivot point for any shaft can be precisely calculated if you know the exact squirt at a given offset.

Platinum uses a 9mm or .354" offset

The Predator Z squirts 32.3mm or 1.27" over a distance of 50"

If you find the exact PP for the Z shaft, when you pivot from center to
.354" offset (actually from the literal center of the CB) the angle of the cue will match the angle described by the above squirt numbers.

So, .354"/PP = 1.27"/50" and PP then = 13.94" (to the literal center of the CB)

Measuring from the tip, subtract 1/2 the diameter of the ball = 1.125" for a PP 12.8" from the tip.

Steve

 

[Flex]

I like the Aim & Pivot Test described in the RSB Faq. http://www.sfbilliards.com/faq.html Section 7

If you're going to do a test to compare squirt, you need to make sure that swerve is out of the test as much as possible. So, long shots shouldn't even be considered, as far as the test goes. The shot should be controlled firm, so no wild warp speed shots either.

So, when I test for squirt, I shoot a straight in shot at no more than a couple of feet, finding the pivot point that allows me to stick that cueball in place, spinning like a madman.

Fred, your advice on how to shoot the shot when testing, "controlled firm" has helped me tremendously.

This afternoon I spent about an hour playing around with your suggestion and found it to be extremely helpful. I've read all the numbers and so on it the posts above, and my comment on it all boils down to this: set up the shot Fred described, and shoot it as he suggests. Obviously "controlled firm" will vary from one person's stroke to another's. So experiment with it for your "controlled firm" shot and groove that speed and stroke into your brain. Once that is seared there, shoot shots at different distances with the same stroke and degree of firmness, and learn to adjust for the various kinds of english employed. Get the "feels" for the shots. And remember that when playing and not practicing what the strength of that "controlled firm" shot really is, because if the stroke is softer, the results will vary, often quite appreciably, and the degree of throw on the object ball may well be very different. In any case, the "aim & pivot" method for those shots is very useful.

Tap, tap, tap, and Rep to you, sir.

Flex

 

[Cornerman]

quote Jal: If Platinum's results are wrong, it's not easy to explain why either.


Jal, the pivot point for any shaft can be precisely calculated if you know the exact squirt at a given offset.

Platinum uses a 9mm or .354" offset

The Predator Z squirts 32.3mm or 1.27" over a distance of 50"

The calculation doesn't seem to be the question, then. The method of shooting then becomes the question. 1.27" over 50" seems like more squirt than I've seen out of a Predator, even with a 314 (that's handwaving, and non-scientific guessing). What exactly is the method of holding the cue/shaft?

Fred

 

[inthezone]

The calculation doesn't seem to be the question, then. The method of shooting then becomes the question. 1.27" over 50" seems like more squirt than I've seen out of a Predator, even with a 314 (that's handwaving, and non-scientific guessing). What exactly is the method of holding the cue/shaft?

Fred

Another way of confirming this is to use two "pins" rather than an OB.

Set up a "gate" slightly wider than a ball with two dowel sections made on a lathe or two salt shakers or whatever. Aim to shoot through the gate and then pivot.

This is how I finally figured out just how strong the throw effect is - and the PP's I got matched the PB site numbers very closely for various shafts.

Steve

 

[Jal]

I like it.

With wetted contact area and spin-induced throw minimized, the pivot points do get lower compared to without wetting, if the desired result for a straight in shot is with the cueball left spinning in place. I think. Is it a factor of 3 or 4 lower? I wouldn't think so. What kind of numbers have you been getting?

Fred

Thanks. I'm not sure if you're asking what numbers I've been getting with actual tests, or in theory. I don't own a Predator and it's been a while since I tested my cue, so I'm afraid it is theory.

For the case of 10 mph cueball speed, (2/5)R tip offset, 5 deg cue inclination, 0.6 deg of throw (predicted by Dr. Dave's throw equations), and 100 speed cloth, the cueball should scoot over about 4.2" after impact according to it. If you compensate, unwittingly, by hitting at some cut angle (6.5 deg) so that the cueball comes to a stop just as it reaches "natural roll" in the other direction, and the balls are one foot apart initially, you're in effect unaware of another 1.2 deg of squirt that doesn't show up in the test.

This would be significant, in that for a shaft with an erroneously measured pivot point of 30", its erroneous infered squirt angle would be about 0.8 degree. Adding in the hidden squirt of 1.2 deg brings it up 2 deg, which agrees with the Predator and Platinum numbers. However, the cueball will move over about 2" in the other direction before coming to a stop (same theory), which is hardly spinning in place. So if these numbers do represent reality, you would likely use less compensation and there would be correspondingly less hidden squirt. That's why I said it doesn't seem to explain the discrepancy. However, there are other things to consider which may change these numbers considerably at these very slow post-impact speeds.

Rather then racking one's brain and using somewhat questionable theory to try and resolve this, it's probably better to just ignore the cueball's behavior and concentrate on the object ball. If you have an idea or two which might explain all of this, I would surely be interested.

Jim

 

[No Illusions]

I got my shaft back from Varney on friday. The instillations looks great. Its been a busy weekend here. Got to play a little pool with it and it does feel better to me than the regular 314 and the 314^2 I have with the moori med tips. The 314 Varney did has a Saber T ferrule and sniper tip.

I have an OB-1 that Kevin changed the ferrule & tip on. IMHO it plays a lot better than before. With that wood ferrule it had a clickish hit. Now it hits perfect. I have the same combo. SabreT and Sniper. Looks a lot better too but I'm old school and like the traditional ferrule. I don't know about all those science test, but I'd bet i know which one Shane likes best.

 

[Jal]

...and the PP's I got matched the PB site numbers very closely for various shafts.

I tend to believe the Predator/Platinum numbers and it's interesting that you obtained similar results. But some technically oriented people have measured pivot points in the 30" - 50" range for the Predator using the pivot method. Compensating for throw just doesn't come close to resolving the differences. It's quite possible that the predicted throw is wrong by a fair amount, but I doubt that it's that far off.

Jim

 

[av84fun]

Cornerman...Regarding my comment...English or "side" does NOT in and of itself, cause swerve (see Science of Pocket Billiards, Koehler, p.76) ...
You stated...

<<Of course. What makes you believe I think otherwise???>>

I thought otherwise, because earlier in the thread you stated...

<<but I found that shooting the same shot at the same speed, but one bridging on the rail , and the other not bridging on the rail, I'd get way more swerve (even as flat as I could humanly get the stick).>>

I assume you are an experienced pool player with excellent eye-hand coordination and an ability to determine whether your cue is level or VERY nearly so, for all practical purposes.

Assuming I am correct on that, then there cannot be "way more swerve" because there is hardly any at all when side is used with a level stroke! I just got finished shooting ten shots down the "tracks" on the cloth made by shooting break shots...and while shooting off the rail...as in the typical 9 Ball break shot...and using a soft stroke with FULL side...the CB rolled EXACTLY along the "tracks" with virtually NO swerve visible to the naked eye.

<<Aside from that, once again, you and I are obviously on different pages. And that's going to lead to a very fruitless discussion. As this post is.>>

I thought this was a forum for discussing the highly varied experiences of the posters here...for the purpose of contributing to the body of knowledge about this sport. I did not presume that this was a forum primarily to serve the purpose of agreeing with your personal experiences.

The fact that yours and mine differ on certain things...it seems to me...would INCREASE general viewer interest and not be a "fruitless discussion" as you suggest. But to each his own.

<<It's almost impossible... no, it's impossible to shoot that length of shot shown with a level cue.>>

In fact, it is NOT impossible...for a robotic machine such as that used by Predator and others...for the EXACT purpose of ACCURATELY measuring the differences between one cue and others. What the machines accomplish is to eliminate the physical limitations and personal biases of human beings.

Finally, with respect to your two foot shot technique...since you agree that humans are limited in their physical abilities...I suggest that they are also HIGHLY limited in their VISUAL abilities as well...ESPECIALLY with stroke speeds sufficient to leave the CB spinning in place after OB contact as per your "test."

Therefore, you cannot tell...with any precision...whether the OB enters the pocket DEAD CENTER or not and to that extent your so-called test of swerve is flawed. Moreover, DISTANCE is a highly relevant factor when the issue of swerve is concerned by operation of simple geometry.

Get the OB close enough to the pocket and you can miss your point of aim by what...a half ball AT LEAST??? But extend the distance and a 1/8th ball miss hit can cause you to miss the pocket entirely.

Sorry you feel my views are a waste of your time. For whatever it's worth, I don't feel the same about yours.

Please know for a FACT that I do not consider my opinions or experience to be infallible. I just know what my experiences are and elect, from time to time, to express them for the consideration of reasonable people.

Regards,
Jim

 

[Cornerman]

I'm misunderstanding you, so I'll break down the statements and see if you and I can get some sense as to how the two numbers may actually jibe.

So if these numbers do represent reality,

Let's use real numbers.
Predator 314
Platinum: 11.8"
Aim & Pivot: >30"

you would likely use less compensation

Less compensation means I would use a longer pivot point, which I do. 30" > 11.8" . So, that makes sense.

and there would be correspondingly less hidden squirt.

Are you saying that the larger true amount of squirt is hidden by spin throw? If so, then yes, I go with that.

That's why I said it doesn't seem to explain the discrepancy.

I'm actually thinking it indeed does explain the discrepancy. Or at least, it starts going in the same direction. I have a longer pivot point because I have to compensate less due to spin throw sharing the "compensating."

If it does explain some things, what would be left is to come up with a relationship between true squirt and throw-corrected squirt. It's not a simple degree offset, which is what I would expect.

Rather then racking one's brain and using somewhat questionable theory to try and resolve this, it's probably better to just ignore the cueball's behavior and concentrate on the object ball.

Absolutely. And, if a player pivots with the Aim & Pivot Method, I think they'll make balls. I'm sure they'll miss if they use the pivot points shown on the chart.

If you have an idea or two which might explain all of this, I would surely be interested.

No, no, no! I think your ideas trump mine, and I think you probably understand the phenomena better.

Fred

 

[Cornerman]

Another way of confirming this is to use two "pins" rather than an OB.

I like it. How about a rubber half pipe? Actually, for squirt angle measurements, I guess the carbon paper at the end of the table will do.

Fred

 

[inthezone]

QUOTE CORNERMAN:
<<Absolutely. And, if a player pivots with the Aim & Pivot Method, I think they'll make balls. I'm sure they'll miss if they use the pivot points shown on the chart.>>


For thin cuts the numbers on the chart should work very well and at any distance (leaving swerve out of it for now) because there is very little throw effect.

For more full hits throw becomes a huge factor and the PP varies greatly;
very long PP for a close OB and approaching the chart numbers when the OB is far away, IME.

Steve

 

[Jal]

...Let's use real numbers.
Predator 314
Platinum: 11.8"
Aim & Pivot: >30"

Agreed.

Are you saying that the larger true amount of squirt is hidden by spin throw? If so, then yes, I go with that.

Yes, but I think post-impact swerve of the cueball (compensating for it) is a larger effect. I expect that when most people perform the pivot test, their cues are no more level than for any other shots. So the cueball's spin axis is inclined and this will cause it to move over to the side the english was applied. I'm sure you know this but I'm mentioning it because you used the term "spin throw".

I'm actually thinking it indeed does explain the discrepancy. Or at least, it starts going in the same direction. I have a longer pivot point because I have to compensate less due to spin throw sharing the "compensating."

Yes. Not to hammer the point, but I think that the throw by itself does not account for much.

And, if a player pivots with the Aim & Pivot Method, I think they'll make balls. I'm sure they'll miss if they use the pivot points shown on the chart.

Well, that's at the heart of the matter. If the true pivot point is around 12" for a low squirt shaft, then backhand english should work pretty good if you bridge at around that location. But if it's >30", then I think you would miss a lot of them unless you slide your bridge hand back there to perform the pivot.

Jim

 

[Cornerman]

. But if it's >30", then I think you would miss a lot of them unless you slide your bridge hand back there to perform the pivot.

Jim

For Predator and other low squirt shafts, it has been suggested to use Front Hand English. That is, grab the cue at the pivot point with your grip hand, and move the tip to the desired english with your bridge hand. Shoot on that new line.

Fred