Do you adjust your aim for different spins and speeds?

[Patrick Johnson]

This seems like a complicated way of expressing the fact that the effect of swerve increases with less speed and/or more length.

pj
chgo

Well it quantifies the effect. Though more complex, it is certainly more valuable.

I will be doing graphs/charts to make the process more understandable and calculable.

Colin

Swerve also varies with changes of tip offset, butt elevation, ball/cloth conditions and even humidity. For effects with so many variables I think it's essential to describe the general principles along with the circumstances and outcome for the specific measurement that was taken - that way when circumstances (variables) change, the player has something by which to understand the changed results.

I enjoy your posts - your willingness to test and quantify things is a very valuable addition to eveybody's understanding.

pj
chgo

 

[Colin Colenso]

Colin and Dave...thanks for your always interesting studies.

You're welcome Jim, glad some people find it interesting

while outside english will throw the OB in the "thin" or over-cut direction, it will ALSO cause the CB to squirt in the "thick" or under-cut direction.

On thinner cuts a small amount of OE, especially if the CB is sliding actually increases the throw (undercuts more) than for the same shot played at soft-medium speed natural roll, which is about 0.7 inches per yard undercut more than the line through centers.

This shows that the relationships between speed, spin and cut angle is more complex and harder to guess than most understand. Hence the need for better predictive methods.

Also, error tolerance varies with distance. You can shoot a shot of a given angle with a given amount of english from 6 inches all day that you would miss by half a diamond on an 8 ft. shot.

IMHO, one of the CRUCIAL things that top players do that the rest of us are less skilled at is to master the interrelationship of squirt and throw over varying speeds and distances!

Also IMHO, while there are techniques, guidlines, cue tips and shafts that can help a great deal in mastering those interrelationships, nothing is a substitute for raw experience resulting from practice and in that case, the top pros have it all over the rest of us.

It is not unusual for champions to practice 6 hours per day.

That translates to hitting 2,000 shots per day...13,000 per week...52,000 per month or 622,000 per year.

Therefore, in their first 10 years, champions have shot in excess of 6 MILLION shots!

There are plenty of APA 9s that have not shot 2 million shots in their lives!

Regards,
Jim

I agree that pros become great through endless repetition, learning and burning into memory hundreds, if not thousands of variations of shots.

However, I believe players in the future can learn more quickly by becoming experts at natural roll potting and then making physical adjustments in bridge length and aim to accomplish any shot required with a high degree of accuracy.

To do this they need to memorise the throw properties as plotted, in part, above, and to become experts in predicting 'effective' pivot points, according to shot speed and length between CB and OB.

Because no one before has had access to quantifiable methods to achieve this, all players have had to learn via lots of guestimating.

Colin

 

[td873]

CB speed alone can't explain a changed OB path - there must be some difference in the contact point (squirt/swerve) or some difference in CB/OB friction (throw).

pj
chgo

IMO, the provided data clearly indicates a different result than you indicate. That is, their experimental data illustrates that speed alone does, in fact, affect an OB path. That is, at the (0,0) point of each graph (i.e., no cue ball spin), the change in angle is different based on speed alone. I also recall something on this point in Jack Kohler's book(s), but I don't have the books handy to review. But, perhaps I am misreading the graphs.

In light of the empirical data provided, I am interested in knowing what your basis is for stating that speed alone cannot explain a changed OB path. Or how the graphs can be better interpreted.

-td

 

[dr_dave]

everything you ever wanted to know about squirt, swerve, throw

Some things to notice are:
1. A soft stun shot make cause you to undercut the shot by around 4 inches if the OB is just 3 feet from the pocket.

2. For soft and medium speed shots, heavy Outside English results in overcutting of up to 5 inches over 3 feet.

3. High power stun, follow or draw shots cause slight undercutting.

This is the kind of information I think is a useful result of the analysis. FYI, I have a lot more conclusions like this, for squirt, swerve, and throw here:

http://billiards.colostate.edu/threads/aiming.html#compensation​

There, I have a list of 34 summary statements of "everything you ever wanted to know about squirt, swerve, and throw."

Regards,
Dave

 

[av84fun]

IMO, the provided data clearly indicates a different result than you indicate. That is, their experimental data illustrates that speed alone does, in fact, affect an OB path. That is, at the (0,0) point of each graph (i.e., no cue ball spin), the change in angle is different based on speed alone. I also recall something on this point in Jack Kohler's book(s), but I don't have the books handy to review. But, perhaps I am misreading the graphs.

In light of the empirical data provided, I am interested in knowing what your basis is for stating that speed alone cannot explain a changed OB path. Or how the graphs can be better interpreted.

-td

My copy of Science of Pocket Billiards (1989 edition) states that..."The magnitude of collison-induced throw depends on cut angle and the amount of friction between the balls. ...the speed of the cue ball did not seem to discernably effect the throw angle.

In his discussion of what he calls "english-induce throw" and what others refer to as SIT or spin-induced throw, he does not mention speed as a variable...that I could find with a quick perusal anyway.

Of course, other studies have been done more recently than Koehler's and Dave and Colin seem to suggest that speed IS a factor so possibly they could point us to their data on that subject.

Regards,
Jim

EDIT: Dave already did point to his findings.

 

[dr_dave]

swerve is a "demon" also

So my questions to members are:
1. Were you aware of any of this?

Yes. But I've done lots or analysis, performed lots of experiments, and written many articles on these topics.

2. Do you ever make conscious adjustments for these changes in throw?

Yes, but only during the shot planning and alignment stage, never during shot execution. As some people have suggested, you should not be thinking about all of this stuff during your stroke. Obviously, this is good advice.

3. Do you think you miss often due to not taking into account these changes in throw?

When using English, I sometimes miss due to inadequate compensation for squirt, swerve, AND throw. I think swerve is the biggest "demon" because it depends on shot speed, cue elevation, shot distance, table conditions, and the type and amount of English and spin. "Cling" is another "demon," where the throw amount is much more than expected; but, luckily, this doesn't happen often.

Again, I have a good list of squirt/swerve/throw aim compensation considerations here:

http://billiards.colostate.edu/threads/aiming.html#compensation
​

Regards,
Dave

 

[Colin Colenso]

Swerve also varies with changes of tip offset, butt elevation, ball/cloth conditions and even humidity. For effects with so many variables I think it's essential to describe the general principles along with the circumstances and outcome for the specific measurement that was taken - that way when circumstances (variables) change, the player has something by which to understand the changed results.

I enjoy your posts - your willingness to test and quantify things is a very valuable addition to eveybody's understanding.

pj
chgo

True PJ,

No description of swerve, as it affects the 'effective pivot point' can be complete without consideration of tip offset, cue elevation, ball/cloth considerations, humidity etc.

I hope to also offer some accurate adjustment methods that take these, and their interrelationships into account. Hopefully in a way such that a player, with a bit of practice, could make the calculations quickly in their heads after assessing the shot they have decided to play.

e.g. Cue elevation might be quantified into 3 levels. 1 slight, 3 steep (bridging over ball). This number might be multiplied by the % of tip offset plus the % of draw, producing a factor which is added to the % pivot point increase as previously determined. I'd have to do some testing to come up with methods that provide pretty reasonable estimations.

It needn't follow perfect physical formula. It would be more like the rough methods that convert Degrees Centigrade to Fahrenheit such as 2xC + 30.

So long as it provides pretty good estimations throughout the range of typical shots.

Colin

 

[Colin Colenso]

IMO, the provided data clearly indicates a different result than you indicate. That is, their experimental data illustrates that speed alone does, in fact, affect an OB path. That is, at the (0,0) point of each graph (i.e., no cue ball spin), the change in angle is different based on speed alone. I also recall something on this point in Jack Kohler's book(s), but I don't have the books handy to review. But, perhaps I am misreading the graphs.

-td

Yes TD,
Speed alone has a considerable effect on the amount of throw.

Throw, while complex is largely determined by the relative speeds between surfaces at impact. Increasing a ball's speed, increases the speeds between the surfaces at impact.

Super hard center ball shots have almost zero throw, relative to the line-of-centers. Very soft center ball shots can produce very high levels of throw. This is a major reason most good players prefer to stun balls in firmly.

Colin

 

[dr_dave]

My copy of Science of Pocket Billiards (1989 edition) states that..."The magnitude of collison-induced throw depends on cut angle and the amount of friction between the balls. ...the speed of the cue ball did not seem to discernably effect the throw angle.

I think that book is very good, but this statement is not very accurate.

In his discussion of what he calls "english-induce throw" and what others refer to as SIT or spin-induced throw, he does not mention speed as a variable...that I could find with a quick perusal anyway.

Of course, other studies have been done more recently than Koehler's and Dave and Colin seem to suggest that speed IS a factor so possibly they could point us to their data on that subject.

Speed has a large impact on both cut-induced-throw (CIT) and spin-induced-throw (SIT).

With CIT, throw is much larger for slower speed shots, but not for small cut angles (e.g., 1/2-ball hit or fuller). For more info, see my September '06 article.

With SIT, throw is much larger for slower speed shots, but not for small amounts of English (e.g., 30% or less). For more info, see my December '06 article.

Regards,
Dave

 

[Colin Colenso]

I think swerve is the biggest "demon" because it depends on shot speed, cue elevation, shot distance, table conditions, and the type and amount of English and spin.
Regards,
Dave

I agree, swerve is the hardest of the lot to adjust for, but I think with study, practice and some good formulas, used in combination with aim & pivot, there is great potential in players being able to gain far better control over it.

Colin

 

[dr_dave]

don't forget swerve

IMHO, one of the CRUCIAL things that top players do that the rest of us are less skilled at is to master the interrelationship of squirt and throw over varying speeds and distances!

Don't forget swerve! Or by "squirt" do your mean "effective squirt" or "sqwerve," which accounts for both squirt and swerve?

Regards,
Dave

 

[TXsouthpaw]

Of course youve gotta adjust for aim,speed,throw and squirt. I thought that was just a given.

 

[Bob Jewett]

...the speed of the cue ball did not seem to discernably effect the throw angle. ...

A more careful experiment shows the rather large effect of speed on throw. See http://www.sfbilliards.com/articles/1995-06.pdf and Phil Capelle's first book. A major point that many seem to overlook is that a stunned cue ball is like the first ball in a close combination for the purposes of throw. A follow-on is that a rolling cue ball is different from the first ball in a close combination.

 

[Patrick Johnson]

CB speed alone can't explain a changed OB path - there must be some difference in the contact point (squirt/swerve) or some difference in CB/OB friction (throw).

pj
chgo

IMO, the provided data clearly indicates a different result than you indicate. That is, their experimental data illustrates that speed alone does, in fact, affect an OB path. That is, at the (0,0) point of each graph (i.e., no cue ball spin), the change in angle is different based on speed alone.

Of course the cut angle changes as speed changes; it's just not because of "speed alone, independent of throw" as you said. The cut angle changes as speed changes because the friction between the two balls changes as speed changes - in other words, because the amount of throw changes.

You may be thinking that throw only happens with sidespin, but it also happens when the CB rubs across the OB without sidespin on a cut shot (it creates sideways friction just like sidespin does).

... I am interested in knowing what your basis is for stating that speed alone cannot explain a changed OB path.

It's pretty simple (at least to me): speed itself isn't a force that acts directly on the OB's direction - it can only change the effectiveness of some other force that does act directly on the OB's direction, like the sideways friction that produces throw.

pj
chgo

 

[unknownpro]

On a block of ice, what is the maximum squirt before miscue? How is that affected by speed? And what is maximum squirt on a real table?

I have always told beginning players to slam a lot of balls because that was the best way to minimize curve and throw effects.

 

[dr_dave]

ice squirt

On a block of ice, what is the maximum squirt before miscue? How is that affected by speed? And what is maximum squirt on a real table?

I have always told beginning players to slam a lot of balls because that was the best way to minimize curve and throw effects.

Squirt is the same on a block of ice as it is on a pool table. Swerve is what varies with friction between the ball and cloth. Squirt, swerve, and throw are separate effects that all come into play when using English. For more info, see:

http://billiards.colostate.edu/threads/aiming.html#compensation​

Regards,
Dave

 

[Patrick Johnson]

On a block of ice, what is the maximum squirt before miscue?

It's different for each shaft.

How is that affected by speed?

Indirectly. Swerve counteracts squirt (more swerve = less net effect from squirt), and since swerve changes with speed the net effect of squirt does too. More speed = less swerve effect = more squirt effect (and vice verse).

And what is maximum squirt on a real table?

That depends on the shaft too.

I have always told beginning players to slam a lot of balls because that was the best way to minimize curve and throw effects.

High speed does reduce swerve and throw. I don't know if it's "the best way".

pj
chgo

 

[dr_dave]

speed doesn't always decrease throw

High speed does reduce swerve and throw.

Actually, strictly speaking, speed doesn't always reduce throw. For more info, see my Setember '06 and December '06 articles.

Regards,
Dave

 

[grindz]

Conclusions

Here's what I think.............

You loved math class and I loved recess.

I live by "The Inner Game of Tennis" and you live by a physics book.

Seriously though, if you can visualize your shot then your subconscious mind can do all that (math) without your conscious mind (ego) getting in the way.

"trust in the force Luke"..................

td

 

[dr_dave]

subconscious "force"

Here's what I think.............

You loved math class and I loved recess.

I live by "The Inner Game of Tennis" and you live by a physics book.

Seriously though, if you can visualize your shot then your subconscious mind can do all that (math) without your conscious mind (ego) getting in the way.

"trust in the force Luke"..................

td

I can't argue with that. If you have enough practice and successful experience under your belt to create perfect subconscious intuition, then you don't need any "pool physics" understanding.

Regards,
Dave (in quest of perfect subconscious intuition)

PS: You don't need "math" and "physics books" to have basic pool physics understanding.