Problem With Our Understanding Of Side

[Cornerman]

You’re right. PJ and myself and the physics writers you mention are on the same page. The problem is that other popular discussion of side refers to tips of english and each are in relationship to the ghost ball line. My first point is that the distance the cue line is from center is the actual lever turning the ball. As long as we discuss old misconceptions and perspectives we learn nothing new.

Now to the new. I mentioned moving off the target line and then pointing the cue line back towards center. Imagine moving the cue line back towards center but not all the way. So imagine moving the width of two dimes away from center then pointing the cue line back half that distance, the width of one dime. Notice where the cue is pointing in relation to the original cue line, it now crosses onto the opposite side of the original cue line. NONE of the present parallel english, FHE or BHE methods of applying side converge back towards the shot line, they ALL diverge. So two new labels enter the conversation, divergent and convergent english. Here is the blasphemy, I’m using the ghost ball line as the reference line, because it is the aim line understood by a majority of players. Even Dr. Dave with his SAWS program uses the deflection adjusted ghost ball line as a reference then following that with a distance/pace adjusted combination of BHE and from the new back hand position a sweep with the front hand to a pre-calculated ratio final position. He recognizes the ingrained, although incorrect perception, of using the ghost ball line. He uses a known reference as a starting point. In that spirit, the terms divergent and convergent are cue line relationship terms relative to an adjusted ghost ball aim line.

This is the second insight, the cue line can be pointed back to and cross the original aim reference line, generating side on a convergent rather than divergent path.

If I understand you correctly (which I'm sure I'm not, because there are some confusing terms), and we were on a table, it reads like your method is awfully similar to mine. And I try not to describe mine in these or any groups because it's too confusion to put on paper.

The highlighted sentence, ... I"m sure you're incorrect, but again, I'm only guessing at your definition of "converge to the shotline."

 

[Patrick Johnson]

The convergent side pivot as I described it would put the tip on the ghost ball line between the two balls.

As I read it, this means none of the stick will be on the ghost ball line.

How does that comport with the principle that the stick's pivot point must always be on the ghost ball line (absent swerve)?

pj
chgo

 

[Imac007]

Squirt is not an issue

Okay, I think I finally have an inkling as to what you're describing.

Assuming the effects of throw and swerve are ignored, and your only goal is to simply compensate for squirt (deflection) such that the OB hits the precise ghost ball location, then every type of side would be "divergent", according to your definition. Any type of "convergent" side, assuming the reference point is the ghost ball line, will never get the ball to the ghost ball location.

Do you agree, or am I misunderstanding something?

You’re getting there. Except that the original ghost ball line is adjusted slightly to make sure the ball does get the ball to the ghost ball location.

The issue with squirt is a non-issue. From Dr. Dave research on squirt we have:


To give some context to the graph. The offsets were using parallel english. This means the torque line (the distance the cue line is from the center of mass when at 90°) is equal to the offset position. It’s basically the lever length that turns the ball on off center hits.

The measurements are in inches. So to compare deflection I will convert everything into mm, since tips use mm.

The largest offset is nearly 13mm. Remember the rounded ball surface and the tip shape determine the exact contact point as does the direction the cue is pointing. With a parallel cue line as used here, the contact point is likely near the inner edge of the shaft line.

The other offsets are 3.81 mm apart. The smallest offset graphed was .21", or 5.33mm. That offset on a hard hit deflected about 1°.

The proposed offset at the ball center was a dimes width or 1.35mm. If the testing has continued and the offset maintained the same incremental change, the next smallest test number would have been 1.5mm. Using the graphed results to establish a trend we find that each lesser offset reduced deflection around a single degree. Logic tells us that at a dimes width (1.35mm), the squirt is neglible, approaching zero. Dr. Dave concurred.

This test used a parallel cue line, the convergent cue line points back towards the center from the outside contact point,. This inflective line when input into the Ron Shepard deflection diagram finds the triangle created by the proposed offset to be a mere sliver. The cue line approaches the contact point to center of mass line, pj’s pet line.

I hope this helps you realize that squirt is not a real factor here. A similar analysis reveals that the same is true for throw, especially with convergent inside english.

 

[DecentShot]

Thank God I don't have to think about any of this stuff when I play. For my mind visuals (I don't dare use the A word, or the A word detectives will scold me ) there is only the contact point and the aiming point. The more severe the angle the more the contact point moves off of the OB and onto the table somewhere. I have no idea what contact angle means etc, but Im enjoying the posters trying to figure it out.

 

[Bob Jewett]

A resounding YES.
...

OK, then, is this an illustration of "convergent" aiming with side spin?

 

[skins]

OK, then, is this an illustration of "convergent" aiming with side spin?

View attachment 528437

If it is. Thats what my diagram was trying to show.

 

[atlas333]

A conversation can be over my head, then again it can be nonsense which is under my head. When people start using a different frame of reference than the rest of the world it is likely to be you or your first cousin. I like to look at the world from an unusual perspective once in awhile for the sake of humor. You do it as a way of life. I'm waiting to see how these convergent and divergent lines work out. Of course parallel english is already using a convergent path. all the rest are too. Because of the modest affects of spin on the object ball, the cue ball always has to strike it in very close to same place.

Hu

Thumbs Down

 

[atlas333]

Okay, I think I finally have an inkling as to what you're describing.

Assuming the effects of throw and swerve are ignored, and your only goal is to simply compensate for squirt (deflection) such that the OB hits the precise ghost ball location, then every type of side would be "divergent", according to your definition. Any type of "convergent" side, assuming the reference point is the ghost ball line, will never get the ball to the ghost ball location.

Do you agree, or am I misunderstanding something?

I think you have it

 

[Seth C.]

If it is. Thats what my diagram was trying to show.

Bob is proceeding in a helpful, step-by-step fashion. I’m not sure exactly where he is heading or will land, but the process will be clarifying.

But I have this front end question. Let’s say that it is the case - and it strikes me that it must be the case - that shots played with side can be pocketed whether the cue is first placed on the cue/GB line and then pivoted, or is instead first placed parallel to that line and not pivoted (or not pivoted as much or in the same way). For me the questions are: Is one of these approaches superior, and if so, why?

I previously posed similar questions in this thread: Is one of BHE or FHE superior to the other (at least in some circumstances), and if so, why? No answers to those questions yet, at least not in his thread. All of the physics theory here should only be of interest to players if it leads to a suggested superior (easier, more consistent, repeatable, etc.) and therefore recommended approach on the table.

 

[Seth C.]

I think you have it

I’m thinking that he does not.

 

[Patrick Johnson]

...shots played with side can be pocketed whether the cue is first placed on the cue/GB line and then pivoted, or is instead first placed parallel to that line and not pivoted (or not pivoted as much or in the same way).

Yes, except that placing the cue parallel to the CB/GB line without angling it is just another cue angle like all the others (except with a "zero pivot"), which can only work infrequently (when swerve exactly cancels squirt).

Is one of BHE or FHE superior to the other (at least in some circumstances), and if so, why?

They're methods for different cues. BHE (moving only the back hand to apply english) works best with high squirt cues; FHE (moving only the front hand to apply english) works best with lower squirt cues. Some combination of the two (what most people mean by "parallel english") is needed for most cues and shots, and is usually adjusted unconsciously "by feel".

pj
chgo

 

[Bob Jewett]

... Let’s say that it is the case ... that shots played with side can be pocketed whether the cue is first placed on the cue/GB line and then pivoted, or is instead first placed parallel to that line and not pivoted (or not pivoted as much or in the same way). For me the questions are: Is one of these approaches superior, and if so, why? ...

Yes, as long as the cue stick ends up on the correct line when it strikes the cue ball to send the cue ball forward with the right spin and speed to pocket the object ball, it makes no difference how you got the cue stick to that particular position. There is only one correct position, but some margin of error is there so you don't have to be perfect.

As far as the best approach routine, I think this one is best: https://youtu.be/9b2bEuhkRJc?t=108 It will get the unwary to raise the bet when they shouldn't.:grin:

My own approach is to simply put the cue stick along the correct line for the shot at hand based on my experience.

 

[Patrick Johnson]

My own approach is to simply put the cue stick along the correct line for the shot at hand based on my experience.

Me too (well, except for that "correct" part).

Do we have any idea yet what the problem is with our understanding of side? I haven't understood a word so far...

pj
chgo

 

[Cornerman]

OK, then, is this an illustration of "convergent" aiming with side spin?

View attachment 528437

If this is the OP‘s definition of converging lines, then for sure there are some backhand English methods that the lines converge just like shown. This is actually a start position before pivoting for a few different Houle methods. I particularly like that the cuestick is pointed at the object ball edge!

Freddie

 

[Patrick Johnson]

...tips of english from the ghost ball line won’t tell you the length of the torque line. In other words it doesn’t tell you how much side is really being applied on the ball, except when using parallel side.

I hope this isn't important to your thesis, because it's backwards.

The length of the torque line is always the amount of tip offset from the ghost ball line, except when cueing parallel with it.

No matter how you need to angle your cue for squirt, if you do it correctly its squirt-affected direction of force will always be parallel with the ghost ball line, so the torque line (amount of spin) is always measured from the ghost ball line to the tip offset.

But it's impossible to cue off center parallel with the ghost ball line and produce a force direction parallel to it, so parallel is the one way that torque length is never measured from the ghost ball line.

pj
chgo

 

[Patrick Johnson]

If this is the OP‘s definition of converging lines, then for sure there are some backhand English methods that the lines converge just like shown.

I think that can only be true for swooping BHE, where the tip is moving in a direction other than where the cue is pointing, essentially "simulating" the normal "divergent" straight-stroked cue angle.

pj
chgo

 

[Seth C.]

Yes, as long as the cue stick ends up on the correct line when it strikes the cue ball to send the cue ball forward with the right spin and speed to pocket the object ball, it makes no difference how you got the cue stick to that particular position. There is only one correct position, but some margin of error is there so you don't have to be perfect.

As far as the best approach routine, I think this one is best: https://youtu.be/9b2bEuhkRJc?t=108 It will get the unwary to raise the bet when they shouldn't.:grin:

My own approach is to simply put the cue stick along the correct line for the shot at hand based on my experience.

Bob - You say “There is only one correct position.” If a “correct” position is one that results in both the OB being pocketed and the CB landing on the intended spot, can’t there be multiple cue angles with which to stroke the CB with side (same side) and accomplish this? Starting with the options of FHE and BHE? And assuming that you disagree with this postulation - at least when the same cue is being used (i.e., assuming that you contend ther is only one cue angle that will work for a given cue), do you agree with pj that the correct position with a LD shaft is not the same as with a standard shaft?

 

[ShootingArts]

both divergent and convergent

If I interpret Imac007's definitions of convergent/divergent correctly, then pure parallel english is neither convergent nor divergent, but sits in the middle of the two cases (because the cue is neither pointing towards or away from the ghost ball line, but is parallel to it). But given finite squirt, we all know that the resulting CB path will not follow the ghost ball line with pure parallel english. Therefore, from the starting point of parallel english, the cue must "diverge" (point away from the ghost ball line) in order to compensate for any squirt. So every cue line must diverge and there are no "convergent" cases, assuming you want to send the CB along the ghost ball line.

They have to use their own frames of reference and their own definitions of words to have a fully convergent path for the cue ball. As I think you, I, and most players recognize, when you use any side spin the cue ball diverges from the target line reference line and then converges with that line at the object ball with only very slight differences in contact point or none at all.

Trying to make sense of this without diagrams is pretty much impossible especially since they can change their references and definitions as they please. It is like trying to work with the old number lines in school and one person deciding that from now on they will use five as their zero reference. Their math can be perfect, but only if you accept five as the new zero.

While this seems ridiculous, whole fields of physics and careers have been built on false premises in the same way. A recent claim is that there is an over 90% probability that we aren't real but only a replication of a real universe. The folks with Phd's in physics can get way out there in lalaland and everyone in the field commend their fantastic work!

Theories of physics are great, mechanics are better if you want to put balls in holes.

Hu

 

[Bob Jewett]

Bob - You say “There is only one correct position.” If a “correct” position is one that results in both the OB being pocketed and the CB landing on the intended spot, can’t there be multiple cue angles with which to stroke the CB with side (same side) and accomplish this? Starting with the options of FHE and BHE? And assuming that you disagree with this postulation - at least when the same cue is being used (i.e., assuming that you contend there is only one cue angle that will work for a given cue), do you agree with pj that the correct position with a LD shaft is not the same as with a standard shaft?

By correct, I mean the cue stick line/position (and speed) that launches the cue ball with the single desired direction, spin and speed. In my view, that is more or less independent of the object ball, although it is nice to pocket the object ball by having the direction correct.

On some shots there are an infinite number of ways to hit the cue ball, make the object ball in the called pocket and bring the cue ball to the desired position. A very simple example is drawing the cue ball straight back one foot on a straight-in shot. There are many, many combinations of speed and elevation and distance below center that will do exactly the same job. There are more complicated examples that include side spin.

 

[jsp]

If this is the OP‘s definition of converging lines, then for sure there are some backhand English methods that the lines converge just like shown. This is actually a start position before pivoting for a few different Houle methods. I particularly like that the cuestick is pointed at the object ball edge!

My understanding of BHE is that you have your cue start along the ghost ball line and pivot the backhand from there around the cue’s pivot point. That should always result in “divergent” lines. It can only become convergent if the pivot point of the cue is on the other side of the CB, which i’m pretty sure is not possible (assuming the entire point of pivoting is to compensate for squirt).