Problem With Our Understanding Of Side

Patrick Johnson

Fish of the Day
Silver Member
Really? Ok, i would move both bridge hand and cue over parallel to original shot line. I call that a parallel shift.
OK, but it can't work except on very specific shots where swerve perfectly counteracts squirt - or unless you make an angle change too.

In fact, I think when most people use the "parallel" term they mean they're just adjusting their stick's angle "by feel" (not using BHE or FHE or a "measured" combination of the two). They may even be unaware they're doing it, and that's why I don't like the term - it disguises what's really happening.

pj
chgo
 

garczar

AzB Silver Member
Silver Member
OK, but it can't work except on very specific shots where swerve perfectly counteracts squirt - or unless you make an angle change too.

In fact, I think when most people use the "parallel" term they mean they're just adjusting their stick's angle "by feel" (not using BHE or FHE or a "measured" combination of the two). They may even be unaware they're doing it, and that's why I don't like the term - it disguises what's really happening.

pj
chgo
You could be dead-on. I just know it 'felt' like a parallel shift 'cause i moved both my bridge and cue over. Could'a been some angle involve but wasn't too into hyper examining what was going on. I just just adjusted my aiming point and shifted over. Whatever this may be called i made a s%^tload of ball with it.
 

Patrick Johnson

Fish of the Day
Silver Member
You could be dead-on. I just know it 'felt' like a parallel shift 'cause i moved both my bridge and cue over. Could'a been some angle involve but wasn't too into hyper examining what was going on. I just just adjusted my aiming point and shifted over. Whatever this may be called i made a s%^tload of ball with it.
Yes, I think that's how most interpret it. Whatever works, of course - I just wish the terminology was more reflective of the reality so noobs aren't misled (unless they want to be, of course).

Thanks,

pj
chgo
 

JazzyJeff87

AzB Plutonium Member
Silver Member
I never understood the term parallel English until I saw a video about B/F HE, I had never even considered trying something like that. I did set up a few shots with Dr Dave’s system and it actually worked but it felt so unnatural since I’ve not spent time with it.

So it seems answered already but I think of parallel English as just when I naturally get down on a shot knowing I’m going to use low right so my aim point needs to be here and I’m going to throw the ball there in the pocket so when I’m down on the shot my bridge and grip hands are still in line, just as if I was shooting a stop shot. Opposed to setting up like a stop shot and then moving my bank hand over 20% or whatever and now my bridge and grip hand are no longer parallel

Lol so I looked at dr Dave’s link there and I basically paraphrased his incorrect explanation for parallel English. I’m not a technical type so don’t judge
 
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Imac007

AzB Silver Member
Silver Member
Parallel english clarification

What’s “parallel English”?

pj
chgo

I believe that pj has much more sinister motives than stated here, by others. He is interested in the truth, not dogma or misunderstanding or misinterpretation. Dr. Dave has weighed in with a link to his resource page on parallel english. The usual use of the term starts with an orientation at the ghost ball line through center on the cue ball. When the cue is shifted parallel to that line, that is the parallel english I claim has been wrongly used as the reference for calculating the effects of english. If all angles in 1° increments were represented in relationship to the shot line, only the parallel english line has a direct relationship to the actual physics force line. It’s like a stopped clock, right in only two contexts, once to the right of center here and once to the left, instead of twice a day.

From: Amateur Physics for the Amateur Pool Player Third Edition by Ron Shepard

BA62F5B0-2427-4511-A56A-5F67DDF24AC3.jpeg

Physics doesn’t care about your intentions or what target line you choose. It only looks at what direction the force comes from, where that is in relation to the center of mass, where on the surface the ball is contacted and what friction variables are there at the moment of contact. The distance between the F line and the R line determine the moment or torque arm distance used in physics calculations.

pj knows this and knows that the deflection line always radiates from the contact point through the center of mass. The R line always parallels the F line. The R line is only the same line as the target line if the cue is shifted parallel. When the cue line diverges from the target line by pivoting from either hand, it is no longer parallel to the target line and the R line and F will now be calculated from parallel to the new cue direction. Physics doesn’t care about your pivot origin, only the actual direction the cue is traveling on at impact.

I will reply to each post in turn as time permits, provided the topic has not already been addressed.
 

BC21

https://www.playpoolbetter.com
Gold Member
Silver Member
I don't believe there's any amount of sidespin that doesn't generate some squirt. It may be offset exactly by swerve at some distances/speeds/elevations/conditions, but that's a variable, not something that's "automatic" for small amounts of sidespin.

If "parallel english" means "cue parallel to the shot line", I think it's an unrealistic and misleading term - because it's so rarely true, it obscures the physical facts of squirt and how we compensate for it, and it encourages habitual practices that limit our games.

pj
chgo

With LD shafts you can line straight up through ccb to your desired cb target/aim, then move the entire cue over to apply a little side spin, like a quarter tip of spin, keeping the cue as parallel as possible to your initial line, and the cb squirt will usually be insignificant. It all depends on the end mass of the shaft.

There are two forces at work during an off-center cb hit.
One force is the weight of the entire cue stick moving along the stroke line. If hit dead center cb then the full weight of the cue simply shoves straight through the cb. At 6oz the cb doesn't put up much resistance and has no effect on the direction of the cue tip or shaft end mass. An off-center hit, however, allows the 6oz mass of cb to influence the path of the tip/shaft because the shaft is forced sideways as the ball begins to rotate. This sideways force, combined with the normal directional force of the stroke, is what determines the path of the cb after being struck. I know you already know all of this, so I'll get to my point....

There are shots where just the right amount of side force and a parallel cue directional force (parallel to the aim line) seem to cancel each out. It could very well be due to a little swerve occurring at the same time, but it doesn't matter. All that matters is knowing that it works without having to consciously make it work by overthinking any aiming compensation or adjustments.
That's what I mean by "automatic".

Oh, and "habitual practices", as you say, aren't always bad. It's how we develop a unique feel for certain shots. I don't care if it's swerve or a tiny massé or magic....if I hit a shot a certain way and get consistent positive results, I'd call that a good thing.
 

Imac007

AzB Silver Member
Silver Member
Understanding your frustration

PJ is of course playing games. He is well aware of what is referred to as parallel english. He has also maintained for decades that the angle the cue stick hits the cue ball doesn't matter, only the location. After thirty years most have given up on trying to change his firmly held opinions although it is easy to demonstrate the lack of truth by exaggerating the angle.

The location of contact one tip to the side of centerline can be a very commonly and successfully used shot, or by moving the bridge and exaggerating the angle it can be an impossible to shoot successfully miscue. Yet PJ's claim has always been that the angle doesn't matter, only the location.

Having ran this rabbit many times before with PJ I'll sit this one out other than saying you are absolutely right about lines of force. Hitting exactly the same spot with backhand english, fronthand english and parallel offset english will each give different results. It is also possible to combine multiple forms of english in one shot with good results sometimes.

I never tried front hand english until after using either parallel or back hand english for many years. Seems odd and I never used it long enough for it to become natural but because the angle is less severe it seems superior to back hand english. I usually use parallel english, just a matter of what I am most comfortable with.

All three work, combinations of English work. Poking another sacred cow but something your post makes obvious you will understand, each form of english lets you hit a different distance out from centerline before a miscue occurs when the target line is used as reference.

Since the lines of force are different and the force that can be applied without a miscue remain the same I have suspected that the angle the cue ball is hit and the distance that the cue ball can be hit without miscueing can only apply the same amount of force through the true vertical line of the cue ball from top center to contact patch, the amount of spin possible on the cue ball remains the same.

I have never seen this physically proven by testing with a robot to eliminate the human factor and have long wanted to see it proven if any of the three types of english or any combination can gain a slight advantage. I think not but that remains unproven as far as I know. I don't wholly trust mathematical proof of such things as I have seen the formulas of similar calculations leave out small variables that affect real world outcomes enough to render the calculations false.

Hu

The problem is with most points of argument, perspective is the determinant of right or wrong. The thing is that pj is right, because all perspectives he was commenting on had to do with point of contact and cueing direction. Target line is a different direction except when parallel english is concerned. All deflection lines regardless of approach line go along a line from the contact point to the center of mass. The Ron Shepard diagram shows that the deflection line is a constant but the other elements, the direction of original force, the angle relative to the center of mass, the plane the R sits on all vary. The R line and F line remain in a parallel proximity to one another, a second constant. PJ is right because physics doesn’t care what direction the original cueing line is on unless the miscue limit is passed then the coefficient of friction part of the diagram becomes relevant. In that case, forces are dissipated and calculated under different circumstances. That is beyond the scope of the spin dynamics intended under the topic.

You are recognizing that the ball does not follow the path from contact point to center of mass and that the ball, despite deflection, has fairly predictable direction related to the original direction of actual force. You are both right. The truth lies in the middle after the variables have each had their say in the eventual force direction. Torque line length determines the actual amount of side, not tips of english. The length of the torque line is determined primarily by the original direction of the cue in relationship to its perpendicular distance from the center of mass, not arbitrary cue tips on the surface. If I use the original target line, move 2 cue tips to the right, then move the cue butt to the right pivoting the cue line back to the center of mass, my tip is offset from the target line by 2 tips but will apply no english on the cue ball. PJ would also be correct, the contact point to center of mass, the R line, the F line and the cue would all lie on the same line and the deflection would calculate to zero.
 
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jsp

AzB Silver Member
Silver Member
There is a problem in perception because the ghost ball line, not the paralleling line through the center, has been used as the reference. Using that as the perspective has all perceived lines of english radiating from or paralleling the ghost ball line. Using those diverging lines the game has missed a whole range of angles with side, not currently used in play. The implications are huge.
I'm still unsure what point you're trying to make. If you want to to discuss pool physics, then you are not presenting anything that Dr. Dave, Bob Jewett, Mike Page, and Ron Shepard have not already talked about for years/decades.

If you're attempting to propose that a better understanding of the physics of side spin will help the average pool player, as it seems from the quote above, then I disagree. None of this stuff will help the average pool player.
 

Seth C.

AzB Silver Member
Silver Member
Im a bit confused.

Is the Imac007 post saying that at a certain distance right or left of center, with a cue (or stroking) line that is parallel to the ghost ball/vertical center cue (or stroking) line, the CB will travel in the direction of the stroke line because the squirt and the friction (with the cue tip) forces are offsetting? I’m thinking that this isn’t the proper translation, because if the OB is spinning, there will be some amount of swerve, even if inconsequential due to the speed and length of the shot.

Is the BC21 post saying something similar but slightly different: that at just the right (small) amount of tip offset, again using a “parallel” stroke line, the squirt and swerve will cancel each other out? I’m thinking that this is the proper translation, but that the conclusion doesn’t hold up UNLESS the CB is hit softly enough, and has enough travel time to swerve, prior to contact with the OB.
 

Imac007

AzB Silver Member
Silver Member
I'm still unsure what point you're trying to make. If you want to to discuss pool physics, then you are not presenting anything that Dr. Dave, Bob Jewett, Mike Page, and Ron Shepard have not already talked about for years/decades.

If you're attempting to propose that a better understanding of the physics of side spin will help the average pool player, as it seems from the quote above, then I disagree. None of this stuff will help the average pool player.

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.
 
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jsp

AzB Silver Member
Silver Member
And misses all shots except those where swerve (a variable depending on distance, speed, conditions, butt elevation, etc.) happens to exactly counteract squirt, right?
Um, aren't you forgetting about spin induced throw?

So I agree, parallel english misses "all shots"...except for some shots, and these shots, and maybe those shots, and don't forget these shots over here.

It's like complaining about the term "ghost ball" because the exact geometrically-determined ghost ball location is almost never the exact location it should be to pocket the shot because of friction.

Both parallel english and ghost ball are still very useful terms. Just know their limitations.
 

jsp

AzB Silver Member
Silver Member
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.
I read this paragraph four times and I still don't understand what you're describing.
 

Patrick Johnson

Fish of the Day
Silver Member
Um, aren't you forgetting about spin induced throw?

So I agree, parallel english misses "all shots"...except for some shots, and these shots, and maybe those shots, and don't forget these shots over here.

It's like complaining about the term "ghost ball" because the exact geometrically-determined ghost ball location is almost never the exact location it should be to pocket the shot because of friction.

Both parallel english and ghost ball are still very useful terms. Just know their limitations.
Every spin shot has a combination of squirt and swerve to account for. The particular combination that results in cueing parallel to the shot line is no more likely to happen than any other cueing angle - a small fraction of all possible cueing angles, like any other single angle. Naming it as if it's a category or technique unto itself just misstates and confuses the actual dynamics IMO.

But it's only a misdemeanor, so no arrests.

pj <- this time
chgo
 

Imac007

AzB Silver Member
Silver Member
Im a bit confused.

Is the Imac007 post saying that at a certain distance right or left of center, with a cue (or stroking) line that is parallel to the ghost ball/vertical center cue (or stroking) line, the CB will travel in the direction of the stroke line because the squirt and the friction (with the cue tip) forces are offsetting? I’m thinking that this isn’t the proper translation, because if the OB is spinning, there will be some amount of swerve, even if inconsequential due to the speed and length of the shot.

Is the BC21 post saying something similar but slightly different: that at just the right (small) amount of tip offset, again using a “parallel” stroke line, the squirt and swerve will cancel each other out? I’m thinking that this is the proper translation, but that the conclusion doesn’t hold up UNLESS the CB is hit softly enough, and has enough travel time to swerve, prior to contact with the OB.

This post shows a player jumping ahead trying to use conclusions based on experience with divergent side. It also reveals a mindset seeing the amount of side from the ball surface, not the center of mass. Despite the fact that I talked about an offset of the width of two dimes, the actual torque arm beside the ball center was set at a dimes width. Twice as wide at the surface than at the ball’s center guaranteed it was not parallel and not divergent. Simple geometry would tell you that the cue line would exit the cue ball crossing the original adjusted aim line at the exit point of that line.

Some things that Dr. Dave research has shown is
1. As the amount of side approaches zero so does throw.
2. As the amount of side approaches zero so does deflection.
3. Very small amounts of side have a very small amount of throw at all speeds.

The example given was a small amount on purpose just trying to bring attention to the fact that the cue line converges with and crosses the original aim line. Wrap your head around where the cue is now pointing. Depending on the distance between the balls, the cue could be pointing well away from the object ball or just a bit to the side. There needs to be a method of applying consistent amounts of side regardless of distance. That will be part of another post, a geometric solution.
 
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BC21

https://www.playpoolbetter.com
Gold Member
Silver Member
......
.....There needs to be a method of applying consistent amounts of side regardless of distance. That will be part of another post, a geometric solution.

Interesting. But I think the best method is called experience.

You could show someone exactly how you do it, as far as applying side spin based on a geometric solution, and if the person has the same stroke quality as you, and they use your cue to shoot each shot as instructed, then your method will work for them in the same manner it works for you. But if they have a better stroke than you, no steering flaws, etc... or if they have a worse stroke than you, unable to consistently strike the cb where they intend to strike it, then the method you show them will not be very consistent for them. And since their cue may cause more or less cb deflection than your cue, the method you show will have to be tweaked to work with a cue of different deflection than yours.

Compensating for english is a very subjective process that players learn through experience, through trial and error. Sure there are some basic methods that can be used to roughly adjust for this, like using bhe or fhe. But these aren't one-size-fits-all type methods because of the difference in individual strokes and individual cues. A player must experiment with his/her own playing cue in order to find the right bridge length that works for using bhe. And even that variable changes when the cb and ob are separated by a greater distance. So in the end it boils down to experience, to table time. But it would be interesting to see this geometric method you speak of, and to see how it can be adapted to different players and different cues.
 
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