Problem With Our Understanding Of Side

Geometric adjustments

BC21 said:

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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All of this is true, when it relates to divergent english. People already use perceived geometric ratios, like 1/2 ball and 1/4 ball, in their thinking. Meanwhile, when the effect of throw and deflection are all but eliminated, the primary adjustment that needs to be made concerns the new cue angle created by moving the cue into position, to apply the side. The adjustment that needs to be made differs based on whether the side converges from the inside side of the shot or whether the convergence comes from the outside side.

Outside converging side moves the cue line into a fat hit relative to the ghost ball line. Inside converging side moves the cue line into an overcut position relative to ghost ball. As a result, the aim line needs to be adjusted for each. In order to simplify and keep the adjustment simple, a geometric fact was used.

Since the cue line and the ghost ball line cross, the choice of where to cross, allows for a consistent ratio of 1:1 to be used. If the cue line originates from a point beside the center of mass and meets the reference aim line at its midpoint the amount of offset at the impact area is equal to the torque line created at the cue ball center. An elongated X crossing in the middle has equal distances between the ends of the lines. That is a 1:1 ratio. It’s a measurable amount of adjustment regardless of length of shot.

If a torque line the width of 2 dimes is used and crosses the ghost ball line at its midpoint and the converging side is inside side, the ball will be overcut into the far side of the pocket. To compensate for the overcut, the original aim line is adjusted to the undercut side of the pocket. Conversely if the converging side is outside side, the initial compensating aim is to the overcut side of the pocket.

The next post will focus on the reasons that convergent side might be chosen over center ball or divergent side.

Bob Jewett said:

I think it's better to wait for Imac007 to explain what he meant. In your diagram you are moving the cue stick parallel a dime and a half.

And when you pivot back half (except it's not half in your diagram), do you pivot about your bridge hand?

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If you are going to think in terms of the ghost ball line and pivots the following comes to mind. Divergent side and parallel side both occur in relationship to the ghost ball line. BHE and FHE pivot from that line. The ghost ball line does not end at the cue ball. It continues to the object ball. If you think about a pivot, the geometric solution I presented would be simply described as follows. Find the ghost ball line to the undercut side of the pocket. Now place your tip on the midpoint of that line between the two balls and pivot the butt of the cue so that the shaft line crosses to the inside side of the shot, the width of two dimes from the center of mass of the cue ball. Where that shaft line exits on the cue ball face is the cueing point on the surface. BTW the width of a dime is about 1.35mm. So 2 dimes width at 2.7 mm are less than a 1/4 tip using a 12mm tip. This qualifies as a small amount of side in Dr. Dave land. If outside side is preferred. Then start with an overcut ghost ball line. Now pivot from the midpoint to the double dime spot on the other side of the ball’s center. That is the cue line for the shot.

Bob Jewett said:

Just so you won't feel too bad, I'll admit that I have the same problem.

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Sorry guys hope subsequent explanations have made things clearer.

Bob Jewett said:

I think it's better to wait for Imac007 to explain what he meant. In your diagram you are moving the cue stick parallel a dime and a half.

And when you pivot back half (except it's not half in your diagram), do you pivot about your bridge hand?

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BTW. I want to thank those who have been reading this and commenting, for your patience. Without the ability to demonstrate with a table and balls, descriptions can be unclear. I’ve tried to go back and clean up some of my posts. This area of exploration and findings have been put together over the last 2 years or so. Bear with me the benefits and use potentials are many and varied. And commenters who claim there is nothing really new are also right. The application of the knowledge is what is novel. On the shoulders of giants...

Bob Jewett said:

Let's start with this. Please explain what you mean by these terms. If you can provide a diagram, that should help. I have no idea what you mean by converge and diverge in this context.

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The simple definition I have is that diverging in this context means pointing away from and converging means pointing towards. Starting at the ghost ball line BHE and FHE point the cue away from the reference target line. I call the english that points away divergent. When the cue line points back towards the target line, I call it convergent.

Thanks for the help. Defining terms helps people understand.

strmanglr scott said:

Glad I got out the extra large bag of popcorn for that OP.

Carry on.

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Move over and pass a bowl, it’s like herding cats.

Bob Jewett said:

So, by a converging side spin situation, I think you mean the following: the cue stick is placed to give some amount of sidespin and the line of the cue stick is pointed in a way that it crosses the cue ball-ghost ball line of centers (which I think is what you call the "reference target line") in front of the shooter.

Is that correct?

If so, we the following basic definitions:

View attachment 528423

View attachment 528424

And here is a typical "diverging" shot with side spin.

View attachment 528425

And here is a typical "parallel english" shot.

View attachment 528427

Do you agree with these diagrams and definitions?

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A resounding YES.
BHE and FHE both pivot from the ghost ball line.
The ghost ball line extends past the cue ball to the object ball.
The convergent side pivot as I described it would put the tip on the ghost ball line between the two balls. Now a simple pivot so that the new cue line crosses just a dimes width distance to the side of the cb center of mass, means neither the bridge hand nor the grip hand are on the ghost ball line, after the pivot.

ShootingArts said:

Bob,

What he is describing is one thing, what he means may be completely another. He seems to be describing setting the bridge up in a completely different location than normal.

I have been seriously considering the likelihood that lmac = pj = lmac but I haven't made any effort to find out.

Hu

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So my explanation got through to at least one reader. And, poor pj, being maligned and persecuted because I defended his deflection line physics, sorry guy. But like he said when you’re out on runway #5, you know the place where things keep going over your head, nothing makes sense.