Does Backhand English Reduce Deflection?

[Jaden]

not to read all of that crap anymore.

Mark this day down on the calendar Colin...this is where I go along with you and am in agreement. (this has to be a first)

Jaden said it correctly in his first post...and then he backpedaled to agree with the Post Hole Diggers thesis on the effects of how hard you hit the CB has nothing to do with how much deflection takes place. BULLSHIT!
Now I know not to read all of that crap any more.

Yes, I admit to backpedaling. That had nothing to do with the post hole diggers association though. I must first explain that everything I am talking about here comes from my experience and knowledge of pool and a raging desire of intelect to figure things out, not from any formal training in physics.

When thinking logically about the interaction of the cue stick, composition of shaft tip etc, and the cueball, one would THINK that speed would effect how much squirt there is; however, what gets my noggin in a bunch is that in effect it doesn't seem to be the case. That's why I explained in the follow up that what I think is happening is a mutual exclusion, rather the amount of additional spin imparted by the off center harder stroke creates additional CB to OB throw canceling the additional squirt. That's what I meant in that follow up post. I didn't mean to say there wasn't additional squirt. Just that it wouldn't seem as though there were in actual effect. Only when using BHE by the way. When using PE yo umay have to adjust more for a harder stroke, it's impossible to tell though because your mind is doing the calculations necesary subconsciously based on experience where with BHE there are no calculations.

 

[Gabber]

Jaden said,
"Yes, I admit to backpedaling.".

There is nothing wrong about changing your mind about something. In fact, I would say its a good sign.
There are many ego's on pool forums and some are so convinced that they are right, they cant see another's point of view.
We have all been guilty of it, [me included] but we live and learn.

Its no sweat.

Cheers,

Gabber

 

[Jal]

... What I am saying is that tips on balls have some loss of friction...

Thanks for elaborating Colin. I'm still not sure if this is the essence of your theory, but this seems plausible (I'm not convinced yet that you wouldn't see random amounts of squirt). If static friction holds throughout the impact period, then the force acting tangential to the surface should add to the force acting through the center of the cueball in such a way that the resultant points in the direction of the cue. However, if some momentary slipping occurs, the tangential force is reduced and the force acting through the center of the cueball will send it off to the side a little, just as with ball/ball collisions (only here the tangential force is greatly reduced since sliding friction is involved throughout).

It seems that at easy way of testing this would be to hit balls with varying surface conditions, from sanded to highly polished, and see what happens.

My apology if I'm misrepresenting your ideas.

Jim

 

[Colin Colenso]

Yes, I admit to backpedaling. That had nothing to do with the post hole diggers association though. I must first explain that everything I am talking about here comes from my experience and knowledge of pool and a raging desire of intelect to figure things out, not from any formal training in physics.

When thinking logically about the interaction of the cue stick, composition of shaft tip etc, and the cueball, one would THINK that speed would effect how much squirt there is; however, what gets my noggin in a bunch is that in effect it doesn't seem to be the case. That's why I explained in the follow up that what I think is happening is a mutual exclusion, rather the amount of additional spin imparted by the off center harder stroke creates additional CB to OB throw canceling the additional squirt. That's what I meant in that follow up post. I didn't mean to say there wasn't additional squirt. Just that it wouldn't seem as though there were in actual effect. Only when using BHE by the way. When using PE yo umay have to adjust more for a harder stroke, it's impossible to tell though because your mind is dhe oing the calculations necesary subconsciously based on experience where with BHE there are no calculations.

Hi Jaden,
May I suggest you experiment with the long rail first 90 degree cut shot (OB on rail). Play it first a half dozen times fast enough that swerve is insignificant. The CB should run 2 lengths of the table after inpact.

Then try it with the same alignment you worked out and hit it very hard...enough to run 5 table lengths. I expect you'll miss to the side by an inch or more, at least more than can be accounted for by swerve alone.

 

[Colin Colenso]

Mark this day down on the calendar Colin...this is where I go along with you and am in agreement. (this has to be a first)

Jaden said it correctly in his first post...and then he backpedaled to agree with the Post Hole Diggers thesis on the effects of how hard you hit the CB has nothing to do with how much deflection takes place. BULLSHIT!
Now I know not to read all of that crap any more.

DM,
If you're reading this...for some reason I miss ya already buddy.

Even miss the expectation of your socratorial debates, not to mention your penetrating assaults.

The whole thing seemed pretty lame....hope to see u here soon. (not many other forums worth considering)

 

[Jaden]

I'll agree with that.

Hi Jaden,
May I suggest you experiment with the long rail first 90 degree cut shot (OB on rail). Play it first a half dozen times fast enough that swerve is insignificant. The CB should run 2 lengths of the table after inpact.

Then try it with the same alignment you worked out and hit it very hard...enough to run 5 table lengths. I expect you'll miss to the side by an inch or more, at least more than can be accounted for by swerve alone.

I know exactly what you're talking about, and even allowing for motor control error at that much of a greater speed,I'll except that there is additional squirt for greater speed, I'm more referring to game play level speeds i.e. moderate speeds when I'm talking about the effect of canceling out. There comes a point when you're hitting hard enough that it doesn't increase the amount of spin on the CB and or the friction between CB/felt decreases the spin. I agree that speed affects squirt, but I know that if moderation is used that the aim and pivot/BHE system is the great equalizer and requires no MANUAL adjustment, that is the only point I'm trying to make.

 

[Colin Colenso]

Thanks for elaborating Colin. I'm still not sure if this is the essence of your theory, but this seems plausible (I'm not convinced yet that you wouldn't see random amounts of squirt). If static friction holds throughout the impact period, then the force acting tangential to the surface should add to the force acting through the center of the cueball in such a way that the resultant points in the direction of the cue. However, if some momentary slipping occurs, the tangential force is reduced and the force acting through the center of the cueball will send it off to the side a little, just as with ball/ball collisions (only here the tangential force is greatly reduced since sliding friction is involved throughout).

It seems that at easy way of testing this would be to hit balls with varying surface conditions, from sanded to highly polished, and see what happens.

My apology if I'm misrepresenting your ideas.

Jim

Jim,
I think you have stated it in a different way, but basically along the same lines of thinking.

I think there must be some degree on non-static friction...some slippage. It seems unlikely that every minute surface interaction locks in immediately. We see chalk dust fly everywhere, so things move around, settle, forces are distributed and these should tend to be along the line normal from the the center of the CB to the contact point/area.

Regarding static friction though, I'm not clear on the physics of this and that it would result in a perfectly linear net force along the line of the cue. I need some study in this area.

Colin

 

[lukeinva]

No it doesnt but if you back hand your opponent a couple times while playing your should win the match hell your hand might even deflect while your doing it but that shouldnt affect your play at all!

 

[jsp]

Hi Colin, nice new avatar. Doesn't look anything like your old picture.

Anyways, I've been doing a lot more thinking on this subject. I also carefully studied RID and your proposed SPID in your website. I totally agree with the RID theory, and believe this is the dominant force regarding squirt (i'm stubborn, i still don't want to use "deflection").

As for your SPID theory, forgive me if I misunderstand, but doesn't the theory essentially say that a component of squirt is due to the forces that are normal (perpendicular) to the cue ball's surface? Summing up all these minute forces gives a resultant force vector normal to the idealized spherical surface of the cue ball, which noncoincidentally goes through the center of the cue ball. SPID seems to be a lot more fundemental than RID since friction is not a significant factor when computing SPID, since it predominantly deals only with forces normal to surfaces.

Take a look at this video from Dr. Dave's website showing high speed video of a miscue. If you notice the initial departure trajectory of the cue ball at the moment of impact, the direction is straight through the cue ball's center. Because there is very minimal friction (which results in the miscue), RID is not a factor (because no spin was imparted on the cue ball) and SPID is isolated. Basically, if there is no friction between the cue tip and cue ball surfaces, then all the force (and squirt) experienced by the cue ball will be SPID and no RID.

So essentially, these two theories (SPID and RD) separate the two components of squirt in relation with friction. In the case of finite friction, there will both be SPID and RID...and assuming there is minimal "slippage", then RID dominates squirt. However, if we remove all friction between cue tip and cue ball, then there will be absolutely no RID, but SPID still remains. I buy that. Colin, let me know if I'm off the boat.

 

[Zorro]

It sounds close to BHE, but you're initial setup has got me slightly confused. Maybe it's your terminology. Anyway, yes, you setup with centerball, then you pivot about your bridge by moving your grip hand (the back hand) to the desired amount of english. Then you would stroke straight through that new point with a normal stroke. That is traditional BHE.

The swiping/swerving type is usually called other things like "swooping into the english."

Fred

Let me put it this way. I line up as if I were making a centerball shot. Then I shift my back hand to apply english. What happens next, I'm not sure. I attempt to strike the CB at the point where I adjusted for english, but at the same time I keep my eye on the contact point of the OB and try to follow through to that contact point. Does that cause my cue to swoop? I don't know. It would seem that because my stance is aligned to a centerball stroke that this fact would cause there to be not only squirt, but a "pulling" of the CB in the direction of the desired route. I have tried to just stroke straight through at the direction of the new angle established by BHE but this does not seem as effective as concentrating on the CP I wish to strike and stroking through as if I were still stroking center ball.

Also, a fact that nobody seems to mention here, the amount of squirt is influenced by the force of the hit. Therefore, even when using BHE, you will get more or less squir depending on the force applied. It then follows that the correction for squirt provided by using BHE is not "automatic" but must be calculated depending on the amount of force applied. I find that at easy and moderate strokes, little or no correction is needed, but with a heavier stroke I must correct, because BHE is undercompensating for the amount of squirt.

You might ask, then why use BHE at all. First, it is easier to apply consistently, and second, for most shots the amount of force used will be right for accurate shotmaking.

I hope I didn't make my newest explanation even more unclear than my initial one.

 

[Zorro]

Ya know, there's not like a digger's union or something. We *are* allowed to have different views...

I think the jury's out on this issue. The simple models suggest squirt is independent of speed. Basically, if the shaft is deflecting the same way on a harder shot as on a softer shot [just more vigorously and bending further] then squirt should be the same. But if a harder shot causes a shaft to bend differently, then the effective endmass can be different.

My opinion is that at least for some shafts harder hit shots squirt more. The problem is neither I nor anybody else that I know has done careful experiments to confirm this or otherwise. They're hard to do. There are other variables, like strokes getting less precise and swerve getting reduced with speed that muddy the waters. I'd like to see some good measurements on this issue.

mike page
fargo

My personal observation is that the harder I hit the CB, the more squirt I get. Sometimes, if I need to hit a ball extremely hard using english, I will have to aim more than a ball's width to one side or the other (even using BHE) in order to compensate for the extreme squirt. How do I know it's squirt? Well, if I am using right hand english, it is whatever causes the CB to go to the left. I call it squirt, but maybe some of you scholars can identify other forces at work. No matter, in practice I still have to compensate for it, whatever you want to call it.

 

[Jaden]

In my experience that isn't the case.

My personal observation is that the harder I hit the CB, the more squirt I get. Sometimes, if I need to hit a ball extremely hard using english, I will have to aim more than a ball's width to one side or the other (even using BHE) in order to compensate for the extreme squirt. How do I know it's squirt? Well, if I am using right hand english, it is whatever causes the CB to go to the left. I call it squirt, but maybe some of you scholars can identify other forces at work. No matter, in practice I still have to compensate for it, whatever you want to call it.

I can hit a shot from a foot away or six feet away soft or really hard, as long as I'm using BHE it hasn't made a sh%t bit of difference so long as I stroke straight through the ball. I know on harder shots there is a greater tendency for people to pull the cue into the shot, or rather NOT stroke straight. I even used BHE with a predator cue and it works just fine, so unless you have a wet noodle for a cue I'd look more at your stroke.

 

[Colin Colenso]

Hi Colin, nice new avatar. Doesn't look anything like your old picture.

Anyways, I've been doing a lot more thinking on this subject. I also carefully studied RID and your proposed SPID in your website. I totally agree with the RID theory, and believe this is the dominant force regarding squirt (i'm stubborn, i still don't want to use "deflection").

As for your SPID theory, forgive me if I misunderstand, but doesn't the theory essentially say that a component of squirt is due to the forces that are normal (perpendicular) to the cue ball's surface? Summing up all these minute forces gives a resultant force vector normal to the idealized spherical surface of the cue ball, which noncoincidentally goes through the center of the cue ball. SPID seems to be a lot more fundemental than RID since friction is not a significant factor when computing SPID, since it predominantly deals only with forces normal to surfaces.

Take a look at this video from Dr. Dave's website showing high speed video of a miscue. If you notice the initial departure trajectory of the cue ball at the moment of impact, the direction is straight through the cue ball's center. Because there is very minimal friction (which results in the miscue), RID is not a factor (because no spin was imparted on the cue ball) and SPID is isolated. Basically, if there is no friction between the cue tip and cue ball surfaces, then all the force (and squirt) experienced by the cue ball will be SPID and no RID.

So essentially, these two theories (SPID and RD) separate the two components of squirt in relation with friction. In the case of finite friction, there will both be SPID and RID...and assuming there is minimal "slippage", then RID dominates squirt. However, if we remove all friction between cue tip and cue ball, then there will be absolutely no RID, but SPID still remains. I buy that. Colin, let me know if I'm off the boat.

Hi jsp,
Sorry I missed your reply and query before.

You're summary is pretty good.

My way of understanding the tip CB collision is one of millions of tiny collisions, each of which are like billiard ball collisions (elastic) which are almost entirely spid (no grip) based.

When tips grip statically to the CB, then all particles lock together and direct the force along the line of the cue. I have put forth the idea that on many shots that we think grip perfectly, that there is actually slippage, many collisions doing their own thing wihout linking together statically.

We do see this on minor miscues using crappy tips and chalks I am quite sure, but it's degree of significance with good equipment is not so clear.

It provided a possible explanation for the common belief that hard shots squirted more, but one must realize there are 2 other factors at play here that could be entirely or significantly responsible for this conception.

They are:
1. Harder shots swerve less
2. Harder shots throw the OB less

These two factors add together in the case of Inside English, such that we must aim significantly thicker to make the pot, giving the illusion of a large amount of squirt.

For Outside english shots the reduction of swerve at speed would have us aim thinner, and the decrease in spin induced throw at speed means we should aim thinner than for the same shot at lower speed which will turn the OB more. Both meaning we must aim thinner, hence suspecting that it is increased squirt actually creating a thicker contact than we are aiming for.

Back to SPID now...

Now SPID doesn't infer that hard shots would squirt more, but it could have provided an explanation for it, and still well might for bad tips or shots with extreme side english.

I suspect that SPID plays a minor role in squirt on most shots, but at the moment that is speculation based on evidence such as the significant reduction in squirt for low-end mass cues. Still more thinking to be done on the subject