rekoons wrote: Iranu wrote:
Dan-cat wrote:This really doesn't make much sense... Much like my explorations with transmitted side on long cut back doubles.
What I mean is, if you hit the right part of the object ball plain ball, they will go in. So why does the side help?
Maybe deliberately putting side on stops you accidentally flicking a random bit on and throwing the ball
Yeah, I've heard that argument as well, the reasoning is indeed along the lines that it could be easier to consistently put the same amount of side on than it is to consistently hit the center
... I don't really think so myself but understand the reasoning. maybe it IS the reason after all, who knows...
I absolutely want to avoid playing with side as much as possible, but for this particular angle it seems to help.
I have some time available while I wait for a truck so I will add a bit to my novella. Perhaps it will be a full fledged novel before I am through. Take note of the bolded bit above.
In my previous post, I hope I emphasized the advantage of occasionally adding Spin Induced Throw or Helping Side to re-direct the object ball onto an unnatural path. That is far, far from the whole story. Now, I will make my second, certain-to-be-controversial statement...contrary to popular belief, adding side to the White is NOT in fact responsible for causing the White to swerve, or arc if you prefer. I expect to see the pitchforks and torches on the horizon now. In fact, I can very easily present some evidence to you from no less than the great Jack Karnehm himself to back up this bold claim. But first I must quantify what I mean that the side is not responsible for the swerve; of course it is! It is just not responsible in and of itself. It is absolutely possible to strike the White in a perfectly measureable straight line while adding a fair amount of sidespin to it. Pros do it all the time; myself and probably most of the amateurs on Snooker Island, not so much. Be patient, it will take quite a bit of time for me to get around to stating what it is that actually makes the White swerve or arc.
I have sifted through a fair amount of instructional materials in my time and among my most treasured possessions are two books from the father of Snooker, Joe Davis. I occasionally loan out some instructional materials and have lost a couple things as a result. However, no one gets their hands on my Joe Davis books unless I am there to oversee. The books don't leave my prying eyes in the presence of others. One of the most profound of the many nuggets of information that is ingrained in my brain goes something like this, "The difference between a professional player and an amateur is that a professional strikes the White ball precisely
where he intends to." That may not seem like much. But it is huge. That is exactly what the scene in The Rack Pack is about where Steve Davis just keeps repeatedly striking the White off the Black cushion while the other guy holds a cue on top of his head to keep him still. Profound.
What does that mean for the rest of us? I am a mechanical engineer by nature. My brain has numbers and percentages constantly swirling around inside. A mechanical engineering principle is that however you may wish to design a machined part, it can never be EXACTLY what you designed it to be. Oh, it will be very, very close but not perfect. If I design a steel cube exactly 1 inch by 1 inch by 1 inch and I want a 1/4 inch diameter hole exactly in the center of one face through to the other side, then THAT design is the one thing that I cannot possibly get machined. It is called TOLERANCING. Maybe one side is just a hair's width too wide or another side is a hair's width narrow, or the hole is just a touch too big, too small, or a tiny bit off center. But a machinist cannot possibly make the part exactly, precisely correct according to the design. Even if he could, it wouldn't stay correct for long. If steel warms up or cools down, even just a little bit, its dimensions will actually change. So the engineer designs the part so that it will serve its function even if it is a little bit off. Your snooker stroke should be designed the same way.
This is where Rekoons' bolded statement comes in. No offence to you of course Rekoons, but when you believe that you are hitting the White center ball, you probably are not. I know
that I am not. That is what Joe Davis is saying. In engineer-speak, Joe Davis means that a professional has a very tight tolerance as to where he strikes the cue ball, perhaps plus or minus a millimeter, too small to even talk about in terms of tip diameter. Me? I have no simple way of measuring it, but just by logic, I expect that the tolerance of my striking White is probably much closer to plus or minus a half cue tip, especially if I am playing a very firm stroke. In millimeters then, that means where I think
I am striking (center ball), I may be rather close, but I may be putting 4 or 5 mm of RIGHT hand side, or perhaps 4 or 5 mm of LEFT hand side on the White. Maybe more. THIS in fact is the reason that I rarely strike center ball. Except for long potting or long safety snicks for obvious reasons. If (because I don't have the time or desire to practice six or eight hours a day like Steve Davis,) my cue tip is really going to sort of hover centered around a particular spot on the cue ball that I intend to strike, then I am better off to strike intending, say, a touch of right hand. In reality, I will either get a proper touch of right hand side, or a bit more than a touch of right hand side (but it will still be right hand side), or my tip may wander back toward center ball in which case White will probably travel a straighter line anyway. All those things are kinda good.
On the other hand, if I try
to strike center ball, then in reality, I may get center ball, or I may get a bit of right hand side, or I may get a bit of left hand side. Now, apply THAT concept to your White ball above the Black scenario, Rekoons, with which you started this thread. Before you learned about the helpfulness of outside english, you would either pot or miss this shot seemingly arbitrarily. Sometimes they would go in, sometimes you would miss a little thick, and sometimes you would miss a lot thick. And all the while you were aiming the same way and you thought
you were striking center ball. See a correlation here?
So when I look at any particular stroke (barring the long pots and safeties mentioned above) I decide is it better played with outside english (if directional throw will be a factor for thinner shots)? or better played with inside english (primarily used for positioning the White on rather thick shots; if you use inside english on thin shots, you will probably miss the pot near certain)? And whichever of those two is better suited (usually outside english maybe 8 to 1 ratio), I will align my tip half to three-quarter tip diameter off the vertical center line of the cue ball.
Of course, many strokes will need to be played with top spin or screw spin as well and this is where the danger comes in. Now we will finally get to why I said side spin does not cause White to swerve. Let's do a thought experiment...
Imagine you are a fantastic basketball player, say, at the level of a mediocre Harlem Globetrotter. You can spin a basketball perfectly vertical on your finger tip. I mean the South Pole of the spinning ball is on your finger, the North Pole is pointing directly, exactly away from the center of the earth. Now........move your finger away and allow the basketball to drop straight down toward the center of the earth (gravity). What happens? The ball hits the ground and it bounces....straight back up. Does it go left? right? forward? back? Why not? The exact South Pole of the ball hits the ground and it is spinning on a theoretical point mass. (In reality, of course, the ball will compress like a pancake so there is a surface contact and friction and a fair amount of the initial spin rate will be absorbed, so the actual RPM's of the ball will be reduced after the bounce.) So it will bounce perfectly straight back up despite the initial spin without any "swerve" or "arc" to any particular direction. But let's back up, go back to spinning the ball on your finger, but then before you release it to drop, pull your finger slowly to your body slightly so the ball "tilts on its axis" away from you, then allow the ball to drop. Now what happens? The answer of course depends on if the ball was spinning clockwise or anti-clockwise. It will either bounce to the left or the right. It wasn't the spin that made it change direction; it was the spin in conjunction with the tilt.
~~~~~~~~wavy lines back to snooker reality~~~~~~~~~~
So it is really the same thing on a snooker table. Undoubtedly, you have learned to hold your cue as horizontal as you possibly can. This is not just to look cool. If you strike off-center on the cue ball so that you impart side spin WITHOUT ANY TOP SPIN OR SCREW SPIN, the cue ball will travel away from the tip in a straight line without curving. The cue ball will simply begin sliding and spinning, balanced perfectly on its "South Pole". The cue ball will not swerve or arc at all. Now, in full disclosure, you will still see the squirt or deflection because that is a function of striking the cue ball off balance, not through the center of gravity......more mass is on one side of the vector of the impact path than the other. So the cue ball will still squirt one way or the other (depending which side you strike of course) and how far it squirts will depend of how far off center you initially struck. This is what Dr. Dave's equation would be all about that we discussed in passing in that other thread. But the thing is that if the cue is PERFECTLY horizontal (to be honest, that is virtually impossible) and strikes along the horizontal centerline (but not on the center point) and the path of the cue stick remains true and parallel to the slate, then the cue ball will deflect, but it will never arc back on line. But in real life, of course, other spins, top or screw, are applied either by accident or design. If we WANT to arc the cue ball back, we raise the butt of the cue up a bit. Jimmy White's famous Masse shot is the ultimate demonstration of this. In my opinion, quite possibly the single greatest exhibition shot ever produced for an audience: https://www.youtube.com/watch?v=5Sk9_hWUDZM
So imagine if Jimmy had elevated his cue to the extreme and simply struck down straight perfectly on the vertical centerline of the cue ball: White would have travelled out toward the Yellow spot, then reversed direction exactly right back where it came from. The side spin and the top/screw spin must work together to make the cue ball curve. If you have one without the other, the cue ball will travel a pretty straight line. THAT is why it is so important to keep your cue stick as horizontal as possible (unless you are purposely trying to swerve): to prevent unintentional spins which are caused by the elevated cue and will lead to curves that you didn't intend.
Oh, and going back to my "evidence" direct from the mouth of Jack Karnehm....it is exactly at 1:30 when he says ".....a touch of right hand side, with a semblance of screw on it...
" That "semblance of screw" is extremely important because it is then transferred to the object as a trace of top spin which is what actually allows the object to tilt and bite into the cloth and travel off in the odd direction. For the record, I ran my numbers through Dr. Dave's calculator so it is confirmed....a "touch" of spin on the White will always transfer to the object as a "trace". It is a fixed ratio.