Centre ball accuracy vs screw accuracy

[hollowmoon]

Interesting today when practising..

I was playing appallingly.. missing very easy pots. Then I tried some long pots off blue spot frombaulk. Again totally wayward.

Then I decided to start hitting the cue ball dead centre rather than screw (which seems to be my default for some reason) and I started knocking in 6-7/10! It was amazing. And so I thought hitting the ball low must really be accentuating my cueing errors where as keeping it simple really helped my aim.

Anyone else experienced something similar?

[Nifty50]

Its harder to hit centre ball when hitting low. Easy to put bit of side on and throw the cue ball.

[hollowmoon]

yep i think that was very apparent.. I was really surprised at how much difference there was!

[vmax]

You're probably doing something different with your cue action when trying to screw back. I was the same with power run throughs until I realised that I was putting a bit of shoulder into it to get that extra pace, strangley something I don't do when screwing back with power because when screwing back I put a flick of the wrist into the stroke for that extra zip.
So I applied that wrist flick to run throughs and it worked so that's now my default stroke for all power shots.

[Zelig]

This is something that could be related to this thread and that I had in mind to ask you all -- more experienced guys -- for a while. Imagine you are going for a pot requiring a non-negligible cut -- say, hitting the OB half-ball or less.
If I strike the CB using top-spin or back-spin, does the final direction of the OB change (even just marginally) with respect to the case in which I use plain ball (that is, I strike the CB right in the centre) ? I know direction changes when I use side, but I always wondered about possible "marginal side effects" of top- and back-spin when no (intentional) side is used.
I don't know what physics says in this respect. If theory says "no change", then any change in direction that I observe when I play should be due to me adding some unintentional side when I try top- or back-spin, correct? I suspect it's my fault, but still, I observe that my back-spin tends to widen the angle taken by the OB. Any suggestions and comments will be deeply appreciated!

[presprout]

Unless it's a perfect elastic collision, then the spin (top or bottom) on the cue ball will impart some (possibly off centre because of the nature of the contact) spin on the object. The thinner the cut, the less this will be. A full ball contact should have the most effect, but you will see it the least because everything is in line. Playing bottom, in principle, should impart more roll on the object ball. Playing top should slightly retard it.

In practice the collision is quite elastic, and my ability sufficiently low, that I don't factor this in, or notice it.

[vmax]

If you think you're missing due to transfered unwanted side you're quite wrong, if you're not cueing straight and imparting unwanted side on the cue ball because you have aimed for a centre cue ball strike then the cue ball has deflected very slightly off the line of aim so will contact the object ball in the wrong place.

Check your cueing by shooting the cue ball over the blue, pink and black spots from the brown spot and back to your tip and if you're concerned about striking low play a drag shot over the spots at a pace not exceeding coming back from the top cushion to the pink spot.
Film your self from in front and behind and look first for head and body movement and if that's ok then look to your grip hand and if that's ok then it's a stance issue and you will need to adjust your feet to get the cue on the line of aim.

If you're right handed and imparting right hand side then you need to stand more to the right and vice versa, reverse for left handers.

[Zelig]

If you think you're missing due to transfered unwanted side you're quite wrong...

… the spin (top or bottom) on the cue ball will impart some (possibly off centre because of the nature of the contact) spin on the object...

Hi both -- I was not talking about spin of the OB, and I did not want to revive the everlasting debate about transferred side (some say it exists, some say it doesn't: I wasn't claiming in either sense): I wrote about direction of the OB after the collision. So the story is: suppose that I make three shots where my CB hits the OB exactly in the same spot of the OB - say, exactly half ball in the "left half" of the OB.

Shot 1: I strike the CB plain (exactly in the centre of the CB). The OB goes to the right, diverging from the line of aim by X degrees.

Shot 2: I strike CB with maximum left side (exactly "West" of the centre of the CB, no top spin and no back spin). The OB goes to the right, diverging from the line of aim by more -- say, X+10 degrees from the line of aim.

Shot 3: I strike the CB with a deep back-spin and no side (exactly "South" of the centre). The OB goes to the right... by how much? I thought that theory would say a divergence of X degrees just like in Shot 1, but when I practice, I have the feeling that I obtain a hybrid case between the previous two shots: the OB seems to diverge from the line of aim by, say, X+5 degrees.

There should be no discussion about Shots 1 and 2: the widening of the angle that we observe in Shot 2 with respect to Shot 1 is not a "transferred side story", it is a change in direction of the OB induced by intentional side: it happens in reality and is acknowledged by everybody.

My actual question was about Shot 3: does physics predict that the OB should diverge by X or by

X+5 degrees? If theory says X, than it is my miserable cue action that adds a bit of unintentional running side when I play these type of shots, which then makes the OB deviate by X+5 degrees (for the same acknowledged reasons that apply to Shot 2).

Whatever the truth is, thanks a lot vmax for your suggestions, I'll do.

Best,

Z.

[hollowmoon]

Hi both -- I was not talking about spin of the OB, and I did not want to revive the everlasting debate about transferred side (some say it exists, some say it doesn't: I wasn't claiming in either sense): I wrote about direction of the OB after the collision. So the story is: suppose that I make three shots where my CB hits the OB exactly in the same spot of the OB - say, exactly half ball in the "left half" of the OB.

Shot 1: I strike the CB plain (exactly in the centre of the CB). The OB goes to the right, diverging from the line of aim by X degrees.

Shot 2: I strike CB with maximum left side (exactly "West" of the centre of the CB, no top spin and no back spin). The OB goes to the right, diverging from the line of aim by more -- say, X+10 degrees from the line of aim.

Shot 3: I strike the CB with a deep back-spin and no side (exactly "South" of the centre). The OB goes to the right... by how much? I thought that theory would say a divergence of X degrees just like in Shot 1, but when I practice, I have the feeling that I obtain a hybrid case between the previous two shots: the OB seems to diverge from the line of aim by, say, X+5 degrees.

There should be no discussion about Shots 1 and 2: the widening of the angle that we observe in Shot 2 with respect to Shot 1 is not a "transferred side story", it is a change in direction of the OB induced by intentional side: it happens in reality and is acknowledged by everybody.

My actual question was about Shot 3: does physics predict that the OB should diverge by X or by

X+5 degrees? If theory says X, than it is my miserable cue action that adds a bit of unintentional running side when I play these type of shots, which then makes the OB deviate by X+5 degrees (for the same acknowledged reasons that apply to Shot 2).

Whatever the truth is, thanks a lot vmax for your suggestions, I'll do.

Best,

Z.

Are you not simply experiencing what I think I was? ie by hitting so low you are accentuating any slight deviation from center and basically sending the CB off line?

[Mark187187]

Well, a spinning ball in any direction is going to cause different friction with the object ball. How much impact will vary by cut angle, cue ball speed, amount of cue ball spin etc. Impact ranges from negligible/undectectable to noticable. You're not going to get a mathematic equation which covers the variables, and you're only going to figure this out by trial and error. My guess is if you're missing half ball cut shots with screw you're simply not as in control during screw shot as plain ball. I don't make any conscious realignment of a half ball shot to account for any possible spin induced throw, and it's not a problem.

[Zelig]

Are you not simply experiencing what I think I was? ie by hitting so low you are accentuating any slight deviation from center and basically sending the CB off line?

I suspect so, that's why I posted in this thread

[hollowmoon]

I suspect so, that's why I posted in this thread

haha.. faiir dos