Close carambole and throw

F

Fastolfe

AzB Silver Member
Silver Member
Hey everybody,

I have a question for you physics buffs. Here's a table configuration: I want to carom the 2 onto the 1 and pocket the 1:

CueTable Help



If I play it like this (i.e. simply aim the 1 with the 2, to determine where I should hit the 2 with the cueball), it doesn't work of course because of throw:

CueTable Help



So instead, I play it like this: I imagine the 2 shifted about 1/4 ball in the general direction of travel of the cueball and aim this imaginary 2 onto the 1. Then I shift my cue back to the real 2, keeping the aiming line parallel, and see where I should really hit the 2:

CueTable Help



(I know the shot looks unlikely, I exagerated a bit to show what I mean with the cuetable thing. I hope it's visible enough).

The shot is quite doable, and my little method seems to work okay, but it seems very sensitive to how hard I hit the cueball: if the cueball hits too slow or two hard, the shot fails (or I try to compensate and get lucky, but it doesn't work very well). If I try to use english, it's even worse.

So my questions are: is throw that sensitive to the speed at which the balls collide? Is there a better method to play that kind of shot? They come up all the time, so I'd really like to predictably make them.
 
Yes it is that sensitive. You also have to take in effect that if you are not striking the cueball dead center that squirt of the cueball changes everything as well. I would hit this so the one falls with pocket speed at most.
 
At high speed, the effect of collision induced throw is lower. Like if the shot were aimed for the center of the pocket, it might throw 1/4th ball to the side. That's at very high speed and with clean equipment.

If making the ball is your only goal I think you hit this one firmly. But the downside is hitting a shot hard decreases accuracy, which is important for the combo.

The decision to hit hard or soft also depends on the game you're playing. In 9 ball, if you miss, you want the object ball to go flying and hopefully end up in a bad place for the opponent. Hanging a ball, especially the 9, would be a mistake. In 8 ball, you can hang it there and block the pocket, and sometimes it's almost as good as making the shot.

Most people play these either quite hard or quite soft... My personal habit to play these shots very slowly (sometimes even in 9b) even though it makes aiming harder. It also helps that I gain a little accuracy from doing a very small, simple stroke.
 
Throw varies with a lot of things. For a complete list, with links to articles (with illustrations, examples, and video links), see:


The best approach on your shot probably varies from one person to the next. I don't have any general-purpose answers; although, more speed will give you less throw (except at small cut angles).

Regards,
Dave
 
dr_dave said:
Throw varies with a lot of things. For a complete list, with links to articles (with illustrations, examples, and video links), see:

Click to expand...

Fantastic info, thanks a lot!

dr_dave said:
more speed will give you less throw (except at small cut angles).
Click to expand...

How strange. Then again, since throw is the product of friction between the balls, I suppose it depends on how long the balls stay in contact and how hard they "press" on each other at that time, so it sort of makes sense:

- near full contact: hard compression, lots of friction, but the balls don't slide much on each other, so no or little throw
- 1/2 ball contact: medium compression, medium contact time, medium slide between the balls = medium throw
- thin cut contact: little compression, so little friction and little throw

I'm kind of pulling that line of reasoning out of my butt, not being a physicist or anything, but it seems to fit your observation. It also fits my own observation, which is that cruddy balls throw more than clean polished ones.

Hmm, cue games can make the brain hurt sometimes :)
 
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