Throw and draw shots?
- Thread starter Billy_Bob
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Throw on Draw
You need to cut more when applying draw (draw increases the throw - the backspin on the cueball applies a little FORWARD spin on the object ball - this forward spin on a cut shot is away from the pocket). As far as amount its a feel thing.
You need to cut more when applying draw (draw increases the throw - the backspin on the cueball applies a little FORWARD spin on the object ball - this forward spin on a cut shot is away from the pocket). As far as amount its a feel thing.
I think that if you are using throw that the most important thing is speed, more speed = less throw. I think that when I use bottom while I throw a ball at medium/soft speed it adds extra angle. I think it has to do with getting the ball rolling with the throw when you use back spin. Oh and the sharper the cut the less throw you will get because there is less energy being transferred between the balls and less contact time.
Speed is important and more speed does mean less throw. But I'm not sure that you could consider it the most important thing.I rack balls said:
Getting the ball rolling does have something to do with it, but there's a better way of looking at it, in my opinion. Picture a flat plane going through the contact point and perpendicular to a line drawn between the centers of the balls at the moment of impact. The friction force always lies in this plane. It can be pointing straight up or down, or to one side or the other, or anywhere in between. In other words, it can be pointing in any of the directions the hands of a clock can point (360 degrees), but it is always within this plane.I rack balls said:
The more draw the cueball has on it, the more the friction force points toward the vertical or 12 o'clock position. This means less sideways throw. The more follow on the cueball, the more the force points downward toward the 6 o'clock position. This also means less sideways throw, or, shall we say, less throw period, since it's the sideways component that affects the shot.
So the fact that the object ball acquires some topspin when draw is used is an effect, not a cause. It's the vertical orientation of the friction force that produces less sideways throw as well as the immediate topspin.
The greater the cut angle, the more the friction force points in the sideways direction, either at 3 o'clock for a left cut, or 9 o'clock for a right cut. This means more throw in the sideways direction, so larger cut angles produce more throw unless sidespin is used to modify it. Although somewhat of a misnomer, this is called "collision induced throw". It comes from the fact that the cueball is partly scooting past the object ball in a sideways direction for all but dead straight on shots.
So more draw or follow equals less throw, always. Greater cut angle equals more throw, generally speaking, but there are exceptions. The net amount of throw is the sum of these two effects. But for any given cut angle, more draw or follow means less throw.
Hope that helps.
Jim
Jal said:
OK, this has got to be the "best post of the year". This really explains everything to me. I have been having trouble with cut draw shots (not pocketing OB) and realized this, but come to think of it, I have also had trouble pocketing the OB with cut follow shots as well!
Thank you for your excellent explanation.
Jim, I've always enjoyed your explanations, but I find myself disagreeing with you on this post...specifically when you say that both draw and follow means less throw. I do believe that draw means less throw, but I argue that follow means more throw.Jal said:
I think this is where you err. I agree that the sideways component is what causes throw, but you're arguing that the sideways component is reduced whether you hit with follow or draw. Assuming the CBs are hit with the same linear speed for all cases (follow, draw, and stun), the magnitude of the sideways component remains unchanged, since the sideways frictional component is caused by the horizontal speed of the CB alone. Any type of vertical spin on the CB has no impact on the sideways frictional component, since the force directions are orthogonal (perpendicular).Jal said:
Whether you hit the CB with follow or draw, you are just adding a vertical frictional component on top of the sideways component. The resulting net frictional direction would be closer to 2oclock with draw and 4oclock with follow. The sideways component for all cases, however, remains the same magnitude.
The question now is does adding an upward or downward frictional component accentuate or reduce the throw effects, assuming the same horizontal frictional component for each case?
I argue that an upward frictional component reduces the effect of throw because it helps the ball roll sooner in the direction of the ideal OB path. A downward frictional component increases the effect of throw because it hampers the ball from rolling in the direction of the ideal OB path.
Thus, you get more throw if you hit the CB with follow and less throw if you hit the CB with draw, compared to the amount of throw if you hit the CB with stun. (That is why it is fairly common knowledge to hit the CB with a bit of draw and outside english to prevent skids/kicks.)
Wow! Thank you Billy Bob for your kind words. Is there some sort of remuneration involved?Billy_Bob said:
I should mention that I oversimplified things when I said that throw increases with cut angle except as modified by spin. In fact, because of what "I rack balls" mentioned above about speed, for shots where there is relatively little to moderate draw or follow on the cueball, throw only increases up to some cut angle and then stars falling off. It starts falling off because of the increased surface speed between the balls as you increase the cut angle.
Where it starts falling off is hard to pin down because it does depend very much on the amount of follow or draw and the speed of the shot. But with very little draw or follow and soft to moderate speed, it happens at roughly a 20-30 degree cut. With more draw or follow, it happens at more severe cut angles. With maximum follow or draw, it doesn't fall off at all but increases all the way up to 90 degree cut. But although it increases all the way up to 90 degrees, it's not very much, reaching a maximum of only about a degree of throw at 90 degrees. In other words, a large amount of follow or draw reduces the throw severely at all cut angles.
It's a little confusing but that's the nature of the beast, I'm afraid.
I'm glad to see you're back to posting (you took a hiatus a few months ago). I'm sometimes amazed at the pool related material you manage to come up with off the net (like that automatic leveling system for shipboard tables a while back!)
Jim
Hi Jsp. Although we still disagree, thanks for the excellent criticism. I appreciate a well laid out argument and yours is so clear that it's immediately obvious where our point of disagreement is.jsp said:
My argument is that there's only so much friction to go around...it's a zero-sum game, so to speak. The magnitude of the friction force is determined by the surface conditions, as quantified by the coefficient of friction, and the magnitude of the compression force acting between the balls. At any moment it's equal to the magnitude of the compression force multiplied by the coefficient of friction (around .06 on average but varying considerably with surface speed).
Draw or follow doesn't change the magnitude of the compression but will have some effect on the coefficient - reducing it some because of increased surface speed (all else being equal). But let's ignore that and treat the coefficient as constant. We can say then that the magnitude of the friction is the same regardless of how much follow or draw is on the cueball. So (I think) you have to conclude that what you give to the vertical component, you have to take away from the horizontal one (vectorally), and visa-versa. In other words, the vertical component does not simply add (vectorally) to the horizontal one, but merely changes the overall direction.
I don't think there is any significant difference between draw or follow because I don't believe the cloth comes into play. Although the magnitude of the friction force is quite large (it can be around a hundred pounds or so!), the contact time is so short that I've figured the downward travel to be only around a thousandth of an inch (or thereabouts) during impact. I doubt that any significant compression/friction force between the cloth and ball can build up with so small a downward displacement. And once the impact is complete, the deed is done and the object ball has acquired its direction, regardless of what happens after that. (An exception would be if the object ball is contacted above its equator and its spin axis is thus tilted, in which case it will definitely curve).
If you're not buying any of this, any further comment is of course welcome.
Jim
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Hey Jim, thanks for the response. Sorry for the delay, but I have been thinking a lot about your reply.Jal said:
Your post and arguments do make sense to me. However, part of me just feels like we are missing something. I have to think about it more. If I don't respond again to this thread, then I concede that you are correct and I am wrong about this.
Without sounding arrogant, I can't help but to feel that this post, although very interesting concerning the physics involved with the different reactions an ob might have after being hit with a draw/follow cb, involves waaaaayyy tooooo much thinking when it comes to the simple ability to pocket balls. I may be very ignorant, and this may be testament that I'm not a very good player, but I have never felt that balls needed to be cut differently (thicker/thinner) when using follow and draw. I'm sure that when put on paper, there must be some kind of affect, but I think it's completely too small of an affect to call for adding this sort of a reaction calculation to your thought process while getting down on a particular shot. If there is a difference in thickness of a cut between follow and draw shots, it has to be so minute that it doesn't need to be added to the pre shot thinking process, and can easy be learned by feel without thought.
If somebody takes all of the info in this post to the pool table with them tonight, they'll be thinking entirely much, and not letting giving their bodies/brains the opportunity to learn from repitition.
Ok everybody..........................ding ding.................round one!!
dave
If somebody takes all of the info in this post to the pool table with them tonight, they'll be thinking entirely much, and not letting giving their bodies/brains the opportunity to learn from repitition.
Ok everybody..........................ding ding.................round one!!
dave
I think you're right Jsp. Between your post and an email I received from a poster on another board (CCB), I've come to realize that there is at least a slight difference between the draw and follow situations, and along the lines you were indicating.jsp said:Hey Jim, thanks for the response. Sorry for the delay, but I have been thinking a lot about your reply.
Your post and arguments do make sense to me. However, part of me just feels like we are missing something. I have to think about it more. If I don't respond again to this thread, then I concede that you are correct and I am wrong about this.
The sideways component of throw does, well, throw the object ball to the side a bit (surprise!). But then any imparted topspin or backspin from the vertical component is, shall we say, no longer "in line" with the object ball's direction and will cause it to masse a little. With draw on the cueball the apparent throw will be reduced, and with follow it will be increased. I haven't figured how big an effect this is yet, but hope to get an answer shortly.
While I think I'm right about the cloth having no immediate effect because of the small vertical displacement that occurs during impact, perhaps you or someone else will take another look at this.
Thanks Jsp.
Jim
There has been a lot debate whether knowing the physics is of any use, and I don't think you'll get much of an argument from those interested in it that you do have to play by feel. But as jsp put it in another thread, a knowledge of cause and effect is almost certainly helpful, particulary to beginners, if only to give you an idea what went wrong and what you have to do to correct it.Tokyo-dave said:
There definitely is a significant difference in the amount of throw between stun shots and those with follow or draw on the cueball. It's enough of a difference to affect the outcome of a shot. CaptianJr indicated above that he has to adjust for it. Knowing you missed because of it, rather than because of a bad stroke or poor aiming, can't hurt, I think. I doubt that there is too much of a difference between follow and draw, but as mentioned in a previous post, I can't say for sure at this point.
But I agree that eventually all of this has to become second nature.
Jim