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View Full Version : Draw and CB 90 degrees vs straight back?



Billy_Bob
12-09-2005, 12:34 PM
When making a cut shot, I've been using draw shots a lot lately to get the cue ball to go 90 degrees from the OB direction to the pocket.

And of course if the shot is fairly straight in, a draw shot will make the cue ball come straight back.

The problem I'm having is with "in-between cut and straight in shots". I'll have a slight cut shot and will think if I cheat the pocket a little, the cue ball will go 90 degrees with a draw shot. But instead the cue ball comes back rather than going 90 degrees.

So what is the dividing line between a cue ball coming straight back as opposed to going 90 degrees? How much of a cut does it need to be?

Bob_Jewett
12-09-2005, 01:18 PM
<blockquote><font class="small">Quote Billy_Bob:</font><hr> When making a cut shot, I've been using draw shots a lot lately to get the cue ball to go 90 degrees from the OB direction to the pocket.

And of course if the shot is fairly straight in, a draw shot will make the cue ball come straight back.

The problem I'm having is with "in-between cut and straight in shots". I'll have a slight cut shot and will think if I cheat the pocket a little, the cue ball will go 90 degrees with a draw shot. But instead the cue ball comes back rather than going 90 degrees.

So what is the dividing line between a cue ball coming straight back as opposed to going 90 degrees? How much of a cut does it need to be?
<hr /></blockquote>
On a shot with draw, the cue ball will not follow a 90-degree line to the path of the object ball. It will draw back from that line. I think you are confused between draw and stun. It is possible to hit the cue ball low and have it arrive at the object ball with no follow or draw. That's a stun shot, and the resulting carom angle is 90 degrees. If the cue ball has either follow or draw, it will depart from that 90-degree line.

A graphical method of calculating the carom angle for any cut and any amount of draw or follow is available for free on-line. Should I look up the URL?

But from your other post about getting lots of knowledge, I suspect that you are pulling our collective leg on this one.

dr_dave
12-09-2005, 03:51 PM
Billy_Bob,

As Bob pointed out, the 90 degree rule applies only for a stun shot. With draw or follow, the cue ball curves away from the tangent line.

See my January '06 instructional article (http://www.engr.colostate.edu/~dga/pool/bd_articles/jan06.pdf) for more info on predicting the cue ball direction for various cut angle draw shots.

Regards,
Dave

<blockquote><font class="small">Quote Billy_Bob:</font><hr> When making a cut shot, I've been using draw shots a lot lately to get the cue ball to go 90 degrees from the OB direction to the pocket.

And of course if the shot is fairly straight in, a draw shot will make the cue ball come straight back.

The problem I'm having is with "in-between cut and straight in shots". I'll have a slight cut shot and will think if I cheat the pocket a little, the cue ball will go 90 degrees with a draw shot. But instead the cue ball comes back rather than going 90 degrees.

So what is the dividing line between a cue ball coming straight back as opposed to going 90 degrees? How much of a cut does it need to be?
<hr /></blockquote>

heater451
12-09-2005, 05:25 PM
I'm reading your "90 degrees" differently from Bob and Dr.Dave. . . .

Physically speaking, they are of course correct with their answers, regarding the 90-deg angle between the paths of the cue ball and the object ball.

I'm interpreting your use of "draw" and "90 degrees", to mean making the cueball re-direct to (roughly) 90 degrees from your cueball path. That is, if you were cutting a ball 30 degrees to the left, you're wanting the cueball to move on a path 120 degrees to the right.

Let me describe it another way:

Imagine a clock-face on the table, where the cueball will be travelling parallel to a line from 6 to 12. The object ball will be off of that centerline, enough to create the 30 degree cut when struck by the cueball--this path would be from the center of the clock, towards the 11. When struck with stun, as Bob and Dr.Dave said, the ob's path will be towards the 11, and the cb will travel towards the 2, the included angle being 90 degrees.

However, I think that you're wanting to send the cueball towards the 3, by using draw. Staying with the clock idea, now imagine the clock-face being vertical, as if in front of the cueball, facing you. Now, if you strike the cb with low-right, you can choose different carom paths (the rebound angle stays the same, but as also mentioned by Bob and Dave, the path will be curved). Of course, the closer to 6 that you strike the cb, the more the path will want to curve back--due to the draw--toward the 6 on the horizontal clock. (Sorry, if the two clocks are confusing.)

BTW, if you are straight-on, and want to run the cueball to the side, you can hit a sort of "light masse", aiming to the opposite side to which you want the cueball to travel. So, if you are straight in on the side pocket, you use lower-right, and shoot the ball so that it curves out to the left, back towards the object ball, and then cuts the ball to the pocket, and continues to the right. It's a tough shot, and one that usually only come into play, when you've blown your position.

If you need diagrams, I can post some WEI shots--I'm just lazy right now. It's been a long week at work. . . .


=======================

Billy_Bob
12-10-2005, 10:11 AM
<blockquote><font class="small">Quote heater451:</font><hr> ...BTW, if you are straight-on, and want to run the cueball to the side, you can hit a sort of "light masse", aiming to the opposite side to which you want the cueball to travel. So, if you are straight in on the side pocket, you use lower-right, and shoot the ball so that it curves out to the left, back towards the object ball, and then cuts the ball to the pocket, and continues to the right. It's a tough shot, and one that usually only come into play, when you've blown your position....
<hr /></blockquote>

Actually I should have asked how to get the CB to go 90 degrees with a straight on shot...

Great answer above. Thanks!

Jal
12-10-2005, 01:51 PM
<blockquote><font class="small">Quote Billy_Bob:</font><hr>...
So what is the dividing line between a cue ball coming straight back as opposed to going 90 degrees? How much of a cut does it need to be? <hr /></blockquote>
I don't know if this is the same graphical method Bob Jewett mentioned above, but here is one way of determining the cueball's direction at natural roll. Here is a link to the diagram in case it's hard to see.

http://ww2.netnitco.net/users/gtech/CBDirection.jpg

http://ww2.netnitco.net/users/gtech/CBDirection.jpg

The red line marked "a" in the first view is the distance of the contact point from the object ball's center. In the top view, draw this line to the center of the ghost ball in the same direction as the tangent line. The cueball's direction when it reaches natural roll is the green line drawn from the tail of the red line through the vertical offset of the tip's point of contact (arrow b).

This is true regardless of the speed of the shot or the amount of friction between the ball and the cloth. It doesn't tell you, though, how far the ball will go in the tangential direction before natural roll sets in. This is dependent on speed and friction. And it will only work when the balls are fairly close to each other and/or you hit hard enough so that the spin essentially doesn't change on the way to the object ball.

These imaginary lines can be drawn right on the cueball as you're facing the shot, to the extent that you can correctly adjust for the apparent foreshortening of the angles from this perspective. If you can accurately picture the circle of tangents as shown in the bottom diagram, this can be used to aid in defining the direction of "a", since the tail of "a" is always on it. Here, a vertical line would represent the before impact direction.

Whether this is a practical way of figuring out where the cueball is going, I'll leave up to you. But it might not be a bad thing to have this schema in mind when practicing, at least from the armchair. /ccboard/images/graemlins/smile.gif

If you want to get the cueball to move 90 degrees to its initial direction on a straight shot, Heater's method is necessary, I think, when the balls are not really very close to each other (within a few inches). If they are, then cutting it with inside english to compensate (via throw) for the cut angle will work, I believe.

Jim

Bob_Jewett
12-12-2005, 10:17 AM
<blockquote><font class="small">Quote Billy_Bob:</font><hr>...
Actually I should have asked how to get the CB to go 90 degrees with a straight on shot...... <hr /></blockquote>
This is a standard trick shot. It's done with masse or half-masse. If you want to practice it, begin with a straight in shot to the side pocket from near the other side pocket (so you can bridge for the masse easily). Elevate 45 degrees at first, and use left or right but no draw or follow. Your aim will almost certainly be wrong at first -- just correct in the needed direction. You should be able to take the cue ball sideways at least a diamond without much trouble. With more elevation and power, you should be able to go the length of the table from a straight-in corner-pocket shot.

Billy_Bob
12-12-2005, 11:19 AM
Thanks much Bob!

I'm getting to where I don't leave myself straight in, but other players leave me this way often. So I think this shot will be well worth spending a lot of time practicing.

Bob_Jewett
12-12-2005, 11:57 AM
<blockquote><font class="small">Quote Billy_Bob:</font><hr> Thanks much Bob!

I'm getting to where I don't leave myself straight in, but other players leave me this way often. So I think this shot will be well worth spending a lot of time practicing.
<hr /></blockquote>
Well, maybe, but I think you usually should escape from such positions by drawing with side spin or accepting a longer shot for your next shot. While I play these "sideways" masse shots frequently as demos, I don't think I've used one in a game situation in over a year, except when playing safe.