Pivot Point

charlieb

AzB Silver Member
Silver Member
I read about the "Pivot Point" but I haven't found any thread on how exactly you find the pivot point.
 
cuetable said:
Please also check this thread started by Mike Page in 2004 RSB
http://pl.cuetable.com/showthread.php?t=466
That's a good description by Mike.

However, be aware that the Pivot Point adjusts only for squirt (cue ball deflection) and not for "swerve", which is the second effect of hitting the cue ball offcenter. Like squirt, swerve is created whenever you hit the cue ball offcenter, and it reduces the amount of "effective squirt" produced (because the cue ball "swerves" back toward the shot line).

So unless you're hitting every sidespin shot hard enough to eliminate swerve, the Pivot Point is only an approximation for how much aim adjustment to make for any given shot - the actual amount varies with shot speed, distance, butt elevation, cloth/ball cleanliness and even humidity. These things can be accurately adjusted for, but only by feel - there's no fixed measurement or system of aim adjustment that accounts for all of them.

pj
chgo
 
Patrick Johnson said:
That's a good description by Mike.

However, be aware that the Pivot Point adjusts only for squirt (cue ball deflection) and not for "swerve", which is the second effect of hitting the cue ball offcenter. Like squirt, swerve is created whenever you hit the cue ball offcenter, and it reduces the amount of "effective squirt" produced (because the cue ball "swerves" back toward the shot line).

So unless you're hitting every sidespin shot hard enough to eliminate swerve, the Pivot Point is only an approximation for how much aim adjustment to make for any given shot - the actual amount varies with shot speed, distance, butt elevation, cloth/ball cleanliness and even humidity. These things can be accurately adjusted for, but only by feel - there's no fixed measurement or system of aim adjustment that accounts for all of them.

pj
chgo

pj,

Extremely well put. I will add that all the factors mentioned apply to virtually every "system" ever invented -- they are never more than approximations.

Mark
 
Patrick Johnson said:
That's a good description by Mike.

However, be aware that the Pivot Point adjusts only for squirt (cue ball deflection) and not for "swerve", which is the second effect of hitting the cue ball offcenter.....
Nor does it adjust for throw, which tends to muck up the aim-and-pivot method for determining the pivot point.

There has been as much as a factor of 2, 3 and up discrepancy between the measurements obtained with aim-and-pivot and those obtained with the robotic tests done by Platinum Billiards. Curiously, Predator's own results only show a relatively modest reduction in squirt and are consistent with the Platinum numbers. Using aim-and-pivot though, some have measured much larger reductions. Mike Page mentions pivot points of 25-30", whereas Predator/Platinums measurements equate to around 12-13" for the Predator shafts.

Who's right?

Platinum does their tests at high speed, most likely so as to keep swerve at a minimum. But this might introduce some tip slippage during impact, thus raising the squirt angles. I doubt it, but it's possible. People who use aim-and-pivot judge a full hit as having the cueball stop dead while spinning. But this does not account for throw and post impact swerve. Since the cueball's spinning, it will still want to move off the line of centers after impact.

So it's impossible to know who's actually getting the correct values. But I would think that Predator has looked at this very closely and would be elated to cite the very low squirt figures (long pivot points), if they could.

Jim
 
Thanks for all of your answers and the links provided! I will look at all the links tonight and hope that I don't get hopelessly confused. In the past I shot with a Predator but a friend made me a new cue with a very stiff shaft. I love the feel of the shaft but the stiffness causes extreme squirt, especially on long shots with english. I want to try all remedies before switching back to a Predator but I can't play hours everyday to get through a learning curve. Hopefully, I can practice more intelligently with the info you have all supplied. Once again. Thanks! What a great Forum Board.
 
charlieb said:
Thanks for all of your answers and the links provided! I will look at all the links tonight and hope that I don't get hopelessly confused. In the past I shot with a Predator but a friend made me a new cue with a very stiff shaft. I love the feel of the shaft but the stiffness causes extreme squirt, [...]

Just want to point out that the stiffness doesn't cause the squirt. You can find high squirt and low squirt stiff shafts, and you can find high squirt and low squirt whippy shafts.
 
Patrick Johnson said:
Like squirt, swerve is created whenever you hit the cue ball offcenter, and it reduces the amount of "effective squirt" produced (because the cue ball "swerves" back toward the shot line).

pj
chgo

Pat...Swerve only happens when the cuestick is elevated. It does not occur with a level cuestick. The CB will never return to the shot line unless there is a "masse'" effect, due to hitting down on the CB.

Scott Lee
www.poolknowledge.com
 
Scott Lee said:
Pat...Swerve only happens when the cuestick is elevated. It does not occur with a level cuestick. The CB will never return to the shot line unless there is a "masse'" effect, due to hitting down on the CB.

Scott Lee
www.poolknowledge.com

However, the cue is virtually always elevated because of the rails. You will almost never shoot with a level cuestick. Therefore, swerve occurs on virtually every shot. (So much for "poolknowledge".)

Mark
 
Scott Lee said:
Pat...Swerve only happens when the cuestick is elevated. It does not occur with a level cuestick. The CB will never return to the shot line unless there is a "masse'" effect, due to hitting down on the CB.

Scott Lee
www.poolknowledge.com
How about on very sloooow shots?
 
charlieb said:
I read about the "Pivot Point" but I haven't found any thread on how exactly you find the pivot point.
Oh, and in answer to your actual question:

1. Mark the center point of a 1-2 foot long 2x4, tape a piece of carbon paper to it (carbon side to the board so it will leave a mark when hit by the cue ball), and stand it on edge against the foot rail, center mark aligned carefully with the center diamond.

2. Lay a 2-foot length of masking tape along the center string near the foot spot (to use as a tip offset and stroking guide).

3. Place the cue ball on the foot spot, align the cue stick parallel with the center string and offset sideways from centerball a set amount (if you use 1/2-inch masking tape to mark the center string, you can align your stick with the edge of the masking tape and get ~1/4-inch of offset).

4. Hit the shot using a low mechanical bridge with the cue stick held level at the cue ball's "equator" (this is one of the few table positions where a truly level stick is possible). Speed is irrelevant with a truly level stick, so hit slowly enough to be sure you're staying online (parallel to the center string) and hitting with the correct amount of sideways offset.

5. Measure the distance from the center mark on the 2x4 to the carbon paper mark made when the cue ball hit. Divide that measurement by the amount of tip offset, then divide the distance of the shot (22-1/8 inches) by that result to get the Pivot Distance. For example, if the tip offset is 1/4 inch and the cue ball hits the 2x4 1/2 inch from the center mark, then the stick's Pivot Distance is 22-1/8 inches divided by 2 (1/2 divided by 1/4), or 11-1/16 inches.

Pivot Distance = Shot Distance / (Total Squirt / Tip Offset)

pj
chgo
 
mbvl said:
However, the cue is virtually always elevated because of the rails. You will almost never shoot with a level cuestick. Therefore, swerve occurs on virtually every shot. (So much for "poolknowledge".)

Mark

We call it 'as level as reasonable to the shot'. :rolleyes: Actually, it has more to do with the amount of elevation. The 2-3 degrees of elevation on the cue, when shooting most 'level cue' shots does not produce a swerve effect (enough to come back to the shot line). When you elevate to 6-10 degrees (or more) there will likely be a significant masse' effect and the CB may come back to, or cross over the shot line (but it certainly doesn't happen all the time).

Scott Lee
www.poolknowledge.com
 
Patrick Johnson said:
That's a good description by Mike.

However, be aware that the Pivot Point adjusts only for squirt (cue ball deflection) and not for "swerve", which is the second effect of hitting the cue ball offcenter. Like squirt, swerve is created whenever you hit the cue ball offcenter, and it reduces the amount of "effective squirt" produced (because the cue ball "swerves" back toward the shot line).

So unless you're hitting every sidespin shot hard enough to eliminate swerve, the Pivot Point is only an approximation for how much aim adjustment to make for any given shot - the actual amount varies with shot speed, distance, butt elevation, cloth/ball cleanliness and even humidity. These things can be accurately adjusted for, but only by feel - there's no fixed measurement or system of aim adjustment that accounts for all of them.

pj
chgo

Perfect description, it does after all come down to a question of feel. That being said, I've found that when you really hit the cue ball firmly, and I mean firmly or hard or whatever, almost at your break speed, the swerve, and many other factors become relatively minor. However, distance does continue to be a factor, and throw on the object ball still must be considered.

In any case, using the pivot point for certain shots can make it way easier than parallel english. Experimentation is the key...

Flex
 
Jal said:
So it's impossible to know who's actually getting the correct values. But I would think that Predator has looked at this very closely and would be elated to cite the very low squirt figures (long pivot points), if they could.

Jim

I had a 314 shaft that I sold to a friend. I didn't like the hit, although I played alright with it.

Now I'm using the OB-1 almost exclusively, and find that the rather long taper on it along with the Platinum Billiards reported approximately 11 inch pivot point to be nice. In practice, I've found after starting to use this shaft about 2 weeks ago (and lots of hours with it) that my bridge length has gotten longer. Where I used to have somewhere around an 8 inch bridge for most regular shots, my bridge has gone to about 11 inches. I like it. And am playing better. Is that due to the shaft, or am I improving a tad? Can't really say, but I do like the longer taper, and the 11 inch pivot point. It's so much easier pivoting around an 11 inch point than an 8 inch one, especially for grip 'em and rip 'em force follows with english. Plus it just seems like my accuracy has gone way up with this combination.

Flex
 
Scott Lee said:
We call it 'as level as reasonable to the shot'. :rolleyes: Actually, it has more to do with the amount of elevation. The 2-3 degrees of elevation on the cue, when shooting most 'level cue' shots does not produce a swerve effect (enough to come back to the shot line). ...
I think this is not true for low-squirt sticks. In any case, even 3 degrees of elevation is more than enough to produce a half-ball of swerve on a long shot, and so must be controlled if long shots with english are to be made.
 
Scott Lee said:
We call it 'as level as reasonable to the shot'. :rolleyes: Actually, it has more to do with the amount of elevation. The 2-3 degrees of elevation on the cue, when shooting most 'level cue' shots does not produce a swerve effect (enough to come back to the shot line). When you elevate to 6-10 degrees (or more) there will likely be a significant masse' effect and the CB may come back to, or cross over the shot line (but it certainly doesn't happen all the time).

Scott Lee
www.poolknowledge.com
Swerve usually doesn't counteract all squirt; but it does counteract a significant part of squirt on just about every shot, and increasingly so as the cloth gets older and dirtier. I think most players underestimate the significance of swerve and therefore underestimate the amount of squirt their sticks actually produce.

pj
chgo
 
Bob Jewett said:
I think this is not true for low-squirt sticks. In any case, even 3 degrees of elevation is more than enough to produce a half-ball of swerve on a long shot, and so must be controlled if long shots with english are to be made.

Are you saying that low-squirt sticks produce more swerve? I thought it would just be more noticeable if you're reducing the squirt.
 
PKM said:
Are you saying that low-squirt sticks produce more swerve? I thought it would just be more noticeable if you're reducing the squirt.
No, I'm saying that if the stick has very low squirt, any elevation will make the path of the cue ball cross the original line of the shot.

Imagine you are lined up for a shot with english, and you bring your stick straight back and forward along a line. That line is parallel to the line of the shot, which passes through the center of the cue ball.

Since your shot will be elevated some -- between 2 and 15 degrees for typical shots. -- there will be some swerve. That is, the cue ball will curve towards the side of the side spin.

Since you are playing with side spin, there will be some amount of squirt -- the initial path of the cue ball will not be parallel to the line of the shot but instead will be at some angle and angled away from the side of the spin.

The question is whether the path of the cue ball will curve enough to cross the original line of the shot. If you are elevated 15 degrees, it is almost certain to cross unless you shoot so hard the ball doesn't have time to curve. If you are elevated 4 degrees, but have a very squirty stick, the cue ball will squirt out so much that the swerve can't bring it back across the line of the shot. If you have a low-squirt stick, the swerve with 4 degrees of elevation may bring the cue ball back across the line of the shot because the squirt didn't take the cue ball very far from the line of the shot.

But some people think that low-squirt sticks have more swerve because the cue ball ends up more on the side of the english. That's not because of increased swerve; it's because of decreased squirt.
 
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