What's your cue's Pivot Point?
- Thread starter Colin Colenso
- Start date
I think you and I need to do the test side by side. I cannot fathom how a Schuler cue could fall into the 20" range. Simple back-hand english could never work with a cue that had a 20" pivot point, but simple back hand english is pretty much all I ever use.mikepage said:
You do have the cueball sitting and spinning in place, right?
Fred
Hi Mike,mikepage said:
The speed I play, I guarantee that swerve is irrelevant.
Anyway, if swerve is occuring, it would make my pivot points appear longer than they actually are.
Please describe the way you determine your pivot point.
btw: I very much doubt that if you bridged at 30" with your cue and then pivoted to hit with BHE with speed, that your CB would follow the same line. Have you tried this?
Colin Colenso said:
I agree with this last statement. Note, however another way, and an equivalent way, to view what a pivot point is. Suppose you're doing your test and you've found the right bridge length. We'll say 10 inches. So the stick will be pointing a ways to the left of the chalk. You'll hit with lets say a half inch of side, and the cueball will head straight for the chalk.
Now, draw two lines from your bridge hand to the end rail. One line is in the direction the stick is pointing and the other line is in the direction the ball goes. Like This
START(
%Pg7O1%Wi2O4%Xr8N1%[D2O5%\j7O0%]D1S4%^j9O1
)END
Note the two similar triangles. Both start at the bridge. One goes to the center of the ball, 10 inches, then over a halh inch, and then back about 10 inches. The other goes straight to the chalk, over several inches, and then back. Here is the key. The two lines diverge by a half inch for every 10 inches down the table.
Note that you can use this idea even if you're not aiming and pivoting and regardless of the bridge length. Suppose, for example you're hitting a ball with a half inch of right english and the pivot point of the cue is 12 inches. It doesn't matter what your bridge length is. If the stick is level, the ball will diverge from the line of the stick by a half inch for every 15 inches of travel. If you hit instead with a quarter inch of english, then the ball will diverge a quarter inch for every 15 inches of travel.
A predator 314 shaft, with say a 40 inch pivot point, hitting a ball with a half inch of english will diverge from the stick direction by a half inch for every 40 inches of travel.
This is just another way of viewing the pivot point that isn't contaminated by pivoting or bridge length or anything like that.
My side pocket example used this view. But it's the same thing.
[/QUOTE]
Colin Colenso said:
No. If hit with a half inch of english, That cueball will travel abour a quarter inch to the right of the original line for every five inches of travel--over two inches after 44 inches of travel.
mike page
fargo
Cornerman said:
Yes, and I have it going to the opposite side the english was applied for shorter pivot lengths and the the same side for longer pivot lengths.
I think there's lots of people who use backhand english with 12 inch bridges and 20 inch pivot points. And if you watch carefully how they pivot, there is a couple mm movement of the bridge itself.
I don't think we can solve this over the internet.
mike page
fargo
Colin Colenso said:
I do it like you do, except instead of aiming for chalk and determining which side of the chalk the cueball hits, I put an intervening object ball about 2o inches from the cueball. When the cueball hits the object ball, it either rifts to the left or drifts to the right or stays still spinning in place. I do the test several times with both left and right english with each bridge length to make sure I get the same results. I sometimes use a bridgehead to pivot about and then shoot the cue along the new line using a comfortable bridge.
Colin Colenso said:
Many many many times.
mike page
fargo
Testing with Predator for Pivot Point
Just an update after testing my cue's pivot point against my friend's new Predator Z-shaft.
I was expecting the Predator to have a longer pivot point, but after about 15 trial hits, with the aid of the accueshot tester (not really necessary, the eye can spot the trend easily) the predator showed a pivot point almost identical to my own cue.
My initial estimate for my cue was a little low. It seems to be around 9-10 inches when I actually measure it instead of guess it. The predator was about the same, maybe 10-11 inches but so close I could use the same adjustments for both cues.
Now as for these 30" pivot points, I just don't believe they will work for the test I describe.
If they work on the CB to OB test, it is probably because the spin transfering throw puts the OB back on the straight track, but this will only work if their is not a long separation between the CB and ON (say 20 inches). Lengthen this to 50 inches and it should be apparent that bridging at around 20 inches with any cue will make the CB deflect considerably opposite the direction of side english being applied.
Just an update after testing my cue's pivot point against my friend's new Predator Z-shaft.
I was expecting the Predator to have a longer pivot point, but after about 15 trial hits, with the aid of the accueshot tester (not really necessary, the eye can spot the trend easily) the predator showed a pivot point almost identical to my own cue.
My initial estimate for my cue was a little low. It seems to be around 9-10 inches when I actually measure it instead of guess it. The predator was about the same, maybe 10-11 inches but so close I could use the same adjustments for both cues.
Now as for these 30" pivot points, I just don't believe they will work for the test I describe.
If they work on the CB to OB test, it is probably because the spin transfering throw puts the OB back on the straight track, but this will only work if their is not a long separation between the CB and ON (say 20 inches). Lengthen this to 50 inches and it should be apparent that bridging at around 20 inches with any cue will make the CB deflect considerably opposite the direction of side english being applied.
Colin Colenso said:
I don't have a Z-shaft. Maybe they are as squirty as you describe. But my predator 314 is not. I just went downstairs and did the "pivot about 20 inches with the object ball 50 inches away" test. It doesn't squirt enough to compensate for that aim change.
mike page
fargo
""""""""When I was in South Dakota last fall, I spoke to a fellow who had
just
had that texas pool school (Randy G?) come to their poolroom for a
couple days. He told me lots of stuff they did. One of the things
he
showed me was "aim & pivot backhand english." (I don't remember what
he
called it). I don't think they were necessarily advocating it--just
showing them lots of things. This fellow was amazed when I pulled two
cues out of my bag: one for which bhe works like a charm on a shot of
my
choice, and the other of which it's a disaster on the same shot.
"That's amazing!" he said. "I wonder if they know about that."
Another thing he mentioned that caught my attention had to do with
three
angles. When I asked further, he said it was just a small part and
that
they were shown these three angles and warned that of course these
were
just convenient reference points--that you'd have to choose many
ball-ball orientations between to actually make shots...."""""""""" Written by Mike Page.
here is a story i found on the net, otaye so BHE or Aim and Pivot doesn't work for all cues? Cause i am shooting with a Mcdermott Cue, and last night i played with my buddies Predator cue with 314 shaft, and i couldn't make some shots but some i could.
just
had that texas pool school (Randy G?) come to their poolroom for a
couple days. He told me lots of stuff they did. One of the things
he
showed me was "aim & pivot backhand english." (I don't remember what
he
called it). I don't think they were necessarily advocating it--just
showing them lots of things. This fellow was amazed when I pulled two
cues out of my bag: one for which bhe works like a charm on a shot of
my
choice, and the other of which it's a disaster on the same shot.
"That's amazing!" he said. "I wonder if they know about that."
Another thing he mentioned that caught my attention had to do with
three
angles. When I asked further, he said it was just a small part and
that
they were shown these three angles and warned that of course these
were
just convenient reference points--that you'd have to choose many
ball-ball orientations between to actually make shots...."""""""""" Written by Mike Page.
here is a story i found on the net, otaye so BHE or Aim and Pivot doesn't work for all cues? Cause i am shooting with a Mcdermott Cue, and last night i played with my buddies Predator cue with 314 shaft, and i couldn't make some shots but some i could.
Good point. Technically, if the OB is hit straight on (pivoting at exactly the cue's pivot point) the cueball should not sit spinning in place but because of throw it should move over to the side the english was applied, by about an inch. The object ball should be thrown in the opposite direction. However, having it spin in place only introduces a small error, less than an inch in the apparent pivot point location.Colin Colenso said:
I'm wondering if both of you (you and Mr. Page) aren't right here, since you haven't actually tested the same cues. If any of you wish to try yet another method, here is one way of doing it. It's pretty much like the test you described but tends to eliminate swerve, and doesn't require one to pivot at some awkward location down the shaft. It's also based on the geometric principle Mike has been describing, so it's like a conglomeration of both your methods.
Place the cueball (or better, a striped ball) at the third diamond from a corner pocket and a quarter ball away from the cushion. Shoot the cueball toward the corner pocket using a quarter ball of "outside" english while aiming parallel to the cushion. Note where the ball contacts the cushion and place the tip of the cue there. The pivot point will then be at the point where the cue crosses the third diamond.
As an aid to the parallel aiming, you can use the edge of a ball frozen to the cushion near the corner pocket, or the edge of a cube of chalk placed on top of the end rail.
To place the ball a quarter ball from the cushion, use a striped ball as the cueball and freeze two balls to the cushion ahead of it, and two behind it. Orient the stripe so that it is aligned with the outer edges of the four balls. If the stripe appears to be approximatley perpendicular to the bed of the table, that's good enough. (If it's 10 degrees off for instance, the edge of the stripe
will still be less than a hundreth of an inch off at the equator.)
This assumes that the stripe is a half-ball in width, which isn't necessarily true. To check this, freeze the striped ball to two other balls (forming a triangle) with the stripe perpendicular to the line-of-centers of the other two. If the edges of the stripe run through the contact points, then it is a half-ball wide.
The reason for using the third diamond is that the butt of most cues will clear the far end rail, making a level stroke possible. With a butt diameter of 1.25" and your fingers rubbing on top of the cloth, the centerline of the cue should be very close to a half-ball above the surface. You can then stroke fairly softly without any appreciable swerve affecting the results.
To apply a quarter ball of english, i.e., to make the actual contact point at the edge of the stripe, you can use your judgement or the following table. It lists the additional offset of the centerline of the cue from the edge of the stripe.
Tip Curvature Additional Offset
Dime..............11/64" (quarter of a dime's diameter)
Nickel............13/64" (quarter of a nickel's diameter)
Quarter..........15/64" (quarter of a quarter's diameter)
Here is a Wei table diagram. In the center, the 13-ball's stripe is being checked.
START(
%AE1D0%BB8[6%CB3[7%DB5[9%EZ5O6%FZ4N3%GB8[3%HB6[8%IB8[9%JC0[9
%KU2D3%LB9[8%M[6N9%NB7[7%OB8[7%PB9[7%WW6D8%Xq6D7
)END
This test gave consistent results with aim-n-pivot on my cue, 18" (to answer your original question). The tip of my cue is pretty thin, ~12 mm, so that may account for this length to some extent.
Jim
This is why it is important to understand that the Aim & Pivot Test will give you the Inside English Pivot Point, if the ball is left sitting and spinning in place. It's the use of the IEPP that is very powerful in "squirt compensation." The devil in the details will show that both squirt and SIT are actually compensated. But, whether people understand the details or not, the use of the IEPP give most people a great squirt aiming tool without much thought.Jal said:
If you only pivot about the "true pivot point," you'll most likely miss all but the very high margin of error shots.
Fred
Wei Table
how to show the Wei Table Diagram sorry for the stupidity. Cole
how to show the Wei Table Diagram sorry for the stupidity. Cole
Colin i did your test and i couldn't see any difference in my bridge lengths, if there was a difference it was by a hair, but the cueball hit the piece of chalk everytime then after the english would take major effect, but the cueball wouldn't deflect off to the sides at all before contact. The Cue i am playing with now is a Mcdermott Cue a Victorian, i have this and a Navigator 2 but the navigator i didn't try this with as i don't play with this cue as much.
I aim center ball then use BHE and i can hit almost the very edge of the cueball and it wouldn't curve or deflect. Is this good or bad, or maybe im just not doing it right. Cole.
Note: After learning how to aim using aim and pivot i have been using BHE everytime i shoot and my shot making has increased alot.
I aim center ball then use BHE and i can hit almost the very edge of the cueball and it wouldn't curve or deflect. Is this good or bad, or maybe im just not doing it right. Cole.
Note: After learning how to aim using aim and pivot i have been using BHE everytime i shoot and my shot making has increased alot.
TheConArtist said:
First select and copy the funny text. You may include the START/END words or not in your selection. Then go here
http://endeavor.med.nyu.edu/~wei/pool/pooltable2.html
and click on the paste button. If you want to change things on the table, do so, and then hit the copy button. Now you can paste the new text code into your post. If you want to download the table to your computer for easier access, click on the help link just below the table and then click on the instructions for doing this off to the right side of the screen (it's easy, I even managed it!).
Jim
Try a 4 inch and then a 24 inch bridge length. Make sure you aren't subconciously adjusting when you make the original aim and make sure to keep your bridge in place after alignment.TheConArtist said:
You should find at 4" the CB will deflect in the direction of the cue, at 24" it will deflect away from that direction. Usually a 1.5" deflection to either side can be noticed.
Thanks for the interesting method Jim!Jal said:
I think you'd need to be careful to get the bridge hand correctly on line and to hit the CB exactly in the same spot to get consistant results.
There may be different definitions of what a pivot point actually determines, so people could measure it in different ways.
But to me, I think it makes sense to say the pivot point should be the bridge length for pivoting a cue, whereby the CB's line of travel remains most constant.
Some could say they have an OE half ball at 3 foot pivot point at 15" and an IE half ball at 3 foot pivot point at 6", as these may send the OB along the same line to the pocket.
But once we start talking about compensation for Spin Induced Throw (SIT) by sending the CB off the original line of aim, then distance becomes a variable and it gets messy.
Anyway, I'm rambling...best I keep testing and thinking. I may put together a comprehensive analysis and system on a website someday soon so I can just refer to that.
Colins test to find your pivot point Add-On, place three balls on rail frozen together remove the middle ball and slide one ball over just a bit more, and aim for the empty space trying different bridge lengths to find your PP. With this test using the balls i was able to tell how much the cueball deflected using english and was able to find my correct bridge length. Again Thanks Colin.
START(
%As1P7%B[4B5%C[5B6%D[3B8%E[6B4%F[2B1%G[6B5%H[4B4%Is0N6%J[3B6
%K[6B4%L[7B9%M[5B5%N[8B7%O[4B7%PO0O5%Wp8O7%XP6O6
)END
START(
%As1P7%B[4B5%C[5B6%D[3B8%E[6B4%F[2B1%G[6B5%H[4B4%Is0N6%J[3B6
%K[6B4%L[7B9%M[5B5%N[8B7%O[4B7%PO0O5%Wp8O7%XP6O6
)END
TheConArtist said:
So how long did you find your pivot point to be?
btw: After testing, I can say that Mike's test, where he aims at a ball 20 inches away, results in a pivot point of almost twice as long as my test. The reason is that the throw from the spin has quite an effect.
If you separate the CB and OB by 40 inches, the pivot point comes in nearer to the pivot point that I measure. at 60 inches they are basically the same.
If the CB and OB are only 10" apart, the pivot point on most cues would be near to the length of the cue. This is because of the SIT.
Though at 10" you can make it work with a 20" bridge using a large offset and a lot of power as squirt is increased and throw is decreased at speed.
The pivot point method I suggested is simply to indicate the cue's basic squirt characteristic.
btw: I found the pivot point will vary at speed. From 14" for slow shots to 7" with a lot of power and extreme english. The slow shot includes some swerve, but the difference is not entirely due to swerve. 10" is a pretty consistant result for medium to firm shots for my cue.
The bottom line for me is that I'm not so concerned with *why* exactly things work, just that on a long shot, I can aim dead center, then pivot my cue using some method that can be used with all bridges, apply english, and have the cue ball go to the same spot as a dead center hit.