Practical demonstration of cue tip path with a Pendulum stroke.

gregcantrall

gregcantrall

Just Don't Dog it. 🤷‍♂️
Silver Member
I constructed a machine that will give a demonstration of the cue tip path with a purely mechanical pendulum stroke. All dimensions were set by measuring my arm/bridge/stroke lengths.

The length of the arm is approximately 14 1/2"
Arm to bridge is just under 40" with the arm plumb, I did not photograph that as my arms were not long enough to hold the camera and tape measure.;)
The bridge length is approximately 8".
The paper is standard 8 1/2 by 11" and the circle drawn on it is 2 1/4".
It was set so the pencil was close to but not touching the circle with the arm plumb. This is the line scribed by the pencil when drawing the arm back and then going forward with the shaft resting on the bridge.

This last picture shows the stroke line versus a straight line.

This is less variation than I had expected. The change in the length of the lever arms accounts for the smaller variation from straight when the cue is drawn back with the tip closer to the bridge.
 
Interesting. How does the plot change when the grip is moved up on the butt? How about back? Is there any grip position that gives a visibly concave-up curve? (Easy for me to ask from the comfort of my computer chair.)
 
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gregcantrall said:
I constructed a machine that will give a demonstration of the cue tip path with a purely mechanical pendulum stroke. All dimensions were set by measuring my arm/bridge/stroke lengths.

The length of the arm is approximately 14 1/2"
Arm to bridge is just under 40" with the arm plumb, I did not photograph that as my arms were not long enough to hold the camera and tape measure.;)
The bridge length is approximately 8".
The paper is standard 8 1/2 by 11" and the circle drawn on it is 2 1/4".
It was set so the pencil was close to but not touching the circle with the arm plumb. This is the line scribed by the pencil when drawing the arm back and then going forward with the shaft resting on the bridge.

This last picture shows the stroke line versus a straight line.

This is less variation than I had expected. The change in the length of the lever arms accounts for the smaller variation from straight when the cue is drawn back with the tip closer to the bridge.
Click to expand...

I said, in the other thread, that I appreciated your efforts.

There is a problem with your machine as I see it relating to a real stroke.

The connection to the 'cue' in your model is only a single point & not the 3 to 5 inches of a hand.

Try this. Go to the table & lock you wrist with a flat wrist. Then swing the arm back with NO wrist movement. I believe you will feel the cue pressing up against your hand in the front & down in the back as the bridge keeps the the entire cue from going down with the front end pointing to the ground.

Mr. Muecci 1st. had the opposite of your problem when building his machine. The connection was too tight & no where near that of human hand.

But even with your nearly perfect single contact point connection to the cue you can clearly see the arc path going through the 'ball'.

Now change the 'cue' so it is angled a bit down as a real cue is for so many if not nearly all shots & start the contact point higher & lower on the ball & see what you get.

Again I appreciate your efforts.
 
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Could be interesting!

Bob Jewett said:
Interesting. How does the plot change when the grip is moved up on the butt? How about back? Is there any grip position that gives a visibly concave-up curve? (Easy for me to ask from the comfort of my computer chair.)
Click to expand...
I do not mind your question(from the comfort of your chair). I welcome the chance to investigate further.:thumbup:
I can set it up with any arm/cue/bridge length you desire. Give me some numbers and I will plot them.

I would predict that a very short arm and short distance between shooting hand and bridge combined with a long bridge would provide the most variation. There will still be a sweet spot, just a shorter one.[/my prediction];)
 
Shorter arm/cue with longer bridge

Ok, I shortened the arm to 12" and moved the bridge back 4". That gave a bridge length of 12" and hand to bridge length of 36".

 
To the extreme

Bob Jewett said:
Snip...Is there any grip position that gives a visibly concave-up curve?
Click to expand...

Took it to the extreme of a 12" arm with 12" hand to bridge and 12" bridge length. This is what I got.

As you can see, I had to get off the paper to find the upcurve even at these extreme numbers.

You can see that with a bridge length of around 6" there would still be a sweet spot. (The area from a couple of inches off the paper to 2" on the paper.)
One last picture with the straight edge.

I hope this is useful.:grin:
 
There are two pivot points in the grip, the wrist and where the cue rests in your hand. It does matter.
 
You sir, have too much free time! :)

Honestly though thanks for taking the time to build such a contraption and posting the results.
 
It appears that you are measuring the arc to benefit your belief unless you think that the tip during contact is meaningless. Why don't you measure from the pocket side of the ball & post those pics?

Also there is no need to use a level as the cue is angled slighty down for most shots. A ruler with inches might be even more informative.

It is about the straight tip travel vs an arc tip travel. So far I have seen no straight line not even with your 'perfect' connection to the cue. I have only seen arcs just as in Bob Jewett's charts.

I do appreciate your efforts.
 
I'm done.

I've tried to give you the benefit of the doubt, even though I disagree with your assessment, but now I'm just done. You are the first and likely ONLY person I will put on 'ignore'.

You refuse to accept any data staring you in the face. It has been described to you many ways, it has been video taped for you, and now it has been posted ala mythbuster style, yet you still cannot accept any proof.

I've got one question that has been nagging at me the entire time, which will go unanswered for me, because you are about to be 'ignored':

You said that you would never disuade anyone from professional help, even if that meant advocating a pendulum stule stroke, and that you yourself would NEVER use the pendulum stroke (after all, you've been using a piston style for 47 years ). With those two things being said...why on earth do you care about a straight line pendulum? Is it just to seem smart...because I gotta tell ya...it is having the complete opposite effect.
 
duckie said:
There are two pivot points in the grip, the wrist and where the cue rests in your hand. It does matter.
Click to expand...
It was not my intention to build an "Iron Byron" for the pendulum stroke.
byron-small.jpg

I tried to show all the particulars of my experiment, so you can draw your own conclusions.

I have no opinion on the merits of any particular stroke.
 
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Heh, heh!

Pidge said:
You sir, have too much free time! :)

Honestly though thanks for taking the time to build such a contraption and posting the results.
Click to expand...
Well as you can see it was constructed from materials I had in my back yard and shop. It only required a screw gun and tape measure to construct. I did not spend a great deal of time searching for materials. I couldn't find my T square so I just grabbed a level for a straight edge. In the text I refer to it as a straight edge and I made sure the bubble was obviously not the intention, [edit out mean remark]but I guess the use of the level for a straight edge could be confusing.

I spent more time editing and posting the pictures than the construction of the machine and the execution of the different trials.

The result was not what I expected.
 
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gregcantrall said:
Well as you can see it was constructed from materials I had in my back yard and shop. It only required a screw gun and tape measure to construct. I did not spend a great deal of time searching for materials. I couldn't find my T square so I just grabbed a level for a straight edge. In the text I refer to it as a straight edge and I made sure the bubble was obviously not the intention, but I guess if you are a half bubble off to begin with the use of the level for a straight edge could be confusing.

I spent more time editing and posting the pictures than the construction of the machine and the execution of the different trials.

The result was not what I expected.
Click to expand...
Well, thanks anyways. Its made for a very interesting read.

The results were not what I expected either. Although not perfectly straight all the way through to contact your experiment doesn't, and obviously can't recreate a pendulum pool stroke in complete perfection. No machine can completely recreate a persons stroke, but we can come pretty close.

Its obvious to me that from your experiment it is more than possible to have a straight stroke for several inches prior to CB contact, and upon contact. Various factors can make this possible, most blatant being the huge part the wrist can play in altering the deviation just before contact. Take into account people will never be able to stay completely 100% in the same place throughout a stroke, with just their forearm and hand moving. Slight rising and lowering of the whole body and shifts of balance in all directions will change the way the cue reacts.

So once again, good job and keep up the good work :)
 
MSchaffer said:
I'm done.

I've tried to give you the benefit of the doubt, even though I disagree with your assessment, but now I'm just done. You are the first and likely ONLY person I will put on 'ignore'.

You refuse to accept any data staring you in the face. It has been described to you many ways, it has been video taped for you, and now it has been posted ala mythbuster style, yet you still cannot accept any proof.

I've got one question that has been nagging at me the entire time, which will go unanswered for me, because you are about to be 'ignored':

You said that you would never disuade anyone from professional help, even if that meant advocating a pendulum stule stroke, and that you yourself would NEVER use the pendulum stroke (after all, you've been using a piston style for 47 years ). With those two things being said...why on earth do you care about a straight line pendulum? Is it just to seem smart...because I gotta tell ya...it is having the complete opposite effect.
Click to expand...

1. Bob Jewett's analysis indicate that the tip travels in 3 arcs in a fixed elbow stroke.

2. randyG said that there is a 'sweet spot' where the tip travels 'level'/straight for several inches.

3. I asked twice in that thread for an explanation as to how so, because I do not see it or exactly how it can happen given the arc line of a pendulum. No answer in that thread.

4. I opened my 'pendulum sweet spot' thread to see if anyone could give an explanation.

5. No real definitive explanation was given up until I bumped it after 6000 views. It has gone over 7,000 in the short time since I bumped it. It was closed.

6. I opened this thread just to gauge in proportion how many on AZB are using what type of stroke.

7. The 'dispute' was brought here by others not me.

8. I have never said that it does NOT exsist but I have said that I don't see how, especially given Bob Jewitt's analysis charts that I had seen.

9.They expend much effort 'attacking' me & my character but provide no conclusive explanation of how or what produces any straight line tip travel in a fixed elbow pendulum stroke & do not even wish to discuss the subject.

If there is straight line tip travel in a pendulum stroke then I would think that a PBIA instructor that is a proponent of that stroke should be able to explain why it happens or how it happens.

Bob Jewett' analysis of an elbow drop 'piston' stroke indicates straight tip travel for that stroke.

The elbow dropping along with other factors is what allows the tip to travel straight.

In the OTHER threads I was merely asking what in a fixed elbow stroke would result in several inches of straight tip travel which appears to be contrary to Mr. Jewett's analysis charts.

I can make no determination of what might only be 3 or 4 millimeters from a video on a computer screen & even IF I could & would agree that there was some straight tip travel. It would not explain what causes it or allows it or makes it happen.

While not a perfect model Mr. Greg's 'machine' is showing the arcing as indicated on Mr. Jewett's charts.

I posted the definition of straight in the other thread because it seems some must have a different perception of what straight is.

I hope that gives you a better understanding of where we are & why.

Best Wishes to You,
Rick
 
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Greg:

Well done! As the readership can easily see, even with a perfectly-joined-pivot (where the arm/hand joins the cue), one can see just how *far* the straight travel of the cue is. The dive after contact with the cue ball is expected, and anyone who's been to SPF school knows this is taught. The dive to the cloth is old hat. In fact, you really have to BREAK the alignment -- really put effort into it -- to get the rise and fall that ENGLISH is brain-spinlocked on.

While this effort is for nothing on the ENGLISH front (you saw his classic twisting, diverting, "let me bury you with 50 unrelated questions to keep you mired in administrivia" response), this is great demonstrative info for anyone on the sidelines truly interested in *why* a pendulum stroke doesn't act the way you think.

Again, well done,
-Sean
 
gregcantrall said:
Well as you can see it was constructed from materials I had in my back yard and shop. It only required a screw gun and tape measure to construct. I did not spend a great deal of time searching for materials. I couldn't find my T square so I just grabbed a level for a straight edge. In the text I refer to it as a straight edge and I made sure the bubble was obviously not the intention, but I guess if you are a half bubble off to begin with the use of the level for a straight edge could be confusing.

I spent more time editing and posting the pictures than the construction of the machine and the execution of the different trials.

The result was not what I expected.
Click to expand...

As I have said, I do appreciate your efforts.

Could you explain, what you mean by the statement that I have highlighted? What did you find that you did not expect?

Thanks in advance should you choose to respond.
 
Pidge said:
Well, thanks anyways. Its made for a very interesting read.

The results were not what I expected either. Although not perfectly straight all the way through to contact your experiment doesn't, and obviously can't recreate a pendulum pool stroke in complete perfection. No machine can completely recreate a persons stroke, but we can come pretty close.

Its obvious to me that from your experiment it is more than possible to have a straight stroke for several inches prior to CB contact, and upon contact. Various factors can make this possible, most blatant being the huge part the wrist can play in altering the deviation just before contact. Take into account people will never be able to stay completely 100% in the same place throughout a stroke, with just their forearm and hand moving. Slight rising and lowering of the whole body and shifts of balance in all directions will change the way the cue reacts.

So once again, good job and keep up the good work :)
Click to expand...

Pidge,

Can you direct me to where you see a straight line?

Thanks,
Rick
 
Mr. Cantrell,

If you have the time & would be so kind, could you measure & relay how much the 'cue' butt raises in your model?

In Neil's video, his butt end raised up about 3 inches from my estimation. Maybe not at his hand as that is hard to see. I would guesstimate that his hand raised maybe near 2 inches.

Thanks if you choose to indulge me.

Rick
 
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