Tip shape

patrick says the larger diameter shaft contacts the the miscue limit point farther from its edge
i think brian your findings agree...yes?
patrick also says on a smaller shaft a dime shape gets you a contact point just inside the edge but on the edge with a nickel shape
i got confused reading some of your posts brian so can you explain your findings agree or disagree?
last brian you talk about contact patch whereas i think of miscue limit as a point
also i think of tip offset for spin as a point with collateral contact based on the tip shape and size of shaft
i believe you put significance or are questioning whether that collateral contact plays a significant role
 
dr dave said this
For applying spin, a smaller-diameter shaft and rounder tip (approximately “dime” radius) are generally recommended. Here are some possible reasons:
in your post sevreal posts above a dime radius on a larger shaft gave a 100% contact to the "contact patch which i think was better than the nickel
i am not sure of the conclusions with the smaller shaft
if you did conclude a larger % contact area of the "contact patch" with the dime than the nickel
then everyone agrees.......:D
✌️
 
BC21 said:
There are quite a few "might be" or "could be" statements there. And sure, as PJ and Bob J have said, there isn't much difference between a nickel and dime shaped tip.

But I find it hard to believe that striking the cb with more tip involved (a full 100% contact patch versus a partial contact patch) is insignificant. There is no data on it that I can find. So it's just as probable as any other "could be" or "might be" that Dr. Dave mentions in the above quote, though the math shows a big difference (nearly a 30% difference in the amount of tip surface area being used).

And too many experienced players have said that they get more action from different cues, different tips, so there's something to that. It's not simply that they "feel" like they get more action. They experience it, see it and feel it.
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Yeah, that particular DD page doesn’t really provide much clear answers. Its more like a diplomatic summary of the various mainstream sentiments & speculations on the topic.

Brian - Since you’re now in the weeds on this, I wonder if you want to try to also factor cue angle into your contact area analysis. Seems pretty intuitive that for example that BHE vs parallel english at the miscue edge are different animals, as one example. Vertical elevation of the cue on draw shots being another.

Cheers
 
bbb said:
patrick says the larger diameter shaft contacts the the miscue limit point farther from its edge
i think brian your findings agree...yes?
patrick also says on a smaller shaft a dime shape gets you a contact point just inside the edge but on the edge with a nickel shape
i got confused reading some of your posts brian so can you explain your findings agree or disagree?
last brian you talk about contact patch whereas i think of miscue limit as a point
also i think of tip offset for spin as a point with collateral contact based on the tip shape and size of shaft
i believe you put significance or are questioning whether that collateral contact plays a significant role
Click to expand...

You are spot on. Yes, the math proves exactly what PJ's diagram shows.

I like the term "collateral contact". And yes, I am trying to prove that the amount of collateral contact has a significant/noticeable effect on the amount of spin generated, mainly when applying maximum or near maximum english.
 
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phreaticus said:
Yeah, that particular DD page doesn’t really provide much clear answers. Its more like a diplomatic summary of the various mainstream sentiments & speculations on the topic.

Brian - Since you’re now in the weeds on this, I wonder if you want to try to also factor cue angle into your contact area analysis. Seems pretty intuitive that for example that BHE vs parallel english at the miscue edge are different animals, as one example. Vertical elevation of the cue on draw shots being another.

Cheers
Click to expand...

The attack angle of the cue might look different or special from the shooter's perspective, but as far as the cb is concerned it makes no difference. Since the cb is a sphere, any angle of approach is in reference to a particular offset from the center of the sphere. In other words, cue angle from the shooter's perspective doesn't matter. If you're cue is jacked up or angled sideways or shooting up through the netting of the corner pocket to send the cb airborne, the cb knows no difference. It simply reacts to the hit based on where it gets hit and how far the impact is from its center.

With that said, however, if you're shooting downward into the cb then it'll feel more force at contact because the tip is driving the ball into the slate, and the slate won't give, so the ball either leaves the table (jump shot) or squirts out from under the tip (massé shot).
 
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BC21 said:
The attack angle of the cue might look different or special from the shooter's perspective, but as far as the cb is concerned it makes no difference. Since the cb is a sphere, any angle of approach is in reference to a particular offset from the center of the sphere. In other words, cue angle from the shooter's perspective doesn't matter. If you're cue is jacked up or angled sideways or shooting up through the netting of the corner pocket to send the cb airborne, the cb knows no difference. It simply reacts to the hit based on where it gets hit and how far the impact is from its center.

With that said, however, if you're shooting downward into the cb then it'll feel more force at contact because the tip is driving the ball into the slate, and the slate won't give, so the ball either leaves the table (jump shot) or squirts out from under the tip (massé shot).
Click to expand...
Not really. What you said pertains to the contact mechanics of theoretical spheres where the only forces are acting perpendicular to the balls. In this discussion we’re also dealing with frictional forces acting tangentially between the surfaces. You can’t really have a discussion about variable contact patches & ignore the effects of friction. On the other hand, as Bob hinted earlier - modeling friction
is super complex & well beyond me. I’m no ME, but this distinction leads to completely different analysis… I was hoping you’d feel like doing a deep dive there, since thats really what we’re primarily talking about here, IMO.

Cheers ✌️
 
Wow. Lots of math, data, analysis and opinion.

My head is spinning like a maximum side-spun cue ball. 😁

So I am going to simply hit balls and experiment with my two shafts with my two shapes and forget about the why as much as I normally appreciate the why so I can understand the how.

Great stuff, all, thanks for the lively and civil discussion.
 
dquarasr said:
Wow. Lots of math, data, analysis and opinion.

My head is spinning like a maximum side-spun cue ball. 😁

So I am going to simply hit balls and experiment with my two shafts with my two shapes and forget about the why as much as I normally appreciate the why so I can understand the how.

Great stuff, all, thanks for the lively and civil discussion.
Click to expand...
Excellent conclusion, obviously no one really seems to know, but they do seem different to most folks. Have fun!
 
FranCrimi said:
Question: Does the tip stay on the cue ball longer during a masse shot?
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I'm guessing yes, but there's another difference: a masse shot drives the CB forward by "pinching" it sideways from underneath the tip (rather than driving it forward in line with the stroke), so the spin-to-speed ratio is dramatically increased.

pj
chgo
 
Patrick Johnson said:
I'm guessing yes, but there's another difference: a masse shot drives the CB forward by "pinching" it sideways from underneath the tip (rather than driving it forward in line with the stroke), so the spin-to-speed ratio is dramatically increased.

pj
chgo
Click to expand...
Bob Jewett said:
I think so, especially for nearly vertical shots.
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I think so too, which is why I think you all should reconsider the issue of tip contact time of the swipe method of applying side spin.
 
If anyone wants a sharp throbbing headache, this link gives a good starting point into the complex world of modeling the contact mechanics of two spheres. Essentially there are families of equations involved, each with many materials & force related input variables… maybe a project for Dr Dave…
 
Last edited:
FranCrimi said:
Question: Does the tip stay on the cue ball longer during a masse shot?
Click to expand...
Patrick Johnson said:
I'm guessing yes
Click to expand...
Bob Jewett said:
I think so, especially for nearly vertical shots.
Click to expand...
FranCrimi said:
I think so too, which is why I think you all should reconsider the issue of tip contact time of the swipe method of applying side spin.
Click to expand...
Seems like apples and oranges to me - CB trapped between tip and table vs. free to move in direction of stroke.

pj
chgo
 
dquarasr said:
Apples and oranges? Is that like 3-ball and 5-ball? Or 3-ball and, um, no-balls-in-the-rack (@Fatboy)?
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Not totally unrelated, but yes I think for masse, from a physics perspective it is much more complex, as you are dealing with the spherical friction contact mechanics of tip to CB (that we’ve already been sort of discussing) as well as the contact mechanics between the CB into the cloth/slate surface. I guess the latter element is there to some extent on any pool shot, but relatively minor…

So for you AZB gray beards, is this the geekiest tip shape discussion ever, or what?
 
Patrick Johnson said:
Seems like apples and oranges to me - CB trapped between tip and table vs. free to move in direction of stroke.

pj
chgo
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You're not assuming that the pool cue is always level during the swipe method, right? It may not be as drastic as a masse but I think there are more similarities than differences, particularly when applying side with back spin, using the swipe method.
 
FranCrimi said:
You're not assuming that the pool cue is always level during the swipe method, right? It may not be as drastic as a masse but I think there are more similarities than differences, particularly when applying side with back spin, using the swipe method.
Click to expand...
Yes, there’s a similarity in the kind of ball/table friction, but the difference in amount is extreme.

pj
chgo
 
Patrick Johnson said:
Yes, there’s a similarity in the kind of ball/table friction, but the difference in amount is extreme.

pj
chgo
Click to expand...
Extreme enough for you to say with confidence that the tip doesn't stay on the ball longer with the swipe method of applying side spin as opposed to other methods of applying it?
 
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