Chalk Experiment Results, with Video

[The Renfro]

Chris,

Excellent summary. The only thing I potentially disagree with, depending on what you are implying, is: "Better chalk grabs better"

My video shows that Blue Diamond and Kamui stick to the CB more, and this can result in larger and more frequent cling/skid/kick. In other words, these chalks helps the CB "grab" the OB more (by creating more friction between the balls). However, there is no evidence in my video that Blue Diamond and Kamui help the tip grab the CB any better than the other chalks.

Regards,
Dave

I am looking at the "larger skid" aspect as being the indicator of the chalk grabbing better... I am also going by ear on the misscue limit test in regards to slip but will try and get a wave form program installed to look at them since what you hear can be subjective to what you expect to hear..... In the end you may be correct to disagree with me... Especially since I am interpretting tests that were not intended to grade the quality of grab or spin ratios...

Chris

 

[buckshotshoey]

If that's what you extrapolated out of my post, I suggest you read it a few more times.


Cliff Notes:

* The purpose of the test is "chalk performance" -- the performance would be gauged as a "factor," a constant if you would.

* It's impossible to determine that constant with a person shooting.

* Chalk performance might be measured in tolerances thaight be too fine to measure on 8 strokes, but could definitely show up in more strokes.

**** Chalk performance in offset could be measured in millimeters, which is a BIG deal in general, but can't be measured when the guy doing the test can't deliver his tip to that degree of accuracy. Most can't, but that does NOT mean that the chalks are equal. Just like most can't experience the difference in performance between a Pinnacle golf ball and a ProV1 golf ball, that does NOT mean the two are equal and that's was the claim of these tests... in a nutshell. It's like having a golfer who shoots 100 hit both and say, "Yup-- they both went 120 yards and neither stopped on the green -- so both are the same."

I agree with some of what you said, but this statement could be just as true......... you NEVER see a robotic arm at a tournament! Maybe adding the human factor into the equation (or experiment) will give a truer representation of the product.

I think it would be a safe assumption that Dave has a pretty good stroke. But to truely add that human equation into the experiment, more people have to set up and run the experiment exactly as the good doctor did.
I doubt any of you will take the time to do it. God knows, I certainly don't have the time to spare.

Dave....your work IS appreciated.

 

[JB Cases]

Chris,

Excellent summary. The only thing I potentially disagree with, depending on what you are implying, is: "Better chalk grabs better"

My video shows that Blue Diamond and Kamui stick to the CB more, and this can result in larger and more frequent cling/skid/kick. In other words, these chalks helps the CB "grab" the OB more (by creating more friction between the balls). However, there is no evidence in my video that Blue Diamond and Kamui help the tip grab the CB any better than the other chalks.

Regards,
Dave

We are talking about friction here right? Basically how much a bit of chalk adds to throw on a cut shot IF the chalk patch happens to be at the impact (contact) point.

So if cue stick deflection is a constant, and tip squirt is a constant, as show in your other video, why isn't chalk friction a constant?

Thus if friction is what determines the amount of grabbiness then why isn't it logical to say that the chalk with the most grab in one aspect of the test wouldn't have more grab in the other aspect?

I think the missing element here is HOW much chalk had to be applied to get the same performance? In other words since your conclusion is that "all" chalks perform equally well in the tip to cueball interaction can you tell us the amount of chalk that was needed to get that same performance?

Here is my test, also flawed by human error, but it is 30 shots with extreme spin from the same position to attempt to discern whatever visible differences could be seen. In this test the shots with Kamui were on average much more consistent than with Masters.

https://www.youtube.com/watch?v=ekGhSBJGmSU

A good combination I found is to have a base layer of Kamui and a top layer of Masters. This seems to make sense to me as it allows for the "stickier" chalk to form a foundation of grip that is likely to stay on the tip longer.

 

[dr_dave]

My video shows that Blue Diamond and Kamui stick to the CB more, and this can result in larger and more frequent cling/skid/kick. In other words, these chalks helps the CB "grab" the OB more (by creating more friction between the balls). However, there is no evidence in my video that Blue Diamond and Kamui help the tip grab the CB any better than the other chalks.

We are talking about friction here right? Basically how much a bit of chalk adds to throw on a cut shot IF the chalk patch happens to be at the impact (contact) point.

That is correct with the cling experiment when I was determining how much the chalk (at the ball-ball contact point) increases the amount of cut-induced throw.

However, the miscue tests are a totally different story. They are testing how well the tip grabs the cue ball (not how well the cue ball grabs the object ball at the ball-to-ball contact point).

So if cue stick deflection is a constant, and tip squirt is a constant, as show in your other video, why isn't chalk friction a constant?

Thus if friction is what determines the amount of grabbiness then why isn't it logical to say that the chalk with the most grab in one aspect of the test wouldn't have more grab in the other aspect?

The miscue limit (and therefore the maximum english capability) of a chalk cannot be described by a single number like a coefficient of friction (COF). The physics of the tip-ball collision is very complicated. For shots within the miscue limit, all chalks grab the ball fine. Even if one chaulk had a tip-to-ball COF much greater than another, it is still possible that both grab the ball sufficiently (without any slip) at different tip offsets to prevent a miscue. Furthermore, both chalks can still have the same miscue limit, as was evident in the video. Again, the miscue limit is not just due to a simple COF number.

A good combination I found is to have a base layer of Kamui and a top layer of Masters. This seems to make sense to me as it allows for the "stickier" chalk to form a foundation of grip that is likely to stay on the tip longer.

That sounds interesting. I'll try to find time to put this through my set of tests when I can find the time.

Catch you later,
Dave

 

[buckshotshoey]

A good combination I found is to have a base layer of Kamui and a top layer of Masters. This seems to make sense to me as it allows for the "stickier" chalk to form a foundation of grip that is likely to stay on the tip longer.

You could be on to something. The masters MIGHT make a good buffer so the Kamui doesn't transfer to the cue ball so bad. Hmmmmmmm.

 

[JB Cases]

That is correct with the cling experiment when I was determining how much the chalk (at the ball-ball contact point) increases the amount of cut-induced throw.

However, the miscue tests are a totally different story. They are testing how well the tip grabs the cue ball (not how well the cue ball grabs the object ball at the ball-to-ball contact point).


The miscue limit (and therefore the maximum english capability) of a chalk cannot be described by a single number like a coefficient of friction (COF). The physics of the tip-ball collision is very complicated. For shots within the miscue limit, all chalks grab the ball fine. Even if one chaulk had a tip-to-ball COF much greater than another, it is still possible that both grab the ball sufficiently (without any slip) at different tip offsets to prevent a miscue. Furthermore, both chalks can still have the same miscue limit, as was evident in the video. Again, the miscue limit is not just due to a simple COF number.


That sounds interesting. I'll try to find time to put this through my set of tests when I can find the time.

Catch you later,
Dave

You say it's sufficient but I tend to disagree (surprise).

If two materials have different degrees of friction, one grabs more than another then it follows that the grab is greater across all uses of that material. In other words all else being equal, force, tip, cue, vector, the extra friction should matter in some way.

What if that way is in fact better grip at all spin positions? What is the net effect of less slippage or does it really not matter? Is there an extra rpm or two generated when one chalk grips more than another? I think that this was not sufficiently answered by your video.

I have to say that if you ever experienced the very bad chalk such as Sportcraft brand then you would definitely have a clear understanding of how awful "bad" chalk is. My thought is that if such "bad" chalk can negatively affect the performance, essentially shrinking the miscue limit, then why can't better chalk increase it?

In other words if Kamui (or other brand) is much more grippy than Masters then doesn't it follow that if the last shred of tip that can reasonably be used to hit the cue ball is used then the grippier chalk should be able to hold that hit more than less grippy chalk. And if that is true then why wouldn't it also grip more going towards center.

I think you have not demonstrated yet what if any the spin differences would be at all offsets with all chalks.

I suggest to Kamui and everyone else that they build a mechanical stroking device to take all human error out and let it show the results of different chalks. Such a device has to be simple to build and could be essentially a crossbow style setup. Force could be determined by how far back the tension is set.

 

[rhatten]

Also all imo 'Tip to cueball' studies must be "shot" (repetitive mechanically) exactly parallel to the table top at CB contact to calculate a 'relative reference value' for chalk print comparison. ... otherwise your simply talking masse shots each other if done by 'hand'... ie think jump shots or highly elevated masse- your simply pinching the CB into the table/cloth (adding CB resistance to forward movement of the cue) producing a longer 'print transfer time/force' when compared to a flat level stroke shot. A 10 degree butt elevated stroke delivery to the CB surface offers a small measurable resistance with either a center a CB skid or masse ... both offer larger 'chalk print transfer times/forces all esle remaining the same than that of a level 0 degree angle stroke.

Ball polish technique or surface cleaning (materials and handling) , chalk application technique as well stroke delivery methodology would have to be vetted and as mechanical as possible for a double blind study to have peer review merit...(if there is a recognized body of professional 'peers' on this subject) so until then... if it feels good, do it.

R

 

[JayKidd]

everyting else being equal, force, tip, cue, vector, the extra friction should matter in
some way.

And if that is true then why wouldn't it also grip more going towards center.

John, let me try to explain some of your questions.

Static friction force is like a reserve pool of counter-slipperage, when the dynamics between the two surfaces demand more counterforce to stay balanced, it tap the friction pool for more. So the extra-friction those "grippier" chalks provide doesn't have to matter when no slipping occurs, since they were never required.

My thought is that if such "bad" chalk can negatively affect the performance, essentially shrinking the miscue limit, then why can't better chalk increase it?

Good point, I think what Dave presented can be interperated as "most brand tested" have enough friction to achieve very close "maximum miscue limit" result in the first few strikes after applying.

From another point of view, the relationship between "offcenter offset" and "COF sufficent to stay grabbed" is not linear. 1/10 of a millimeter outward near the miss-cue limit would require a much larger increase in COF to cover since the surface slope change much more rapidly there than near center. So that the null-results Dave recorded can be explained this way: "Even if Kamui has 5% higher COF than Master has, this 5% advatage may only translate into less than 1% miscue-limit increase, probably to a negligible extant".

I suggest to Kamui and everyone else that they build a mechanical stroking device to take all human error out and let it show the results of different chalks.

I think Kamui did claim to have built such a device or devices to that end. And their claim of increased spin/decreased deflection were confirmed on it/them. Although I don't think they release enough details regarding the specs of the robot.

Such a device has to be simple to build and could be essentially a crossbow style setup. Force could be determined by how far back the tension is set.

Good idea. I think add a high-resolution camera setup to verify the resulting speed of the striking arm would further confirm the objective velocity.

 

[JayKidd]

Chris, I don't think spin/speed ratio would change by choice of chalk as long as there were no slip occur during contact. Given the same impact speed vector and contact point, I am still trying to build a physic model in which the other factors such as tip and shaft have some contributions to the spin/speed ratio. But I think the chalk is not one of those hidden factors.

I may need some finite element simulations to quantify the theory first.

 

[The Renfro]

Chris, I don't think spin/speed ratio would change by choice of chalk as long as there were no slip occur during contact. Given the same impact speed vector and contact point, I am still trying to build a physic model in which the other factors such as tip and shaft have some contributions to the spin/speed ratio. But I think the chalk is not one of those hidden factors.

I may need some finite element simulations to quantify the theory first.

I would agree that with no slip the same tip offset with only a change in chalk to the equation would have no area for increase in spin.... Re watch the misscue limit section of Dave's video if you get a chance... I belive there was slippage on the 1st and 3rd shot with Lava and on the 3rd shot with Blue Diamond... Most of the other strikes caused similar sounds and paths across the sheet protector at the bottom of the video... Only the 2nd shot using Kamui seemed to shorten the angle even tho Dave was moving further out on the cueball.... That tends to make me think there had to be some slipping occuring that was so small that it may not have been felt or heard........

 

[JB Cases]

Chris, I don't think spin/speed ratio would change by choice of chalk as long as there were no slip occur during contact. Given the same impact speed vector and contact point, I am still trying to build a physic model in which the other factors such as tip and shaft have some contributions to the spin/speed ratio. But I think the chalk is not one of those hidden factors.

I may need some finite element simulations to quantify the theory first.

Years ago Pat Johnson had outlined a test to prove that the type of cue doesn't matter when it comes to generating spin. This was back when Predator was marketing their cues with a 'gives 25% more spin' claim. Pat had a test where you had to shoot a certain shot and mark where the cue ball ended up. The idea was that no matter what cue you used you could absolutely NOT get the ball to end up in the same spot with any other offset. You could hit the ball with a different offset and more or less speed but IF you hit the ball with the same offset and speed then no more spin was produced regardless of the cue.

I tested this and found it to be true for level cues.

But when it comes to masse' shots if I used a carom cue then I could get way more spin than if I used a pool cue.

When I lived in Germany I had a billiard supply shop. Our pool table was surrounded by four walls of pool cues. I had a twin set of cues from an italian maker, I forget the name, not Longoni. One of the cues was set up for pool with a metal screw in the butt and a pool "pro" taper to 13mm at the tip and the other was set up for carom at 57" and with a wood screw in the shaft and a conical taper down to 11.5mm at the tip.

Back then I would mess around a lot on our table at night, trying cues and trying shots. One time I was messing with the trick shot where you freeze two balls at one end and hang another ball on the same rail at the other end. The idea is to make the frozen ball and the cue ball doubles the rail all the way down to make the other ball. Another variation is to make the frozen ball and masse' around an interfering ball to make the other ball. Anyway, I was messing with the italian cues and trying this shot and with the pool cue I could barely make the cue ball double the rail much less get down table.

With the carom cue I could easily double the rail several times and often make the object ball. So after discovering this I tried it out on various masse' shots and found that the carom cue made it easier for any kind of masse'.

--------------------------------------------------

why does this matter?

Well, to me it matters because I do think that cues have performance differences. But where do those differences come from? The internal structure, the balance, the taper, type of wood, ferrule, endmass, tip, chalk? Humidity, muscle tension while holding different weights.

We all know it's easier to jump with a dedicated jump cue, we know it's easier to masse' with a dedicated masse' cue. I think that people seem to have this idea though that all pool cues, and anything resembling a pool cue such as a snooker cue or a carom cue, all have the same performance within a very tight range.

I think we all accept that deflection is tunable at this point. I think we accept the concept of radial consistency as valid and available. But we don't much about anything else really on how all the other variables affect performance. We have seen a lot of marketing points, seen very little testing that everyone agrees is fair.

---------------------------

What i get out of all this and Dr. Dave's videos is - pool is tough - not only do cues all perform differently but other factor influence results a lot, chalk, ball condition, tip hardness, cloth conditions, humidity, stroke tics, etc... tons of tiny variables with infinite combinations that can throw the shot off just a hair in the wrong direction.

These are all things that professional class players get attuned to and which amateurs either don't really develop a feeling for OR they simply dismiss as superstition.

 

[dr_dave]

Chris, I don't think spin/speed ratio would change by choice of chalk as long as there were no slip occur during contact.

Exactly! If there is slip between the tip and OB during impact, that would be considered a "bad hit" resulting in a miscue or partial miscue. In these cases, the CB would not head in the expected direction (accounting for the natural amount of squirt or CB deflection).

Given the same impact speed vector and contact point, I am still trying to build a physic model in which the other factors such as tip and shaft have some contributions to the spin/speed ratio. But I think the chalk is not one of those hidden factors.

The type of chalk does not affect spin/speed ratio for a good (non-miscue) hit.

Concerning the effects the tip and shaft can have on CB speed and spin, this is covered fairly well in the following resources:

cue tip hardness effects
cue tip size and shape effects
getting more spin with an LD shaft
shaft endmass and stiffness effects
TP A.30 - The effects of cue tip offset on cue ball speed and spin
TP B.7 - Effect of squirt on the amount of spin

Enjoy,
Dave

 

[Don Owen]

A philosopher I like once said, “If two people disagree at least one of them is wrong”. With that in mind, I postulate the following without any proof from testing:
1. If there is no miscue then coefficient of friction (dynamic, kinetic) is not involved between cue tip and cue ball because coefficient of friction relates only when surfaces are sliding (slipping).
2. If there is no miscue then all chalks preform identically.
3. If there is no miscue then different chalks cannot affect spin (spin/speed) differently.
4. If there is no miscue then different chalks cannot affect squirt (deflection) differently.
5. If there is no miscue then the question of more or less grip on the cue ball has no meaning. If there is no miscue the “grip” on the cue ball is absolute regardless of which chalk is used.
6. I am doubtful that different chalk brands will have identical miscue limits. Two cubes of the same brand or two applications from the same cube will have measurably different miscue limits.
7. I could probably go on…

 

[dr_dave]

A philosopher I like once said, “If two people disagree at least one of them is wrong”. With that in mind, I postulate the following without any proof from testing:
1. If there is no miscue then coefficient of friction (dynamic, kinetic) is not involved between cue tip and cue ball because coefficient of friction relates only when surfaces are sliding (slipping).

Agreed.

2. If there is no miscue then all chalks preform identically.

Agreed.

3. If there is no miscue then different chalks cannot affect spin (spin/speed) differently.

Agreed.

4. If there is no miscue then different chalks cannot affect squirt (deflection) differently.

Agreed.

5. If there is no miscue then the question of more or less grip on the cue ball has no meaning. If there is no miscue the “grip” on the cue ball is absolute regardless of which chalk is used.

Agreed.

6. I am doubtful that different chalk brands will have identical miscue limits. Two cubes of the same brand or two applications from the same cube will have measurably different miscue limits.

That's what I would think also; but in my experiments, I was not able to find measurable or noticeable differences. Maybe other (non-friction) physics effects going on during the collision (tip deformation, tip and shaft elastic-wave interactions at the tip-ball interface, etc.?) contribute more to the miscue limit than just the static and dynamic COFs between the tip and CB (which should vary with the type of chalk)?

7. I could probably go on…

Agreed.

Regards,
Dave

 

[Bob Jewett]

(different chalks should have different miscue limits)

That's what I would think also; but in my experiments, I was not able to find measurable or noticeable differences. Maybe other (non-friction) physics effects going on during the collision (tip deformation, tip and shaft elastic-wave interactions at the tip-ball interface, etc.?) contribute more to the miscue limit than just the static and dynamic COFs between the tip and CB (which should vary with the type of chalk)? ...

About 10 years ago I had a student who had his own table. Being a 49ers fan, he had covered the table with red cloth and had red chalk to match. I avoided vomiting and began the fairly basic lessons. When we got to draw, he kept miscuing. I said, "Let me show you how the stroke should look," and proceeded to miscue several times. The chalk he had simply did not work well. I got some other red chalk for the next lesson as did he. None of the red chalk worked for either of us, although blue chalk (which leaves really ugly marks on red cloth) did work OK. The student changed his cloth to green and his chalk to blue.

My conclusion: some chalk does not work nearly as well as other chalk.

Maybe bad chalk is hard to find but I suspect it still exists. I've encountered some really bad chalk in taverns.

 

[Poolplaya9]

A philosopher I like once said, “If two people disagree at least one of them is wrong”. With that in mind, I postulate the following without any proof from testing:
1. If there is no miscue then coefficient of friction (dynamic, kinetic) is not involved between cue tip and cue ball because coefficient of friction relates only when surfaces are sliding (slipping).
2. If there is no miscue then all chalks preform identically.
3. If there is no miscue then different chalks cannot affect spin (spin/speed) differently.
4. If there is no miscue then different chalks cannot affect squirt (deflection) differently.
5. If there is no miscue then the question of more or less grip on the cue ball has no meaning. If there is no miscue the “grip” on the cue ball is absolute regardless of which chalk is used.
6. I am doubtful that different chalk brands will have identical miscue limits. Two cubes of the same brand or two applications from the same cube will have measurably different miscue limits.
7. I could probably go on…

I have said all these exact same things on here in the past and fully agree.

To put it in simpler terms, you always hear people talking about "slippage". I think slippage which does not result in a miscue, at least for all practical purposes, does not exist. There isn't really such a thing. There is either no slippage and no miscue, or there is slippage which IS the miscue. There is no in between where the tip is slipping but does not miscue.

When you have one surface that is round and smooth and very hard and low friction (the cue ball), and it gets hit at a very high speed and at a relatively shallow effective angle by something else round such as a pool tip, the tip is not going to let go and start slipping and then grab back on again and stop slipping, nor is any "controlled but constant slippage" possible that doesn't result in a miscue. Once slippage begins there simply isn't enough friction left to allow for either one and the tip is going to continue slipping until it slips right off the edge of the cue ball, otherwise known as a miscue. Essentially there are two possible states, full grip, or full slip (miscue).

And if there is no meaningful slippage occurring without a miscue, then one type of tip or chalk cannot impart more spin onto the cue ball than any other type of tip or chalk for hits with the same tip offset from center ball (same amount of english).

Since there is either slippage (miscue), or no slippage, and since all chalks impart the same spin for the same amount of tip offset/english, then the only other way a chalk might be able to allow you to "impart more english" is if it allows you to do so by being able to hit further from the center of the cue ball without miscuing. I also agree that with some types of chalk there is certainly a noticeable and measurable difference in the amount of tip offset you can hit the cue ball with before miscuing. I think it is a case where for any decent quality chalk (which includes most of the major brands/types out today) the differences are pretty negligible and there is little practical difference among the best brands in terms of the miscue limits, but with some lesser chalks the difference can be quite noticeable and measurable. Dr. Dave didn't use the crappiest chalks in his experiment and so we only got to see how the better chalks are all the same in miscue limit for all practical purposes.

I suspect there is more disparity in the miscue limits between different types of chalk the softer you hit the cue ball, and possibly even enough to demonstrate and measure, even among the better chalks. I would be curious to know for sure although it likely would not be enough to make any practical difference even if true.

I also believe that if someone is demonstrably and measurably getting more spin from one chalk (or tip) type over another with hits of the same amount of tip offset from center ball (same amount of english), then the cause of this is that they are not actually hitting the cue ball with the same tip offset from center ball (same amount of english) like they think they are. Most likely their subconscious is adjusting and causing them to hit closer to center ball than they are intending to for those chalks or tips that they happen to have less confidence in for whatever reason. Same actual tip offset and same speed of hit will result in the same amount of spin on the cue ball regardless of the brand/type of chalk used.

 

[The Renfro]

I have said all these exact same things on here in the past and fully agree.

To put it in simpler terms, you always hear people talking about "slippage". I think slippage which does not result in a miscue, at least for all practical purposes, does not exist. There isn't really such a thing. There is either no slippage and no miscue, or there is slippage which IS the miscue. There is no in between where the tip is slipping but does not miscue.

I think this is the whole point of contention... I disagree with this premise... I think there are a whole range of partial misscues caused by slippage between the surfaces since chalk is a combination of abrasives, fillers and binders.. And the Abrasives will vary in size, quantity and quality of cutting surface.....

Based on experiences using masters after using Kamui and Blue diamond on a pneolic tip for a few years there are instances where slippage can be felt even tho there was no complete misscue... I think we have all have hit shots where the impact sounded different and the shot still goes but we don't get what we wanted on the cueball..... This happens when there is enough grip to keep the cueball on track but there was not enough grip to create the rotational force.. This is what Bob Jewett was experiencing with the red chalk in his example.....

I am converting Dr Dave's video to audio and will look at the wave forms tomorrow on the shots I think had slippage... I may record some shots today and do the same with the resulting video....

Chris

 

[Ron Swanson]

As ever, my own personal experience contradicts much of the good doctor's findings.

I find the notion of all chalk, tips and shafts essentially producing the same results to be palpably absurd.

A chalk test cannot even begin without having a cube of Pioneer as the starting point.

 

[Poolplaya9]

Based on experiences using masters after using Kamui and Blue diamond on a pneolic tip for a few years there are instances where slippage can be felt even tho there was no complete misscue...

Everything I was referring to was in regards to leather playing tips that were properly maintained and chalked. When you start getting into different materials other than leather, or improperly maintained or improperly chalked tips, things may be different (because you are then dealing with materials/circumstances that come with very different amounts of friction). Let's keep the discussion on leather tips that are of a hardness that is appropriate for playing and that are properly maintained and chalked.

I think we have all have hit shots where the impact sounded different and the shot still goes but we don't get what we wanted on the cueball.....

Just because a hit sounds "different" doesn't necessarily mean there was some slippage that did not result in a miscue. There can be plenty of other good explanations for a shot sounding funny to us.

I think maybe we can even miscue sometimes and not even really realize it was a miscue but where we definitely noticed that the shot sounded or felt or looked funny. I think this might especially be possible with miscues that happened with a closer to center ball hit but where the tip was not holding chalk well because it was either incapable of holding chalk well or simply because we just failed to chalk it well. Because the tip started closer to the center of the cue ball the cue ball was able to clear/leave the tip before the tip was able to slide off the edge of the ball. There may be other scenarios as well where the ball is able to clear the tip before the tip slips off the side of the ball, and in these cases it is probably harder to identify it as a miscue although we will likely know that something wasn't quite right.

This happens when there is enough grip to keep the cueball on track but there was not enough grip to create the rotational force.

This makes no sense at all. For starters, if the cue ball is hit off center then any grip/friction will impart spin. Even a miscue has a little grip/friction and imparts a little spin. But if there is enough grip that you didn't miscue, then without doubt you had enough grip to impart some decent spin.

This is what Bob Jewett was experiencing with the red chalk in his example.....

He was experiencing miscues, not diminished spin when hitting with the same tip offset amount.

I am converting Dr Dave's video to audio and will look at the wave forms tomorrow on the shots I think had slippage... I may record some shots today and do the same with the resulting video....

Until you can demonstrate that those "sounds" that you are hearing are caused by slippage, and always caused by slippage (which for starters requires proving slippage even exists), then just because you hear sounds that seem unusual to you does nothing toward showing if there was any slippage or not.

 

[Bambu]

I have said all these exact same things on here in the past and fully agree.

To put it in simpler terms, you always hear people talking about "slippage". I think slippage which does not result in a miscue, at least for all practical purposes, does not exist. There isn't really such a thing. There is either no slippage and no miscue, or there is slippage which IS the miscue. There is no in between where the tip is slipping but does not miscue.

When you have one surface that is round and smooth and very hard and low friction (the cue ball), and it gets hit at a very high speed and at a relatively shallow effective angle by something else round such as a pool tip, the tip is not going to let go and start slipping and then grab back on again and stop slipping, nor is any "controlled but constant slippage" possible that doesn't result in a miscue. Once slippage begins there simply isn't enough friction left to allow for either one and the tip is going to continue slipping until it slips right off the edge of the cue ball, otherwise known as a miscue. Essentially there are two possible states, full grip, or full slip (miscue).

And if there is no meaningful slippage occurring without a miscue, then one type of tip or chalk cannot impart more spin onto the cue ball than any other type of tip or chalk for hits with the same tip offset from center ball (same amount of english).

Since there is either slippage (miscue), or no slippage, and since all chalks impart the same spin for the same amount of tip offset/english, then the only other way a chalk might be able to allow you to "impart more english" is if it allows you to do so by being able to hit further from the center of the cue ball without miscuing. I also agree that with some types of chalk there is certainly a noticeable and measurable difference in the amount of tip offset you can hit the cue ball with before miscuing. I think it is a case where for any decent quality chalk (which includes most of the major brands/types out today) the differences are pretty negligible and there is little practical difference among the best brands in terms of the miscue limits, but with some lesser chalks the difference can be quite noticeable and measurable. Dr. Dave didn't use the crappiest chalks in his experiment and so we only got to see how the better chalks are all the same in miscue limit for all practical purposes.

I suspect there is more disparity in the miscue limits between different types of chalk the softer you hit the cue ball, and possibly even enough to demonstrate and measure, even among the better chalks. I would be curious to know for sure although it likely would not be enough to make any practical difference even if true.

I also believe that if someone is demonstrably and measurably getting more spin from one chalk (or tip) type over another with hits of the same amount of tip offset from center ball (same amount of english), then the cause of this is that they are not actually hitting the cue ball with the same tip offset from center ball (same amount of english) like they think they are. Most likely their subconscious is adjusting and causing them to hit closer to center ball than they are intending to for those chalks or tips that they happen to have less confidence in for whatever reason. Same actual tip offset and same speed of hit will result in the same amount of spin on the cue ball regardless of the brand/type of chalk used.

Interesting post, but I don't know. What about the old "miscue and make it" shot? I can't be the only one whose seen that. Maybe on some level, there could be such a thing as slippage. Of course, the tip itself would also factor in. Who knows, maybe the cue too.