Tip Function

[mikepage]

[...] However, for a given brand of tip, say Moori, or Talisman, going from the tip each labels as soft or hard and comparing the hit and so on, there is no doubt they play differently and a hard tip will send the cue ball further on any given shot. [...]

Flex

Flex - It makes no sense to say there's no doubt about something when the only reason you're posting if because someone is expressing doubt.

I have no doubt you believe what you're saying...

mike page
fargo

 

[Craig Fales]

I noticed in that video that the tip is only in contact for a very short time....
________

 

[Cornerman]

misconception 3 caveat: A soft tip may give slightly more spin for a given offset. Imagine a hard tip contacting a cueball on a sidespin shot with a 10 mm offset. During the 1 ms or so the tip is on the ball, the ball begins to rotate. When the ball leaves the tip, the offset might be 11 mm instead of 10. The *effective* offset, the one that determines the spin-to-speed ratio for the cueball might be the halfway mark, 10.5 mm. Now do the same shot with a soft tip. It stays on the ball a little longer. So it may start at 10 mm and end at 11.5 mm. It's *effective* offset might then be 10.75 mm, slightly bigger than the 10.5 mm of the hard tip. This is a small effect that Bob jewett has talked about. I think to a reasonably dood approximation you can ignore it.


mike page
fargo

At some critical point, the tip will fall off the ball during rotation. Since the softer tip stays on longer, its limit of starting offsets must be slightly less than a hard tip.

So in the end, the maximum spin is probably really close to the same.

Fred

 

[Andrew Manning]

The relevant coefficient of friction is between the chalk and the ball, not between the leather of the tip and the chalk.



This comes up a lot and it's a red herring. The force that accelerates a car isn't really a friction force between the rubber and the road; the force is larger for wider tires because it's a shear force. The rubber at the surface is pulling away from the rubber just above it and so on. It's a special rubber thing. Static friction forces don't work that way. For static friction, like we have here, the frictional force is independent of the area of contact.




It is the amount of time each spring takes to compress and decompress that determines the contact times. That's why the soft tip has a longer contact time. Either collision can be and is somewhat inelastic. There's no a priori reason to believe collision with a soft tip is more inelastic than with a hard tip.

I've tried to measure distance a ball goes for an identical hit for different tips. I can't measure a difference. I then took several shafts with different tip hardnesses and bounced them off of slate from a fixed height. I measured the heights they bounced to. There were differences, but the differences really had no correlation with the tip hardnesses. In fact the one that transferred the most energy back had a soft tip. I included a bungee tip in this test.

mike page
fargo

It's only a shear force if the tires are spinning, otherwise it is static friction, but that's sort of beside the point. You're saying that the only variable in static friction is pressure (force/contact area), and there is another variable, the coefficient of static friction, which is different for every pair of surfaces pressed together. The implication that softr leather and harder leather have the same coefficient cannot be correct, although I don't have data to show how close they are to each other. Also, I don't think the only friction involved is between the chalk and the ball, I think no matter how well you chalk, there's leather touching the ball during contact. Additionally, I think some chalk slides along the tip during contact, meaning the friction between tip and chalk is also important, and I'm certain that softer leather grips grains of chalk much better.

You may be right about the spring constants and ball speed, but I still think there's a reason my jump/break cue has a phenolic tip, and I don't think it's the feel.

-Andrew

 

[Cornerman]

implies identical surface dynamics (the inherent coefficient of friction for the hard and soft tips),

I think the chalk determines the coefficient of friction. Unless the chalk doesn't stick to the tip, which seems to be less dependent on hardness and more dependent on material (of the tip or the chalk).

Fred

 

[Cornerman]

Take if from me, I've played around with this sort of thing a lot.

Take it from me, many people have and continue to do so.

Get a very soft tip and break with it. Now do the same with a super hard phenolic tip. You tell me the soft tip and the phenolic play the same.

Sticking with leather and its range of hardness and ability to hold chalk, imo, is paramount in these discussions.

If you're going to use phenolic on one end of the spectrum, then you have to be willing to use, say, a powder puff or equally non-analogous soft material. How about the cream filling of a Hostess Cupcake? Of course they won't play the same, nor will they be fair to include in the testing.

But, if you limit your testing between for example a hard water buffalo tip (Triangle or hard LePro) and a soft water buffalo tip (ElkMaster), I think your results will be more meaningful.

Fred <~~~ I wouldn't take it from me.

 

[Cornerman]

It's only a shear force if the tires are spinning, otherwise it is static friction, but that's sort of beside the point.

Um... that's pretty much right. Therefore, in static friction, the area of contact isn't a factor. Basic physics 101 says that the coefficients of friction are nearly independent of surface area.

In the tip/ball collision, I think it's static friction. I believe the Jacksonville showed that it was static, and not a shear force.

Fred <~~~ It doesn't look like a shear force to me

 

[Jaden]

The relevant coefficient of friction is between the chalk and the ball, not between the leather of the tip and the chalk.



This comes up a lot and it's a red herring. The force that accelerates a car isn't really a friction force between the rubber and the road; the force is larger for wider tires because it's a shear force. The rubber at the surface is pulling away from the rubber just above it and so on. It's a special rubber thing. Static friction forces don't work that way. For static friction, like we have here, the frictional force is independent of the area of contact.




It is the amount of time each spring takes to compress and decompress that determines the contact times. That's why the soft tip has a longer contact time. Either collision can be and is somewhat inelastic. There's no a priori reason to believe collision with a soft tip is more inelastic than with a hard tip.

I've tried to measure distance a ball goes for an identical hit for different tips. I can't measure a difference. I then took several shafts with different tip hardnesses and bounced them off of slate from a fixed height. I measured the heights they bounced to. There were differences, but the differences really had no correlation with the tip hardnesses. In fact the one that transferred the most energy back had a soft tip. I included a bungee tip in this test.

mike page
fargo

For these tests, did you use a mechanical arm that was applying the same amount of speed and energy for shots with both tips, because if you used your arm, there's no way that that could be definitive.....

 

[Jaden]

the question of static friction.....

I think that in what we are describing it would be better to use kinetic friction; however, either one is a moot point though. The difference of friction between hard or soft tips would only be applicable if they were already in contact with one another, because the surface properties react differently when the initial contact occurs due to differing compression characteristics, static friction could not be applied solely on its' own. In measuring circular motion it is necesary to include "tension or compression in a rod" Because the tension or compression will differ between the soft and hard tips, so will the resultant friction be different producing differing amounts of spin. It may very well be negligible but it will be there.

 

[Jerry Yost]

Food for thought

I visited Tony Sciannella of Black Boar cues one day (Very analytical type of guy in my opinion) and he demonstrated something for me. Keep in mind that I have subsequently made some assumptions based on observations made during the demonstration (i.e., I don't recall Tony specifically telling me what I'm about to say). Tony wrapped a wide rubber band around the tip of a cue and asked me to try and pocket a ball. It was extremely difficult to control the cue ball unless hit perfectly center ball. What I assumed was happening is that the rubber contracted and rebounded so quickly it prohibited the cue ball from staying in contact with the tip thus making control more difficult.

 

[Jaden]

I visited Tony Sciannella of Black Boar cues one day (Very analytical type of guy in my opinion) and he demonstrated something for me. Keep in mind that I have subsequently made some assumptions based on observations made during the demonstration (i.e., I don't recall Tony specifically telling me what I'm about to say). Tony wrapped a wide rubber band around the tip of a cue and asked me to try and pocket a ball. It was extremely difficult to control the cue ball unless hit perfectly center ball. What I assumed was happening is that the rubber contracted and rebounded so quickly it prohibited the cue ball from staying in contact with the tip thus making control more difficult.

What was probably the case was the opposite. The rubber is so much more pliant and liquid than leather that it compressed more easily creating greater friction and less slide making it difficult to control the amount of spin and squirt and just about anything at all.

 

[jsp]

misconception 3 caveat: A soft tip may give slightly more spin for a given offset. Imagine a hard tip contacting a cueball on a sidespin shot with a 10 mm offset. During the 1 ms or so the tip is on the ball, the ball begins to rotate. When the ball leaves the tip, the offset might be 11 mm instead of 10. The *effective* offset, the one that determines the spin-to-speed ratio for the cueball might be the halfway mark, 10.5 mm. Now do the same shot with a soft tip. It stays on the ball a little longer. So it may start at 10 mm and end at 11.5 mm. It's *effective* offset might then be 10.75 mm, slightly bigger than the 10.5 mm of the hard tip. This is a small effect that Bob jewett has talked about. I think to a reasonably dood approximation you can ignore it.

You summed up the whole story in this "caveat". This is all that you need to know about this subject.

A soft tip DOES give more spin for a given starting offset because the contact time is longer, not because you have a better grip (like Mike said, you do not have a better grip with a soft tip, because they are both the same).

Because the impact time is longer, the cue tip has more time for it to be dragged by the rotation of the CB, effectively increasing the initial offset of the stroke. When all is said and done, the effective offset of the stroke is greater, and hence more spin.

Mike, although I agree with your explanation to caveat #3, I disagree that you treat it only as a caveat, because it tells the whole story. This "small effect" cannot be ignored. Even in your example, a 0.25mm effective offset difference is significant enough for many shots (think long kick shots).

So to sum up my opinion...YES, softer tips give more spin because the contact time is greater.

 

[Billy_Bob]

What I would encourage every serious player to do is get tip replacement tools so you can replace your own tips, then get a cheap cue and a variety of tips.

Get phenolic, elk master, Moori soft, Moori hard, Tiger break/jump tip, and other tips.

Then install a tip and try it out for a week. Then on to the next tip.

I did this and learned a lot. Best lesson I ever had. Then you will not need to rely on what other people say about various tips. Just go by what you have learned first hand.

Note that when first learning to replace a tip, you can damage your ferrule easily, so learn on a cheap cue, not your expensive playing cue.

 

[Flex]

What I would encourage every serious player to do is get tip replacement tools so you can replace your own tips, then get a cheap cue and a variety of tips.

Get phenolic, elk master, Moori soft, Moori hard, Tiger break/jump tip, and other tips.

Then install a tip and try it out for a week. Then on to the next tip.

I did this and learned a lot. Best lesson I ever had. Then you will not need to rely on what other people say about various tips. Just go by what you have learned first hand.

Note that when first learning to replace a tip, you can damage your ferrule easily, so learn on a cheap cue, not your expensive playing cue.

Great advice, Billy Bob. That's just what I did, but with over 10 different tips. Plus I used the same tips sometimes on different shafts to see which combinations work better for me.

Nothing can really replace that sort of experience.

Flex

 

[Billy_Bob]

...That's just what I did, but with over 10 different tips. Plus I used the same tips sometimes on different shafts to see which combinations work better for me.

Nothing can really replace that sort of experience.

Great! I get the feeling that some people on these forums are not giving "unbiased" opinions when it comes to tips. Same thing with cues.

Some people may have a financial "interest" in particular brands, so say these are the best, etc. Or may say another brand is bad. You never know if the "advice" you are reading is unbiased or not.

So you wind up with conflicting advice. Best to find out for yourself.

 

[mikepage]

[...]
Mike, although I agree with your explanation to caveat #3, I disagree that you treat it only as a caveat, because it tells the whole story. This "small effect" cannot be ignored. Even in your example, a 0.25mm effective offset difference is significant enough for many shots (think long kick shots).

[...]

I don't see what the advantage is. You can get a comparably sized increase in spin for the same stick offset by going from a nickel to a dime radius.

But there are no free lunches.

Either way-- soft tip or a dime radius tip-- may give a little more spin for a given offset, but the flip side is the miscue point will occur at a smaller stick offset (as Fred said, there will be likely be the same maximum spin). This may actually be a disadvantage. If the entire range of spins is crunched into a smaller range of stick offsets, it's harder to zero in on a particular desired amount of spin--like tuning into a radio station when the entire range of stations spans just a quarter turn of a dial.

mike page
fargo

 

[mikepage]

Great! I get the feeling that some people on these forums are not giving "unbiased" opinions when it comes to tips. Same thing with cues.

Some people may have a financial "interest" in particular brands, so say these are the best, etc. Or may say another brand is bad. You never know if the "advice" you are reading is unbiased or not.

[...]

Another reason this whole concept of having serious discussions using fake junior-high chat-room style names is a problem, imo.

mike page
fargo

 

[Cornerman]

Great! I get the feeling that some people on these forums are not giving "unbiased" opinions when it comes to tips. Same thing with cues.

Some people may have a financial "interest" in particular brands, so say these are the best, etc. Or may say another brand is bad. You never know if the "advice" you are reading is unbiased or not.

So you wind up with conflicting advice. Best to find out for yourself.

Wow. What posts on this thread could possibly have given that kind of feeling?

Fred

 

[Billy_Bob]

Wow. What posts on this thread could possibly have given that kind of feeling?

I don't mean this thread specifically. Just any question about "best" tips in general. Or any question about "best" cue, etc.

And that was my problem starting out. One person would say this was best. Another would say that was best.

So I got fed up and decided to learn for myself what was best. And this can get to be expensive when it comes to shafts/cues! Tips are not too expensive to experiment with if you can replace them yourself....

 

[Mungtor]

Um... that's pretty much right. Therefore, in static friction, the area of contact isn't a factor. Basic physics 101 says that the coefficients of friction are nearly independent of surface area.

Friction is independent of surface area, but the coefficient of friction does change based on pressure and/or load. I don't know about leather, or whether the limiting coefficient is the chalk-to-ball one or the tip-to-chalk one. Rubber, for example, behaves so that the coefficient of static friction decreases as load increases.

In the tip/ball collision, I think it's static friction. I believe the Jacksonville showed that it was static, and not a shear force.

Fred <~~~ It doesn't look like a shear force to me

If you don't have a shear force, you're in pure compression, and static friction would be irrelevant, wouldn't it? A center ball hit works with or without chalk because there is no shear, but any offset requires it. Or so it appears to me.