Cue Tip Contact Myth-Busting Truths in Super Slow Motion

[Monti]

Ball-ball contact times are much shorter than tip-CB contact times per the info here:

ball-ball contact time​

A chalk mark causes more throw due to increased friction, not increase contact time. For more info, see:

cling/skid/kick​

Throw is also greater for slow-speed stun shots, again, not because the contact time is changing, but because the friction is greater at slower speed per the info and demonstrations here:

throw speed effects​

Thanks Dave
If a chalk mark creates more spin due increased friction , then can one tip compared to another not have more friction and have an effect?

 

[WobblyStroke]

One thing that I think is safe to assume happens with tip compression which usually means a softer tip is that as the tip compresses the tip will be touching more of the cue ball closer to center effectively reduce the amount of spin.

Your 'safe assumption' is wrong. Just like when drawing a shot, only the top of the tip contacts the ball and should be the reference point for how low you are actually hitting the CB, with sidespin, it is the center-side of the tip that contacts the ball first. Any extra contact surface would occur towards the outside of the ball.

As explained above somewhere, tip deformation only comes into play at the miscue limit. Given that a soft tip stays in contact longer, it rides around while in contact with the ball farther which makes it more likely to miscue or partially miscue as it reaches the miscue point at a time a harder tip would have already lost contact with the ball. In other words, a hard tip can start out with a slightly larger initial offset at contact than a soft tip which needs to start a touch closer to center to allow for the extra bit it will ride around on the ball before reaching the miscue limit.

 

[Bob Jewett]

... In the meantime, if you would reply to my initial response to you, it would be much appreciated. ...

Please do your homework first. You seem to be capable of it. A conversation on a technical subject is difficult if one party has none of the standard knowledge of the subject and is just winging it.

 

[pvc lou]

Please do your homework first. You seem to be capable of it. A conversation on a technical subject is difficult if one party has none of the standard knowledge of the subject and is just winging it.

ouch

 

[dr_dave]

Ok Doctor Dave,

You gave me a lot of homework to do...I thought I was done with school. Gosh!

For your and the audience's convenience, I have color coded and enumerated my response. I hope that it is not made in excessive haste.

1) "because of the contact time being too long": already, it seems that you are conceding my point...that the contact time has an effect.

Typical cue tips have contact times in the 1-2ms second range, where differences do not have any important effects. But if you change the contact time significantly (e.g., by using a soft rubber tip instead, which is not suitable for playing pool), the physics is very different.

2) If you want to claim my statements are wrong (which make sense and agree with accepted theory): I feel that you are taking my skepticism of your claims personally. I hope I'm wrong, because neither a scientist nor a pool player should.

I was simply stating that if you want to be skeptical and propose alternative theories that go against current knowledge and understanding, you need to convincingly justify and test your claims. This is how science works. I won't do it for you because I don't believe the time would be well spent. This isn't spite, just honesty.

4) A soft tip does not provide as efficient a hit, so more cue speed is required to get the same CB speed and spin: Here, there is much room for discussion, as your compatriot and also resident scientist, Mike Page, has challenged you on this question. My response to this is: at the end of the day, the question is: what is the effect of the tip hardness on the amount of imparted spin?...all else being equal...i.e. cb speed and so on.

Mike Page has correctly pointed out that it might be possible to create a soft tip suitable for playing pool that might have a better hit efficiency than a typical hard tip also suitable for pool. I have not seen one yet, but I agree with him that it might be possible.

5) You can definitely get more effective sidespin with a slower-speed shot, especially with a below-center hit, either with a soft tip or a hard tip, using a drag shot: This statement seems to me to be beside the point. The question is: Is there a difference between what you get if the tip is hard or soft? Whether you hit high or low is irrelevant...the location is the same, the difference is the tip's material properties.

The statement is very much on point, because several people have suggested doing comparisons with the same cue speeds. This could give misleading results.

 

[dr_dave]

If a chalk mark creates more spin due increased friction , then can one tip compared to another not have more friction and have an effect?

No. Within the typical miscue limit, a hard tip grabs the CB just as well as a soft tip. More friction is not necessary. There is no sliding between the tip and ball during contact.

The difference with ball collisions is the balls slide along each other during most hits. The amount of friction makes a big difference when there is sliding between the surfaces.

 

[fastone371]

Your 'safe assumption' is wrong. Just like when drawing a shot, only the top of the tip contacts the ball and should be the reference point for how low you are actually hitting the CB, with sidespin, it is the center-side of the tip that contacts the ball first. Any extra contact surface would occur towards the outside of the ball.

As explained above somewhere, tip deformation only comes into play at the miscue limit. Given that a soft tip stays in contact longer, it rides around while in contact with the ball farther which makes it more likely to miscue or partially miscue as it reaches the miscue point at a time a harder tip would have already lost contact with the ball. In other words, a hard tip can start out with a slightly larger initial offset at contact than a soft tip which needs to start a touch closer to center to allow for the extra bit it will ride around on the ball before reaching the miscue limit

I don't think I am entirely wrong, if we are using the edge of the stripe on a striped ball as the miscue limit there is far more than the edge of the tip contacting the cue ball. In fact if its a hard tip I would be willing to bet the the edge of the tip doesn't even contact with the cue ball.

 

[pvc lou]

Typical cue tips have contact times in the 1-2ms second range, where differences do not have any important effects. But if you change the contact time significantly (e.g., by using a soft rubber tip instead, which is not suitable for playing pool), the physics is very different.

This is the claim you make, which is in dispute.

I was simply stating that if you want to be skeptical and propose alternative theories that go against current knowledge and understanding, you need to convincingly justify and test your claims. This is how science works. I won't do it for you because I don't believe the time would be well spent. This isn't spite, just honesty.

The alternative theory has been stated multiple times in this thread, which is as follows: Tip hardness affects contact time (by a factor of up to 2 at least), and that this chain of effects has some significant influence on spin/speed ratio.

Thank you for educating me on "how science works." I would add one thing to that: scientific inquiry/knowledge is independent of any appeal to authority.

I admit that I am disappointed that you find my proposed test not-worthwhile, but c'est la vie.

Mike Page has correctly pointed out that it might be possible to create a soft tip suitable for playing pool that might have a better hit efficiency than a typical hard tip also suitable for pool. I have not seen one yet, but I agree with him that it might be possible.

Not sure what you mean by "suitable," here.

The statement is very much on point, because several people have suggested doing comparisons with the same cue speeds. This could give misleading results.

I think you have muddled several effects in the statement I highlighted in blue. Cue speed vs. hitting high vs. low on the cb introduce multiple physically distinct effects. The question at hand is tip hardness. I am open to the possibility that I have misunderstood you.

 

[dr_dave]

Typical cue tips have contact times in the 1-2ms second range, where differences do not have any important effects. But if you change the contact time significantly (e.g., by using a soft rubber tip instead, which is not suitable for playing pool), the physics is very different.

This is the claim you make, which is in dispute.

Try using a very soft rubber tip on a CB. I have. The amount of CB deflection is shocking (and unacceptable).

When testing a range of tips actually used to play pool, I was not able to detect any important differences in CB deflection with tip types. See:

Mike Page has correctly pointed out that it might be possible to create a soft tip suitable for playing pool that might have a better hit efficiency than a typical hard tip also suitable for pool. I have not seen one yet, but I agree with him that it might be possible.

Not sure what you mean by "suitable," here.

A tip that is "suitable" has a hit efficiency in an acceptable range (by pool players) and does not result in an amount of CB deflection in an acceptable range (to pool players).

 

[pvc lou]

Try using a very soft rubber tip on a CB. I have. The amount of CB deflection is shocking (and unacceptable).

When testing a range of tips actually used to play pool, I was not able to detect any important differences in CB deflection with tip types. See:

"I was not able to detect any important differences in CB deflection with tip types."

Ok, so your evidence is anecdotal, based on your capacity to strike the ball. Forgive me for suggesting that this does not constitute a scientific assessment of the generic effects of tip hardness, nor contact time, on generated spin.

A tip that is "suitable" has a hit efficiency in an acceptable range (by pool players) and does not result in an amount of CB deflection in an acceptable range (to pool players).

Hmm. Ok. Maybe my brain is too small and slow to understand the relevance of the following statement made by you:

"Mike Page has correctly pointed out that it might be possible to create a soft tip suitable for playing pool that might have a better hit efficiency than a typical hard tip also suitable for pool. I have not seen one yet, but I agree with him that it might be possible."

What does this have to do with the so-called busted myth that tip hardness affects spin on the cb?

 

[dr_dave]

Maybe my brain is too small and slow

Thank you for being honest.

 

[Monti]

No. Within the typical miscue limit, a hard tip grabs the CB just as well as a soft tip. More friction is not necessary. There is no sliding between the tip and ball during contact.

The difference with ball collisions is the balls slide along each other during most hits. The amount of friction makes a big difference when there is sliding between the surfaces.

Thanks. I think I’ve got it now. If I imagine the cue tip is acting like a flat piece of metal contacting the ball with it’s edge then what’s above or below it doesn’t matter

 

[pvc lou]

Thank you for being honest.

double ouch

 

[pvc lou]

 

[dr_dave]

I finally finished the revisions to the cue tip hardness resource page, which now includes a dedicated section related to getting more spin with tips of different hardnesses. Check it out. Please let me know if you spot any typos.

I think I've made all the explanations as convincing a possible, backed up by supporting resources.

If, after reading the page and checking out the supporting resources, people still think a softer tip can impart more spin, then there is nothing more I can do to convince them. And if that is the case, I hope they will try to do their own careful testing to show that their ideas hold merit.

Enjoy:

revised cue tip hardness effects resource page​

 

[PoolPlayer4]

A soft tip does not provide as efficient a hit, so more cue speed is required to get the same CB speed and spin.

One thought on this that is not directly on point, but has occurred to me as a soft tip user: if a soft tip requires more cue speed, and cuing accuracy must have some kind of decline at higher speeds (assumption), does that mean switching to a hard tip could lead to more consistent cue delivery just by virtue of fewer shots needing higher speeds? Or, is the difference not enough to matter?

 

[Patrick Johnson]

One thought on this that is not directly on point, but has occurred to me as a soft tip user: if a soft tip requires more cue speed, and cuing accuracy must have some kind of decline at higher speeds (assumption), does that mean switching to a hard tip could lead to more consistent cue delivery just by virtue of fewer shots needing higher speeds?

Yes.

Or, is the difference not enough to matter?

Yes.

pj <- not Dave - take seriously at your own risk
chgo

 

[Patrick Johnson]

Try using a very soft rubber tip on a CB. I have. The amount of CB deflection is shocking (and unacceptable).

Why so much?

pj
chgo

 

[dr_dave]

Try using a very soft rubber tip on a CB. I have. The amount of CB deflection is shocking (and unacceptable).

Why so much?

A much longer contact time creates a much larger effective endmass.

PS: Please read through my newly-revised revised cue tip hardness effects resource page and let me know if you spot any errors or if you have any suggestions for improvement. Thanks!

 

[Patrick Johnson]

A much longer contact time creates a much larger effective endmass.

Thanks.

PS: Please read through my newly-revised revised cue tip hardness effects resource page and let me know if you spot any errors or if you have any suggestions for improvement. Thanks!

Look forward to it.

pj
chgo