Tip Contact Time

ENGLISH! said:
Ken,

You're more than welcome, but keep in mind as I said, I may be wrong.

Best Wishes,
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I think you are spot on Rick. I was blessed with more help today from dr9ball! One of the things he mentioned was stance and balance.

Again a big THANK YOU to you three for the help! It is appreciated!

Going out to hit some more balls right now! Or as Paul Bertholy would tell me (when I was 15) "back to the salt mines!"

Respectfully,

Ken
 
Sloppy Pockets said:
[...]
FWIW I have no scientific evidence of what Fran is claiming, but I think her observations deserve more careful thought. The impulse from the cue is a force-time integral (look at the image below). Even if the same amount of momentum is transferred with both soft and hard tips (same area under the curve), the much higher peak force with the hard tip may be enough to overcome the frictional force component from the chalk at large tip offsets, thereby leading to an increase in miscue potential.

Anyway, just a thought...
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I think a bigger factor in the difference of miscue potential with hard vs soft tips is the contact AREA. A soft tip compresses more, and the contact area (the chalk mark on the cueball) is larger.

An inadequately-chalked tip will have chalked areas followed by bald areas followed by more chalked areas. For a given shot, it could be that a miscue will occur if, say, more that 30% of the contact area is bald. This may be more likely to happen when the contact area is small.
 
my 2 cents, (IANAI)

When you want to transfer spin from the CB to an OB, dirty balls and slow speed pass on more spin(similar to cling effects). The contact time between the 2 balls is clearly longer than with clean and faster hits if ya think about it. Therefore, it seems obvious to me that a longer contact time between TIP and CB will result in more spin with less speed(as long as there is no miscue).
 
mikepage said:
I think a bigger factor in the difference of miscue potential with hard vs soft tips is the contact AREA. A soft tip compresses more, and the contact area (the chalk mark on the cueball) is larger.

An inadequately-chalked tip will have chalked areas followed by bald areas followed by more chalked areas. For a given shot, it could be that a miscue will occur if, say, more that 30% of the contact area is bald. This may be more likely to happen when the contact area is small.
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Mr. Page,

I agree with most of what you say, but could you elaborate on the 30% part more likely to happen with a smaller tip. 30% is 30%. I understand that 30% of a smaller area is smaller but if it is still chalked, I don't fully understand your point.

Best Regards,
 
mattp...Deliberate spin transferred between CB & OB happens infrequently, doesn't last long, and when it happens, it happens only to a very small degree (all ball collisions cause a minute amount of spin transfer). Contact time between tip and CB is miniscule at best (.0001 seconds), and nothing you can do will cause it to be significantly longer.

Scott Lee
http://poolknowledge.com

mattp said:
my 2 cents, (IANAI)

When you want to transfer spin from the CB to an OB, dirty balls and slow speed pass on more spin(similar to cling effects). The contact time between the 2 balls is clearly longer than with clean and faster hits if ya think about it. Therefore, it seems obvious to me that a longer contact time between TIP and CB will result in more spin with less speed(as long as there is no miscue).
Click to expand...
 
ENGLISH! said:
Mr. Page,

I agree with most of what you say, but could you elaborate on the 30% part more likely to happen with a smaller tip. 30% is 30%. I understand that 30% of a smaller area is smaller but if it is still chalked, I don't fully understand your point.

Best Regards,
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Let's say a tip is chalked like this: 2mm with chalk, 1mm bald, 2mm chalk, 1mm bald, 2mm with chalk, 1mm bald... In this case, with a 3mm wide contact area, you always get at least two-thirds of the contact area with chalk.

But with a 2mm-wide contact area, you can get as low as 50% chalked
 
mattp said:
my 2 cents, (IANAI)

When you want to transfer spin from the CB to an OB, dirty balls and slow speed pass on more spin(similar to cling effects). The contact time between the 2 balls is clearly longer than with clean and faster hits if ya think about it. Therefore, it seems obvious to me that a longer contact time between TIP and CB will result in more spin with less speed(as long as there is no miscue).
Click to expand...

Matt,

I agree with you. Just one day last week I went from a pool hall where the transfer of english was minimal with clean balls & a slighty lighter cue ball to a bar table where the tranfer was nearly excessive due to the very dirty balls & heavier cue ball.

I think the easiest way to increase the tip contact time is to go to a soft tip. Going from a very hard tip to a soft tip like an Elk Master or a Kamui Super Soft can possibly double the contact time from the .001 second range, so often preached about, to possibly as much as .002 of a second. That would be a 100% increase. I think that anyone that shoots with a lot of english can certainly tell the difference in the spin to speed ratios. For those that do not shoot with much english, the difference might only be a perception in how hard or how soft the hit would feel.

Best Regards,
 
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ha

1st of all Scott and friends, I was obviously using the spin transfer example as an ANALOGY. I was not advocating spinning(deliberately) balls in every shot(although many high level players including world champions say they do this).

Question...how long is the collision between balls? Because clearly speed plays a very big roll in CIT and spin transfer for throwing balls in different ways.

Slower speed=longer contact time. So how are these effects insignificant?
If contact time is so short that it doesn't matter, why bother chalking?

I also think sometimes that people don't read the whole thread and then take posts out of context.
 
I agree English. If I play on on nine footers at this classy joint and then go to the bar tables I'm over throwing balls left and right. Luckily the pockets are bigger than Eurasia. :smile:
 
mattp said:
I agree English. If I play on on nine footers at this classy joint and then go to the bar tables I'm over throwing balls left and right. Luckily the pockets are bigger than Eurasia. :smile:
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Matt,

What's worse, for me, is going from the dirty bar table where I've adjusted my aim for the conditions along with the heavier cue ball to the pristine conditions with a lighter cue ball & tighter pockets. It takes a bit of time to 'real eyes' that I can't spin them in as easily. I hate both the heavier & lighter cue balls. All I want is a cue ball that is the same size & weight as the object balls. That is my subconscious base line for english.

Regards & have a Happy New Year,
 
... Question...how long is the collision between balls? Because clearly speed plays a very big roll in CIT and spin transfer for throwing balls in different ways.

Slower speed=longer contact time. So how are these effects insignificant?
If contact time is so short that it doesn't matter, why bother chalking? ...
Click to expand...
This post seems to demonstrate a very, very serious misunderstanding of how collisions between relatively hard objects work. Mostly, the duration of the collision plays no part. Most of the analysis works just fine if the collision is assumed to be instantaneous. That people tend to dwell on contact time is a demonstration to me of the need for better science education in high schools and universities.

To answer the first question directly, the time of contact between pool balls is about 200 microseconds or roughly one fifth of the time of tip-to-ball contact. This has been measured in several ways.

The comment above that it is increased contact time between dirty balls that causes increased throw is, to my understanding, wrong. It is the increased friction between the balls that the dirt causes that increases throw. That does not depend on the contact time. I have had the experience of clean, polished balls having very large throw due to how they were polished (with car products).

As to why you should bother chalking, it is to increase the friction between the tip and the cue ball. It has nothing to do with contact time.
 
Bob Jewett said:
This post seems to demonstrate a very, very serious misunderstanding of how collisions between relatively hard objects work. Mostly, the duration of the collision plays no part. Most of the analysis works just fine if the collision is assumed to be instantaneous. That people tend to dwell on contact time is a demonstration to me of the need for better science education in high schools and universities.

To answer the first question directly, the time of contact between pool balls is about 200 microseconds or roughly one fifth of the time of tip-to-ball contact. This has been measured in several ways.

The comment above that it is increased contact time between dirty balls that causes increased throw is, to my understanding, wrong. It is the increased friction between the balls that the dirt causes that increases throw. That does not depend on the contact time. I have had the experience of clean, polished balls having very large throw due to how they were polished (with car products).

As to why you should bother chalking, it is to increase the friction between the tip and the cue ball. It has nothing to do with contact time.
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Mr. Jewett,

That sounds interesting. Can you elaborate as to how an increase in friction does not also result in an increase in contact time with all other things being equal? To me, slippery is slippery & sticky is sticky. What am I missing?

Regards,
 
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Bob Jewett said:
This post seems to demonstrate a very, very serious misunderstanding of how collisions between relatively hard objects work. Mostly, the duration of the collision plays no part. Most of the analysis works just fine if the collision is assumed to be instantaneous. That people tend to dwell on contact time is a demonstration to me of the need for better science education in high schools and universities.
Click to expand...

Or maybe it's just that some people have way too much time on their hands.

All this contact time stuff has got my head spinning more than Juanjo Trilles' CB. My goal in life just became finding out what kind of tip he uses.

Another thought percolating is that I'll have to make a switch from my 30 yr.old Sneaky Pete with a dime radius Le Pro to some expensive custom cue with an expensive, super hi tech, super soft tip.
Also a new hi speed video camera so I can check my contact time daily.

I'm pretty sure this is the way to go but before I pull the trigger I'd like a little feedback.

Mr. Jewett, will these changes allow me to continue spinning the ball the same way I've been spinning it for the last 50 yrs?

Wishing everyone health, happiness & increased contact time in the coming new year.
 
I dont really care about tip contact time....never thought about it.

But I can say this because it is what I feel in my grip hand.
Using center ball and below my grip hand feels as though the QB is stuck to the end of my cue. Using above center to high it is a little more difficult to get that feel in my grip hand. But you can with practice.

I dont punch the ball unless it is required by the shot. I always try to feel the cue ball. If I cant feel the QB (and its weight) I dont stand a chance of putting it where I want.

JMHO

John
 
I have learned a lot about the tip impact on the cue ball which I did not know before this thread. And yes, I think too deeply about nothing a lot of the time. <shrug>

Thanks to all the contributors of this thread!

Ken
 
Thanks for that explaination Bob. It's sad when we try to HELP players understand how things really work on a pool table, and they take exception, believing instead that we're trying to put them down, or make fun of them...which is definitely not the case. Thanks for the time measurement for ball collisions. I knew it was short, but didn't realize it was that short. It's not unusual for even world champion players not to understand how the science works (let alone logically explain it)...even though they can do things that most of us are not able to duplicate.

mattp...I apologize if you thought I was putting you down...that was not my intention.

Scott Lee
http://poolknowledge.com

Bob Jewett said:
This post seems to demonstrate a very, very serious misunderstanding of how collisions between relatively hard objects work. Mostly, the duration of the collision plays no part. Most of the analysis works just fine if the collision is assumed to be instantaneous. That people tend to dwell on contact time is a demonstration to me of the need for better science education in high schools and universities.

To answer the first question directly, the time of contact between pool balls is about 200 microseconds or roughly one fifth of the time of tip-to-ball contact. This has been measured in several ways.

The comment above that it is increased contact time between dirty balls that causes increased throw is, to my understanding, wrong. It is the increased friction between the balls that the dirt causes that increases throw. That does not depend on the contact time. I have had the experience of clean, polished balls having very large throw due to how they were polished (with car products).

As to why you should bother chalking, it is to increase the friction between the tip and the cue ball. It has nothing to do with contact time.
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Has anyone ever recorded a hi speed video of the tip hitting the CB with an elbow drop and extended follow through?

I know I saw one a while back that Dr. Dave did, but I assume that was using a pendulum stroke with no elbow drop. I wasn't sure if he did one with an elbow drop.
 
BeiberLvr...Tip contact time doesn't change with a piston stroke (elbow drop) or a pendulum stroke...both are around one-thousanth of a second. The piston stroke just requires better timing, and is prone to more small errors (read: less repeatability for many players). :D

Scott Lee
http://poolknowledge.com

BeiberLvr said:
Has anyone ever recorded a hi speed video of the tip hitting the CB with an elbow drop and extended follow through?

I know I saw one a while back that Dr. Dave did, but I assume that was using a pendulum stroke with no elbow drop. I wasn't sure if he did one with an elbow drop.
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Hey Scott, no need to apologize but I accept:smile:
I think it's great that you guys give your expert opinions for free on this and other forums. I've met you in Jersey and know many peeps you taught. You obviously care deeply about this sport.
That being said:sorry: Sometimes the way you choose to respond to certain posts can be a little strange.
For example, by posting a bunch of facts about CB OB collision time the way you did in response to my post, people may infer that I was advocating spinning in all your shots which clearly had nothing to do with my post.

Anyhoo, Bob(while I obviously respect your expertise and have read a lot of your work for many years) I have a hard time wrapping my head around the idea that contact time does not play a role in spin transfer(but then again I am not a physicist). But I would love for you to expand on this.

It just seems to me(and again I guess I am wrong) that if you are gripping something that contact time is longer.
Using a ball to ball ANALOGY:p again...why would slower speed result in more friction causing CIT?


P.s. to the peeps making comment like why waste time on this, my answer is that some of us enjoy learning, debating, teaching and talking all things pool. I don't have a table(apartment) so when I am mellowing out at home I enjoy watching pool videos and reading forums and talking pool with my friends. Do I have a problem:embarrassed2:
 
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