Does Tip Hardness Influence Cueball Deflection?

What?

An increased amount of surface area contacting the cue should increase the total amount of friction. Per square nm or mm it would be the same, but a softer tip would have more nm of area - thus more friction.
Patrick Johnson said:
I don't believe the amount of contact area has much to do with total friction. A smaller contact area usually has the same total amount of friction, just spread over a smaller area.

pj
chgo
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RBC said:
Jal,

You are right that the cue ball would go to the side in a miscue, even without the shaft slapping it from the side, but it would not travel very far. Most of the energy of the cue shaft would remain in the cue shaft and not be transfered to the cue ball because there is very little friction between the two. Therefore, when you miscue and the cue ball moves significantly to the side, that is cause by the shaft hitting the side of the cue ball. Occasionally you will see someone miscue so bad that the barely graze the side of the cue ball and it moves just a few inches. However, in most cases the cue ball moves at least a few feet to the side which means that it must have received that energy from something, and that something is the cue shaft slapping the cue ball from the side. You can actually here the second impact if you listen carefully.


Royce Bunnell
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Royce,

If you will, take a look at this video.

http://billiards.colostate.edu/high_speed_videos/new/HSV_B-36_miscues.wmv

I think it's pretty clear that in the majority of the shots, the cueball picks up most of its transverse velocity from the initial collision. I'm judging this in part from the fact that after all the impact(s) business is over with, it appears to travel in a direction which is fairly close to a line going from the contact point with the tip through its center. There are exceptions.

You don't really need friction in the normal direction (through the center of the cueball) to have a force acting on it. In fact, by definition, that's not a "friction" force.

Just my take.

Jim
 
eyesjr said:
An increased amount of surface area contacting the cue should increase the total amount of friction.
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eyesjr,

That's not really true. An example oft given in physics books is that of a brick laying (or sliding) on some surface. The brick has a certain weight "W." If it's in contact with the surface through one of its large faces with area "A", the pressure it's exerting is W/A. If it's in contact with one of its smaller faces with area "a", the pressure is W/a. The friction force is the product of the pressure times the area times the coefficient of friction, u. So for these two cases, the friction is equal to:

F1 = u*(W/A)*A = u*W

F2 = u*(W/a)*a = u*W

It's the same in either case.

Jim
 
Jal said:
eyesjr,

That's not really true. An example oft given in physics books is that of a brick laying (or sliding) on some surface. The brick has a certain weight "W." If it's in contact with the surface through one of its large faces with area "A", the pressure it's exerting is W/A. If it's in contact with one of its smaller faces with area "a", the pressure is W/a. The friction force is the product of the pressure times the area times the coefficient of friction, u. So for these two cases, the friction is equal to:

F1 = u*(W/A)*A = u*W

F2 = u*(W/a)*a = u*W

It's the same in either case.

Jim
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Jim and PJ are correct about the friction force being independant of area. I was incorrect in a previous post.

I still wonder if the contact time is longer with a soft tip than with a hard tip and if that would make a difference.

As I said in my very first post, I expect the effect to be small, even if it theoretically exists.

But if there is a measurable or theoretical basis for saying all other things being equal, soft tips give more english then, by the same token, soft tips would reduce squirt, even if by a very small amount.

I frankly don't know how you could devise an experiment where you could keep "everything equal except the tip hardness." You would have to use the same cue, the same robot. Then folks would argue the chalking was not the same.... How many angels can dance on the head of a pin?
 
of course it does.

i will state as fact the following to be true with either triangle or lepro tips, i don't care what anybody else says, this is true....... a harder tip will put more spin on the cb and deflect more (all other things being equal of course). be careful of people who say you will get more spin and less deflection with a soft tip, this makes no physical sense whatsoever; in physics you can't have your cake and eat it too. you will get less deflection and less spin with a soft tip. this makes sense physically and it is DEFINITELY what is experienced on the pool table, that is what is important, not friction coeficients, haha. if you got more spin and less squirt with soft tips then everybody who ever played would have (or should have) as soft a tip as possible. but this is not what we see so it is probably not the case (actually, it is most definitely not the case).

ask any top player how long he NEEDS to play with a new tip before he'll bet big with his own and i bet you'll get anwers in the week or weeks (eg 2 weeks) range.... and the above is why, a new tip of the same brand is generally softer.
 
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enzo said:
of course it does.

i will state as fact the following to be true with either triangle or lepro tips, i don't care what anybody else says, this is true....... a harder tip will put more spin on the cb and deflect more (all other things being equal of course).
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One problem is if you pour through old posts here on AZ and before that on rec.sport.billiard, you will find equally emphatic I don't care what anyone says this is a fact claims from good players that...

--hard tips get more spin
--soft tips get more spin
--stiff shafts get more spin
--whippy shafts get more spin

One consequence of this proliferation of mystical wisdom is that at least one major cue company has run a very successful advertising campaign based on the this technology gets more spin claim.

One problem with even good players holding these views is that they're self-reinforcing; if you think you can really juice up the cueball with this stick, you probably can.

be careful of people who say you will get more spin and less deflection with a soft tip, this makes no physical sense whatsoever; in physics you can't have your cake and eat it too. you will get less deflection and less spin with a soft tip. this makes sense physically
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OK, we're listening ...

[...]
ask any top player how long he NEEDS to play with a new tip before he'll bet big with his own and i bet you'll get anwers in the week or weeks (eg 2 weeks) range.... and the above is why, a new tip of the same brand is generally softer.
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Can you think of any other hypotheses for why this might be true?
 
i don't care what anybody else says, this is true.......
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That's the same as saying "I don't care if this is really true or not; it's what I believe and that's all that matters to me." The rest of your post is your unsupported impressions being promoted as undeniable facts. Not knowing the difference is how pool myths get perpetuated.

pj
chgo
 
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Shaft said:
I still wonder if the contact time is longer with a soft tip than with a hard tip and if that would make a difference.
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Shaft,

I think measurements done by various people (Bob J., Dr. Dave) have pretty well established that softer tips do yield longer contact times. What this means in the grand scheme of things isn't all that easy to figure. For instance, a softer tip also produces less force between it and cueball. So although it's in contact longer, the cueball doesn't pick up speed and spin as fast. If all other things were equal, these would cancel each other and hard and soft tips would produce the same result. Energy efficiency is one thing that can be different. Some of the latest measurements by Dr. Dave and Bob J. indicate that softer tips are a little less efficient.

Shaft said:
As I said in my very first post, I expect the effect to be small, even if it theoretically exists.
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Amen. And measurements done by Dr. Dave support this.

Shaft said:
But if there is a measurable or theoretical basis for saying all other things being equal, soft tips give more english then, by the same token, soft tips would reduce squirt, even if by a very small amount.
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There's reason to believe they might produce slightly more squirt. Again, measurements done by Dr. Dave seem to confirm this, although the tips were mounted on different cues (same model though). A longer contact time might mean more effective endmass, since the wave that travels down the cue from the tip has time to travel farther. And if you actually did get more english, relative to linear speed, for whatever reason, you should see more squirt because the end of the cue is being pushed sideways more by the english.

Jim
 
I believe.......

yes I believe....If somebody is so concerned about deflection and squirt then they won't be consistent in shot making. Thinking about whether it will squirt left or right or deflecting here and there is not right. All a person has to do is get used to the deflection or squirt of their shaft and remember it. Get used to the cue and shoot with the deflection or squirts. Sorry I am not giving any philosphical theory here but reading about all the perfections of it just confuses people.
Take care,
Sharknu
 
Randy G.

Would you like to play a few sets.....then after it we are done we can sit and talk about squirt and deflection. LOL
Sharknu
 
Oooops

or should I say Royce? Or Randy...doesn't matter....they both know lots on the subject. Seems like Royce knows alot about that subject. Maybe Royce could show me a few things??? Let me know if you wanna shoot Royce and show me some things Then after we are done you can tutor me on it.
Sharknu
 
Sharknu,

It seems as though you don't care for me, or for my contributions to this thread. That's fine if you feel that way, believe me, I am ok with it. I would like to play some pool with you! You may be better than me, or you may not be, we will just have to see.

But, this thread was started by Shankster8 with the intention of learning more about the game that he likes. I think he has the right to ask this question, I mean this is a forum. So, if you want to call me out that's fine, but please don't hijack this thread away from its intended purpose.


Thanks!

Royce Bunnell
 
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