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longhair
03-04-2005, 11:14 PM
Hey Bob Jewett and all the other physics types:

If you hit very very softly, especially with a follow stroke, sometimes you might hear or feel a funny vibration. Is it possible that this is actually a multiple contact?

sjm
03-04-2005, 11:28 PM
Not sure what physics has to do with it, but the answer is yes, you can double hit the cue ball even when there is no object ball near the cue ball. Obviously, the danger of doing so is far less in this situation.

longhair
03-04-2005, 11:38 PM
Not sure what physics has to do with it, but the answer is yes, you can double hit the cue ball even when there is no object ball near the cue ball. Obviously, the danger of doing so is far less in this situation.
I guess I should say that I meant unintentionally. I mean a single clean stoke as if to move the cueball two or four feet, depending on conditions. I'm really asking about the feeling, or noise, of the shot. Like a slight ferrule or joint imperfection, but only some times.

Rod
03-04-2005, 11:45 PM
I guess I should say that I meant unintentionally. I mean a single clean stoke as if to move the cueball two or four feet, depending on conditions. I'm really asking about the feeling, or noise, of the shot. Like a slight ferrule or joint imperfection, but only some times.


Maybe that's what you have, a loose ferrule , tip not completely glued on (common), loose weight screw or butt rubber plug.

Rod

longhair
03-05-2005, 12:10 AM
Maybe that's what you have, a loose ferrule , tip not completely glued on (common), loose weight screw or butt rubber plug.

Rod
Yeah, I know. But I really don't think that's what it is. I'm not doing a very good job of asking a question. Have you ever felt a slight vibration, on a very soft follow shot, with a cue that is otherwise completely solid?

chefjeff
03-05-2005, 07:18 AM
Hey Bob Jewett and all the other physics types:

If you hit very very softly, especially with a follow stroke, sometimes you might hear or feel a funny vibration. Is it possible that this is actually a multiple contact?

Bob Byrne (or was it Jewett?) did an article in BD a few years ago and talked about an experiment a college student did that, using high-speed photography, showed without a doubt that the cuetip hits the cueball at least 5 to 6 times on every shot.

So, now what?

Jeff Livingston

sjm
03-05-2005, 08:26 AM
I am suddenly reminded of what our recently departed friend John Ervolino used to say when he felt his opponent was guilty of a double hit. Johnny would look his opponent in the eye and say "you hit that at least twice."

DaveK
03-05-2005, 12:25 PM
Yeah, I know. But I really don't think that's what it is. I'm not doing a very good job of asking a question. Have you ever felt a slight vibration, on a very soft follow shot, with a cue that is otherwise completely solid?

I do an exersize for practicing soft shots, put the cb in the jaws of a corner pocket and try to take as many strokes as possible (hit the cb as short as possible) over to the nearest other corner. I also do this trying to shoot the cb 1/4 diamond, 1/2 diamond, 3/4 etc. When I started this practice a few years ago the double-hit was somewhat common. It doesn't take much of a twitch to cause a double hit when shooting that softly, from my experience only. I guess this somewhat parallel to golf where double hits most often occur on short wedge shots (ie 'soft' swings) around the green.

Dave

longhair
03-05-2005, 01:11 PM
Thank you for your replies.

It sounds like other have felt this and understood it the way I did.

DaveK,
how did you stop making double hits in your exercise? Did it just take a smoother stoke?

cheffjeff,
I don't suppose you know where I can find that article online? As I type this I realize I haven't even checked the BD website yet. lazy.

Grady
03-05-2005, 03:26 PM
Thank you for your replies.

It sounds like other have felt this and understood it the way I did.

DaveK,
how did you stop making double hits in your exercise? Did it just take a smoother stoke?

cheffjeff,
I don't suppose you know where I can find that article online? As I type this I realize I haven't even checked the BD website yet. lazy.



Most of the time the speed of the cue ball will tell you whether or not you hit the cue ball more than once. As an example, let's say the cue ball is 6 inches behind the object ball you're going to shoot and straight in towards a far pocket. You have decided to use high english and make the cue cue ball travel most of the length of a 9 foot table. If the cue ball doesn't travel pretty slowly, you've commited a foul, unless you have a great stroke and are able to execute a power follow shot in this instance.

mjantti
03-06-2005, 02:09 PM
This has been covered in a few books:

START(
%Am3J3%Pl7K7%Wl7M6%Xm4U0%Yd4E0%Zl3K0%[g8D3%\l3J7%eA1a6
)END

If you have the cueball near the object ball and you're cutting it maybe half ball or thinner(cue direction is the red arrow) using heavy outside english, you might hit the cueball twice quite easily. The problem of perceiving this foul is the fact that there isn't much difference between the double hit speed and the legal hit speed. Only thing that changes is the path of the cueball, legal shot will have the cueball travelling along the tangent line (green arrow)and the foul shot will have the cueball travelling more towards the first cushion (blue arrow).

Any opinions on this shot ? Grady ?

Grady
03-06-2005, 04:05 PM
This has been covered in a few books:

START(
%Am3J3%Pl7K7%Wl7M6%Xm4U0%Yd4E0%Zl3K0%[g8D3%\l3J7%eA1a6
)END

If you have the cueball near the object ball and you're cutting it maybe half ball or thinner(cue direction is the red arrow) using heavy outside english, you might hit the cueball twice quite easily. The problem of perceiving this foul is the fact that there isn't much difference between the double hit speed and the legal hit speed. Only thing that changes is the path of the cueball, legal shot will have the cueball travelling along the tangent line (green arrow)and the foul shot will have the cueball travelling more towards the first cushion (blue arrow).

Any opinions on this shot ? Grady ?



I'm not a scientist but I'll tell you what I think happens on this shot. Before doing so let me say that I'm not at all sure how long the cue stick stays in contact with the cue ball, time or distance. Or whether what english is used affects the length of time those aforementioned spheres touch each other.
I believe that the stick stays in contact long enough on the shot you've shown, that it is still in contact when the cue ball hits the object ball. The striking of the object ball causes the cue ball to veer off to the left a bit and while this changes the course of the cue ball I don't think it is a foul.
Personally, I have always lobbied for fouless push shots. So such an action couldn't be a foul.
In closing let me say that Tony of Black Boar believes that the amount of time the stick stays in contact with the object ball is the exact amount of time that it takes for the shock wave of the collision to travel from the butt of the cue to the tip and back. I'm not sure I require this much info in my game but I do hope I was of some help to you.

Bob Jewett
03-06-2005, 05:31 PM
Bob Byrne (or was it Jewett?) did an article in BD a few years ago and talked about an experiment a college student did that, using high-speed photography, showed without a doubt that the cuetip hits the cueball at least 5 to 6 times on every shot....
Nope. Most shots are single hits. Hal Mix related a third-hand story of an ultra-high-speed video that was made (on real film) a long time ago, but the details of the experiment are not known. My suspicion is that for that film, the shaft was directed at the ball by an air gun or a small cannon. See "Dr. Dave" Alciatore's high-speed videos for more recent results.

DaveK
03-06-2005, 08:04 PM
DaveK,
how did you stop making double hits in your exercise? Did it just take a smoother stoke?

Yep, as my stroke got smoother the hit got cleaner. Its hard to put a smooth stroke on the ball when barely moving the cue stick forward.

As a secondary exersize, and one where the double is even more likely, try to shoot the cb into an ob as softly as possible from one side of the table to the other. As you get better at hitting this soft the difficulty goes up because the balls get closer together !

Dave, who still whacks the CB a few times on ultra-soft shots now and then, and calls a foul if the opponent doesn't see it

CaptainJR
03-07-2005, 06:25 AM
Is it possible to double hit without an object ball?

Well I know it is now! This isn't really what you all are talking about but it happened to me this weekend so I'll mention it. I was left safe behind my opponents balls. It was 8-ball and I think he had six of his high balls left on the table. With his balls all over the place I didn't see any way to kick at either of my two balls. I was about one inch from his ball so a normal jump shot wasn't possible so I tried to hit the cue ball straight into the rail and make it jump back toward me. You all know the shot and I've done it successfully before, but this time I didn't get my cue stick out of the way quick enough. There is plenty of time to get it out of the way when playing this. I just wasn't, oh I don't know, alert or ready or something. So there you have it. A double hit without an object ball.

chefjeff
03-07-2005, 07:51 AM
Nope. Most shots are single hits. Hal Mix related a third-hand story of an ultra-high-speed video that was made (on real film) a long time ago, but the details of the experiment are not known. My suspicion is that for that film, the shaft was directed at the ball by an air gun or a small cannon. See "Dr. Dave" Alciatore's high-speed videos for more recent results.

Thanks for the clarification, Bob....my memory must be playing tricks on me.

Jeff Livingston

Bob Jewett
03-07-2005, 05:42 PM
Thanks for the clarification, Bob....my memory must be playing tricks on me.

Jeff Livingston
For an amazing on-line demo clip that shows a tip hitting a ball, see Windows Media Video file

http://www.bskunion.at/efler/Faszination_Dreiband_Windows_Media_9.wmv

Note that if your browser doesn't know what to do with a WMV file, you probably will not see anything useful.

There is only one contact. On the Jacksonville Project video, there was some indication that there were multiple hits on side spin shots, but I think that was due to the way Iron Willie held the stick.

chefjeff
03-08-2005, 07:09 AM
For an amazing on-line demo clip that shows a tip hitting a ball, see Windows Media Video file

http://www.bskunion.at/efler/Faszination_Dreiband_Windows_Media_9.wmv

Note that if your browser doesn't know what to do with a WMV file, you probably will not see anything useful.

There is only one contact. On the Jacksonville Project video, there was some indication that there were multiple hits on side spin shots, but I think that was due to the way Iron Willie held the stick.

That is just too cool of a video. What a great way to wake up. Thanks.

I especially loved that billiard shot....what a beautiful game! Were they (who is they, anyway?) using fluorescent chalk and/or just black light? This would be an interesting way to play for a special event perhaps, or for training even.

Also, I noticed the ferrule was very tiny...was it yours?

Jeff Livingston

mjantti
03-08-2005, 07:41 AM
Very cool video ! It seemed the temperature of the cueball increases slightly on a heavy masse shot ? :eek: Also, on a hard shot (I presume), part of the chalk disappears before the tip hits the cueball... at least one shot closeup showed a chalk cloud around the tip before the impact. Wow.

Bob Jewett
03-08-2005, 01:34 PM
Very cool video ! It seemed the temperature of the cueball increases slightly on a heavy masse shot ? :eek: Also, on a hard shot (I presume), part of the chalk disappears before the tip hits the cueball... at least one shot closeup showed a chalk cloud around the tip before the impact. Wow.
The video that the clip is from was shot and produced by a group in Austria. I think the player was Andreas Efler. The part of the cue ball that rubs on the cloth is heated and the cloth is heated in masse shots. (The false-light videos are infrared (heat) not ultraviolet (black) light.)

Also, the spots where the cue ball jumps on the cloth are visible.