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Billy_Bob
02-18-2005, 12:26 PM
Ok, let's see if I've got this right (get out your red pen)....

Double hit...

A double hit occurs when the tip of your cue hits the cue ball, then the cue ball hits the object ball, then the cue ball stops, then your cue continues forward hitting the cue ball a second time.

Evidence of a single hit is that the cue ball will stop after it hits the object ball, or if follow is applied, the cue ball will briefly stop or hesitate after contact with the object ball, then continue forward.

Evidence of a double hit is that the cue ball follows the object ball without any hesitation. And you can sometimes hear a double click, but not always, especially if the balls are very close.

Situations where a double hit is likely to occur are when the cue ball is very close to the object ball, but not frozen to the object ball. Or even when the cue ball is say 6 inches away from the object ball and a follow through stroke longer than 6 inches is used. In general: A follow through stroke longer than the gap between the balls is used.

Avoiding a double hit: A nip shot may be used (a shot with a very short follow through - shorter than the gap between the cue ball and object ball). There is also a draw nip and a follow nip shot. Or in the case of the cue ball being 6 inches away from the object ball, using a follow through less than 6 inches. Or if a 5 inch gap, a follow through of less than 5 inches, etc. Or striking the cue ball at a 45 degree angle.

Note: Some players advise in the situation where the cue ball is less than a chalks distance from the object ball to shoot at a 45 degree angle, however a properly executed nip shot would be legal. And note that if the cue ball is further away from the object ball than the width of a cube of chalk, a double hit may *still* occur if the follow through stroke is longer than the gap between balls. So if there is a gap of three chalk cubes and your normal stroke has a long follow through, you are in danger of causing a double hit.

When practicing nip shots and hitting the cue ball dead center, the cue ball will stop if executed properly, but will follow the object ball if a double hit occurs. For a draw nip, I shoot down on the ball but I can't get much draw (when balls are very close). For a follow nip, I guess you just nip high rather than center, but I can't get much follow.

Double hit high speed video - cue ball follows object ball...
http://www.engr.colostate.edu/~dga/pool/high_speed_videos/new/HSVA-12.htm

Legal hit - cue ball stops - notice short follow through stroke...
http://www.engr.colostate.edu/~dga/pool/high_speed_videos/new/HSVA-9.htm

Legal hit with follow - Cue ball stops, then continues forward...
http://www.engr.colostate.edu/~dga/pool/high_speed_videos/new/HSVA-11.htm

Push Shots...

When the cue ball is frozen to the object ball, it is legal to hit the cue ball with a normal level stroke. And the balls must be declared "frozen" prior to the hit.

However a push shot in this situation is not legal. What is the difference between a normal hit and a push shot?

An example I found is to place the cue ball on the foot spot, then freeze the object ball directly behind it as if it was spotted (Wei below). In this case, you could have two different interactions with the balls...

Normal behavior of balls: You aim half way between corner pocket and short rail center diamond (red arrow in below Wei) and cue ball will move toward corner pocket (black arrow).

Push shot behavior of balls: You aim at corner pocket (black arrow), hit cue ball slowly a little on the right and "push" the cue ball toward the corner pocket with a long slow follow through.

Question: What is an illegal push shot and what is a normal stroke?

Wei...

http://endeavor.med.nyu.edu/~wei/pool/

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Fred Agnir
02-18-2005, 01:24 PM
<blockquote><font class="small">Quote Billy_Bob:</font><hr>Question: What is an illegal push shot and what is a normal stroke?
<hr /></blockquote>An illegal push is exactly what it sounds like: pushing the cueball. Putting the tip up to the cueball and pushing it as you would push a push broom. Illegal push shots have nothing to do with any object balls and only have to do with the tip and the cueball.

I think wildfire misinformation has spread across the world (like bar rules) concerning push shots. In cluster games like 14.1 and one-pocket, push shots are/were common in frozen combinations. I think at some point, the frozen combination itself was then misrepresented as a "push shot" when in fact it's not. A push shot is a push shot. It describes the stroke, not the shot.

BCA rules:
"3.23 PUSH SHOT FOULS. It is a foul if the cue ball is pushed by the cue
tip, with contact being maintained for more than the momentary time
commensurate with a stroked shot. (Such shots are usually referred to as
push shots.)"

and Bob Jewett's FAQ:

5. ** What is a push shot?

At pool, a push shot involves a very special kind of stroke and is
played when the cue ball is frozen to the object ball -- this stroke is
a foul. (At pool it is legal to shoot towards a ball the cue ball is
frozen to, assuming no other foul, and with a normal stroke.) In a
push shot, the tip is brought slowly, slowly, very slowly up to the cue
ball until it is just touching or about to touch, and then the tip is
accelerated for the shot. "

Fred

Fred

Bob_Jewett
02-18-2005, 01:26 PM
<blockquote><font class="small">Quote Billy_Bob:</font><hr> ...

Question: What is an illegal push shot and what is a normal stroke?...
<hr /></blockquote>
I think this is explained in the RSB FAQ under the heading "What is a push shot?" The RSB FAQ (rec.sport.billiard Frequently Asked Questions list) is available on the SFBA web site, among other places.

pooltchr
02-18-2005, 04:18 PM
I think they have covered the push shot part of your question. As for the double hit when the cue ball is very close to the object ball, your "nip shot" may very well still be a double hit. Try this test:
Clean the chalk off the cue ball and place it close to the object ball. Chalk your cue very well. Shoot your shot, then closely examine the cue ball. In most cases, even when you think you didn't double hit, you will often see the chalk mark on the cue ball, and then very close to it, another smaller lighter chalk mark....that was the second hit. You will be surprised how often both marks are there, even when you think you only hit the cue ball one time.
There is a way to shoot the shot legally. It involves choking up on the cue ball, and having your grip hand home when you are in the set position. It's not real easy, but it can be done with practice. Just know that even when you learn to do this legally, some will still call a foul, because many players think it's automatically a foul if you shoot straight into a shot with less than a chalk cube distance between cb and ob.
Steve

Billy_Bob
02-18-2005, 07:20 PM
<blockquote><font class="small">Quote pooltchr:</font><hr>...It involves choking up on the cue ball, and having your grip hand home when you are in the set position...<hr /></blockquote>

By "choking up", do you mean short bridge or a very short distance between your bridge hand and the tip of your cue?

And by "grip hand home" do you mean that the grip hand is placed fully forward to where it would be at the end of a normal follow through - so basically your grip hand can't move much more forward, thus a very short stroke?

Anyway I tried that and bingo! Easy short stroke every time!

Thanks.