Rules of Thumb in Pool

[ENGLISH!]

Rules of thumb

I totally disagree with the close balls no throw or cut , although maybe I'm misunderstanding the terminology. Anyway I just shot & made such a shot as this yesterday. When the balls r close the effect of cut is negated to varying degrees by what I call push but I do not mean with the cue. It is the momentum of the ball hitting the other that 'pushes' the ball a little in the opposite direction of the cut. This can be offset somewhat by english, cutting the object ball to the right use left english & vise versa, As for the shot I had, it was a close ball combo aimed outside of the pocket where if normal cutting was use it would have momentumed even farther out of the pocket. So, I cut it the other way with english to make the 1st ball throw & momentum the target ball into the pocket. Now when shooting these types of shots speed is as important as anything else. I hope this explains it but maybe the terminology is not correct. In any case close balls can be influenced by spin, momentum, & cut if only slightly, but multiply that influence by time & length & it is enough to decide who is shooting next, you or your oppoment. I'm not trying to start any arguements so please don't attack me. I'm only attempting to explain what I know from experience works. Maybe it's not science, maybe it's magic, or maybe it's what they say about Jack Nicklaus, he wills the ball into the hole. Can you throw a ball 90 degrees laterally to an incline & have the ball roll 'uphill'? The answer is yes, if the ball is spinning & the spinning force overcomes the gravitation force applied by the incline.
The same thing can be done as my combo shot, with the cue ball & object ball close. it is a combination of balancing cut, momentum, & spin to get your desired result, That's not an easy thing to do but it is possible.

 

[Patrick Johnson]

The 45-to-1-in-4 rule is a specific case of a much more general rule of slopes. That is: if you are cutting a ball down the rail and the cue ball is coming in at a slope of X (1:1 for a 45-degree angle) the outbound path of the cue ball away from the cushion will have a slope of X:4. (or 4:X, depending on whether you measure slope relative to the rail or the perpendicular to the rail)

In the diagram above, the red shot (A) has an incoming slope of 4:2 so the outbound slope should be 1:2 which puts the cue ball into the corner pocket and not a diamond from the pocket as drawn. (A 45-degree approach would be from the center spot roughly and not the head spot.)

The main point here is that the 1:4 slope away from the cushion is not automatic (unlike the 30-degree rule for a half-ball hit) and varies in direct proportion to the incoming slope.

A simpler (for me) way to visualize this:

The CB's rebound angle off the rail will exceed 90 degrees by only 1/4 of what its "mirror" rebound angle (without the OB) would.

I think this same principle also applies to carom angles without the rail (i.e., the CB's follow path will exceed the tangent line angle by about 1/4 of what its straight path would).

pj
chgo

 

[DogsPlayingPool]

... When the balls r close the effect of cut is negated to varying degrees by what I call push but I do not mean with the cue. It is the momentum of the ball hitting the other that 'pushes' the ball a little in the opposite direction of the cut...

Are you referring to CIT? I believe the term you are looking for here is CIT - Cut (or Collision) Induced Throw.

http://billiards.colostate.edu/normal_videos/new/NVB-86.htm

 

[Saturated Fats]

....with a cueball that's rolling before contacting the object ball. On a stun shot, the cut angle that produces equal distances is 45-degrees.

I agree with the stipulation. I have edited the original post to reflect that.

Thank you.

 

[CreeDo]

In the diagram above, the red shot (A) has an incoming slope of 4:2 so the outbound slope should be 1:2 which puts the cue ball into the corner pocket and not a diamond from the pocket as drawn. (A 45-degree approach would be from the center spot roughly and not the head spot.)

oops, you're right. No idea why I placed the cue ball on the spot there, it was supposed to be 45 degrees. I think because in the video Ralph mentioned "Coming from the spot" when he means coming from the rail parallel to the spot. Anyway, I fixed the diagram and verbiage. Thanks for catching that.

 

[chefjeff]

I use this Rule of Thumb in 8-ball quite often:

Shoot softly.

If I have two ways to get shape, one a hard hit and the other a soft hit, and they're about 50/50, I choose the soft hit.

A guy can win a lot of games in 8-ball simply shooting softly.

Jeff Livingston

 

[ENGLISH!]

I use this Rule of Thumb in 8-ball quite often:

Shoot softly.

If I have two ways to get shape, one a hard hit and the other a soft hit, and they're about 50/50, I choose the soft hit.

A guy can win a lot of games in 8-ball simply shooting softly.

Jeff Livingston

I agree, but I also use high left or right & low left or right on almost every shot to improve the shape position. I need to with my eye problem.

 

[chefjeff]

I agree, but I also use high left or right & low left or right on almost every shot to improve the shape position. I need to with my eye problem.

I do, too. I learned a lot watching Don McCoy and I'm not sure I've ever seen him shoot a shot without some spin on it. He actually says he puts on it whatever the shot requires.

The guy who originally taught me 8-ball had two Rules of Thumb:

1. Shoot soft.

2. Think.

Both have served me well over the years as good Rules of Thumb.

Here's another R of T: Don't live by Rules of Thumb. :wink:


Jeff Livingston

 

[Bob Jewett]

Here's another related to half-ball hits:

The half-ball right-angle draw cue ball path --
If you play a half-ball shot (30-degree cut) with good draw, the cue ball will end up going about 90 degrees from its starting path. (This was pointed out by George Onoda in one of his articles in Billiards Digest.)

 

[Cornerman]

I think I got the rule against draw from Fred Agnir. (As with any rule like this, there are exceptions, but with ball in hand they are rare.)

.

Thanks Bob. It's been one of my "guidelines" with team mates a long time. As always, it's a rule of thumb, and once in a while a player needs to go against the thumb.

Freddie <~~~ going with the thumb

 

[Patrick Johnson]

Bob Jewett:
The half-ball right-angle draw cue ball path --
If you play a half-ball shot (30-degree cut) with good draw, the cue ball will end up going about 90 degrees from its starting path.

I use this one pretty often. It's a particular case of this one:

Jal:
Trisect System for Draw Shots (Dr. Dave) - With a healthy amount of draw (i.e., equivalent to striking the cueball one-quarter radius below center and not having it lose any backspin on the way to the object ball), the cueball will draw back at very close to three times the cut angle from straight back at you.

pj
chgo

 

[3RAILKICK]

Is there a similar

Jal posted-

Trisect System for Draw Shots (Dr. Dave) - With a healthy amount of draw (i.e., equivalent to striking the cueball one-quarter radius below center and not having it lose any backspin on the way to the object ball), the cueball will draw back at very close to three times the cut angle from straight back at you. As a corollary, with maximum draw, the theoretical limit is twice the cut angle from straight back at you, though generally unachievable because of some spin loss from friction during the collision.



rule of thumb for slight angle cuts with a soft rolling cb? Say you are shooting an almost straight in to the corner from short distance. You need a breakout or position on a ball on the short rail -it seems that the rolling cb moves down approximate 3x cut angle line after contact.

Is this about right or does it just seem that way? It seems fairly reliable on slight angle cuts.

OP-Great topic.

 

[Patrick Johnson]

Jal posted-

Trisect System for Draw Shots (Dr. Dave) - With a healthy amount of draw (i.e., equivalent to striking the cueball one-quarter radius below center and not having it lose any backspin on the way to the object ball), the cueball will draw back at very close to three times the cut angle from straight back at you. As a corollary, with maximum draw, the theoretical limit is twice the cut angle from straight back at you, though generally unachievable because of some spin loss from friction during the collision.



rule of thumb for slight angle cuts with a soft rolling cb? Say you are shooting an almost straight in to the corner from short distance. You need a breakout or position on a ball on the short rail -it seems that the rolling cb moves down approximate 3x cut angle line after contact.

Is this about right or does it just seem that way? It seems fairly reliable on slight angle cuts.

OP-Great topic.

This probably approximates the rule of thumb I'm familiar with: "the CB's follow path will exceed the tangent line angle by about 1/4 of what its straight path would."

As I mentioned below, Bob's 1:4 rule for cut shots along the rail sounds like this same principle with the lateral direction reversed by the rail.

pj
chgo

 

[Jal]

rule of thumb for slight angle cuts with a soft rolling cb? Say you are shooting an almost straight in to the corner from short distance. You need a breakout or position on a ball on the short rail -it seems that the rolling cb moves down approximate 3x cut angle line after contact.

Is this about right or does it just seem that way? It seems fairly reliable on slight angle cuts.

OP-Great topic.

3Rail, first of all I owe you a big apology for not getting back to you eons ago on the general topic of CB direction. I didn't want to respond until I had done more work on it (namely, real world deviations from the ideal because of various factors), but things obviously got out of hand. My sincere apology. (I did finally post up something on that several months ago, but not directly to you.)

I had to look up the answer to your observation (3X the cut angle) on Dr. Dave's VEPS, because it'll take me a while to see if the math works out to something like that. I probably shouldn't reveal any of his content without his permission, but I will say your figure (3X) is fairly close to his.

Jim

 

[Jal]

This probably approximates the rule of thumb I'm familiar with: "the CB's follow path will exceed the tangent line angle by about 1/4 of what its straight path would."...

Patrick, isn't that for thin cuts?

(Something else I looked up in VEPS.)

Jim

 

[Razor]

From Grady for judging whether there is a kiss or not on certain 'cross the face' bank shots: "If you can shoot the cue ball past the object ball straight into the pocket, no kiss..."

Heard many times on Accu-Stats commentary. That's the best summary I can provide. Perhaps someone else can elaborate if that is not clear or inaccurate.

RIP Professor

 

[randallt6]

90 Degree Rule – Dave Alciatore
The first and most well-known reference line is the tangent line predicted by the 90 degree rule. For a stun shot (aka a “stop shot at an angle”), where the cue ball is sliding with no top or bottom spin at object-ball impact, the cue ball will head exactly in the tangent line direction, which is perpendicular to the object-ball direction.

Can somebody please explain this better to me or make a diagram? I cant quite wrap my head around it, although it may click when i get a chance to get to a table.

thanks
Randall <-----kinda slow sometimes :sorry:

 

[scottyr44]

Ive always gone by the object ball being equal distance from the long and short rail =kiss. of course this is only for the cross face one pocket type shots

Sent from my SPH-D710 using Tapatalk 2

 

[dr_dave]

Good work, and great thread. FYI, several other useful rules of thumb can be found here:

Top 100 Pool and Billiards "Secrets" and "Gems"​

The following are good additions to your list:

• The trisect system predicts the angle the CB direction changes for a good-action draw shot is 3-times the cut angle.
• For a fairly full hit, with a ball-hit-fraction greater than 3/4, the CB will deflect about 3-times the cut angle (see where the CB goes for different cases).
• For a fairly thin hit, with a ball-hit-fraction less than 1/4, the CB will deflect about 70-75% (about 3/4) of the angle between the aiming line and the tangent line (see where the CB goes for different cases).- The optimal tip height for speed control is 20% of the radius above center (see optimal tip height for speed control).- With a full-hit rolling CB shot, the CB travels about 1/7 the distance of the OB after impact (see ball travel distances).
• With a rolling-CB half-ball hit, the CB and OB separate at close to same speed and same angle (see speed control article).
• With a 45-degree-anlge stun shot, the CB and OB separate at the same angle and distance (see speed control article).
• The miscue limit is half of the cue ball's radius from the center, which is the width of the stripe on a striped ball (see "tips" of English articles).
• FHE and BHE can be used to compensate aim for squirt and swerve when using English.
• When playing a safety in 9-ball, try to leave the OB away from a cushion (see "big ball" effect).
• Faster speed can help bank shot accuracy and consistency (see advantages of fast speed).
• For rolling-ball kicks or banks, the through-diamond aiming system is very reliable.
• With shallow-angle kicks, the contact-point mirror system can be very effective.
• For cross-corner bank shots, it is very important to know how to detect and avoid double kisses.
• Bob Jewett's two-times-fuller and ten-times fuller systems are useful to aim frozen carom and kiss shots.
• Maximum CIT, with no English, occurs with slow speed at about a 1/2-ball hit (see maximum throw).
• Maximum SIT occurs occurs with slow speed and about 50% English (see maximum throw).
• Maximum throw, under typical conditions, is about 1 inch per foot of CB travel, which is about 5 degrees.
• Gearing outside English can be used to eliminate throw, but this might not be the best approach for all people and situations (see using outside English to prevent throw and cling).
• The optimal tip height for a lag shot is 20% of the ball radius above center (see lag shot).
• Knowing where different balls tend to go in a 9-ball rack can be useful to know (see pattern racking strategy).
• In 8-ball, a 2nd-ball break from side can be used to make the 8-ball on the break.
• If you use a break cue with a natural pivot length well matched to your bridge length, stroking errors will not affect your accuracy (see pivot-length article).
• For best jump results, aim between the center of the CB and resting point on the cloth (see jump shot article).
• The Coriolis aiming system for masse shots can be very effective.

Enjoy,
Dave

PS: In case you haven't noticed, I love "rules of thumb!"

While reading through some older Bob Jewett BD columns, I noticed that Bob uses a number of "rules of thumb". I find them very helpful and decided to gather as many of these together as I could. Below are fifteen rules of thumb that I gathered from various places. The names that I have credited for these represent the first place I saw them - not necessarily an original source. I don't really know the original sources for these.

If not stated clearly, please correct them as you see fit or ask for clarification, if necessary. I hope you find them helpful too. Would you like to add any to the pool of knowledge?

90 Degree Rule – Dave Alciatore
The first and most well-known reference line is the tangent line predicted by the 90 degree rule. For a stun shot (aka a “stop shot at an angle”), where the cue ball is sliding with no top or bottom spin at object-ball impact, the cue ball will head exactly in the tangent line direction, which is perpendicular to the object-ball direction.

Avoiding Double Kisses – Freddie The Beard
When the balls line up on a straight line to the middle of the FACING of the corner pocket (the facing on the long rail), the bank is a dead kiss. It is extremely difficult to beat the kiss when the balls are on a line to the middle of the FACING.
When the balls line up on a straight line to the MIDDLE of the back of the POCKET, there is no kiss.
When the cue ball and an imaginary ball at the contact point for the bank are on a line to the center of the pocket, there is a dead kiss if you use follow with no English.
These kisses are usually easy to evade by using English or draw to send the cue ball on a non-kiss path.
The aim on the object ball must be adjusted to allow for the ball action needed for a non–kiss bank.

Throw When Balls Are Close – Bob Jewett
If the balls are a quarter-inch apart, there is no throw or cut, no matter how you hit them.

6:1 Rolling Cue Ball Ratio – Bob Jewett
The ratio of about 6:1 is a useful rule of thumb when playing soft position. Suppose the object ball is six diamonds from a pocket, and you want the cue ball to follow straightforward not more than about one diamond after the collision. If you just get the object ball to the pocket — six diamonds of travel — the (rolling) cue ball will roll forward about one diamond. Another way to state this is that on a full, soft follow shot, the cue ball will go forward one ball for each diamond the object ball travels. At a later time, Bob gives the ratio as 7:1.

Ball in Hand – Bob Jewett
With ball in hand, you should never place the cue ball for a draw shot.

Two Rail Banking – Bob Jewett
If a ball is sent along roughly a 45-degree angle between the short rail (first) and the long rail (second) it will go close to two rails into the corner.

45 Degree Rule – Dave Alciatore
If the CB rolls into the short rail at roughly a 45-degree angle, it will head fairly close to the center of the table after contacting the long rail.

Importance of Rolling Cue Ball Through the Center of the Table – Danny Basavich
A cue ball rolling through the center of the table for position cannot scratch unless coming directly from the direction of a pocket (or first hitting at least one more rail). Stated differently, unless the cue ball is rolling straight from a pocket, it cannot scratch directly in a pocket after passing through the center of the table.

Banking Frozen Object Balls – Bob Jewett
If the cue ball is straight out from the frozen object ball, the ball has to be at least one diamond up the rail from the target pocket for the bank to be possible using all techniques.

Half Ball Carom (30 Degree Rule) – Dave Alciatore
If the object ball cut angle is anywhere from 15 degrees to 45 degrees, a rolling cue ball is deflected by very near 30 degrees from its original path.

Equal Distance – Bob Jewett
After a half ball hit with a rolling cue ball, the cue ball and object ball will travel a similar distance.

Shortening Banks By Hitting Firm and Full – Bob Jewett
Banks that are dead using a mirror system (for example from diamond 3 to diamond 1.5), can be shortened by hitting full and firmly (for example, diamond 3 to diamond 1). The idea is if you can get the shot to match the mirror system by subtracting 1 from the cue ball's location, the bank is "on" for the system. So, if you subtract 1 from cue ball's 3, you get 2-to-1, which is a standard mirror bank. Therefore it is “on” for a full, firm bank.

Cue Ball Deflection On Nearly Full Shots – Bob Jewett
If you cut the object ball just a little to one side (3/4 ball or fuller), a rolling cue ball will be deflected about three times the angle to the other side. For example, a five degree cut to the left will result in the cue ball being deflected to the right about 15 degrees.

Path of Rolling Cue Ball After Hit – Shawn Putnam
This is a system to predict the direction the cue ball will go on a rather full hit (about ¾ ball or fuller) after rolling into the object ball with follow. To send the cue ball in a particular direction, visualize the spot on the far side of the object ball that points to where you want the cue ball to go and then aim the cue ball to that point on the far side of the object ball.

Sidespin/Squirt Ratio – Bob Jewett
Two tips of English will produce twice the squirt angle of one tip.

 

[dr_dave]

\I had to look up the answer to your observation (3X the cut angle) on Dr. Dave's VEPS, because it'll take me a while to see if the math works out to something like that. I probably shouldn't reveal any of his content without his permission, but I will say your figure (3X) is fairly close to his.

Jim,

You or others don't need my permission to reveal any of the content on any of my DVDs, provided you don't break any Copyright Laws in the process (e.g., posting video clips from or making illegal copies of the DVDs without my permission).

Concerning the 3X rule, details and illustrations can be found in my November '11 BD article.

Regards,
Dave