Rules of Thumb in Pool

[Saturated Fats]

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?

From www.dictionary.com:
rule of thumb:
noun
1. a general or approximate principle, procedure, or rule based on experience or practice, as opposed to a specific, scientific calculation or estimate.
2. a rough, practical method of procedure.

Note that ROTs need not be true 100% of the time – These are the “usually” rules as opposed to the “always” rules.

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.

 

[Bob Jewett]

...
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.
...

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.)

In the two-rail bank, the first cushion the ball hits is the short cushion and it approaches that cushion at a 45-degree angle. This kind of shot can depend a lot on speed on new cloth.

 

[Jal]

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....

Great idea for a thread and many thanks for taking the time to type them all out! I have a couple of nitpicks, if you will:

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.

At a quarter-inch separation (2.5" between centers), you can drive the object ball away from the line of centers. Without throw, the theoretical limit (90-degree cut angle) is just about 26-degrees off the line of centers. With throw - and I see no reason why there wouldn't be throw - the limit is a little less. So I'm not sure what you mean by "no throw or cut."

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

....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.

To try to add something:

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.

On the Gold Crowns in my room, a half-ball hit will successfully bank the object ball when it's one diamond from the end rail. When two diamonds, an ever so slightly thinner than quarter-ball hit (to my eyes) does the job.

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.

Jim

 

[Autist]

Best thread I've seen in a long time. Thank you!

 

[stouter2386]

There's some good info here thanks

 

[Mitchxout]

In the two-rail bank, the first cushion the ball hits is the short cushion and it approaches that cushion at a 45-degree angle. This kind of shot can depend a lot on speed on new cloth.

I'm confused. Isn't this the same as Dr Dave's 45' rule to find the center of the table?

 

[GeoEnvi]

Great thread! Many of these are the same little nuggets of pool wisdom that I try to pass along whenever a league-mate asks for a hint.


Sent from my iPhone using Tapatalk

 

[LAlouie]

Avoid missing. Avoid miscues as they lead to missing as well.

 

[Patrick Johnson]

Great thread - I hope we get lots more rules of thumb contributed and they get added to the RSB Pool & Billiard FAQ, which is brought out of retirement to become the most useful sticky ever on AzB's Main Forum.

pj
chgo

 

[Patrick Johnson]

Bob Jewett:
In the two-rail bank, the first cushion the ball hits is the short cushion and it approaches that cushion at a 45-degree angle. This kind of shot can depend a lot on speed on new cloth.

Mitchxout:
I'm confused. Isn't this the same as Dr Dave's 45' rule to find the center of the table?

Maybe the difference is that the center-of-the-table shot is for a cue ball with transferred spin from the object ball it just pocketed, which shortens the two-rail path.

I think most one-pocket players know the 45 degree short-long two rail bank. Like other bank/kick tracks it's actually a "fan" of angles that includes 45 degrees, a little steeper toward the doubled corner and shallower farther away.

pj
chgo

 

[Bob Jewett]

I'm confused. Isn't this the same as Dr Dave's 45' rule to find the center of the table?

No. Here is a typical end-rail-long-rail bank to a corner pocket. The angle of the object ball into the first cushion is about 45 degrees. That varies with speed, table, closeness to the corner and such, but it's pretty close, mostly.

 

[Bob Jewett]

... 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. ...

Let me clarify this. For some distance of ball-ball separation in a close combination, if the first ball is cut a little away from the line of centers, the effect of that cut on the angle of the second ball is canceled by the throw that also occurs on the shot. For a fairly large range of "cuts" of the first object ball into the second, that distance is nearly constant. When two balls are that far apart, it is hard to get the path of the second object ball away from the line of centers.

This depends on lots of things, including the cleanliness of the balls, the speed of the shot, the angle of approach of the cue ball, etc. But when I see two object balls about 1/4-inch apart, I know that it will be harder to manipulate the angle.

 

[Maniac]

Rule of thumb #1: Always post up BEFORE the action begins.

Maniac (kind of a weird post coming from a "non-gambler")

 

[Patrick Johnson]

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.

This simple way to know the minimum distance the CB must travel after pocketing the OB has come in handy for me more than once.

pj
chgo

 

[Patrick Johnson]

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.

Another way the center-of-table path is important is as a reference from which to calibrate adjustments for shorter and longer paths.

Whatever hit on the CB is required to achieve a 45-degree angle into the first rail off the OB, add follow to go longer than the center-of-table path and add draw to go shorter.

pj
chgo

 

[madmiller]

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

I don't agree with this rule. Sometimes you use a draw shot when making a ball from ball in hand position to break up a cluster. Or for example, in 9 ball, sometimes when 9 is hanging and there's no way to play a combination, you can make a ball and draw the cueball to make the 9. There are few other scenarios too that come up once in a while.

 

[CreeDo]

Just saw an excellent series of youtube videos from Ralph Eckert about various rules of thumb. I love these videos because they assume you already know all the basics and go straight to the good stuff.
Here's the playlist: http://www.youtube.com/playlist?list=PL4B9E5D76AE9F913F&feature=plcp
All credit Ralph Eckert.

disclaimers: you can use headspot/footspot interchangeably. Cue ball paths depend on how much you cheat the pocket and the condition of the equipment.

Rolling Cue Ball Ratio, Revisited
For rail cuts near 45 degrees... natural follow will cause a cue ball to drift forward about 1 diamond for every half table of travel.

Example: Object ball on the long rail, 2 diamonds away from the far corner. Cue ball cutting it from about 45 degrees.
The 90 degree line would carry the cue ball straight across the table to the opposite long rail (2 diamonds from the pocket). But with natural top, it will land about 1 diamond from that pocket. So after travelling half the table's length, it moved forward 1 diamond.

Example 2: A similar angle, cutting a ball that's in the middle of the short rail, cue ball on the side rail (again around 45 degrees). With natural top, when the cue ball passes the side pocket it will have moved forward 1 diamond. After travelling the entire length of the table, it will have moved forward 2 diamonds... which puts it right in line to scratch.

2-Rail Return Path for long 30-45 Degree Cuts
With the CB on the head spot, and OB on the foot spot... cutting into either corner with natural follow will send the cue ball two rails right through its original position, or a a bit short of that.

If you move the cue ball sideways up to one diamond (so that the cut is fuller) the return path is still more or less directly through the starting point of the cue ball.

You can also move the CB closer to the object ball by a diamond or even more.
In that case, the return path is not through the cue ball's starting point, but where the cue ball would be if you imagined increasing the distance of the cut until the cue ball was resting on the kitchen line. That imaginary cue ball position is where the actual cue ball will pass after going 2 rails.

2-Rail Return Path for short 30-45 Degree Cuts
A natural-follow 45 degree cut, with the object ball on the head spot and the cue ball parallel to it on the long rail... If you cut this ball in the corner, the cue ball hits the first rail near the side pocket, and comes back to your side of the table about 2 diamonds 'above' the opposite side pocket. If you move both balls closer to the head rail by a diamond... the cue ball still hits about the same spot on the 2nd rail, because now you're not cutting the ball as thin. The fuller hit sends the cue ball more 'sideways'. This means whenever both balls are the same distance from the rail, and about 1-2 diamonds away from it, you can expect to hit the same spot on the 2nd diamond.

Measuring "Straight In" Banks
It's well-known that bank shots don't go on a perfect mirror (like from diamond 2 to diamond 4) because they bite into the rubber rails and come up a bit short... at least they do if struck with any speed vs. softly rolling them in. This system allows you to anticipate that and help you spot a straight in bank that can be struck at a more normal "firm" speed. Obviously this is a bit subjective, but the system is logical and it pays to figure out a speed that makes the system work.

Example 1: a quarter table bank, e.g. from 2 to 1: if you move the cue ball closer to the pocket by about 1/4 diamond, this is now a straight in bank when struck firmly.

Example 2: a half table bank, from 4 to 2: adjust a half diamond, so you're actually shooting from 4 to 1.5.

Example 3: a full table bank (object ball near the corner pocket, cue ball near the side pocket, banking into far corner): adjust a full diamond. So from 8 to 3.

There are other videos, some in german, but I found these tremendously useful.

 

[Bob Jewett]

...
Rolling Cue Ball Ratio, Revisited
For rail cuts near 45 degrees... natural follow will cause a cue ball to drift forward about 1 diamond for every half table of travel.
...
Example 2: A similar angle, cutting a ball that's in the middle of the short rail, cue ball on the side rail (again around 45 degrees). ...

....

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.

 

[Saturated Fats]

I don't agree with this rule. Sometimes you use a draw shot when making a ball from ball in hand position to break up a cluster. Or for example, in 9 ball, sometimes when 9 is hanging and there's no way to play a combination, you can make a ball and draw the cueball to make the 9. There are few other scenarios too that come up once in a while.

Please allow that a rule of thumb need not be true/completely accurate in all cases:

rule of thumb (noun)
1. a general or approximate principle, procedure, or rule based on experience or practice, as opposed to a specific, scientific calculation or estimate.
2. a rough, practical method of procedure.

 

[chefjeff]

I don't agree with this rule. Sometimes you use a draw shot when making a ball from ball in hand position to break up a cluster. Or for example, in 9 ball, sometimes when 9 is hanging and there's no way to play a combination, you can make a ball and draw the cueball to make the 9. There are few other scenarios too that come up once in a while.

That's true but Rules of Thumb are not for the 'once in a while,' but for the 'most often.'

fwiw,

Great thread!...and I rarely use these R of T's.

Jeff Livingston