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Easy way to measure an angle in degrees
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Bob Jewett
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Easy way to measure an angle in degrees - 07-31-2020, 04:18 PM

In case you want to measure an angle for any reason and happen to have a cue stick in your hand....

A one-degree angle has a spread of one inch in 57 inches. If you place your tip at the center of the ghost ball and pivot around it from the line to the pocket to the line of the shot (over the cue ball), the number of inches the bumper on the cue travels is the number of degrees of the cut angle.

To be precise, you should measure the distance around the arc of the travel of the bumper, but for cut angles up to 30 degrees the straight-line distance between the two positions of the bumper is pretty close.

If you're working on your aiming you might try measuring the angle for each cut by this quick and simple method. Of course you need to be able to see how many inches a distance is. A couple of useful references: A proper-sized hand has a span of nine inches. A dollar bill is six inches.

Another point on accuracy: The perfect cue length to get one degree per inch is 57.2958 inches. A 58 inch cue or even a 60 inch cue is not going to be off very much and if you always measure with the same cue, you will get used to "degrees" that are a little large or small.


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Last edited by Bob Jewett; 07-31-2020 at 04:32 PM.
  
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07-31-2020, 04:31 PM

Here's a diagram:

Name:  CropperCapture[624].png
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Size:  15.8 KB


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07-31-2020, 09:26 PM

Quote:
Originally Posted by Bob Jewett View Post
In case you want to measure an angle for any reason and happen to have a cue stick in your hand....

A one-degree angle has a spread of one inch in 57 inches. If you place your tip at the center of the ghost ball and pivot around it from the line to the pocket to the line of the shot (over the cue ball), the number of inches the bumper on the cue travels is the number of degrees of the cut angle.

To be precise, you should measure the distance around the arc of the travel of the bumper, but for cut angles up to 30 degrees the straight-line distance between the two positions of the bumper is pretty close.

If you're working on your aiming you might try measuring the angle for each cut by this quick and simple method. Of course you need to be able to see how many inches a distance is. A couple of useful references: A proper-sized hand has a span of nine inches. A dollar bill is six inches.

Another point on accuracy: The perfect cue length to get one degree per inch is 57.2958 inches. A 58 inch cue or even a 60 inch cue is not going to be off very much and if you always measure with the same cue, you will get used to "degrees" that are a little large or small.
Thanks for the great on table estimation tool.
  
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08-01-2020, 03:00 AM

What’s the purpose of knowing the cut angle?
  
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08-01-2020, 03:28 AM

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Originally Posted by duckie View Post
What’s the purpose of knowing the cut angle?
it lets you know how far from the edge of the ball you have to hit or aim......
  
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08-01-2020, 06:16 AM

Here's the method I use. It gives a good approximation of the cut angle and the location of the CP.

https://forums.azbilliards.com/showthread.php?t=472005


My Vorpal cue jabbed 'er wonky and the shot went snicker-snack. 'Twas brillig.
  
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08-01-2020, 07:06 AM

Quote:
Originally Posted by Vorpal Cue View Post
Here's the method I use. It gives a good approximation of the cut angle and the location of the CP.

https://forums.azbilliards.com/showthread.php?t=472005
tl;dr

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08-01-2020, 07:38 AM

Quote:
Originally Posted by Patrick Johnson View Post
tl;dr

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Lost my universal cryptic decoder ring. Retransmit in the clear.


My Vorpal cue jabbed 'er wonky and the shot went snicker-snack. 'Twas brillig.
  
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Bob Jewett
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08-01-2020, 08:01 AM

Quote:
Originally Posted by Vorpal Cue View Post
Lost my universal cryptic decoder ring. Retransmit in the clear.
I had no idea what he meant either, so I did a google search. It means "too long; didn't read".

Your method seems to have many steps, calculations and memorized cardinal angles. It seems to me immensely complicated compared to estimating one distance.


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08-01-2020, 08:18 AM

The angles can be thought as this sequence:

15, 25, 35, 45, 55, 65, 75, 90

There're only off by a few degrees and not too hard to remember.

The base of the triangle can be overlapped to the center to center line to give the CP also.


My Vorpal cue jabbed 'er wonky and the shot went snicker-snack. 'Twas brillig.
  
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08-01-2020, 08:29 AM

  
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08-01-2020, 12:37 PM

Quote:
Originally Posted by Bob Jewett View Post
I had no idea what he meant either, so I did a google search. It means "too long; didn't read".

Your method seems to have many steps, calculations and memorized cardinal angles. It seems to me immensely complicated compared to estimating one distance.
I'm sure Vorpal's method is interesting math/geometry, but I doubt it'll get much attention in this short-attention-span pool forum.

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08-01-2020, 02:15 PM

The exact angle doesn't much matter if you're using the ghostball, which is what is shown in the 19° example. I mean, if you can recognize where the cb needs to be, using the ghostball method, then knowing the exact angle is insignificant -- just aim for the ghostball.

Another way to estimate the angle, or better yet the cb-ob relationship, is here.....https://youtu.be/C_lxXEFzCG0. The method doesn't involve estimating inch by inch from 60 inches away. It simply uses a hand distance and a ball's width to help determine the fractional aim lines, not exact angles or measurements that need to be calculated.

Last edited by BC21; 08-01-2020 at 10:02 PM.
  
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Bob Jewett
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08-01-2020, 03:51 PM

Quote:
Originally Posted by BC21 View Post
The exact angle doesn't much if you're using the ghostball, which is what is shown in the 19° example. I mean, if you can recognize where the cb needs to be, using the ghostball method, then knowing the exact angle is insignificant -- just aim for the ghostball.
...
Some people like to know the actual cut angle of the shot they are shooting. The system I showed is an easy way to find that angle. Do you have a better way to measure the cut angle if someone wants to do that?


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08-01-2020, 04:06 PM

Quote:
Originally Posted by BC21 View Post
Another way to estimate the angle, or better yet the cb-ob relationship, is here.....https://youtu.be/C_lxXEFzCG0. The method doesn't involve estimating inch by inch from 60 inches away. It simply uses a hand distance and a ball's width to help determine the fractional aim lines, not exact angles or measurements that need to be calculated.
I like it - a clever use of available measuring tools, well explained.

So is Bob's, by the way - in fact, I think "measuring inch by inch from 60 inches away" might actually be simpler (and more accurate?) than estimating handspans and ball widths. And the measured angles can also be translated to fractional CB/OB alignments using the same 15-degree steps you do.

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chgo

Last edited by Patrick Johnson; 08-01-2020 at 04:10 PM.
  
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