Dead Crab Aiming System

C

CueAndMe

AzB Silver Member
Silver Member
I just think this is brilliant and deserves its own thread. The forum member, Dead Crab, came up with a way to determine the angle of a shot using the joint of his cue.
Here's how it works. Correct me if I'm wrong Dead Crab:
-Place cue tip behind object ball pointing directly at pocket.
-Imagine a line running perpendicular to the joint of your cue(about 30" from center of object ball) intersecting the cue ball/object ball line.
-Estimate, in inches, the length of that line.
-Double your estimate to arrive at the shot angle in degrees

Here's an example:

CueTable Help



Dead Crab also suggests being able to quadruple the distance arrived at from using this technique from half way between the joint and the tip.

I happen to have an extra long shaft of 32" and I find that running the line perpendicular to the CB/OB line as opposed to the cue works well for me, especially when I place the tip somewhere near where the center of the ghost ball would be.

Never in my youth did I forsee myself thanking a dead crab, but thanks Dead Crab.
 
bluepepper said:
I just think this is brilliant and deserves its own thread. The forum member, Dead Crab, came up with a way to determine the angle of a shot using the joint of his cue.
Here's how it works. Correct me if I'm wrong Dead Crab:
-Place cue tip behind object ball pointing directly at pocket.
-Imagine a line running perpendicular to the joint of your cue(about 30" from center of object ball) intersecting the cue ball/object ball line.
-Estimate, in inches, the length of that line.
-Double your estimate to arrive at the shot angle in degrees

.
Click to expand...

Is it legal to use a tape measure in a money game?
Can I use a protractor?
 
Honestly, it's pretty easy to estimate since you can visually divide up references like your cue stick shaft or diamonds or your own hand and fingers.
 
Agreed, a very handy way to determine the angle. Also, if you use the full length of the cue, the distance between the two lines in inches is approximately the angle in degrees. No conversion needed. Very hand for fuller angles such as 5-10 degrees.

Colin
 
LAMas said:
Is it legal to use a tape measure in a money game?
Can I use a protractor?
Click to expand...
Take a pocket knife and turn your shaft into a ruler. Just notch every inch. Works perfect.

-td
 
The blue line should be perpendicular to the CB-OB line.

That way the hypotenuse formed by the right triangle is 30"


Then the sin(cutangle) = (perp length")/30"
or
cutangle= arcsin(perp/30)

which happens to have the nifty property that doubling the perp distance approximates the cutangle.

Examples: perp distance of 4"---> calculated cutangle 7.7 degrees
perp distance of 9"---> calculated cutangle 17.45 degreed

So if you estimate the cutangle by doubling the perp distance, you will have a very good estimation of the cut angle.

Is this legal? Yes, it is. You can use the stick and hand in aiming. There is no rule against it.

Does it delay the game? Not for me it doesn't. I shoot a lot faster than those players who check the reverse angle and take 10 warm up strokes.

Knowing the cut angle only helps if you have an aiming system to tie it to, can deliver the cue ball where it has to be, and have the cue ball go where you want it to.

However, for the geometrically inclined, knowing the cut angle can lead to an exact aiming point. The rest depends on having an accurate stroke and knowledge of cue ball control. For some of us, it works a lot better than touchy-feely systems. But, to each their own.
 
bluepepper said:
... The forum member, Dead Crab, came up with a way to determine the angle of a shot using the joint of his cue.
Click to expand...

That's an interesting technique for measuring approximate angles, but I don't get how knowing the approximate angle translates to an "aiming system".

pj
chgo

[Edit: Dead Crab's post crossed mine in the mail:]

Dead Crab:
Knowing the cut angle only helps if you have an aiming system to tie it to...

However, for the geometrically inclined, knowing the cut angle can lead to an exact aiming point.
Click to expand...

I think your angle measuring technique is clever, but is finding an aiming point from the degrees of cut angle really practical?

pj
chgo
 
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This scheme has limited application as it breaks down quickly as the angle opens up. For a game that requires such a high degree of accuracy, I would say it is of limited value. How does knowing the cut angle help you anyway...does that get converted to a fractional ball or something????

Here's some quick math to point out the problems.

deadcrabsangletheory.jpg


EDIT: for the math eagle-eyes out there...I used "3.14" to convert from degrees to radians therefore the accuracy is diminished...90* should be infinite.
 
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There is a math breakdown here.

Let us assume that you estimated the perp distance to be 20 inches.

arcsin (20/30) is 41.8 degrees.

So the the estimated angle of 40 degrees, is short by 1.8 degrees, not the 8 degrees as stated above.

Finding an aiming point for on-ball hits is quite easy. Aim one mm off center for each degree of cut. This works real well up to 30 degrees, and then requires some adjustment. For this cuts over 45 degrees, I use the "overlap" aiming method because it gets too hard to visualize aiming points off ball.
 
Hey guys- a couple of notes about this system:
I have independantly devised a similar system, which you may also be interested in here

There is a major flaw in the system that could be easily corrected - I have mentioned this to DeadCrab before. Mosconiac hinted at it. Basically, using a perpendicular measure is not the best way to estimate the angle. It works well for small angles, but terribly for larger angles. A much better way is to make an iscosolles triangle. If you are interested in a comparison, take a look at these two images:
here
and here
 
Finding an aiming point for on-ball hits is quite easy. Aim one mm off center for each degree of cut. This works real well up to 30 degrees, and then requires some adjustment. For this cuts over 45 degrees, I use the "overlap" aiming method because it gets too hard to visualize aiming points off ball.
Click to expand...

To each his own, I guess. I'd expect the error factor to be way more than tolerable after a few millimeters, especially on top of roughly estimating the angle in the first place.

pj
chgo
 
Who needs the Comedy Channel when you can read this thread. Arcsins, tangents, sins, OMG.....

I'm gonna buy a TI-84 for my next match....

l.....m........f......a.ooooooooooooooo
 
Like I say, it ain't for everyone.

Personally, when I need a 5/16th bolt, I can go over to a bench and pick one up. I won't pick up a 1/4", or a 3/8" by mistake. Not ever. I guess I assume everyone can do this. Maybe not.

They differ by about 1.6mm. So without even trying I am already good at resolving 1.6 mm from across the room. What might I do with some practice? I'd say about a mm.

I can also tell time and do some practical geometry. It is the only thing they taught me in high school that has been worth anything. I know that a 15 degree cut has the aim point on the OB at either 5 or 7 o'clock (depending on the cut direction). A 20 degree cut has to be aimed at 4:40 or 7:30. Not so tough. Provided you know what the cut angle is.

I only play pool for a couple of hours a week, if that. I've been playing a little over a year. At my age, I don't have time to hit a million balls and develop a great "feel" for where to aim.

I miss a lot, but when I do it usually isn't because I botched the aim point. Based on recent threads, it would seem a lot of people do.
 
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