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Johnnyt
07-01-2010, 05:43 AM
On an exactly 30 deg. angle shot into a 4 1/2" pocket, how many deg can you be off and still make the ball at pocket speed? Johnnyt

steev
07-01-2010, 06:06 AM
On an exactly 30 deg. angle shot into a 4 1/2" pocket, how many deg can you be off and still make the ball at pocket speed? Johnnyt

It depends on distance to pocket and OB angle to pocket.

-s

Junkyarddog
07-01-2010, 06:07 AM
On an exactly 30 deg. angle shot into a 4 1/2" pocket, how many deg can you be off and still make the ball at pocket speed? Johnnyt

It depends on how close or far away you are to the pocket. If the ball is sitting in the pocket you can be off almost 90 deg. If you are shooting across table you can only be off a couple.

steev
07-01-2010, 06:20 AM
Let's say the OB is a foot away from the jaws, straight out from the pocket (45), With 4.5" pockets and 2.25" balls, this leaves 1.125" on either side of the ball. So, you've got a right triangle with legs 12" and 1.125". Tangent(theta) = 1.125/12 = 3/32 = 0.09375

<begin errors>
0.09375rad * (180/pi) = 5.37147933 (while this line is true by itself, it's not the answer)
<end errors>

-s

edit: i screwed up. hang on.

so, if tan theta is 0.09375, theta = arctan(0.09375) which comes out to 5.35582505 (0.0934767812rad)

3andstop
07-01-2010, 06:35 AM
This question exemplifies what I've been preaching on and off in various threads. This degree thing, IMHO is a very bad way to visualize shots. Not only would I be willing to bet the ranch that you couldn't draw a 30 degree angle on paper time after time without a protractor, but to decide you see one on a pool table and use it as a shooting reference is much more abstract. Besides that, the distance from the OB to the pocket plays way too much into the accuracy of the shot regardless of how well you see degree angles.

Johnny you must have seen the thread on aiming with the side of your cue stick. IMO forgetting TOTALLY about "degree" angles, and practicing this method will raise your game a ton ( provided you have a good level, smooth delivery and complete your stroke properly).

You will need the method less and less and become comfortable knowing the angle of the shot, regardless of specific degrees. In situations where the shot just doesn't feel right, you can always go back to sighting the shot with the side of the cue stick since you are aiming at a definite point with a definite straight edge.

steev
07-01-2010, 06:41 AM
I would like to add re: the math involved. Measuring angles here is so not the way to go. You're frequently not aiming for 'center pocket', many tables allow you the cheat the pocket beyond its dimensions using the rubber, etc etc.

It seems that you're trying to standardize things by measuring, but every shot is so different when looked at this way, the results are virtually meaningless.

-s

Johnnyt
07-01-2010, 06:50 AM
I would like to add re: the math involved. Measuring angles here is so not the way to go. You're frequently not aiming for 'center pocket', many tables allow you the cheat the pocket beyond its dimensions using the rubber, etc etc.

It seems that you're trying to standardize things by measuring, but every shot is so different when looked at this way, the results are virtually meaningless.

-s

Thank you. This is why I tried some of the aiming systems. The ones that came with drills worked for me until I stopped doing the drills (practice). I whent back to feel a few weeks ago and my game came right back up in a few hours. I'm not sorry I tried the aiming systems. I got the WHY out of some of them and tossed the rest. Thanks again for yoyr time. Johnnyt

Johnnyt
07-01-2010, 07:02 AM
This question exemplifies what I've been preaching on and off in various threads. This degree thing, IMHO is a very bad way to visualize shots. Not only would I be willing to bet the ranch that you couldn't draw a 30 degree angle on paper time after time without a protractor, but to decide you see one on a pool table and use it as a shooting reference is much more abstract. Besides that, the distance from the OB to the pocket plays way too much into the accuracy of the shot regardless of how well you see degree angles.

Johnny you must have seen the thread on aiming with the side of your cue stick. IMO forgetting TOTALLY about "degree" angles, and practicing this method will raise your game a ton ( provided you have a good level, smooth delivery and complete your stroke properly).

You will need the method less and less and become comfortable knowing the angle of the shot, regardless of specific degrees. In situations where the shot just doesn't feel right, you can always go back to sighting the shot with the side of the cue stick since you are aiming at a definite point with a definite straight edge.

Thank you for the input. I can pocket balls well so I think I was just trying to find the magic bullet for the whole game after 60 years of playing. I can still beat the 9-ball ghost w/o bih on a bb and most of the time I know exactly why I missed a shot. Even when I don't know for sure I know it was something (I) did or didn't do right. That's what I like about pool...it's all on you. Pool is so mental after you get good at it. Johnnyt

MitchAlsup
07-01-2010, 08:15 AM
Let's say the OB is a foot away from the jaws, straight out from the pocket (45), With 4.5" pockets and 2.25" balls, this leaves 1.125" on either side of the ball. So, you've got a right triangle with legs 12" and 1.125". Tangent(theta) = 1.125/12 = 3/32 = 0.09375

so, if tan theta is 0.09375, theta = arctan(0.09375) which comes out to 5.35582505 (0.0934767812rad)

Now 5.35 degrees on a ball 2.25" in diameter means you have a contact point that is 0.21" wide for this shot. {5.35/360 *2.25*2*pi = 0.21009}

steev
07-01-2010, 08:26 AM
Now 5.35 degrees on a ball 2.25" in diameter means you have a contact point that is 0.21" wide for this shot. {5.35/360 *2.25*2*pi = 0.21009}

but it's 5 in either direction. also, i don't know where you got that math, but i think i disagree...

-s

NewStroke
07-01-2010, 08:28 AM
On an exactly 30 deg. angle shot into a 4 1/2" pocket, how many deg can you be off and still make the ball at pocket speed? Johnnyt

One huge variable is missing. How deep is the hole or does the table have a return system?

steev
07-01-2010, 08:29 AM
circumference = pi * d = 2.25 * 3.1415 = 7.069"

7.069/360 * 10.7 = 0.210106389" (inches per degree times degrees of error allowed, 5.35 * 2)

well i'll be damned, i no longer disagree.

-s

steev
07-01-2010, 08:46 AM
Interesting side note: the cut angle is irrelevant to this discussion, more or less.

If it was a severe cut, part (up to half?) of the contact area would be hidden from the CB, further reducing its effective size.

-s

Eric.
07-01-2010, 09:24 AM
Thank you for the input. I can pocket balls well so I think I was just trying to find the magic bullet for the whole game after 60 years of playing. I can still beat the 9-ball ghost w/o bih on a bb and

Johnnyt


Johnny,

For a guy that has been playing this game for 60 years, "can still beat the 9-ball ghost w/o bih on a bb" and supposedly has robbed people at Pool, why do you bother with this trivial stuff that can't help your game? Do you really think your eye can discern between 30 deg and 32 degrees??

I still wonder about some of the weird-azz, novice-like questions you ask, lol!


Eric

LAMas
07-01-2010, 09:25 AM
On an exactly 30 deg. angle shot into a 4 1/2" pocket, how many deg can you be off and still make the ball at pocket speed? Johnnyt


OK,
I'll bite.:)

Worse case would be a CB in the jaws of a 4.5" pocket shooting at the diagonally opposite pocket on a 9 foot table - the angle would be 30 degrees to that pocket.

The pocket is cut at 45 degrees to the corner of the table so the CB would enter at a 15 degree off square (45 - 30 degrees). The pocket mouth would be 4.45" wide.

Subtracting the 2.25" diameter CB leaves 2.2" or 1.1" on each side of the ball to the jaws.

The diagonal or hypotenuse from corner to corner is 119.35".

Sin (a) = 1.1" (s) / 119.35" (h)
Sin (a) = .0092
Angle a = .5 degrees rounded off

You can only be off 1/2 a degree to each side of the center of the target pocket or 1 degree total.

The error can be larger if you graze the jaws and bank the ball off the jaw.

in any case it's a small number.

Was that usefull?:)

alstl
07-01-2010, 09:58 AM
On an exactly 30 deg. angle shot into a 4 1/2" pocket, how many deg can you be off and still make the ball at pocket speed? Johnnyt

Many variables there. Side or corner pocket? 30 deg angle from the cue ball to object ball, but where is the object ball in relation to the pocket? If you are shooting down the long rail at the corner pocket you have more room to miss on the long rail side than the short rail. Distance to the pocket is another variable.

It is a good question though, especially if you need to cheat the pocket a little to get shape.

deep
07-01-2010, 10:39 AM
If you hit the 1 degree off for every meter the ball travels it will be roughly 17.46mm of the target line. So if the ball is 1.5 meters away from the pocket and you hit it 2 degrees off it will arrive the pocket 52.4mm off the target line, which is a little over 2".

So being 1 degree off = 0.21" off the target line for every foot traveled, i think...........:speechless:

Johnnyt
07-01-2010, 12:53 PM
Johnny,

For a guy that has been playing this game for 60 years, "can still beat the 9-ball ghost w/o bih on a bb" and supposedly has robbed people at Pool, why do you bother with this trivial stuff that can't help your game? Do you really think your eye can discern between 30 deg and 32 degrees??

I still wonder about some of the weird-azz, novice-like questions you ask, lol!


Eric

Why don't you do both us a favor then and ignore my posts. I mean there only trival anyway and I'm "supposedly" a liar anyway. John Terrell

Eric.
07-01-2010, 01:12 PM
Why don't you do both us a favor then and ignore my posts. I mean there only trival anyway and I'm "supposedly" a liar anyway. John Terrell

Actually, I do think you have potential to be "full of it", but thats besides the point. I guess you're a lil sensitive about the "liar" thing and missed the message; IMO, it's over complicating the game to try to measure exact angles by eye. If anything, youre better off visualizing what a "3/4, 1/2, 1/4, etc hit" is, than trying to figure out if you're off by 1 degree.


Eric >lol

woodyosborne
07-01-2010, 02:25 PM
for hours of entertaining reading get a copy of Jack Koehler's book The Science of Pocket Billiards. i think it will clear things up for us all. i never did get through all of the book.

CarlB
07-01-2010, 05:19 PM
Contrary to my better judgement, I'll throw in my 2 cents.

Every single math problem I have seen on here is missing some things. You can do a semi-simple math problem IF you take into consideration that you do not want the ball to touch a rail at all.

However, *pause* :D

You would need to consider many things amongst what has already been mentioned regards which angles, distances travelled, etc.

This unknown and almost impossible to account for is the rail. Not to mention if I use left or right english you have to account for throw plus reverse spin off the rail.

It boils down to if you know the table and knowing how far you can "cheat" the pocket from experience. I can say with slight certainty no one is sitting at the table with a paper and pencil doing the math during a game.

Carl Bekowitz