stun stroke

[Patrick Johnson]

Me:
...there is a good reason to avoid the combination of stun and sidespin whenever possible: a stun hit maximizes throw...

jsp:
I think there is a better reason to avoid the combination of stun and NO sidespin whenever possible, precisely because a stun hit maximizes throw.

It's not really that simple. With a stunned cue ball:

Throw is maximized with no sidespin when the cut angle is about 30 degrees (half ball hit).

Throw is maximized with a little outside spin for cut angles greater than 30 degrees.

Throw is maximized with a little inside spin for cut angles less than 30 degrees.

Throw is maximized with about 1/2 maximum sidespin for straight-on shots.

pj
chgo

 

[alstl]

A stun shot isn't hard to learn even for a beginner and is a valuable shot.

Call it whatever you want but another valuable shot is when you hit the ball hard when straight in or at a slight angle and roll the cue ball forward a short distance. This shot takes a little more time to get the hang of but can add a lot to your game if you learn to control it properly.

Both are good shots for a beginner to practice.

 

[TheNewSharkster]

I havent read this entire thread so no flames please

A stun shot is simply a shot where the cue ball is sliding on the felt when it contacts the object ball. It can be a straight in shot (where it will most likely stop if you hit the OB head on) or a cut shot. In a cut shot the cue ball will seperate from the object ball at 90 degrees. This is important because it basically defines the 90 degree rule which is important to know for positional play and break outs (or avoiding a scratch).

 

[teedotaj]

A stun shot isn't hard to learn even for a beginner and is a valuable shot.

Call it whatever you want but another valuable shot is when you hit the ball hard when straight in or at a slight angle and roll the cue ball forward a short distance. This shot takes a little more time to get the hang of but can add a lot to your game if you learn to control it properly.

Both are good shots for a beginner to practice.

how do you do that? you do that with a bit of force right?? Is that when you put slight amount of tops like Creedo said?

 

[Andrew Manning]

how do you do that? you do that with a bit of force right?? Is that when you put slight amount of tops like Creedo said?

Yep, you hit the ball firmly and barely above center. It's very sensitive to tip placement, though, so you have to have a very accurate stroke. Just a little bit too high, and you roll forward waaaayyyy too far. Just a little bit too low, and you stop dead.

-Andrew

 

[Patrick Johnson]

...another valuable shot is when you hit the ball hard when straight in or at a slight angle and roll the cue ball forward a short distance.

how do you do that? you do that with a bit of force right?? Is that when you put slight amount of tops like Creedo said?

Many combinations of speed and tip height will produce the same result, depending largely on distance. A firm hit at centerball or slightly high avoids babying shorter shots, but longer shots are easier hit low, like a stop shot aimed short so the CB gets partly rolling before hitting the OB.

pj
chgo

 

[dr_dave]

Excellent summary!

FYI to others, my stun FAQ page has links to some good videos and resources related to stun.

Regards,
Dave

Just to boil it all down:

"Stun" simply means that the cue ball has no forward or backward rotation. If the CB is "at stun" when it hits an object ball it will either stop (full ball hit) or carom and remain on the tangent line (cut angle).

The presence or absence of sidespin doesn't change the definition of stun.

When the CB is hit so that it has begun to rotate forward (but isn't fully rolling) when it hits an OB, that is often called "stun rollthrough" or something similar, but it isn't technically a "stun hit".

Like CreeDo, I don't like the term "stun stroke" because:

1. strokes are generally the same (speed and CB contact point are usually the only things that change)

2. "stun hit" (like almost every hit) can be accomplished with different combinations of speed and CB contact point

pj
chgo

P.S. I use the term "hit" to mean what speed and spin the CB has when it hits an OB. I don't use it to mean how the tip hits the CB for the same reasons that I don't like the term "stun stroke": it implies there are differences other than speed and contact point, which I believe mostly don't exist.

 

[dr_dave]

Again, excellent summary. If people want to see resources related to these topics, I have a good summary with lots of links here:

http://billiards.colostate.edu/threads/aiming.html#English_effects​

Regards,
Dave

It's not really that simple. With a stunned cue ball:

Throw is maximized with no sidespin when the cut angle is about 30 degrees (half ball hit).

Throw is maximized with a little outside spin for cut angles greater than 30 degrees.

Throw is maximized with a little inside spin for cut angles less than 30 degrees.

Throw is maximized with about 1/2 maximum sidespin for straight-on shots.

pj
chgo

 

[alstl]

how do you do that? you do that with a bit of force right?? Is that when you put slight amount of tops like Creedo said?

The best answer is to go to a pool room and practice the shot. After a while you will "feel" how to do it without thinking about it.

 

[pdcue]

IMHO - there are quite a few millionaire snooker players that use the exact same stroke on every shot, and due to this they've made it accurate and repeatable to an extreme degree not seen in pool.

The stun stroke only differs from the follow stroke in tip placement. Other than that, they're the same stroke.

The stun stroke is equally possible with a full or abbreviated follow-through. The reason the short follow-through helps you "kill" the CB, is because having a short follow through makes you hit the ball softer than you think, because you stop acccelerating the cue earlier in the stroke to anticipate not following through. So you end up with a "kill" shot, because you hit the ball softer.

When using a "stun stroke", I use a backswing proportional to how hard I want to hit the ball, I use a pendulum stroke, I accelerate the cue smoothly up to contact, I hit the ball at or below center according to how far away the OB is and how hard I'm hitting the ball, and I follow through to my natural finish.

Just like any other shot.

-Andrew

I don't know about you, but I personally don't ever hit the ball softer than I think I do, nor harder, neither - YMMV

You have sort of bumped into what really does matter, ie, is the cue
accelerating at contact?

Dale

 

[Patrick Johnson]

You have sort of bumped into what really does matter, ie, is the cue
accelerating at contact?

Like followthrough, this only makes a difference to how accurate your stroke is - it doesn't matter to the CB whether the cue is accelerating, decelerating or neither, only what speed it's going at the moment (1/10,000 second) of contact.

pj
chgo

 

[dr_dave]

Like followthrough, this only makes a difference to how accurate your stroke is - it doesn't matter to the CB whether the cue is accelerating, decelerating or neither, only what speed it's going at the moment (1/10,000 second) of contact.

Agreed, except for the 1/10,000 second (see cue tip contact time). I know you know the correct number is closer to 1/1,000 (0.001) second, but others might not.

If people are more curious about acceleration, I have a pertinent video and other resources here:

http://billiards.colostate.edu/threads/stroke.html#acceleration​

Regards,
Dave

 

[Patrick Johnson]

...I know you know the correct number is closer to 1/1,000 (0.001) second...

Oops.

Typos are so easy to do, yet I never get an extra zero on my paycheck. What's up with that?

pj
chgo

 

[Andrew Manning]

I don't know about you, but I personally don't ever hit the ball softer than I think I do, nor harder, neither - YMMV

My apologies, Mr. Reyes. I assumed you were mortal.

You have sort of bumped into what really does matter, ie, is the cue
accelerating at contact?

Dale

Hate to keep disagreeing, but that also really doesn't matter. What matters is how fast it's going at contact, which is a direct result of how much it accelerates before contact.

-Andrew

 

[Jal]

Like followthrough, this only makes a difference to how accurate your stroke is - it doesn't matter to the CB whether the cue is accelerating, decelerating or neither, only what speed it's going at the moment (1/10,000 second) of contact.

pj
chgo

I agree with the latter half of your statement, but not sure about the first part.

Follow-through, being an indicator of what went on before contact, tends to be correlated with cue speed; not absolutely, but typically. I'm pretty sure that's what Andrew Manning was referring to earlier. Once the tip reaches the cueball, its speed already established, then, as you point out, it essentially doesn't matter to the cueball whether it's accelerating, cruising, or decelerating. But all else being equal, if it's cruising, it'll have more speed than if it's decelerating; and if it's accelerating, it'll have more speed than if it's cruising. Or, alternately, it takes less applied force to get it up to some particular speed when you shift toward the accelerating end of the spectrum.

From a purely physics point of view, the worst thing you can do in the cause of cue speed accuracy is to decelerate before impact. Final speed becomes more sensitive to several variables. (Not sure if that's what you meant by stroke accuracy.) Whether this is offset by some physiological advantage (e.g., better motor control), I couldn't say.

Jim

 

[dr_dave]

Good post!

Regards,
Dave

I agree with the latter half of your statement, but not sure about the first part.

Follow-through, being an indicator of what went on before contact, tends to be correlated with cue speed; not absolutely, but typically. I'm pretty sure that's what Andrew Manning was referring to earlier. Once the tip reaches the cueball, its speed already established, then, as you point out, it essentially doesn't matter to the cueball whether it's accelerating, cruising, or decelerating. But all else being equal, if it's cruising, it'll have more speed than if it's decelerating; and if it's accelerating, it'll have more speed than if it's cruising. Or, alternately, it takes less applied force to get it up to some particular speed when you shift toward the accelerating end of the spectrum.

From a purely physics point of view, the worst thing you can do in the cause of cue speed accuracy is to decelerate before impact. Final speed becomes more sensitive to several variables. (Not sure if that's what you meant by stroke accuracy.) Whether this is offset by some physiological advantage (e.g., better motor control), I couldn't say.

Jim

 

[Patrick Johnson]

From a purely physics point of view, the worst thing you can do in the cause of cue speed accuracy is to decelerate before impact.

Can you explain this in layman's terms? It seems you're saying decelerating is bad but accelerating isn't. Why would that be?

pj
chgo

 

[eldowan]

Can you explain this in layman's terms? It seems you're saying decelerating is bad but accelerating isn't. Why would that be?

pj
chgo

My shot in the dark:

When you are at the end of your back stroke, just before the forward stroke begins,you accelerate the cue until its maximum speed before impact with the cue ball (assuming hitting at cruising speed).

When you are decelerating before impact, you are making a change in which muscles are used and how. Some muscles may be let to go slack, some may work to forcefully slow the ball. This could introduce error because of an imbalance in force applied compared to what was going on during the initial stroke, before deceleration. So decelerating may cause your stroke to deviate from the intended path, hitting a spot you are not intending.

Aceleration, however, would imply that there is a constant and consistant use of muscle power for the duration of the stroke, just like hitting the ball with a constant speed, except that the cruising speed hasn't been reached yet (thus the acceleration at impact)

That was my initial gut reasoning to the question you are posting. I've been way wrong before, and it would supprise me if it wasn't to happen again. So take this explanation with the grain of salt it deserves, yadda yadda yadda.

 

[Ponytail]

My shot in the dark:

When you are at the end of your back stroke, just before the forward stroke begins,you accelerate the cue until its maximum speed before impact with the cue ball (assuming hitting at cruising speed).

When you are decelerating before impact, you are making a change in which muscles are used and how. Some muscles may be let to go slack, some may work to forcefully slow the ball. This could introduce error because of an imbalance in force applied compared to what was going on during the initial stroke, before deceleration. So decelerating may cause your stroke to deviate from the intended path, hitting a spot you are not intending.

Aceleration, however, would imply that there is a constant and consistant use of muscle power for the duration of the stroke, just like hitting the ball with a constant speed, except that the cruising speed hasn't been reached yet (thus the acceleration at impact)

That was my initial gut reasoning to the question you are posting. I've been way wrong before, and it would supprise me if it wasn't to happen again. So take this explanation with the grain of salt it deserves, yadda yadda yadda.

Sounds pretty close to me....

 

[Jal]

Can you explain this in layman's terms? It seems you're saying decelerating is bad but accelerating isn't. Why would that be?

pj
chgo

A few years ago I wrote a program that spit out the errors in cue speed resulting from unintended changes in this or that variable. Applying force up to and through impact ("accelerating through") resulted in the least variation in cue speed, as I recall, in all categories except for variations in bridge length and magnitude of peak force. (Errors from deviations in peak force magnitude were the same whether accelerating, cruising, or decelerating.) Some of the other variables were muscle timing (i.e., stretching or contracting the force function over time), grip position, backstroke length. Deceleration produced the largest errors.

This was not a sophisticated study of biomechanics. It didn't address how the overall shape of the force function (force versus time) might change as a result of different nerve signals being sent when we intentionally or unintentionally change this or that. It just manipulated an assumed force function, which in its unmanipulated state, seemed to be a reasonable representation gleaned from accelerometer data (Dr. Dave has them available at his site).

I'm not advocating "accelerating through " for your typical shot, just noting the results. It isn't as efficient, energy-wise, as "cruising through", which is the most efficient - but doesn't produce the most cue speed. Decelerating was the clear loser from this (simple physics) perspective.

The errors from bridge length variation, where cruising did better than accelerating, assumed the shooter didn't notice the variation and adjust muscle-timing accordingly. To the extent that a shooter does and can, accelerating may be better here too, as far as speed errors are concerned.

Jim