Break accuracy v. speed - please quantify

[C.Milian]

I don't think it's a matter of hitting the one ball as much as it is hitting it in a exact spot that is the issue, ( center ball).

As long as your enjoying what you are doing that's all that really matters. You enjoy hitting them hard and I enjoy hitting them accurately so that I can keep shooting.

Thing is...I believe my hit on the cue ball will be better 6 months from now so my accuracy on the break shot will inevitably increase. I don't think holding back on the force I'm able to put behind it, will help with accuracy all that much. I guess sometimes the cueball with get loose but not often enough to really matter.
If you watch some of the monster breakers, they're already behind that cue ball exactly where they need to be to send it straight at the one. Once they are zoned in, there is so much power behind their break I don't think it matters if they are slightly off.
Some people advise looking at the cue ball last on the break shot, but the cue ball is so huge you don't need to fixate on it( maybe there is more to it) . At least I don't. My entire focus is on the one ball and sometimes the stack and how hard I want to drive the cue ball at it.
Bustamante and Alex are two I have observed that does not hold back either. Shane looks like he uses a little more of a controlled break, but I'm not too sure. I don't play much ten ball so I don't know if controlled is better than power for that particular break.

 

[derangedhermit]

That is the reason why I square the cosine in my formula, to get the force component that is in the same direction as the CB's pre-contact direction.

So my table would be...

.9 => .99
.7 => .91
.5 => .75
.3 => .51
.1 => .19

If you are trying to pocket a ball at random and have a nice spread, is it more important to be moving the balls toward the foot rail (what you are calculating) or moving the balls in any direction (what Jal is calculating)? At first I thought "any direction" is the right answer, but you get some nasty clusters if you go too far that way.

Given both tables, I would say the following rule is true: "If you keep the cue ball from hitting a rail, that tells you that you are putting almost all the energy possible into the object balls." That is, the accuracy requirement for keeping the cue ball in the middle of the table is tougher than the accuracy requirement for a high energy transfer.

 

[Cdryden]

Thing is...I believe my hit on the cue ball will be better 6 months from now so my accuracy on the break shot will inevitably increase. I don't think holding back on the force I'm able to put behind it, will help with accuracy all that much. I guess sometimes the cueball with get loose but not often enough to really matter.
If you watch some of the monster breakers, they're already behind that cue ball exactly where they need to be to send it straight at the one. Once they are zoned in, there is so much power behind their break I don't think it matters if they are slightly off.
Some people advise looking at the cue ball last on the break shot, but the cue ball is so huge you don't need to fixate on it( maybe there is more to it) . At least I don't. My entire focus is on the one ball and sometimes the stack and how hard I want to drive the cue ball at it.
Bustamante and Alex are two I have observed that does not hold back either. Shane looks like he uses a little more of a controlled break, but I'm not too sure. I don't play much ten ball so I don't know if controlled is better than power for that particular break.

Good points, but I think the pro's have already reached a degree of accuracy where they are able to crank up the power and maintain accuracy. I have not. In fact I would bet that most of us who think they have in fact haven't.
I guess I look at it the opposite way, the more power you use the more it amplifies inaccuracies. I think of it like the golf swing, if you focus on good fundamentals and mechanics you will achieve power. But if you focus on power you will loose accuracy and shank the ball.

I may be wrong, who knows, but so far I have had allot of success this way. The only way I can quantify break speed vs accuracy is by my results. Which have been pretty good thus far. For me accuracy will always trump power.

 

[joelpope]

Thank you very much.:thumbup: I do break with an LD shaft, to reduce cue ball squirt. Beyond that, I haven't focused enough on the cue <-> cue ball contact point. Missiing a dead-center hit may be caused as much or more by hitting the cue ball off center as by aim line. I'll get some impact tape and spend some practice time in discovery. I think I'll put a square on the 1-ball as well as the cue ball. I hope it's thin enough so the cue ball stays on the table.

You will be surprised

You can pick up a cue with a crosshatch on it, just mark the top of the hatch for reference. It is amazing how your body moves the cue on the break stroke. I know of one top pro who has to aim a tip and a half below center and a half tip to the right in order to deliver the cue tip to the exact center of the cue ball. It's just the way his body reacts on the extreme stroke. It solved the problem making that adjustment.

I have to aim almost two tip below center to hit center ball as I tend to come up on the power stroke

 

[jsp]

If you are trying to pocket a ball at random and have a nice spread, is it more important to be moving the balls toward the foot rail (what you are calculating) or moving the balls in any direction (what Jal is calculating)? At first I thought "any direction" is the right answer, but you get some nasty clusters if you go too far that way.

Not sure I understand you here.

Given both tables, I would say the following rule is true: "If you keep the cue ball from hitting a rail, that tells you that you are putting almost all the energy possible into the object balls."

Yeah, I would say that's a pretty good rule.

That is, the accuracy requirement for keeping the cue ball in the middle of the table is tougher than the accuracy requirement for a high energy transfer.

But they go hand in hand, just as you said in your previous statement. Keeping the CB in the middle of the table (neglecting backspin/topspin and getting kicked) means you have a high energy transfer.

 

[dr_dave]

If you consider only the total energy transfer between cue ball and the rack of balls (9, 10, or 15 - I think it makes no difference), what does the trade-off look like between cue ball speed and off-center hits?

I'm trying to get a feel for how accurate you need to be. For example, will being off center 1/16" (1.6mm) cost the equivalent energy of 1 mph lower cue ball speed? How about 1/4"? I guess the relevant speed range is about 18-25mph.

Assume a tight rack (all balls touching). I think, based on intuition, the energy drop off increases non-linearly as the contact point moves further away from a center hit.

A graph would be outstanding!:grin:

I don't have a graph; but anecdotally, it is obvious that the penalty for a non-square hit is huge (and very nonlinear).

That why people always say: "Only use as much power as you can control." ... because being inaccurate with the hit hurts you more than the added power can help.

Regards,
Dave

 

[Cdryden]

.

That why people always say: "Only use as much power as you can control." ... because being inaccurate with the hit hurts you more than the added power can help.

Regards,
Dave

Excellent reply! This is what I was trying to say in a nutshell.

 

[derangedhermit]

I don't have a graph; but anecdotally, it is obvious that the penalty for a non-square hit is huge (and very nonlinear).

That why people always say: "Only use as much power as you can control." ... because being inaccurate with the hit hurts you more than the added power can help.

Regards,
Dave

I'm glad you chimed in. But from what I have read above, the cue ball can be 1/4" off dead center at impact and still transfer 99%, and almost 1/2" off, and still transfer 95%. That's a lot more room for error than I would have guessed, and that's why I said keeping the cue ball off a rail is the tougher requirement on accuracy, and an easy check to see that you are plenty accurate enough.

 

[joelpope]

I'm glad you chimed in. But from what I have read above, the cue ball can be 1/4" off dead center at impact and still transfer 99%, and almost 1/2" off, and still transfer 95%. That's a lot more room for error than I would have guessed, and that's why I said keeping the cue ball off a rail is the tougher requirement on accuracy, and an easy check to see that you are plenty accurate enough.

I don't agree with those stats

I have heard that every one degree off center is a five percent loss, obviously the math doesn't work to zero but I believe it is a more rapid decline than the posted numbers

More important, you lose the cue ball on an of center hit

 

[Cdryden]

I'm glad you chimed in. But from what I have read above, the cue ball can be 1/4" off dead center at impact and still transfer 99%, and almost 1/2" off, and still transfer 95%. That's a lot more room for error than I would have guessed, and that's why I said keeping the cue ball off a rail is the tougher requirement on accuracy, and an easy check to see that you are plenty accurate enough.

I don't know if that much is really transferred or not but I would be more concerned with what will happen to the CB when you are 1/2 inch off the head ball, especially with full power.

 

[dr_dave]

Off topic here, but didnt Dr. Dave run deflection tests and determine that speed does not effect deflection?

That is correct. Speed does not affect squirt (AKA cue ball deflection). Proof can be found here:

squirt speed effects resource page​

However, speed (and conditions and cue elevation) has a huge effect on swerve. But with a break shot (at very fast speed), swerve is not a significant factor. That's why using a cue with a natural pivot length well matched to your preferred break bridge length can create a huge advantage. The squirt created by stroking errors will exactly cancel the stroking errors; so if your initial aim is good, the hit will be square regardless of how non-straight your stroke might be (assuming you don't miscue). More info, and demonstrations can be found here:

break technique and equipment advice​

Regards,
Dave

 

[derangedhermit]

Not sure I understand you here.

Jal's formula/table is technically correct, but it's rather misleading because it calculates the magnitude of the force in the direction through the center of the one ball from the contact point. So for a 10% hit, it is true that about 44% of the CB's initial momentum (magnitude) gets transferred to the one ball, but for a 10% hit the contact point is almost completely on the side of the one ball and the direction of the force is almost completely sideways. Compare that to the force if the direction is oriented straight through the rack.

That is the reason why I square the cosine in my formula, to get the force component that is in the same direction as the CB's pre-contact direction.

Leave the rack on and break from the head spot. You show how far the entire rack will move towards the foot rail. Jal shows the total distance the entire rack will move in any direction. Right? My question is, which of these is more useful when looking at the chances of pocketing a random ball and getting a nice spread. It's not clear to me that your method is more enlightening. I suspect the best model might be somewhere between the two.

 

[dr_dave]

... from what I have read above, the cue ball can be 1/4" off dead center at impact and still transfer 99%, and almost 1/2" off, and still transfer 95%.

I don't believe those numbers at all. I would need to see very convincing theoretical or experimental proof before I would. I suspect the numbers would be more like: 100% transfer with no error (and CB stun), 95% transfer with 1/16" error, 90% transfer with 1/8" error, 75% transfer with 1/4" error, 50% transfer with 1/2" error, etc. (but I don't have scientific proof).

Regards,
Dave

 

[Cdryden]

I don't believe those numbers at all. I would need to see very convincing theoretical or experimental proof before I would. I suspect the numbers would be more like: 100% transfer with no error (and CB stun), 95% transfer with 1/16" error, 90% transfer with 1/8" error, 75% transfer with 1/4" error, 50% transfer with 1/2" error, etc. (but I don't have scientific proof).

Regards,
Dave

These numbers sound a little more realistic to me, but I would expect it to be even worse at a 1/2 inch.

 

[Bob Jewett]

I don't know if that much is really transferred or not but I would be more concerned with what will happen to the CB when you are 1/2 inch off the head ball, especially with full power.

Yes. If the cue ball does not have enough speed left to get to a cushion, it is less likely to scratch.

 

[alstl]

9 ball break is a different animal, can't compare to 10 or 15. With 10 or 15 balls I get best results hitting hit hard and making solid contact. That's assuming you aren't gimmicking the rack. If you are a rack mechanic then you produce different results.

 

[dr_dave]

These numbers sound a little more realistic to me, but I would expect it to be even worse at a 1/2 inch.

I could easily agree with that, even without proof.

Regards,
Dave

 

[Bob Jewett]

To look at the original question slightly differently, just consider the energy transfer from the cue ball to a single ball. The nature of that is not going to be much different from hitting a full rack. This simpler problem was solved a long time ago:

The velocity of the object ball is proportional to the cosine of the cut angle and the velocity remaining on the cue ball is proportional to the sine of the cut angle. What we are mostly interested in is energy transfer, and energy is proportional to the square of the velocity. Here is a table for various cases:


So for a 15-degree cut (about a 3/4-full hit) 93% of the energy is transferred into the object ball leaving 7% on the cue ball.

In fact the transfer of energy into a single ball is more efficient than into the rack as you can see by the fact that the cue ball bounces back after hitting a full rack -- it takes some energy away when it bounces back.

 

[derangedhermit]

I don't believe those numbers at all. I would need to see very convincing theoretical or experimental proof before I would. I suspect the numbers would be more like: 100% transfer with no error (and CB stun), 95% transfer with 1/16" error, 90% transfer with 1/8" error, 75% transfer with 1/4" error, 50% transfer with 1/2" error, etc. (but I don't have scientific proof).

Regards,
Dave

Well, I took them from Jal's table:
.9 ball hit = .99 of full head on force
.7 = .95
.5 = .87
.3 = .71
.1 = .44
and jsp's table:
.9 => .99
.7 => .91
.5 => .75
.3 => .51
.1 => .19

If .1 ball = .225 inches:
99% is .9 balls, about a quarter inch
95% is between .7 and .8 balls, or between 0.45 and 0.675 inches.

jsp pointed to the logic and math behind. It doesn't match my intuition either, but there is enough description to say where they are going off track, if indeed they are.

I gotta go practice. Later!

 

[Cdryden]

To look at the original question slightly differently, just consider the energy transfer from the cue ball to a single ball. The nature of that is not going to be much different from hitting a full rack. This simpler problem was solved a long time ago:

The velocity of the object ball is proportional to the cosine of the cut angle and the velocity remaining on the cue ball is proportional to the sine of the cut angle. What we are mostly interested in is energy transfer, and energy is proportional to the square of the velocity. Here is a table for various cases:

View attachment 209055
So for a 15-degree cut (about a 3/4-full hit) 93% of the energy is transferred into the object ball leaving 7% on the cue ball.

In fact the transfer of energy into a single ball is more efficient than into the rack as you can see by the fact that the cue ball bounces back after hitting a full rack -- it takes some energy away when it bounces back.

I haven't really grasped this chart yet but one thing I wanted to mentioned in regards to accuracy vs power is that most people don't realize that the CB is often airborne when it strikes the head ball in a power break. Not always, but more so with beginners. So when I say "off center" I mean vertically as well as horizontally.

I'm sure most know this but it is worth mentioning when discussing a power break. The harder you hit it the more likely it is that the CB will become airborne.