Gearing English Compensation - Thoughts & Questions

[Colin Colenso]

I would appreciate Dr. Dave's insights into my contemplations below, but thought I'd throw it out there for anyone who has an interest.

Dr. Dave has proposed a 40% rule / guide, whereby if we offset the tip by 40% of the distance from the center object ball to contact point, we create an amount of outside english which cancels out the Contact Induced Throw (CIT).

I'll include the diagram below and add further posts to give more information.

 

[Colin Colenso]

This 40% seems to be based on the graph below, posted in Dr. Dave's Billiard Digest article linked to here: http://billiards.colostate.edu/threads/English.html#outside

I wonder if Dave could define % english and describe or chart how tip offset is related to the actual amount of spin in terms of revolutions per second.

For most angles that we commonly play, say 5 to 40 degrees, the chart below is reasonably linear.

I also assume that this chart is for a sliding CB with OE.

 

[Colin Colenso]

With that introduction, let me posit a few questions, based on some trialing of this 40% system which tended to lead me to over-cutting most shots.

My first contention is that forward roll or draw on the CB may decrease the amount of tip offset required as it reduces the influence of CIT. This is presented in my diagrams attached below by a curved black line. I'm not married to this contention, but thought it worth considering.

My main contention is that I believe we learn to perceive a pot line that takes into account some throw, say for example the pot line required for a medium speed (CB up and down table length 3 times without hitting an OB speed), with natural follow.

To align for an angled pot this way, we have to aim a little thinner on the OB to allow for a little throw, compared to the Line-Of-Center (LOC) aim point.

I created the comparative charts below based on data provided for me by Dr. Dave.

The charts are for 3/4 ball hits (approx 15 degrees left to right cut) and the effect of various spins on the CB for a medium speed (as described above) shot.

The chart on the left compared throw to Line of Centers, and you can see that % English for 15 degree sliding shot corresponds to about 20% to achieve gearing english as Dave's graph above would suggest. Hence my suggestion that the chart is for sliding CB, not rolling CB.

The chart on the right represents throw comparison for a slightly thinner hit, which is the pot line for medium speed rolling follow. This shows about 14% Outside English is required for gearing english if we choose this thinner pot line as our starting point.

This would bring the 40% rule down to about a 30% rule, and if follow acts further reduce the offset requirement as I speculate, perhaps a 15-20% rule may be more effective.

 

[ENGLISH!]

Hi Colin,

I'll say that I don't bring a slide rule with me when I play pool.

I'll assume that the 40% is for when hitting on the equator of the ball. So, what about when hitting at 12:30 & 5:30 & all the locations in between? I understand that you would have to go farther out but how much farther? 47* or 58%?

Dr. Dave speaks technically while CJ Wiley speaks in terms like a bit & a touch.

I don't know about the rest of you but I'm not very good at consciously calculating percentages of millimeters & then executing a hit of 17.335 from center.

Nothing against Dr. Dave. I'm not bashing the knowledge. The info is good to know but I don't walk around making peace signs to the table for the 30* rule & I learned how the ball comes off before I ever heard it was 30* & learned from the good Dr. that the peace sign for most individuals is about 30*.

All that said, if any of that info. helps & speeds up one's development then it's a great thing for them & that's all that matters to them.

I've said it before that some play the game like athletes while others play it like intellectuals (not that one can't be both). The thing is that we almost have never seen a science intellectual playing at the top level, not even as hobby for them.

If the game is a sport, then it would seem that it is more conducive to be played by athletes than intellectuals. That said a bit pf smarts has always been good for an athlete to have.

I hope my points can be seen, understood, & not misunderstood.

Sorry for waxing long & perhaps a bit off the specific topic.

Ged Dey 2 Ya. & Best 2 All.
Rick

 

[Colin Colenso]

One more observation, before I leave you all alone to scratch your heads, is that my high speed throw plot, based on Dr. Dave's data shows a considerable reduction in % English required for gearing outside english, to half, at just 10% for a 15 degree cut.

The charts showed insignificant difference in gearing english requirements from slow to firm speeds. Firm being approx 4 table lengths of CB travel, say 14mph.

So on very firm shots, we may need to reduce our formula to a 15-20% rule.

 

[ENGLISH!]

Colin,

I now see that you have addressed some of my 'concerns' & inferred that we simply learn by the doing process.

Perhaps that is why athletes (even pro pool players) can not explain the whys & wherefores of what they just do.

Best 2 Ya...& All,
Rick

 

[Colin Colenso]

Hi Colin,

I'll say that I don't bring a slide rule with me when I play pool.

I'll assume that the 40% is for when hitting on the equator of the ball. So, what about when hitting at 12:30 & 5:30 & all the locations in between? I understand that you would have to go farther out but how much farther? 47* or 58%?

Dr. Dave speaks technically while CJ Wiley speaks in terms like a bit & a touch.

I don't know about the rest of you but I'm not very good at consciously calculating percentages of millimeters & then executing a hit of 17.335 from center.

Nothing against Dr. Dave. I'm not bashing the knowledge. The info is good to know but I don't walk around making peace signs to the table for the 30* rule & I learned how the ball comes off before I ever heard it was 30* & learned from the good Dr. that the peace sign for most individuals is about 30*.

All that said, if any of that info. helps & speeds up one's development then it's a great thing for them & that's all that matters to them.

I've said it before that some play the game like athletes while others play it like intellectuals (not that one can't be both). The thing is that we almost have never seen a science intellectual playing at the top level, not even as hobby for them.

If the game is a sport, then it would seem that it is more conducive to be played by athletes than intellectuals. That said a bit pf smarts has always been good for an athlete to have.

I hope my points can be seen, understood, & not misunderstood.

Sorry for waxing long & perhaps a bit off the specific topic.

Ged Dey 2 Ya. & Best 2 All.
Rick

Hi Rick,

I understand your points and accept that this type of inquiry and information may only be interesting to some and of significant useful value at the table for even less.

The variables at play and the effort required to implement them may provide an argument for a much more intuitive approach to learning to play using english at the various angles, speeds and so on.

Since adapting BHE, while my Inside English has improved 100%, my application of Outside English has improved little. Part of the reason for this is that we know that in most cases, small changes in % outside english leads to significant cut angle change compared to similar changes in % Inside English.

I'm hoping to narrow down the variables and find a more predictable method of applying OE, based on a clear understanding of the physical principles involved.

I don't think it's too hard to estimate cut angles of say 5,10,15,20,30,45,60 and memorize the required tip offsets for these angle regions at 2mm, 4mm, 6mm, 8mm, 10mm, full tip and tip + 2mm. (That is just rough math btw.)

[Edit]: Added thought: The question remains, that if I get the math right, will I be able to apply it accurately enough to produce significant improvements in my use of OE.

Colin

 

[ENGLISH!]

Hi Rick,

I understand your points and accept that this type of inquiry and information may only be interesting to some and of significant useful value at the table for even less.

The variables at play and the effort required to implement them may provide an argument for a much more intuitive approach to learning to play using english at the various angles, speeds and so on.

Since adapting BHE, while my Inside English has improved 100%, my application of Outside English has improved little. Part of the reason for this is that we know that in most cases, small changes in % outside english leads to significant cut angle change compared to similar changes in % Inside English.

I'm hoping to narrow down the variables and find a more predictable method of applying OE, based on a clear understanding of the physical principles involved.

I don't think it's too hard to estimate cut angles of say 5,10,15,20,30,45,60 and memorize the required tip offsets for these angle regions at 2mm, 4mm, 6mm, 8mm, 10mm, full tip and tip + 2mm. (That is just rough math btw.)

[Edit]: Added thought: The question remains, that if I get the math right, will I be able to apply it accurately enough to produce significant improvements in my use of OE.

Colin

Colin,

Your last statement (edit) is where the rubber meets the road.

I'd just rather trust my subconscious mind to handle that kind of stuff than I would my math skills & then my body to do what my conscious mind is telling it when my subconscious mind knows that my conscious mind has made an error or that the program has a flaw.

Best 2 You & Good Luck with the Project,
Rick

PS I hope the outcome is worth the effort. I kind of lean to the beat of the efficiency end. Sort of like, why move a dozen logs over there when I can just move 3 over here.

 

[hboat333]

I have always been amazed by how much english affects cut angles (SIT). I used to use lots of outside english and still have a propensity to overcut shots due to what I call a 'spin out'. For me, I seem to have better accuracy by using a small amount of low inside english. Except for very full shots (where the inside dramatically changes the cut angle), I believe that any amount of spin breaks the cling of stun action and reduces the amount of CIT. Am I the only one who took years to learn to aim fuller when using draw? I strongly agree w/ Jewett and urge everyone to reference his '06 BD article, 'Where's The Rub' found on this page; http://www.sfbilliards.com/articles/2006.pdf

And, do some players really do a calculation of cut angle to dictate tip offset as a percentage? Sheesh, I just learned that I'm too stoopid to play pool.

 

[Patrick Johnson]

Except for very full shots (where the inside dramatically changes the cut angle), I believe that any amount of spin breaks the cling of stun action and reduces the amount of CIT.

From straight on to half ball cut it's a sliding scale: 1/2 maximum spin produces the most throw for straight shots - no side spin produces the most throw for half ball shots (assuming stun in both cases) - something between 1/2 max & none for shots in between.

pj
chgo

 

[Colin Colenso]

I have always been amazed by how much english affects cut angles (SIT). I used to use lots of outside english and still have a propensity to overcut shots due to what I call a 'spin out'. For me, I seem to have better accuracy by using a small amount of low inside english. Except for very full shots (where the inside dramatically changes the cut angle), I believe that any amount of spin breaks the cling of stun action and reduces the amount of CIT. Am I the only one who took years to learn to aim fuller when using draw? I strongly agree w/ Jewett and urge everyone to reference his '06 BD article, 'Where's The Rub' found on this page; http://www.sfbilliards.com/articles/2006.pdf

And, do some players really do a calculation of cut angle to dictate tip offset as a percentage? Sheesh, I just learned that I'm too stoopid to play pool.

That's kind of where the rubber meets the road, as Rick suggested above.

Like you I've pretty much learned to use less outside, rarely going more than 1/4 tip.

The exceptions are firm straightish shots with follow or draw, where the throw actually diminishes to some degree with more offset (% english). Also, for attempts at fine cuts sometimes. Otherwise I avoid heavy outside english unless position demands it.

I haven't done much measuring as described above and this is probably why I am not too sure most the time, if my misses are caused by poor alignment or not enough or too much outside english.

For my inside english shots, I can identify the cause much more readily, be it speed or alignment.

 

[Colin Colenso]

From straight on to half ball cut it's a sliding scale: 1/2 maximum spin produces the most throw for straight shots - no side spin produces the most throw for half ball shots (assuming stun in both cases) - something between 1/2 max & none for shots in between.

pj
chgo

Very good point Patrick!

The main exception, according to my charts is for very slow hits, as shown in the top left chart below. Most common shots will fall into the 50% range you mentioned.

The charts below indicate a 7/8th (approx 7 degree) left to right cut shot played from very slow (top left) to very hard (bottom right). The right side of the charts indicates outside english. Most have maximum throw at around 50% outside english, except for the very slow shot which has more throw with more outside english up to about 80%. For very hard shots, the throw effect maxes out at about 35%, then decreases with more outside.

Note that each color band represents 1 inch per yard of throw. So a very slow 7 degree cut can be deviated left by about 5 inches over 1 yard with 80% OE and if hit with 60% IE, it will deviate about 4 inches per yard to the right of aim.

 

[Colin Colenso]

Note: I did not intend to discount the veracity of Dr. Dave's 40% rule, but to seek out more information on the variables and to establish practical protocols for its implementation, taking into account aiming methods.

As I attempt to align for a slight overcut from the LOC, I should have more success with less offset. By contrast, many have a tendency to align to undercut, in which case more offset may provide them greater success, with regard to pocketing balls, not with achieving perfect gearing english.

Colin

 

[dr_dave]

I would appreciate Dr. Dave's insights into my contemplations below, but thought I'd throw it out there for anyone who has an interest.

Dr. Dave has proposed a 40% rule / guide, whereby if we offset the tip by 40% of the distance from the center object ball to contact point, we create an amount of outside english which cancels out the Contact Induced Throw (CIT).

I'll include the diagram below and add further posts to give more information.

For those interested, much more information on this topic can be found on the outside english resource page.

Here's a video demonstrating how the technique is applied at the table:
NV E.3 - Using "Gearing" Outside English to Eliminate Throw, from HAPS I

Regards,
Dave

 

[dr_dave]

This 40% seems to be based on the graph below, posted in Dr. Dave's Billiard Digest article linked to here: http://billiards.colostate.edu/threads/English.html#outside

The graph is less useful than the visual interpretation of rule, which is much easier to apply at the table. The 40% rule is based on the fairly simple physics documented in: TP A.26 - The amount of sidespin required for "gearing" outside english.

I wonder if Dave could define % english and describe or chart how tip offset is related to the actual amount of spin in terms of revolutions per second.

"Percentage english" is defined and illustrated in detail on the percentage english resource page. Percentage english is an alternative to "tips of english" to describe where the tip contact point is between center ball (0%) and the miscue limit (100%). The relationships among tip offset, percentage english, and cue ball spin can be found here:

TP A.12 - The relationship between cue ball spin and cue tip offset
TP A.25 - The relationship between spin-rate-factor and percent-english

For most angles that we commonly play, say 5 to 40 degrees, the chart ... is reasonably linear.

Agreed, but the 40% rule is exact at all angles, so there is no need to limit things to a linear range.

I also assume that this chart is for a sliding CB with OE.

That's correct. It also applies to immediate-roll follow shots. When significant drag is involved (e.g., with draw shots or center-ball hits at long distance and/or slow speed), things become much more complicated. CB drag increased the effective amount of sidespin. For more info, see the drag shot effects resource page. So when attempting to get gearing outside english (and no throw) with a drag shot, you need to use less tip offset than the 40% rule suggests. This would obviously require some judgement based on conditions and shot speed.

Regards,
Dave

 

[dr_dave]

With that introduction, let me posit a few questions, based on some trialing of this 40% system which tended to lead me to over-cutting most shots.

Several factors can result in overcuting:

1.) You might be aiming instinctively to compensate for throw a little (i.e., you might be targeting a GB position slightly on the thin side of the ideal line-of-centers GB aim).

2.) You might not be judging the actual tip contact point on the ball accurately due to the curvature of the tip and the curvature of the ball (with draw/follow shots) or due to the difficulty of judging the 40% offset.

3.) With drag shots, especially over larger distances and/or slower speeds, the effective amount of sidespin is greater, so you need to aim at less than 40%. For more info, see the gearing outside english and drag effects resource pages.

4.) You might not be compensating for squirt and swerve perfectly (i.e., the CB might not be arriving exactly at the desired GB position).

Regards,
Dave

 

[dr_dave]

my high speed throw plot, based on Dr. Dave's data shows a considerable reduction in % English required for gearing outside english, to half, at just 10% for a 15 degree cut.

Again, this could be due to any of the factors I just listed.

I think the most likely factor is the greater net CB deflection associated with fast-speed shots. There will be very little swerve at fast speed, so squirt will be the dominant factor. As you know, the throw equations and plots don't take squirt and swerve into consideration.

Are you using pure BHE with a fixed bridge pivot? If so, are you varying bridge length appropriately to account for how squirt and swerve vary with various shot parameters (speed, spin, distance) and table conditions?

Catch you later,
Dave

 

[dr_dave]

... I believe that any amount of spin breaks the cling of stun action and reduces the amount of CIT. ...

That is a good belief to have, because it is true!

CIT is definitely maximum for stun shots, especially at slower speed. Both topspin and bottom reduce CIT. For more info, see throw draw and follow effects (which includes links to several related articles, including Bob's) and maximum throw.

Regards,
Dave

 

[Colin Colenso]

Again, this could be due to any of the factors I just listed.

I think the most likely factor is the greater net CB deflection associated with fast-speed shots. There will be very little swerve at fast speed, so squirt will be the dominant factor. As you know, the throw equations and plots don't take squirt and swerve into consideration.

Are you using pure BHE with a fixed bridge pivot? If so, are you varying bridge length appropriately to account for how squirt and swerve vary with various shot parameters (speed, spin, distance) and table conditions?

Catch you later,
Dave

Hi Dave,
Thanks for the feedback! I'll study all those links to try to fill in a few gaps.

When using BHE, where swerve becomes a factor due to a combination of increased distance and lower speeds, I employ what I've referred to as an 'Effective Pivot Point', which is longer than a cue's natural pivot point.

It's a little bit of a guessing game, as table conditions vary considerably....but that is and has always been a challenge for anyone using english over distance and at lower speeds.
I haven't got my head completely around the math, but looking at my line of center throw charts, it suggests that a component of follow or draw may not affect the 40% rule. Would you contend this is right, ignoring any swerve effects such shots may bring into play?

Note: As I've mainly studied my throw charts that use slight over cutting as a reference, an exact symmetry doesn't appear, but this subject has got me looking at the LOC reference charts more closely.

Colin

 

[ENGLISH!]

Note: I did not intend to discount the veracity of Dr. Dave's 40% rule, but to seek out more information on the variables and to establish practical protocols for its implementation, taking into account aiming methods.

As I attempt to align for a slight overcut from the LOC, I should have more success with less offset. By contrast, many have a tendency to align to undercut, in which case more offset may provide them greater success, with regard to pocketing balls, not with achieving perfect gearing english.

Colin

Hi Colin,

Your last statement is how I learned to play growing up in my teens. It allows a more full hit between the CB & OB. It's sort of the reverse of TOI with the 3 part pocket system, but with different CB outcomes.

Best 2 Ya & All,
Rick