Table Difficulty Factor (TDF) for measuring table "toughness"

Sloppy Pockets

AzB Silver Member
Silver Member
I modified the rails (per RKC specs) and installed Artemis cushions on my red labeled
Diamond Professional, bringing it up to the blue label specs. Cloth is Simonis 760.

50x100 = 1.00 TSF, 4 1/2 = 1.00 PSF, 5/8 = 1.02 PAF, 1 3/4 = 1.03 PLF = 1.05 TDF

All measurements done in Autocad, at 1 to 1 scale. Measuring on the table was too difficult.


Very nice! Yes, as some of us have been saying all along, measuring the table itself is "fraught with peril". I had to redo mine as explained below. IMO both your photo and your method of measurement should be included on Dr. Dave's resource page as a guide to accurately measuring pockets. FWIW I think you should also consider using the software to show the actual facing angle, and/or show a measurement of the cushion width.

After Cigar Dave mentioned that his cushions are 2 1/8" wide (which is 1/8" wider than "typical"), I got to thinking that I hadn't bothered with mine when I reported my measurements. Turns out they are only 1 7/8" wide. This explains why I got an actual facing angle of 144º when measured very carefully with a sliding bevel and protractor, when in theory I should only have an angle of 143º with the 1" difference between mouth and throat measurements.

I took some masking tape and extended the lines of the facing. Then I placed pieces 1/8" (eyeballed only) outside the seam between the rail and the cloth. You can see in the photo that the distance measured across the intersections of these two new sets of lines is really 3 7/8" instead of the 4" I reported earlier. This is a 1 1/8" difference, or 9º more open than 135º, which comes out to the same 144º that I measured with the bevel and protractor.

In other words, the difference between pocket mouth and throat measurements is absolutely meaningless unless it can somehow accurately provide the actual facing angles that are of interest for determining the PAF.
 

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Sloppy Pockets

AzB Silver Member
Silver Member
Dr. Dave, my new TDF is 1.03, based upon:

TSF = 8'+ = 0.95
PSF = 5" = 0.95
PAF = 1 1/8" (144º) = 1.14
PSF = 1 3/4" = 1.00
 

cigardave

Who's got a light?
Silver Member
Dr. Dave, my new TDF is 1.03, based upon:

TSF = 8'+ = 0.95
PSF = 5" = 0.95
PAF = 1 1/8" (144º) = 1.14
PSF = 1 3/4" = 1.00
SP - Based on your photo, it appears to me that the masking tape that you laid along the face of the subrails is off a bit... perhaps close to 1/8" where we can see the top of the red/brown subrails.

Is that what you intended?
 

Sloppy Pockets

AzB Silver Member
Silver Member
SP - Based on your photo, it appears to me that the masking tape that you laid along the face of the subrails is off a bit... perhaps close to 1/8" where we can see the top of the red/brown subrails.

Is that what you intended?

Yes, that's exactly what I intended.

Varying cushion widths will give different results when using Dr. Dave's method to arrive at a PAF. It would have been pretty easy to lay it right along the seam, but what I did brought the combined width of the cushion + rail to 2" instead of 1 7/8".

On my table, the cushions could be 12" wide, at which point they would converge to a point at the back of the (extremely deep) pocket. That would give a PAF of 5.0 according to Dr. Dave's method, but the pocket facing angle itself would remain 144º at all points along the facing.

It is the angle itself that is needed for an accurate assessment of the difficulty factor presented by the PAF. You can't just fudge this stuff, these little 1/8" difference are huge as the apply to the angles in real life.
 

JC

Coos Cues
How about a second parallel PAF table for those with the technology to measure the actual pocket angle? The table will have the exact relation to the theoretical yet hard to measure throat angle comparison for the purpose of overall TDF. That way those who can do so will have a more precise total and those who can't measure the angle will have a "close as they can measure" assessment. It could be notated which method was used. Both total end numbers would theoretically be the same if the ruler guy did all his measurements right. The angle measure person would be of course more precise. I know Dave said he want's to use only a ruler but this topic seems to be crying out for more precision. Again, an angle gauge can be bought from Harbor Freight for three and a half dollars for those inquiring minds with an income.

JC
 

Sloppy Pockets

AzB Silver Member
Silver Member
How about a second parallel PAF table for those with the technology to measure the actual pocket angle? The table will have the exact relation to the theoretical yet hard to measure throat angle comparison for the purpose of overall TDF. That way those who can do so will have a more precise total and those who can't measure the angle will have a "close as they can measure" assessment. It could be notated which method was used. Both total end numbers would theoretically be the same if the ruler guy did all his measurements right. The angle measure person would be of course more precise. I know Dave said he want's to use only a ruler but this topic seems to be crying out for more precision. Again, an angle gauge can be bought from Harbor Freight for three and a half dollars for those inquiring minds with an income.

JC

Let's just nominate Oldschool to accept photos of peoples pockets and measure them in AutoCad.:thumbup:

BTW I was driving past my local HF yesterday and picked up one of those contraptions. They work great, giving me the same angle that I got using the sliding bevel and protractor. At this point I'm considering buying several dozen and just sending them to everyone interested in the topic. At $3.49 apiece I'd be way ahead of the game instead of trying to figure out how the average Joe can get the correct angles using just a single ruler.;)
 

oldschool1478

AzB Silver Member
Silver Member
No promises but......
Here is SloMoHolic's Pocket Photo.
Would be be more accurate if taken parallel to slate over shelf.
 

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dr_dave

Instructional Author
Gold Member
Silver Member
I modified the rails (per RKC specs) and installed Artemis cushions on my red labeled
Diamond Professional, bringing it up to the blue label specs. Cloth is Simonis 760.

50x100 = 1.00 TSF, 4 1/2 = 1.00 PSF, 5/8 = 1.02 PAF, 1 3/4 = 1.03 PLF = 1.05 TDF

All measurements done in Autocad, at 1 to 1 scale. Measuring on the table was too difficult.
Nice job with the Autocad measurements!

I get the following instead:

oldschool1478 -- 9':1.00 -- 4 1/2":1.00 -- 5/8":1.00 -- 1 3/4:1.00 -- 1.00

Please double check your numbers and let me know if I've made an error.

Thanks for posting,
Dave
 

dr_dave

Instructional Author
Gold Member
Silver Member
Just for the sake of comparison...

I have a Diamond Pro 9' table (red label rails). It was purchased new, directly from Diamond in 2005. The cloth has never been replaced, and the rails have never been disassembled since the initial installation.

I remeasured my pockets using the post-it note method and a couple of rulers. The throat on my table is right between your measurements, and it looks like my rails extend to just inside the leather:

View attachment 282904

Here are my updated measurements:
Mouth: 4.5"
Throat: 3.625"
Shelf: 1.375" (to the start of the slate radius)
Shelf: 1.4375" (to the edge of the slate)

TDF = 1.02

I hope this helps!

-Blake
Thanks for the new numbers. I've updated your entry.

Regards,
Dave
 

dr_dave

Instructional Author
Gold Member
Silver Member
Dr. Dave, my new TDF is 1.03, based upon:

TSF = 8'+ = 0.95
PSF = 5" = 0.95
PAF = 1 1/8" (144º) = 1.14
PSF = 1 3/4" = 1.00
Thanks for the update. Here's the latest:

Data reported by AZB users in table difficulty factor (TDF) order, based on the table size factor (TSF), pocket size factor (PSF), pocket angle factor (PAF), and pocket shelf factor (PLF):

name -- TSF -- PSF -- PAF -- PLF -- TDF
tough 10' table -- 10':1.10 -- 4":1.15 -- 3/4":1.02 -- 1 7/8":1.03 -- 1.33
MahnaMahna -- 10':1.10 -- 5 1/2":0.85 -- 2":1.15 -- 2 1/2": 1.15 -- 1.24
dr_dave example "B" -- 9':1.00 -- 3 7/8":1.20 -- 5/8":1.00 -- 1 7/8":1.03 -- 1.24
Bonus Ball -- 9':1.00 -- 3 7/8":1.20 -- 1/8":0.97 -- 3/4":0.98 -- 1.14 (Bonus Ball table)
rexus31 -- 9':1.00 -- 4":1.15 -- 3/8":0.98 -- 1":0.98 -- 1.10
Qaddiction -- 9':1.00 -- 4 1/8":1.10 -- 3/4":1.02 -- 1 3/8":0.99 -- 1.11
FatBoy -- 9':1.00 -- 4":1.15 -- 1/4":0.97 -- 1":0.98 -- 1.09
TATE -- 9':1.00 -- 4":1.15 -- 1/4":0.97 -- 7/8":0.98 -- 1.09
cigardave -- 9':1.00 -- 4 1/2":1.00 -- 1":1.08 -- 1 3/4":1.00 -- 1.08 (typical Pro-Cut Diamond)
Sloppy Pockets -- 8'+:0.95 -- 5":0.95 -- 1 1/8":1.14 -- 1 3/4":1.00 -- 1.03
SloMoHolic -- 9':1.00 -- 4 1/2":1.00 -- 7/8":1.04 -- 1 3/8":0.98 -- 1.02
dzcues Gandy Big G -- 9':1.00 -- 5":0.95 -- 15/16":1.08 -- 1 1/2":0.98 -- 1.01
dzcues -- 9':1.00 -- 4 3/4":0.98 -- 5/8":1.00 -- 1 7/8":1.02 -- 1.00 (typical League-Cut Diamond)
"standard" table -- 9':1.00 -- 4 7/16":1.00 -- 9/16":1.00 -- 1 5/8":1.00 -- 1.00 ("standard")
oldschool1478 -- 9':1.00 -- 4 1/2":1.00 -- 5/8":1.00 -- 1 3/4:1.00 -- 1.00
mamics -- 9':1.00 -- 4 5/8":0.98 -- 13/16":1.04 -- 1 1/4":0.95 -- 0.97
JC -- 9':1.00 -- 4 7/16":0.98 -- 9/16":1.00 -- 1 3/8":0.98 -- 0.96
12squared -- 9':1.00 -- 4 7/8":0.95 -- 3/4":1.02 -- 1 1/2":0.98 -- 0.95 (typical Gold Crown)
rexus31 friend GC -- 9':1.00 -- 4 1/4":1.05 -- 1/4":0.95 -- 15/16":0.95 -- 0.95
Neil -- 7':0.85 -- 4 1/8":1.10 -- 5/8":1.00 -- 1 3/8":0.99 -- 0.93
iusedtoberich -- 9':1.00 -- 5 1/8":0.90 -- 1":1.06 -- 1 1/2":0.98 -- 0.93 ("loose" GC)
MSchaffer -- 9":1.00 -- 5 1/10":0.90 -- 3/4":1.02 -- 1 3/4":1.00 -- 0.92
SloMoHolic league table -- 8':0.90 -- 4 3/4":0.98 -- 3/4":1.02 -- 1 5/8":1.00 -- 0.90
BRussell -- 8':0.90 -- 5":0.95 -- 13/16":1.04 -- 1 1/2":0.98 -- 0.87
Dopc -- 8':0.90 -- 4 1/2":1.00 -- 3/4":1.02 -- 1 1/4":0.95 -- 0.87
dr_dave -- 8':0.90 -- 4 3/4":0.98 -- 5/8":1.00 -- 1 3/8":0.98 -- 0.86
dr_dave example "A" -- 8':0.90 -- 5":0.95 -- 1/2":0.98 -- 1 3/8":0.98 -- 0.82
Mooneye -- 7':0.85 -- 4 3/4":0.98 -- 3/4":1.02 -- 1 1/2":0.97 -- 0.82
dzcues Valley "bar box" -- 7':0.85 -- 4 1/2":1.00 -- 0":0.94 -- 1/2":0.95 -- 0.76
dr_dave Valley "bar box" -- 7':0.85 -- 4 1/2":1.00 -- 0":0.94 -- 3/4":0.95 -- 0.76 (typical Valley/Dynamo "bar box")
 

dr_dave

Instructional Author
Gold Member
Silver Member
SP - Based on your photo, it appears to me that the masking tape that you laid along the face of the subrails is off a bit... perhaps close to 1/8" where we can see the top of the red/brown subrails.

Is that what you intended?
Yes, that's exactly what I intended.

Varying cushion widths will give different results when using Dr. Dave's method to arrive at a PAF. It would have been pretty easy to lay it right along the seam, but what I did brought the combined width of the cushion + rail to 2" instead of 1 7/8".

On my table, the cushions could be 12" wide, at which point they would converge to a point at the back of the (extremely deep) pocket. That would give a PAF of 5.0 according to Dr. Dave's method, but the pocket facing angle itself would remain 144º at all points along the facing.

It is the angle itself that is needed for an accurate assessment of the difficulty factor presented by the PAF. You can't just fudge this stuff, these little 1/8" difference are huge as the apply to the angles in real life.
I was assuming that cushion thickness is close enough to 2" on most tables to not make too much of a difference in the throat measurements. Maybe I should make it clear that the throat measurement should be made 2" back from each nose for better accuracy and consistency.

Thank you for sharing your results and insights.

Regards,
Dave
 

dr_dave

Instructional Author
Gold Member
Silver Member
How about a second parallel PAF table for those with the technology to measure the actual pocket angle? The table will have the exact relation to the theoretical yet hard to measure throat angle comparison for the purpose of overall TDF. That way those who can do so will have a more precise total and those who can't measure the angle will have a "close as they can measure" assessment. It could be notated which method was used. Both total end numbers would theoretically be the same if the ruler guy did all his measurements right. The angle measure person would be of course more precise. I know Dave said he want's to use only a ruler but this topic seems to be crying out for more precision. Again, an angle gauge can be bought from Harbor Freight for three and a half dollars for those inquiring minds with an income.

When I can find the time, I plan to make some improvements in the TDF document. One thing I plan to do is list the facing angles in addition to the the 2"-back-throat measurements in the PAF table for people who have an angle measuring device and know how to use it properly.

Thank you for your input and for pushing me on this.

Catch you later,
Dave
 

SloMoHolic

When will then be now?
Silver Member
Dr Dave,

I just wanted to chime in (without any numbers) to say I think this is an EXCELLENT project. As I review the current list, I am reminded of many discussions about these same tables, and I believe the TDF numbers are really starting to align with the subjective and qualitative opinions that AZB members have expressed in those threads.

I believe I can speak for many people here on AZBilliards, when I say:



THANK YOU!

And

GREAT JOB!




Sincerely,

-Blake
 

dr_dave

Instructional Author
Gold Member
Silver Member
As far as pocket opening goes, a simple comparison of a 4" pocket to a 4.5" pocket would show the 4" pocket as 11% smaller. Reality is a 4" pocket is considerably more difficult than 4.5". If you deduct for the diameter of the ball, the margin of error on a 4.5" pocket is 2.25". On a 4" pocket the margin is 1.75". The difference between them is close to 21%. That I think is pretty accurate.
Good analysis! I had done something similar also (for all of the factors) before I posted the original version of the document. However, this analysis doesn't translate directly to a useful factor for the effect pocket size has on outcome of play (e.g., a BU score). For example, for many shots, especially for a better player, a significant portion of the pocket margin is available for pocket cheating. In other words, many balls can be easily pocketed, and making the pocket smaller does more to limit pocket cheating than cause misses. In other words, the 21% number you cite doesn't mean 21% more shots will be missed with a 4" pocket compared to a 4.5" pocket (although, this might be true for some types of shots and some players). I hope that makes at least a little sense.

I've tried to vary the numbers and ranges to best characterize a large range of shots and players, and have the results be inline with people's experiences, but this is a tough thing to do without lots of meaningful and accurate data. Regardless, the TDF is still useful as a relative measure, even if the number doesn't have an exact and literal interpretation.

Thank you for your input,
Dave
 

dr_dave

Instructional Author
Gold Member
Silver Member
Dr Dave,

I just wanted to chime in (without any numbers) to say I think this is an EXCELLENT project. As I review the current list, I am reminded of many discussions about these same tables, and I believe the TDF numbers are really starting to align with the subjective and qualitative opinions that AZB members have expressed in those threads.

I believe I can speak for many people here on AZBilliards, when I say:

THANK YOU!

And

GREAT JOB!


Sincerely,

-Blake
Thanks Blake! I appreciate the positive feedback.

The TDF system is far from perfect, but everybody's input has been very useful in making improvements. Hopefully the system can be improved more as time goes on.

Regards,
Dave
 

cigardave

Who's got a light?
Silver Member
Dave - Just a thought... I believe at this point in time the list of table owners, their measurements, their factors and their TDFs are somewhat of a mish-mash of data generated by individuals applying different measuring processes.

For example, FatBoy submitted his measurements and calculations at a point prior to the suggestion of using Post-It notes to extend the pocket facings and subrail facings, calling into question comparing his table's TDF to others in the list.

Perhaps it makes sense to denote which data has been generated using the same (latest) process.
 

dr_dave

Instructional Author
Gold Member
Silver Member
Dave - Just a thought... I believe at this point in time the list of table owners, their measurements, their factors and their TDFs are somewhat of a mish-mash of data generated by individuals applying different measuring processes.

For example, FatBoy submitted his measurements and calculations at a point prior to the suggestion of using Post-It notes to extend the pocket facings and subrail facings, calling into question comparing his table's TDF to others in the list.

Perhaps it makes sense to denote which data has been generated using the same (latest) process.
I think I prefer just asking people to correct their data if they think the measurements were not done carefully or properly the first time. Some people did the measurements correctly the first time. Some people have posted corrections. If other people want to post corrections, I am happy to make the changes.

Regards,
Dave
 

SloMoHolic

When will then be now?
Silver Member
The Valley 6' barboxes at my league's pool hall have the following dimensions:

6-foot table (Yes, SIX foot table)
Mouth: 4.5"
Throat: 4.5"
Shelf: 5/8"

I assumed a 6' table would have a TSF of 0.80 based on the available TSF factors.

TDF = 0.71

A 7' table has the foot spot 63" from the head rail. A 6' table has the spot 54" from the head rail. My cue is 58" long.

ahujyser.jpg


I believe this gives me the distinct honor of being on the very bottom of the list. :)

-Blake
 
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