Technical standards section D line 8: flexibility rant.

[Sewer bill]

In the most up to date revision:

"8) Flexibility - The disc is held on its edge in a vertical position perpendicular to a scale with
a precision of at least 2 oz. (56.7 g). The upper rim of the disc is then gradually pressed
down within 5 seconds. The flexibility rating is determined at one of two points, depending on
how the disc reacts to applied pressure.
For discs that buckle, the flexibility rating corresponds to the point when the maximum weight
is registered on the scale. For discs that do not buckle, the rating refers to the weight at the
point when the inside rim-to-rim distance is at 50 percent of the disc's diameter. The
temperature of the disc is to be no higher than 25 degrees Celsius (77 F) when the test is
performed. The ratings of three samples are determined, and the median score is used as
the final rating. Discs that are unable to be bent to 50% of their diameters fail the flexibility
test. Manufacturers are required to send samples of the most rigid discs they want
considered for PDGA approval."


In my opinion, this needs revisiting, more transparency, and results posted for each batch of discs tested in a specific blend of plastic. Here's my points.

1. This current language of the rule leaves open the possibility of dangerously stiff discs and plastic compounds as are already present in discs today that can and do pose a danger to pedestrians, fellow disc golfers, spotters and spectators.

2. There isn't a defined deformation per weight applied range it's simply referred as the rating with no description of the range of what a pass or fail actually is.

3. There are already industry standards for plastic hardness and durometer readings should be mandatory for each plastic blend available. There is a direct relationship with respect to durometer and overall stiffness independent of wing geometry.

4. Temperature not exceeding 77f is absolutely ridiculous, people throw discs in below freezing. If a disc is approved at room temperature it could easily fail the same deformation test at 30f.

5. For people like me, the consumer, the user of the allegedly regulated product, nothing is more irritating than completely arbitrary descriptions from manufacturers and intentionally vague language from governing bodies. For example, I recently purchased 10 esp wasps from discraft described as "These ESP Swirl Wasps were made to Chris' exact preferences. These are softer and grippy with a little bit of give and a slight dome."
These wasps are easily the stiffest blend of discraft plastic I have ever owned. It implies there's even more stiff plastic available.

6. I as a regular person with a pdga number should have access to the specific ranges and metrics used to determine a pass or fail I belive this section d(8) is worded intentionally vague so people like me can't go and prove with their own standards that there are and were discs that should not be pdga approved for play in sanctioned events.

Final point. If the pdga wants to be as murky as possible about flexibility they should be just as murky about paint or stickers on discs as those don't actually pose an increased danger to pedestrians or any measurable advantage to the player.

With minimal ribbing I can also be convinced to rant about disc weight.

 

[Countchunkula]

When you let an industry regulate itself, they basically always tailor the regulations to allow current practices. Exceptions would be if the litigation risk already makes current practices untenable, manufacturers are in the process of transitioning anyway, or if one (or a group) of manufacturers have outsize control/influence over the regulatory body and weaponize it against their competition.

I agree that it's nuts to test a disc for flexibility in a single plastic blend. At the very least, you'd want to test the least flexible plastic the manufacturer plans to offer, but I doubt the manufacturers agree.

 

[Cgkdisc]

With regard to the flex spec, it was primarily needed to prevent discs made of non-flexible materials like metal or wood. The standard has been enforced sporadically when a player reports to the PDGA that a particular disc model appears to be inflexible. Jeff Homburg will check it out, and in some cases, certain runs of discs were either recalled or "disapproved" if the samples tested did not meet the spec.

 

[Sewer bill]

With regard to the flex spec, it was primarily needed to prevent discs made of non-flexible materials like metal or wood. The standard has been enforced sporadically when a player reports to the PDGA that a particular disc model appears to be inflexible. Jeff Homburg will check it out, and in some cases, certain runs of discs were either recalled or "disapproved" if the samples tested did not meet the spec.

This is kind of shocking and not at all shocking simultaneously. Thanks for the insight.

 

[thatdirtykid]

enforced sporadically when a player reports to the PDGA that a particular disc model appears to be inflexible. Jeff Homburg will check it out, and in some cases, certain runs of discs were either recalled or "disapproved" if the samples tested did not meet the spec.

Has this happened before aside from wizards?

 

[Cgkdisc]

Has this happened before aside from wizards?

Yes, a few times but I don't recall the details.

 

[Sewer bill]

Yes, a few times but I don't recall the details.

Is there like an anonymous tip line I can drop some suggestions in for review.

 

[biscoe]

There's a link for the Technical Standards Working Group on the PDGA site. Jeff Homburg also posts on this site occasionally so may be reading it anyway.

 

[txmxer]

The standard was created for one purpose and you want actual useful information about the plastic from an end users perspective, which is not the purpose of the standard.

This is where brick and mortar stores provide a service. You get to touch/feel the plastic and can judge it for yourself. Not sure that any spec test is really going to provide the kind of information you seek, although it could be more informative than what is provided.

 

[Sewer bill]

The standard was created for one purpose and you want actual useful information about the plastic from an end users perspective, which is not the purpose of the standard.

This is where brick and mortar stores provide a service. You get to touch/feel the plastic and can judge it for yourself. Not sure that any spec test is really going to provide the kind of information you seek, although it could be more informative than what is provided.

Kind of on point. I do belive I can blind touch guess durometer though from working with so many different casting compounds that it really would be convenient to know ahead of time what it is.

But also, after coming back to disc golf from a 10 year break, some of these new discs feel dangerously stiff so I was kind of blown away in the technical standards component of the pdga rules there isn't actually any listed I can verify myself with my own durometer gauges or make a deformation gauge using a referenced technical standard.

 

[txmxer]

Kind of on point. I do belive I can blind touch guess durometer though from working with so many different casting compounds that it really would be convenient to know ahead of time what it is.

But also, after coming back to disc golf from a 10 year break, some of these new discs feel dangerously stiff so I was kind of blown away in the technical standards component of the pdga rules there isn't actually any listed I can verify myself with my own durometer gauges or make a deformation gauge using a referenced technical standard.

I think this rule goes back to the dark ages of disc golf (probably 80's or early 90's?). The idea of using industry standards to evaluate materials would have been completely foreign to the fledgling sport.

 

[Jeffrey Homburg]

I think this rule goes back to the dark ages of disc golf (probably 80's or early 90's?). The idea of using industry standards to evaluate materials would have been completely foreign to the fledgling sport.

Here's the article I wrote on the then-new flex test back in 1994. https://www.pdga.com/files/1994_disc_revisions_rim_configflex.pdf

 

[Jeffrey Homburg]

In the most up to date revision:

"8) Flexibility - The disc is held on its edge in a vertical position perpendicular to a scale with
a precision of at least 2 oz. (56.7 g). The upper rim of the disc is then gradually pressed
down within 5 seconds. The flexibility rating is determined at one of two points, depending on
how the disc reacts to applied pressure.
For discs that buckle, the flexibility rating corresponds to the point when the maximum weight
is registered on the scale. For discs that do not buckle, the rating refers to the weight at the
point when the inside rim-to-rim distance is at 50 percent of the disc's diameter. The
temperature of the disc is to be no higher than 25 degrees Celsius (77 F) when the test is
performed. The ratings of three samples are determined, and the median score is used as
the final rating. Discs that are unable to be bent to 50% of their diameters fail the flexibility
test. Manufacturers are required to send samples of the most rigid discs they want
considered for PDGA approval."


In my opinion, this needs revisiting, more transparency, and results posted for each batch of discs tested in a specific blend of plastic. Here's my points.

1. This current language of the rule leaves open the possibility of dangerously stiff discs and plastic compounds as are already present in discs today that can and do pose a danger to pedestrians, fellow disc golfers, spotters and spectators.

2. There isn't a defined deformation per weight applied range it's simply referred as the rating with no description of the range of what a pass or fail actually is.

3. There are already industry standards for plastic hardness and durometer readings should be mandatory for each plastic blend available. There is a direct relationship with respect to durometer and overall stiffness independent of wing geometry.

4. Temperature not exceeding 77f is absolutely ridiculous, people throw discs in below freezing. If a disc is approved at room temperature it could easily fail the same deformation test at 30f.

5. For people like me, the consumer, the user of the allegedly regulated product, nothing is more irritating than completely arbitrary descriptions from manufacturers and intentionally vague language from governing bodies. For example, I recently purchased 10 esp wasps from discraft described as "These ESP Swirl Wasps were made to Chris' exact preferences. These are softer and grippy with a little bit of give and a slight dome."
These wasps are easily the stiffest blend of discraft plastic I have ever owned. It implies there's even more stiff plastic available.

6. I as a regular person with a pdga number should have access to the specific ranges and metrics used to determine a pass or fail I belive this section d(8) is worded intentionally vague so people like me can't go and prove with their own standards that there are and were discs that should not be pdga approved for play in sanctioned events.

Final point. If the pdga wants to be as murky as possible about flexibility they should be just as murky about paint or stickers on discs as those don't actually pose an increased danger to pedestrians or any measurable advantage to the player.

With minimal ribbing I can also be convinced to rant about disc weight.

Thanks for all your disparaging remarks. I don't have time to rebut all your remarks and set the record straight, but suffice it to say, much more thought went into this standard than you will ever know. 1. What specific compounds do you think are present in discs that pose a danger? 2, Believe it or not, many light discs are more rigid than heavier ones. There is not a good regression formula for predicting the flex from the weight. That surprised me a bit, but it's true. 3. I've looked at those industry standards, but have rejected those and others. I have a durometer and I did tests with it but rejected using that as a standard (one that Steady Ed had suggested decades ago, FYI). The problem with the durometer is that it ignores the reality of the geometry of the disc, which has an enormous effect on the flex and must be considered. For example, discs with wider rims are significantly more rigid and that is irrespective of the plastic formulation. 4. Temperature is a significant factor in the flex. Of course, we all know that discs are more rigid at lower temperatures. We needed a standard temperature for comparison and we chose the upper limit of that to be at a common temperature at which we play. I think your argument is "absolutely ridiculous." 5. Take this up with the manufactures, not PDGA TS. 6. If you have difficulty performing this simple test, contact me and I can fully explain it in a way you can understand. Final point: How did you come to a conclusion that the "PDGA wants to be as murky as possible about flexibility...". With statements like that, it's difficult to take your views very seriously. If you haven't already read this, I recommend you check my original on the flex test? https://www.pdga.com/files/1994_disc_revisions_rim_configflex.pdf

 

[Sewer bill]

Hey cool thanks for the reply and the link to the article.

The compounds I was referring to aren't something like a chemical that leaches into the throwers hand to pose a danger, more so that they can alter the disc stiffness at different temperatures in a nonlinear manner as they are added and adjusted to streamline the molding process to reduce rejects. These slip right past the current test.

My statement about the pdga being murky is based on the lack of data and processes used in other industries to determine ranges and tolerances. While comprehensive for its purpose, as you stated you rejected conventional industry standards for plastic testing. I do really appreciate you providing the article so I can go perform my own tests exactly to the pdga standards.

At the end of the day it's just my opinion and you can toss it in the trash with my other opinions and I truly I meant no disparaging comments specifically at you.

For what it is, the approval process works as designed and I still belive there's room for improvement and I belive we will see that change someday.

 

[uncle pennybags]

Re: Flex test temperature variation
If you wanted to get really you could choose 3-4 'standard' temperatures that discs are thrown in and do the flex test in each. Weight the results and average them together. It would make testing that much more involved, but would eliminate one more question/variable about each disc approved.

Re: variation in manufactures materials
Maybe if manufacture wants to have multiple variations of the same material they should have to do a separate approval just for that? This would likely add a huge amount of time to the approval process and may not currently be viable (or nesscarry). As I (vaguely) recall there have been some targeted instances of this, like Gateway G9i. But to apply it across all brands, thought interesting from a data & testing standpoint, would be daunting.

 

[Sewer bill]

Re: Flex test temperature variation
If you wanted to get really you could choose 3-4 'standard' temperatures that discs are thrown in and do the flex test in each. Weight the results and average them together. It would make testing that much more involved, but would eliminate one more question/variable about each disc approved.

Re: variation in manufactures materials
Maybe if manufacture wants to have multiple variations of the same material they should have to do a separate approval just for that? This would likely had a huge amount of time to the approval process and may not currently be viable (or nesscarry). As I (vaguely) recall there have been some targeted instances of this, like Gateway G9i. But to apply it across all brands, thought interesting from a data & testing standpoint, would be daunting.

It feels on brand for disc golf tech approval to be all done by hand but simultaneously behind the times when disc manufacturing is nearly lights out at the bigger companies.

It could be a nearly automated process to tech discs and obtain a lot more information but there's few people who care and there's even less who would actually care what that data means.

We're in this grey area where there's room to improve but the incentive just isn't there and people like me who bitch about it are really just background noise.

 

[Jeffrey Homburg]

Hey cool thanks for the reply and the link to the article.

The compounds I was referring to aren't something like a chemical that leaches into the throwers hand to pose a danger, more so that they can alter the disc stiffness at different temperatures in a nonlinear manner as they are added and adjusted to streamline the molding process to reduce rejects. These slip right past the current test.

My statement about the pdga being murky is based on the lack of data and processes used in other industries to determine ranges and tolerances. While comprehensive for its purpose, as you stated you rejected conventional industry standards for plastic testing. I do really appreciate you providing the article so I can go perform my own tests exactly to the pdga standards.

At the end of the day it's just my opinion and you can toss it in the trash with my other opinions and I truly I meant no disparaging comments specifically at you.

For what it is, the approval process works as designed and I still believe there's room for improvement and I belive we will see that change someday.

You might be surprised by how much time I've spent looking at what other industries do in testing plastics over the last four decades. I compiled a number of books on plastic engineering. The most rigorous I found was in the pharmaceutical industry in terms of the physicochemical properties of containers used for pills. I also looked at the UL Laboratories and even inquired on the cost, which was a minimum of $10K per object, so that is not feasible for disc golf. Yes, I know there are many other measures that can be done on plastics in discs. Because of the equipment costs, most of that equipment, the testing fees would have to be increased many-fold to afford that. But more importantly, are they really necessary? We considered more sophisticated tests, but opted for simpler tests that worked for our purposes and that allowed companies to easily do their own tests before submitting samples.

That doesn't mean that we think Tech Standards are perfect and should never be changed. But we have to choose our battles carefully. Right now I aim to explore 3D-scanning as a way to obtain all measures but those from the flex test and as a way to provide a permanent archive of the physical properties of discs. I also want to improve the way the PDGA deals with PPM (post-production modifications like UV printing, dyes, stickers/decals, and many others. I want this to be comprehensive, but it's very difficult to convince the many stakeholder of disc golf of the necessity of this approach enough to reach a consensus. I'm also concerned that discs do not pose risks of chemical exposure, but I probably need someone with more expertise in that area, like a chemical engineer or toxicologist.

I don't mind people expressing their opinions, quite the opposite, so long as they are respectful. I rarely have time to visit DGCR, however, and so this isn't the best place to reach me. I and the PDGA may not be perfect, but we are very dedicated and doing our very best. Of that you can rest assured. My time is divided in many ways, however, spending my time fighting to solve the climate change problem, serving on the editorial board of a major international journal called SOIL, doing research and writing publications, and spearheading PDGA TS. Consequently, I have to balance these important task to the best of my ability which can be difficult.

If you want to see the state of the art in PDGA TS, check out my presentation at the Masters Worlds in Flagstaff a few months ago.

https://www.researchgate.net/publication/372853321_The_Past_Present_and_Future_of_PDGA_Technical_Standards

 

[Sewer bill]

Once again thank you for the comprehensive reply I have no doubt you aren't passionate and diligent in your disc golf efforts and contributions along with finding realistic solutions at cost and scale.