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Official Q&A: VRC 2022-2023: Spin Up

Usage Guidelines All Questions

<R9> Non-Shattering Plastic


GOTEM
2-Jun-2022

Recently VEX released the “PET Sheet Variety Pack”, which contains in VEX’s words, “Plastic sheets with “on-pitch” holes, can be used as a lightweight alternative to back your robot’s mechanisms. Includes 3 different sizes”. It is unclear whether or not these parts count against the plastic limit as described by <R9>.

<R9> states the following.

A limited amount of custom plastic is allowed. Robots may use custom-made parts cut from certain types of non-shattering plastic. It must be possible to have cut all of the plastic parts on the Robot from a single 12” x 24” sheet, up to 0.070” thick

<R6> states this.

Robots are built from the VEX V5 system. Robots may be built ONLY using official VEX V5 components, unless otherwise specifically noted within these rules. Teams are responsible for providing documentation proving a part’s legality in the event of a question. Examples of documentation include receipts, part numbers, official VEX websites, or other printed evidence.

On the surface, it seems fair to suggest that the new PET sheet variety pack does not count against the plastic limit. It is clearly a part meant for robot construction and is directly listed as a V5 part. Nothing would suggest that it would count against the plastic limit in <R​9>. <R​6> would seem to imply that the only other rules that could affect part legality would apply to non-VEX V5 parts. The corollary on <R6> states that “non-Robot products” are an exception to this, and this seems to be the only such exception that exists. The way the rules are written, anything with a “V5” label on the VEX website that is meant for robot construction is legal and does not count against any plastic limit.

Most modifications to non-electrical components are allowed. Physical modifications, such as bending or cutting, of legal metal structure or plastic components are permitted. a. Internal or external mechanical repairs of VEX Limit and Bumper switches are permitted. i. Modifying the metal arm on the Limit Switch is permitted. ii. Using components from these devices in other applications is prohibited. b. Metallurgical modifications that change fundamental material properties, such as heat treating or melting, are not permitted. c. Pneumatic tubing may be cut to desired lengths. d. Fusing / melting the end of legal nylon rope / string (see <R7e>) to prevent fraying is permitted. e. Welding, soldering, brazing, gluing, or attaching parts to each other in any way that is not provided within the VEX platform is not permitted. f. Mechanical fasteners may be secured using Loctite or a similar thread-locking product. This may ONLY be used for securing hardware, such as screws and nuts.

<R22> also seems to mean that any part derived from a VEX-legal structure part is also legal.

Up to this point, everything seems fairly cut-and-dry. It seems clear that the GDC intends for these new parts to be legal and not count against the plastic limit. As the rules are written, the fact that PET Sheet Variety Pack is listed as a V5 part makes it legal in unlimited amounts, and <R22> makes it legal to cut or machine any shape out of them that it is physically possible. There don’t seem to be any discrepancies in the rule, until another VEX part is introduced.

VEX also sells polycarbonate sheets (image attached) and they are listed as V5 parts, and as the description states are “a great solution for making simple brackets”. This seems to meet the established criteria for being legal in unlimited amounts: being listed as a V5 part and being intended for robot construction.

Now, I find it likely that the GDC intends these polycarbonate sheets to follow the plastic limits as described by <R​9>. Anything else would simply fail to make sense.

This leaves a discrepancy. As the rule is written, if the PET Sheet Variety Pack is legal for use in unlimited amounts, as is intended, so must the Polycarbonate Sheets.

My questions regarding non-shattering plastic usage can be separated into 4 main parts and several sub-parts.

  1. What counts against the plastic limit?
  • Does the PET Sheet Variety Pack count against the plastic limit?
  • Do the VEX-sold Polycarbonate Sheets count against the plastic limit?
  • If the answers for these are different, why? They are otherwise both sheets of non-shattering plastic less than 1/16" in thickness.
  • Can any structural (non-electronic) part listed under the “V5” label on the VEX website be considered legal to use and modify in unlimited amounts for use on a VRC robot?
  1. What exactly is “custom-made” as referred to in <R9>?
  • If a gusset was cut from vex-sold polycarbonate, would that be considered “custom-made”?
  • If a gusset was cut from vex-sold aluminum plate, would that be considered “custom-made”?
  • If a gusset was cut from a vex-sold PET sheet, would that be considered “custom-made”?
  • If the answers to these are different, where does the difference lay?
  • Is any VRC-legal part modified in accordance with <R22> also legal? Are there any limitations to this? If so, what are they?
  1. What color of VEX V5 Smart Motor cartridge would Grant Cox be? I feel like he has strong green cartridge vibes.

  2. Does <R9> allow for plastic use that could not physically have come from the same sheet?

  • Is it legal to use both Delrin and Lexan on the same VRC robot, considering that it would be pretty hard to find a composite sheet made of both polycarbonate and acetal monopolymer?
  • Is it legal to use both 1/16” polycarbonate and 1/32” polycarbonate on the same VRC robot, given that the GDC already seems to assume slicing a plastic sheet the thin way to be impossible? (lol)
  • If one were to use any of the PET Sheet Variety Pack, would they then be prevented from using any other kind of non-shattering plastic?

I would greatly appreciate it if, in addition to the direct answer, the GDC could share some of the reasoning behind their decision, in order to make it easier for the community to extend this decision to future parts that VEX may release, as well as what the GDC intends the spirit of the rule to be.

Thank you for your time.

Answered by committee
  1. What counts against the plastic limit? Does the PET Sheet Variety Pack count against the plastic limit? Do the VEX-sold Polycarbonate Sheets count against the plastic limit?

Yes, the PET and Polycarbonate sheets sold by VEX count towards the allowable plastic limit. They are not exceptions to R9. If anything, they could be considered an exception to R6. We will be sure to clarify this in a future Game Manual update.

  1. What exactly is “custom-made” as referred to in <R9>?

We think that the answer given to question 1 satisfies the intent behind this question. If not, please feel free to rephrase and re-submit.

  1. What color of VEX V5 Smart Motor cartridge would Grant Cox be? I feel like he has strong green cartridge vibes.

A blue cartridge that has been spraypainted green.

  1. Does <R9> allow for plastic use that could not physically have come from the same sheet?

Yes. Please see R9-b:

b. Plastic parts do not have to be literally cut from the same original 12” x 24” sheet. However, all individual parts must be able to “nest” or rearrange into a 12” x 24” area.