Answered: Clarification on cutting of plastics as per <R7f>

[holbrook]

<R7f> says:

Robots are allowed the following additional “non-VEX” components:
…

Non shattering plastic from the following list; polycarbonate, acetel monopolymer (Delrin),
acetal copolymer (Acetron GP), POM (acetal), ABS, PEEK, PET, HDPE, LDPE, Nylon (all
grades), Polypropylene, FEP; as cut from a single 12" x 24" sheet up to 0.070" thick.
i. Plastic can be mechanically altered by cutting, drilling or bending etc., but it cannot be
chemically treated, melted or cast. Teams may heat the polycarbonate to aid in
bending.

In reference to similar allowances in Appendix E, says:

Note: these are not measured by “volume”. Teams are restricted as though the components they are
constructing were made from the raw materials listed.

Question 1: Given that this clause is specifically included in the VEXU appendix and not included in the Game Manual, are VRC teams restricted in the measurement of the amount of plastic used (notwithstanding the prohibition on melting or casting)? i.e., can plastic of different types or thicknesses be used, provided that the total volume of all plastic used is less than 20.16 cubic inches?

Example for Question 1: Let’s say I want to use the following plastic parts on my robot: One 3" x 5" rectangle cut from a sheet of 0.035" thick ABS, and One 4" diameter circle cut from a sheet of 0.070" think HDPE. Would this be legal under <R7F>?

Question 2: Must all plastic parts used actually be cut from the same sheet, or can they be cut from multiple different legal 12" x 24" sheets (each no more than .070" thick), as long as the total 2-dimensional area of these parts does not exceed that of a single 12" x 24" sheet?

Example for Question 2: Let’s say I start with a 12" x 24" sheet of allowable plastic, and cut two 12" x 11" rectangular pieces for use on a robot. This leaves me with a 12" x 2" piece of plastic left, this piece having an area of 24 square inches. I then get out a new 12" x 24" sheet of plastic (identical to the previous sheet) and cut from it a circle with a 4" diameter (having an area of ~12.56 square inches) for use on the same robot. This circle could not have been cut from the remaining piece of sheet 1, but is lesser in area than that piece, and the total area of all pieces used on the robot (the two 12" x 11" rectangles plus the 4" diameter circle) is less than the area of a single 12" x 24" sheet. Would this be legal under <R7f>?

Thanks in advance.

[Karthik]

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Question 1: Given that this clause is specifically included in the VEXU appendix and not included in the Game Manual, are VRC teams restricted in the measurement of the amount of plastic used (notwithstanding the prohibition on melting or casting)? i.e., can plastic of different types or thicknesses be used, provided that the total volume of all plastic used is less than 20.16 cubic inches?

Different thickness may be used up 0.070", provided that the total area does not exceed that of a single 12" x 24" sheet. This is very different than being restricted to a total volume of 12" x 24" x 0.070" = 20.16 in^3.

Example for Question 1: Let’s say I want to use the following plastic parts on my robot: One 3" x 5" rectangle cut from a sheet of 0.035" thick ABS, and One 4" diameter circle cut from a sheet of 0.070" think HDPE. Would this be legal under <R7F>?

Yes, this is legal, since both a 3" x 5" rectangle and a 4" circle can be cut from a 12" x 24" sheet, and since both thicknesses are less than or equal to 0.070".

Question 2: Must all plastic parts used actually be cut from the same sheet, or can they be cut from multiple different legal 12" x 24" sheets (each no more than .070" thick), as long as the total 2-dimensional area of these parts does not exceed that of a single 12" x 24" sheet?

You can use multiple physical sheets for convenience, however all parts must be able to be reassembled into a single 12" x 24" sheet.

Example for Question 2: Let’s say I start with a 12" x 24" sheet of allowable plastic, and cut two 12" x 11" rectangular pieces for use on a robot. This leaves me with a 12" x 2" piece of plastic left, this piece having an area of 24 square inches. I then get out a new 12" x 24" sheet of plastic (identical to the previous sheet) and cut from it a circle with a 4" diameter (having an area of ~12.56 square inches) for use on the same robot. This circle could not have been cut from the remaining piece of sheet 1, but is lesser in area than that piece, and the total area of all pieces used on the robot (the two 12" x 11" rectangles plus the 4" diameter circle) is less than the area of a single 12" x 24" sheet. Would this be legal under <R7f>?

No, this would not be legal. These three pieces could not be reassembled into a single 12" x 24" sheet.

[holbrook]

Different thickness may be used up 0.070", provided that the total area does not exceed that of a single 12" x 24" sheet. This is very different than being restricted to a total volume of 12" x 24" x 0.070" = 20.16 in^3.

So, based on this, would the example for question 2 outlined in my original post be legal if the two original 12" x 24" sheets used were different thicknesses and/or made from different materials?

[Karthik]

So, based on this, would the example for question 2 outlined in my original post be legal if the two original 12" x 24" sheets used were different thicknesses and/or made from different materials?

No. As stated above this would not be legal as the three pieces described in Example 2 could not be reassembled into a single 12" x 24" sheet.