Custom Plastic Sheets Rule Confusion

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The intent of the area/thickness constraints is to limit the number of custom plastic parts used in
Robot construction, not to define an absolute volume. For example, using a sheet which is 0.035”
thick does not permit two 12” x 24” sheets’ worth of parts.
Since there are no rules banning how you cut the sheet, could you not cut the 0.070 sheet from the “middle” to form two 0.035 sheets, and then cut those sheets? It would comply by the looks of it, and does not violate as many rules as I can think of, since theoretically it works just the same, just with more complex geometry.
(I am new to VRC I just transferred from iq)

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You “could”. However you would have to actually using the cut sheets on your robot instead of just using commercially bought 0.35 inch poly. You would probably also want to describe the process used in depth in your engineering notebook to convince inspectors.

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Ok! Thank you so much! That would be a pretty cool proscess to go through! I appreciate the help.

It would be illegal due to part b. All parts have to nest into a 12 x 24 area. There is no height attached to that part of the rule, so two sheets cut from 1 would be illegal

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You came up with an important notion to test, but it turns out that you can’t do it. This is one of those circumstances where you have to read the material a few more times. R18 a) uses that exact example as something you can’t do. When you had that thought about a thinner sheet after reading though, ideally you would have checked to see if that thought is covered in the text. R18 b) explains that you have to be able to nest the parts in a notional sheet and continues to be specific about area available in that nesting, which is again the single sheet’s-worth. The italics note at the end it says ‘all individual plastic pieces must be able to theoretically “nest” or rearrange into a 12” x 24” area’, which pretty much nails it. It does seem like it could be put more succinctly overall, but that’s a living document maintained by a group under time constraints. This is good reading practice. You have to create and test foundations in your mind to support building comprehension of the message - for example, imagining contraditions like a thin sheet and then going back to the text. That usually takes a few passes when it’s technical stuff that’s new to you.

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Understandable. Thank you for the correction!

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Technically under R18b and the attached note it would still be legal. Although height is never mentioned in either of these, we can site G3 “Use common sense” and quote the fact that it is not in fact talking about the total surface area of the parts. Because it is not using surface area and instead says it must be able to nest in a 12”x24” sheet(see R18a, R18b, figure 35, and the attached note), we can assume that the sheet referenced would be the original 0.07” sheet, not the new thickness of the cut pieces since it is theoretically possible to have them all be cut from the same sheet. R18a even indirectly specifies that it is talking about the original sheet of plastic’s dimensions. Therefore when nesting your parts, it would be reasonable to say that as long as it was all cut from or could have been cut from a single 12”x24”x0.7” sheet it satisfies the requirement.

TLDR

R18a specifies that it is discussing the original sheet width so since it is theoretically possible to cut it from the original sheet it would satisfy the requirements set by R18 as described in points a and b.

The rule does not assume a .07" starting sheet, only requires that the material be no thicker. Rule 18f indicates the thin PET sheets count to the total area. Note and figure 35 indicate cut from a single sheet. I don’t see how G3 is in your favor here.

IIRC this concept was put forward in a previous year Q&A and denied.

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Legal parts do not become illegal given physical modification. If some part (plastic) is legal, a certain way of cutting it cannot make it illegal.

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When I said “the original .07inch sheet” I was referring to this hypothetical of cutting it in half, not the rule itself as it never states the thickness of the sheet.

Correct, that is why since technically it was or could have been cut from a singular sheet, not 2 factory made 0.035” sheets it should be legal under G3. The premise of R18 is that it must be cut from a single sheet no thicker than 0.07” thick, it never specified what direction you must cut it just that it must be able to fit within a single sheet, which this technically would.

Now that you mention it this does seem familiar, I would go find it again but it doesn’t seem worth the effort since Q&A’s don’t carry over between seasons. I’m sure someone will make a new one this year.

side note

I can see both sides of the argument but as an inspector I would likely actually side with you until there was an official ruling. And thanks for the debate :wink:

Im sorry, what is IIRC and could you please clarify?

IIRC stands for If I Remember Correctly

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This is true, however you would have made two separate sheets, and the rule says you must be able to arrange all parts into a single sheet. So the sheet you start with to make parts for your robot is the .035" sheet. G3.

I’m not saying you cannot bifurcate the sheet the hard way and use the product. I’m saying that in making hard cut, you are making single sheets for two teams.

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I’ll go ahead and be snarky and respond with LMGTFY. https://www.google.com/search?q=iirc

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But only if you are allowed to stack parts on top of parts to fit within the 12x24 requirement. If stacking to achieve the area were allowed, the (4) 9.5" circles in figure 35 would be allowed as well.

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last time this was asked was here
https://www.robotevents.com/VRC/2018-2019/QA/1
I doubt you would get a different answer this year.

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No, R18a confirms the point that they are illegal as they were not cut from the same sheet according to the figure description.

Ok, point made, and the remainder of R18a about the two sheets of .035… you are ignoring this because the mythical split sheet that becomes two sheets it is still somehow one sheet?

G3: if you make two sheets from one sheet, they are now two sheets.

The intent of the rule is that all plastic parts in a bot can be arranged on a 12"x24" plane with no volume. Does the gdc need to get to the “no volume” distinction to get everyone to the G3 logic that the R18 verbiage is clearly working toward?

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I think there is fundamentally a problem with attempting to write 2D rules for a very much 3D game.

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