Just noticed that Rev 6 of Game Manual has been posted. Rules about plastic and aluminum sheets have been changed. One of my teams will have to rebuild a significant component. Three different forum answers explicitly said their design was OK (Other Parts and Materials: #3, #11, & #22). They used two pieces of plastic 12.5 x 16 to create a cylinder. But the two pieces had to be cut from two different 24x24 sheets. Fix will be to cut each piece in half 12.5 x 8, but at this late date with the whole robot already together this will be major rework. Any one else in this kind of jam?
I suspect that the rev is simply poorly worded and that the q&A’s allowing multiple sheets remain in effect. Previous wording was ambiguous.
As always, check w/FIRST for an official ruling.
Oh wow Chuck, I see what you mean. Those rules didn’t say 1 sheet when I read them in October, and in November I missed the fact that some of the Q&A’s state/imply 1 sheet. Post #3’s adjectives imply 1 sheet, but even I missed that since later posts explicitly state multiple sheets.
Yet the update will overrule the Q&A posts that predate it. Since the update is official and very specifically states 1 sheet, (and the only post-update forum reply states 1 sheet as well) inspectors shouldn’t accept robots that cut from more than 1 sheet of the same material. We have 1 robot affected out of 4, though I think that’s more about luck of the draw during the design iterations than anything. The affected robot may have to redo their helix shell depending on how high it is (I can’t remember if it’s 13" or 10" after all of the redesigns).
Posts that say 1:
Here, though it says “a sheet” instead of “one sheet” … additionally, it is pre-update
Here (post-update according to the revision history of the update, but I don’t know that the update was published on that date…)
And there are posts that say multiple, yet they’re before the update.
Here
Here
1 sheet it is aklego – don’t assume you can bend the rules just because previous wording was confusing. The update was put in before the first competitions in early December, so no one is “grandfathered” in.
Another contradiction is answer to post #9
http://forums.usfirst.org/showpost.php?p=30794&postcount=9
Poster asked if two different thicknesses of same material could be used if total area did not exceed 576 and 24" size constraints were not exceeded and answer was “yes”. This is clearly not possible with the “Not more than 1” addition to the rule.
JesseK,
At our tournament, Q&A’s trump the game manual. Date is not an issue. If FIRST has changed its mind and wants to disallow something they have specifically OK’ed on multiple occasions, they will need to issue a further Q&A invalidating the posts listed above.
If you really want to split hairs, “not more than 1 sheet” will disqualify teams that have cut a sheet in half as they now have multiple sheets. Shall we enforce this rule?
That said, I don’t believe that it is FIRST’s intent to make a massive rule change. Changing rules by stealth 3 days before the first tournaments is simply inconsistent w/FIRST’s credo. I still think it is simply an issue of poor wording in an attempt to clear up a previous ambiguity.
But, as I said above, check w/FIRST for an official ruling.
Based on past Q&A, a simpler rewording would have just specified the total # square inches allowed, and left off the whole 24x24 specification. That was confusing from the get-go.
Hard to beleive that whoever made that last change had read all the Q&A’s.
Having to ensure that all our pieces can come from one sheet of 24x24 will mean dissasembling the entire robot. I’d ask for clarification, but TIMS is down so I don’t know my password 
I have not kept up on the Q&A forum, so clarifications there allowing parts to be cut from more than one sheet are a surprise to me. I think the wording of Rev. 6 of the manual makes the most sense and should remain, but our robots were designed with that restriction in mind from the beginning.
The maximum dimension of 24" is an important limitation, as it prevents teams from, say, using a piece of stock that is 1" wide and 576" long.
Following are my as yet unanswered (and therefore not visible) posts to the FTC Forum:
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On the basis of the answers to questions #3, #11, & #22:
#3 answered on 9/22/09
A: the total area of each type of material must be less than or equal to 576 sq. in. (i.e., 24" x 24") and the individual pieces must be able to be cut from a 24"x24" piece of raw material.
#11 answered on 9/29/09
A: Yes, as long an the total area and max. dimensions don’t violate the limits
#22 answered on 10/8/09
A: Teams may use aluminum sheet with the following restrictions:
- Total combined area of all aluminum sheet is 24” x 24” in area (576 sq. inches) or less.
- No piece of aluminum may exceed 24 inches in length.
- Sheet thickness shall be 0.0625” or less.
- All of the pieces of aluminum sheet used in robot construction do not have to be cut out of the same 24” x 24” sheet of aluminum as long as the total area and maximum length rules are not violated.
over the past 2 months the students designed a ball lifting mechanism utilizing a PETG plastic cylinder 8" in diameter and 16" in height. The cylinder is constructed from two pieces of PETG 12.5" x 16". Total area is 400 square inches and all dimensions are less than 24". However, the two pieces had to be cut from two different 24x24 in sheets. This was not a problem based upon the above answers. Now, in R6 of the Game Manual just recently posted the words “Not more than 1” were added to the rules pertaining to the plastic and aluminum sheets. It seems unfair to make this rule change at this late date after competitions have already been held. This is not a clarification, but a major change which contradicts not just one but three official forum answers that have been posted for more than two months. Please advise what I should tell the students about their completely fabricated and working design
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Rev 6 rule changes to <R5> c.1, c.2, c.3, c.4, and c.6 also directly contradict answer to post #9 in Other Parts and Materials
Quote:
Originally Posted by 2009FTC3658
Q: Is it possible to use more than one thickness of a particular material as long as the total area for that material does not exceed 576 sq. in. or the extent constraint? For example, use a 12" x 24" x 0.0625 sheet of Polycarbonite and a 12 x 24 x 0.093 sheet of Polycarbonite. This would constitute a total for Polycarbonite of 24" x 24" that is within the thickness limit.
A: Yes.
Woo Hoo.
Manual update 7 has just been posted and the latest Q&A rulings have been re-instated… specifically:
Polycarbonate plastic sheet (e.g. Lexan), not to exceed 576 sq. inches total area, 24” maximum dimension, and not greater than 0.10" thick.
Kydex plastic sheet, not to exceed 576 sq. inches total area, 24” maximum dimension, and not greater than 0.040” thick (1 mm).
ABS plastic sheet, not to exceed 576 sq. inches total area, 24” maximum dimension, and not greater than 0.0625” thick.
PETG sheet (aka Vivak® Copolyester Sheet) not to exceed 576 sq. inches total area, 24” maximum dimension, and not greater than 0.080” thick.
Much clearer.
Yes, but what about Aluminum sheets?
Same…
It was just further down the page.
Download it !!!
Unless they mean to restrict diagonals, they probably shouldn’t use the confusing term “maximum dimension”. (It would probably have been better to have said something about each part’s perimeter being traced within its own theoretical 24 in side length square, and a total area within all perimeters of less than 576 in2 per material.)