Jordan asked a question about this in the official Q&A; but because it is a question near and dear to my heart I thought I would post my opinion here.
When you look at the regulations for an official field, there is no mention of whether the tiles go above, or below, or at the same height as the bottom of the field wall panels Vex sells.
However, there are drawings that specify on the dimensions of an official field (notice that the field walls Vex sells are just one way to create an official field, not the only way. Wooden 2x4s or PVC, combined with pegboard, are other official ways to frame a field).
There are (fairly large) tolerances on the dimensions of an official field.
For these reasons, while you will certainly find that many field tiles are prepared using the advice given in some of the documentation Vex gives out; an official field is anything that meets the specs. Robots should be designed to deal with the possible variations, if you want them to work on any official field, instead of only on most of the official fields.
Gateway and Roundup field specs show foam floor to top of perimeter distance. Isn’t this enough? If this is correct then I agree the CAD files are wrong.
If combining the the CAD with the tolerances specified else where in the rules, is close enough to the dimensions shown in this Illustration, then the CAD isn’t wrong. It is instead, simply different (but it is still “official”).
There is more than one way to create a field that satisfies the specifications (the drawings and other specified dimensions, combined with the tolerances) and is therefor official.
I’m having trouble finding the document with the tolerances in it, I looked in the gateway and low cost field spec pdfs and at some of the organizer documents in the wiki. Could you point me at the right one as I plan on building our team it’s own field perimeter this summer (somewhere in between the low cost suggestion and the official field in cost) and want to get it as correct as I can.
Ok, makes sense, I had read that before but saw it as an assembly tolerance rather than a design tolerance, I was looking for something on the drawings. I still think that if the field spec is going to be shown to three decimal places ( as in 11.328" ) then the CAD file should be the same. Other dimensions in the CAD are correct (at least to two decimal places) such as the wall thickness at 1.274". In practical terms it doesn’t really matter, i don’t plan on constructing any more accurate than 1/8".
In a quick walk down memeory lane, I’ll add that I made my first set of PVC_plus_Pegboard framing 12’ x 12’ on the inside.
Then I found out that the field size is only nominally, 12’ x ‘12 (and the tiles are only nominally 2’ x 2’).
My field interior was 3.5" too big, and the tiles definitely didn’t fill it up.
Time to get out the saw… again. FYI - Pegboard is great for things like field walls and flat-sided goals, but it makes a HUGE amount of dust when you cut it with a table saw (and 2X a HUGE amount when you cut it twice).
Common sense will prevail, I think this thread is just in the spirit of some engineering folks doing what we do best and being anal.
Out of interest I went back and took a look at the CAD for roundup, this does indeed show the foam tiles within the field perimeter. Most of the instructions for field assembly discuss assembling the field and then placing the foam tiles inside afterwards.
I agree that for gateway if the goals are attached to the field perimeter the base of the goal is almost flush with the base of the perimeter. This implies that the foam tiles must indeed be below the field perimeter otherwise there is no way for them to be installed. For those that cut the tiles this may mean that either the lower goal support will not be attached to the perimeter so it can be raised enough for the flooring to fit underneath or that the perimeter will have to be raised by using spacers so that the whole weight of the perimeter is not supported by the goals.
I guess we’ll all find out later when someone has all the parts.
On the other hand, using the Clean Sweep equipment, if you put the field panels on top of uncut tiles (a useful thing to do when/if a gym teacher or school principal is planning to shoot anyone who scratches the gym floor), the Clean Sweep dividing wall sagged down to rest on the tiles in the middle of the field, and didn’t rest on the field tiles at the field edges .
That year the added field parts anticipated that fields, using the panels Vex sells, would not be resting on top of the tiles.
Final thought - For Clean Sweep using the Vex panels and uncut tiles, the misalignment was cured easily by using Zip Ties instead of using screws to attach the Clean Sweep wall to the Perimeter panels. Maybe zip ties will be equally useful this year.
While not required by the rules, the most common configuration (by far) of “official” fields will be with the perimeter resting on the floor, and the tiles with cut edges being placed inside the perimeter. This is how the fields will be assembled at World Championships.
