After a few practice rounds and field measurements our team has come to the realization that the Loading Station for gears and fuel is not the proper height off of the carpet. As stated in the Game Manual the proper height is 2 feet 1 inch (25 Inches), the loading stations at the Palmetto regional are 25.5 to 25.75 inches off of the carpet. The FTA at the event measured and came to the same conclusion, however he stated that nothing can be done. Any suggestions would be greatly appreciated as the difference in the specifications and what is on the field is causing errors in loading. Thank you.
Rules state +/ .5 inches for a tolerance on critical dimensions and even bigger on others. Go back and look at the problems teams had in 2013 with the low rung of the pyramid being lower than teams were expecting… Its just something your going to have to deal with.
I would argue the height of the feeder station is very much a critical dimension and this concerns me a ton
This concerns me a lot.
Teams are not given the luxury of +/-.5" on their robot height and in my opinion with dimensions like this neither should FIRST. 1/2" easily breaks a very large amount of gear pockets which means a large portion of teams will lose a significant piece of their robots functionality and wont know so sometimes until their first match of their event.
When I first saw the title, I was worried that like a few rotors were missing or something.
I know everyone’s design is different, but at least for us (we might be a minority), a slightly higher loading station can only be a good thing.
At least its not under-sized…?
Perhaps we are a minority, but an undersized chute would help us.
Unfortunately, this is just part of the game. What if the floor at a venue varies by +/- 0.5"? Would you hold FIRST accountable then? The field is a lot larger than your robot, so naturally will have more variation, and they aren’t CNCing every single piece to the nearest 0.001", it’s just impractical. Plus, these rules have been part of FRC forever, so teams should go into the season expecting the field to have some variance. This is not unlike the real world, and is just another challenge to overcome.
This couldn’t be a venue problem, it’s just a FIRST problem. It’s not the height of the floor, it’s the height from the carpet to field element, which is controlled 99% by the field element itself. For regionals, FIRST contracts out a company to build the fields. I find it pretty astonishing that they can’t hold better than a 1/2" tolerance when our students easily made our field elements to much better tolerances. But I did enjoy your CNC strawman.
We were at the Rochester Rally preseason event, with a full wooden field provided graciously by 1511. We had a situation where since one of the feeders was too high, the gear went right over our feeder loading mechanism right into our ball hopper. Were that to happen in a real match, that would render us unable to shoot or place gears for the rest of that match.
Knowing that this flaw exists has allowed us to fix it on our actual robot and with how we feed the gears, but I’m sure some other teams could have a similar issue if the fields were too much out of spec.
I like that you used the issue to improve the robots ability to handle field variance. I always tell our students that things exist with tolerance so when we design we need to take that into account.
On a side note, sorry about it being a little off. I do think we ended up fixing it…I think. 
The competition ARENA is modular and assembled, used, disassembled, and shipped many times during the competition season. It will undergo wear and tear. The ARENA is designed to withstand rigorous play and frequent shipping. Every effort is made to ensure that ARENAS are consistent from event to event. However, ARENAS are assembled in different venues by different event staff and some small variations occur. For details regarding assembly tolerances, please refer to the 2017 FRC Field Assembly Drawing. Successful Teams will design ROBOTS that are insensitive to these variations.
Field tolerances will vary from region to region, and it does suck when the variance does not occur in your favor. Despite this, I do not think it is fair to compare the lack of variance on FRC comp-bots to the presence of variance on the field.
While you make one robot per season, the GDC oversees the creation of many more replicas of the game field. Mass production generally means an overall degradation of similarity. Asking a company to keep in line when making numerous copies of a field is not proportional to asking a team to keep in line when making a single robot.
With all this in mind, it looks like you have some qual matches to play tomorrow, and I hope that your team can overcome this hurdle.
This didn’t seem right to me, so I checked the Field Component Drawings (page 147 for those wondering) for the actual tolerancing. The drawings give a dimension of 25.00±.13". If OP’s measurements are correct, then the feeding station is clearly out of spec. Unfortunately, I can’t seem to find any protocol for rectifying this situation, and I am not sure that it is even physically possible for the regional volunteers to correct this issue.
Additionally, I couldn’t find any tolerance in the official season rules or document larger than 0.25". If any exist, please correct me.
I hope teams affected by this can find a solution to this issue.
The individual component is +/- .13" but that’s just to the base of the feature I’m sure. Now account for all the rest of the tolerances, and the tolerances of the parts it mates with, and the tolerances of the parts they mate with. There is a reason a screw or bolt has a thru hole typically at least .010" larger than the major diameter of the thread, and those holes tend to have a tolerance of +/- .010" whereas the mating threaded hole probably has a tolerance of +/-.005" location wise.
Tolerance stack up is a thing. This is something every engineer needs to be able to account for. It happens all the time in the real world, and the looser the tolerances, the more likely you are to make “good” parts, and the less expensive they tend to be.
We are at this event, and the out of spec and/or inconsistent field elements from pegs to peg lifters to velcros to peg heights is unfortunately a problem for many teams I observed including us.
As an example, peg height is 12" vs 13 1/2 " which is what we built for and the same as the practice field. When they get deformed downwards it’s even worse. We made adjustments to gear height last night for our robot, but for other teams their design doesn’t allow them to easily.
Even the Velcro strips are different that releases the rope. Size, brand and shape on the same airship!
Their were so many HPs getting fouls for reaching over because their rope got stuck as they were released.
This is the thing that bothers me. The first part as far as our robot, but the last part more fundamentally. If they can build practice fields to spec, why not real ones? Last year the rock wall was too wide (and perhaps some others), and back in 2013, not only were the rungs low, but so were the loading ramps.
Any word on variation/error in the davit and touchpad heights? An inch or so off wouldn’t affect us at all, but any more than that and we’ll want to tweak our ropes.
And for the record, a higher feeder is less of an issue for us than a lower one would be. Remembering the lesson of 2013, we designed for about 1" short with an open overhead (until it goes flying over our light & camera bar about 5" above our ramp), and we can probably tweak for another 1/2" or so between consecutive matches by limiting the rise on our intake ramp extension.
The drawing with the ±.13 tolerance is referencing the entire assembly and I assume that the position of the bottom of the assembly is defined by the carpet. The assembly is resting on the ground.
25.5 inches is within the 1/2" tolerance? I’m really confused. If you designed to such tight tolerances despite having played basically any FRC game ever, I don’t know what to tell you. This kind of thing happens every year, and it is explicitly warned about in the manual.
This is concerning. A little bit of extra flex in the spring is whatever, but being 1.5" off is HUGE, especially if it’s not consistent between fields. That sounds to me like something got assembled wrong/upside-down.
From my reading of S07, it shouldn’t be a penalty for the HP to contact a rope that got stuck as long as no part of it is below the airship deck (eg. the rope is “Deployed”). Are they just giving penalties for pilots reaching out over the railing?