1/4" Frame Perimeter Protrusion Rule

Per R01:

The ROBOT (excluding BUMPERS) must have a FRAME PERIMETER, contained within the BUMPER ZONE, that is comprised of fixed, non-articulated structural elements of the ROBOT. Minor protrusions no greater than ¼ in. (~6.3 mm) such as bolt heads, fastener ends, weld beads, and rivets are not considered part of the FRAME PERIMETER.

Is it reasonable to assume that the phrasing ‘such as bolt heads, fastener ends, weld beads, and rivets’ would also include gusset plates, so long as they were at or under 1/4" protrusion from perimeter? I would like to be comfortable with an answer before we weld these gussets to our frame… kind of hard to undo.

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Please note that any answers to this question are unofficial, and the final decision is up to the robot inspector. I would encourage you to ask at the official FRC Q+A to get a response that will hold more substance should an inspector think that your robot is illegal.

“The official answer to Q+A question ### was …” holds a lot more weight than “Some guy on Chief Delphi said …”

That being said I would ask you to consider the fact that gusset plates tend to have larger surface areas than bolt heads or weld beads. I am not sure if that will have any effect on the rule. Either way I would recommend building a bit smaller than the maximum size (0.5-1" less in each dimension) so that you don’t get tripped up by stuff like this.

I interpret the rule as allowing any protrusion less than 1/4", as the examples are list with “such as” and with “etc.” at the end in R02.

However, I would also recommend this, as people will interpret the rule differently.

Keeping in mind that only this year’s rules are the rules… Last year gusset plates were not considered minor protusions. Too much area was the logic behind that I believe. Also keep in mind that the maximum external dimensions are an absolute. They don not allow for minor protrusions.

Echoing the unofficial nature of the answers here. I believe the answer would come down to the string test. If your gusset plates end up inside the string, they will count.

I see there being a big difference between gusset plates and bolt heads. I would not consider a gusset plate a “minor protrusion”.

As others said, I would not count gusset plates as minor protrusions. Last year my team had the very end of round shafts sticking out with snap rings on the end (acting as a long bolt almost) and we were very cautious about that. I would ask First Q & A but I would not have gusset plates outside my frame perimeter.

It would probably be a good idea to make your frame dimensions just a bit smaller so that the thickness of a gusset would not raise such questions. We have typically made the length and width each 1/2" narrower than the maximum allowed. There won’t be that much less space to install components.

It’s not too late for this advice: DON’T design your robot to the maximum allowed size. Make it small enough that minor protrusions, gussets, etc. don’t end up becoming a point of contention with the inspectors, and a source of heartache for your team.

Designing an inch or so less than frame perimeter max on each side shouldn’t change your capabilities and makes for MUCH less hassle/concern during inspection. Same goes for designing to robot to be 5lbs under the weight limit (although that’s often much harder)

One of the things I have learned from doing new product development and manufacturing support for over 30 years is that if you are designing right to the limits, you are probably doing something wrong.

This, on both counts. A plate which contacts the taut perimeter string IS the frame perimeter at that point.

We typically build ~.5 inch under the frame perimeter to allow for gussets and minor faults. I’d highly recommend doing this.

All of the things listed prior to the etc are fasteners of some type. That means anything else on the list implied by the etc would also need to be fasteners. Gusset plates are not fasteners

That being said, if they become part of your frame perimeter then you don’t have any problems.

Unless they cause the frame perimeter to not fit in a 33" x 28" rectangle.

As many have said, previous years rules have treated gussets as frame not fastener. The thinking seems to come down to intent and surface area as you can route out the back side of your BUMPER plates for minor protrusions, without compromising the strength and integrity of the plate. Given that the bumper rules are basically worded the same, they are likely to be interpreted the same. (all caveats and cautions about previous years rules having no impact should be considered)

Still having said that, I would expect they would treat gussets the same this year, which means they would partially define and increase the FRAME PERIMETER.

The method used to assess your compliance against the sizing rules are not defined in the manual and may not be consistent between events. Being clearly in compliance makes getting through inspection MUCH MUCH easier. We aim for being at least 1/2" under sizing rules and 1/2 pound under weight limits at a minimum. We usually bring our robot up to max weight using easily removable ballast, so we can deal with potential issues with weight in.

Modifications to pass inspection can be painful, upsetting, and most importantly time consuming. You want to be out on the FIELD for practise matches, impressing team scouts and getting real field drive experience, not frantically resizing your frame and rebuilding your bumpers.

Frame perimeter is different than starting configuration!
BOLT HEADS CANNOT PROTRUDE BEYOND 28" X 33"–This will catch a lot of teams this year! ref. R03 : question 190 : question 143

Shame on FIRST! :mad:

Gussets have been considered “frame” and aare not ‘boltheads’, ‘weld beads’, etc. I would suspect that welding gusset plates would also make an extension of the frame greater than 1/4".

Please stop spreading inaccuracies about the rules. I’ve already explained QAs 143 and 190 in my other post, but I’ll copy R01 in here again for good measure.

Posted in the other thread but I’ll copy it here since this seems mildly more relevant.

Speaking as an LRI and 20 year participant, you’re wrong. Read the first sentence of qa190 again. There is no exception to R03 for minor protrusions. If bolt heads make you wider than 28", then you’ve got a problem and we’re going to have to fix it. Way back when there was a sizing box your robot had to fit in and if you didn’t, even by an 1/8" from a bolt head, you had work to do.

Mr. B, the suggested long and wide chassis configurations in the assembly guide look reasonably likely to be legal. Is your concern the square config? I’m on my phone so I can’t check if the noted 27.5" width is to the frame or bolt heads. If it’s to the frame, I agree that’s going to be mighty close, as the hex heads are likely 1/4" tall. It’s solvable at a competition, though annoying. The solution is taking out all the axle bolts and telling the machine shop (or someone with a lathe, or a drill and file) to make the bolt heads 1/16 or 1/8 shorter. I’ve literally done this on my team when the chassis team cut things too fine. (We were young).

There’s a large number of illegal ways to assemble the kit chassis, and it’s on teams to make sure they’re doing it right. Even young teams. I’d personally be super happy if every oversized team I saw this year has this problem, because it’s way easier to fix than “We didn’t cut the frame at all and we’re 33x32.”