I know this has come up once or twice on CD already, but after tonight, I think it deserves to be brought up again with its own thread. I was at a group-build type of event this evening, helping about a dozen teams identify issues that may come up during inspection. By far the most common issue, and the hardest one found to fix, is R03.

In the STARTING CONFIGURATION, the maximum ROBOT size (excluding BUMPERS) must be constrained to a volume of 33 in. by 28 in. by 55 in. tall (~83 cm by ~71 cm by ~139 cm tall)

What tripped up these teams (about 25% of those attending!) were the “minor protrusions” allowed in R01/R02. As clarified in the following Q&A responses, those protrusions still must be within the 28x33" dimensions of the robot!


This is most common with teams building a kitbot to the maximum dimensions. If your outer plates are exactly 28", then the bolt heads and bearings that stick out from them hang over the 28" limit and make your robot illegal - you need to put the outer plates at no more than 27.5". At this point it’s probably too late to plan ahead for that if you haven’t already, but you still have over a week to get it fixed! Please talk with the teams around you to make sure they understand this rule and don’t show up at competition with a lot of work to do!

I’d be uncomfortable with the kitbot outside frame at 27.5, personally. That puts the bolt heads right at 28" which leaves zero tolerance for assembly error. I’d either put the outside frame at 27", or grind the bolt heads 1/16" shorter.

Given that Everybot puts the frame at 27.5" I’m thinking there will be a lot of bolt head grinding at competitions. I’m considering bringing about 12-16 pre-ground axle bolts and just trading them with problem teams and sending the unmodified trades to the machine shop to be shortened for the next teams.

I suppose depending on how strictly the inspectors want to enforce this, it could be a very major issue for some teams. Given that there are 3 QAs about this I expect it will be enforced strictly.

I will make sure this is checked at the ICC week zero on January 18th.

Given that 25% of the teams you checked yesterday were out of compliance with this, I wonder if the thread title might be more appropriate as “OMG, R03 doesn’t say what you think it does! Everyone Panic!”

Perhaps not.

I actually think that thread title would be more appropriate. I personally know those 3 teams that need to cut their robots in half. That sucks. Any team that shows up to an event with that problem is done. Their experience is ruined. I’m not a fan of the lack of publicity that this rule has gotten. I’m also not a fan of the rule itself.

Yeah this is a real problem especially as it is way stricter than the rules from last year. People have trouble understanding why bolt heads were exempt last year (because max dimensions were by bumper) and now are a showstopper this year.

My team would have shown up with the same problem - thanks to some posts on CD, we reread the rules and q&a more closely and fixed the problem in week 3.

It’s been a few years now since robot size was this strict. I’m trying to remember the last time the sizing box was used, but if I’m not mistaken it was back around 2010? Sizing box was unforgiving–miss a bolt head, you had to take off the bolt head. (I’m excluding 2015’s Transport Configuration.)

Then FIRST measured by the Frame Perimeter–nice, flexible, and didn’t count bolt heads–for a few years. This lasted until 2016, then they did the “bumpers in the volume” in 2017. And now we’re back to the box for a year or so.

This one rule actually makes me wonder if this is an old but unused game idea that the GDC updated for use this year. It seems so weird that they’d throw away the progress they made on simplifying sizing rules.

I appreciate you posting this.

We had 4 small bolt heads sticking out of the maximum size volume. I’m certain we won’t be building a frame this close to maximum size ever again.

5 of the 15 teams that were here/checked in at SpecCheck were out of compliance (we found one more this morning). That is alarming. 4607 is investing in a couple portable bandsaws to bring to our regionals (kidding/not kidding).

I am afraid by the time Week Zero scrimmages happen it will be too late for most teams. And since most teams don’t even have access or go to Week Zero will be in for a rude awakening come their first Event.

Cutting and drilling as I type. Thanks for the PAST, this would have been a huge issue come competition for us.

You got me worried…

We built the kit chassis, 32.xx" long, 27.5" wide at the outside of the frame rails. We are using the kit bumper mount brackets (with different hardware to attach the bumpers to them, but that’s not relevant). Today we installed the brackets, and measured the width across them, it is 28" +0.00/-0.02" as best we can tell.

A bit tight for comfort.

The bolt heads all extrude less than the brackets.

If it doesn’t fit by a little bit, we could take the corners of the chassis apart, enlarge the screw holes, and reassemble it while held “smaller”. That would gain us a small fraction of an inch.

After our 2008 sizing box experience, I wonder if we really should do something more drastic?

Ugh… I told the team to not build 28" and we even had a discussion on it before the base was built. Now we are shrinking the entire base by 0.5" due to those things beyond 28" pretty major surgery on our base.

Its pretty clear in the 2018 inspection form

Starting Volume – Less than 33 in. by** 28 in**. by 55 in. tall (~83 cm by ~71 cm by ~139 cm tall) <R03>
No minor protrusion clause

This will bite a bunch of teams that assume 28" is good , thanks for posting this PSA on R03 its what it took for my team to listen . Much better now than in our competitions.

You’re far from alone. If our small sample size is any indication, ~25% of teams could be looking at similar issues.

If you build the kitbot to be 28" by 33" (pretty logical thing to do for a rookie/inexperienced team) YOU ARE ILLEGAL. This is a terrible rule that does nothing to contribute to a positive experience for teams. It’s a “gotcha rule” that will ruin people’s FRC experience.

It would be convenient if the size limit was something like 27.5" or 28.5" instead of rounded off to an inch number. Then we could design a half inch under and not be off by a half a hole on our one inch hole patterns.

For anyone who really read the rules, or who has been following the Q&A, or threads in CD it is not a surprise.

Unfortunately, these are not common activities for many rookie teams and even some long standing ones.

The problem is that if you did not see it by now, it is unlikely a PSA on CD is going to help you. Even a email blast for the mothership is likely going to be too late by now.

Is unfortunate, but at least it is not like a subtle interpretation of a rule changed, R03 always said max size 33" x 28". Q190 was answered 22 days ago.

Luckily the most common “offenders” are going to be kitbot chassis, with those beefie 1/4" thick bolt heads. As Kevin noted, it is easy to get 1/4" or a 1/2" back with a grinder. We will definitely be bringing our grinders and a bunch of discs to competitions.

The axle bolts and churro screws have about 1/4" of head sticking out. The bearing sticks out about 1/8". Past the frame rail.

From Rules & Expectations for FIRST Robotics Competition Events, “Machine Tools at Events”:

It does say sanders are allowed, though I have seen belt sanders throw sparks. A random orbit sander may be a good alternative, or as mentioned above, a portable band saw. For extremely tight spaces, a metal blade on an oscillating multi-tool could work.

The way the kit chassis works, if you built it at 27.5" wide, things only stick out 1/4", and you should be able to get it to spec without having to grind anything. If you built it 28" wide, then grinding would completely remove the heads from the axle and churro bolts, and go half way through the bearings, and your robot won’t work very well. But you could take one side off of the end plates, and move it in half an inch, and reassemble.

We ended up taking off one of the outer frame rails off and reducing everythig inside by 1/2" or one hole worth… took a while and its a tight wheel fit but it works. We now are good, not fun though and fairly tedious. So we have asynchronous sides now.

I guess it depends on what’s on top, whether it’s better to make the side assembly narrower, or the middle part of the robot narrower. Ours would probably be easier to scoot the whole side assembly over.