Our current frame is about .25" over the frame perimeter limit (R3-A)
We’re going to cut two of the corners at 45 degrees which will put us under the 112" perimeter limit.
My question: do those two new 45 degree angles now count as sides? R19 says “If a side is shorter than 8 in., the entire side must be protected by BUMPER” I suppose it is, since the bumper is coming from the sides and front/back.
What do you think? Any precendent of teams doing this to meet the perimeter limit?
So they need bumpers on these angles. How are we thinking that would work if the corners are really small? I’m thinking 0.5" long or so. Technically you need a piece of 3/4" wood plus noodles, etc. along that length. Except mitering in a 0.5" long piece of plywood there seems pretty difficult…
Just out of curiosity, what were the dimensions you were aiming for? Did you try to do something like 33"x23" and it ended up over? Always plan for your robot to be out of square, so make it just a little less on each side.
Every year teams like to push the limits with sizing… one of the nice things about the old sizing box was that it kept teams from pushing them too much. Of course, that was also the bad thing, as every robot absolutely had to fit inside the box.
Now with the frame perimeter rule introduced last year, it’s a lot easier to get people compliant if they’re just a little over. For anything up to a 1/4", you don’t really need to cut off a corner… simple rounding all of the corners a little bit is usually enough to get you there, which still leaving each corner as something a normal observer would call a corner and not a side.
That said, as an inspector if I had a team show up where they made a clear decision to cut off a corner (to the point where I can easily define two corners and a side where the single corner used to be) to make the size requirement but still treated it as a rectangular robot for the bumpers, I would be a little annoyed. And an annoyed inspector is a thorough inspector!
Also be aware of R26:
BUMPERS must be supported by the structure/frame of the ROBOT (see Figure 4-10). To be considered supported, a minimum of ½ in. at each end of the BUMPER must be backed by the FRAME PERIMETER. Additionally, any gap between the backing material and the frame
Emphasis mine. Clipping the corner of the frame perimeter but still using a right angle for your bumpers would leave at least part of the end of the bumper unsupported, and the way I read the rule support has to exist from the edge of the bumper inwards at least 1/2".
I have to ask what your frame is made of and perhaps you could give us a picture? There may be some other method of meeting the perimeter rule that you have not thought of. You have some very qualified and experienced LRIs answering above and they are speaking from that experience. We want you to play while meeting the rules.
That’s not quite what the rule says. R21 specifies how the bumpers are to be constructed and what materials you can use. For example, R21 does NOT allow you to bolt a big hunk of steel to the bumper “just to add weight”. It does, however, allow you to construct your fastening system (how you attach to the robot) however you like. So if your fastening system is a big hunk of steel with some holes through it that let the bumper mount to your frame, it’s fine by R21.
Bumpers do have their own weight limit (20 lbs), though, as seen in R20.
That’s what I was trying to get at. You’re allowed to choose your own fastening system and construct it with as much (or as few) materials as required. Any weight beyond what is required to construct your bumpers (however you want) is not allowed.
What rule says this? I just read through the rules on bumpers, and didn’t find anything that limits parts or weight based on the intention of those parts or weight. There’s a 20 pound limit total (R20).
I doubt Al will give a ruling here on CD, but he will likely give great advice, and history.
R21 says how bumpers must be constructed. Plywood, pool noodles, cloth, optional angle as a cloth clamp, and a “robust fastening system”. No other items are allowed to be used to construct bumpers as that would go beyond the guidelines specified in R21.
The term “robust fastening system” is vague and generally inclusive. You are allowed to design your own fastening system using any parts you wish. Once you have your fastening system, you can’t add any additional materials to bumpers even if you’re under the 20 lb bumper weight limit.
The bottom line is you can use steel as part of your fastening system if you can meet the weight limit. If your fastening system doesn’t involve steel, you aren’t allowed to add it even if you’re under the weight limit.