I’ve been re-reading the rules, and it seems like I have been mis-interpreting the requirements for bumper support. I was under the impression that short bumper segments, like the minimum 6" segments on the corners of a frame perimeter side, need to be supported fully along their lengths. This would prohibit teams from building their frame like shown below, requiring them to extend their front and back frame profiles along the whole bumper length.
Now that I check the rules again, I don’t actually think this is a requirement. The governing rules that I see are R24 and R33.
R24 says each corner needs at least 6" of bumper protection, but says nothing about the support for that bumper. R33 says that each bumper side must be supported by at least 1/2" in the corner and every <8" along its length. As far as I can see, there’s nothing that would make the original frame design illegal as I originally thought, since the side bumper rail supports at least 1/2" in the corner and the wheel well is less than 8".
I’d like to get a second (or third or fourth) opinion on this. Was I mistaken at first, or am I missing something on my re-read? Thanks.
Practically you need support along all 6 inches because the bumper needs to be supported at both ends for at least 1/2". The easiest way to do this is almost always to support it along it’s entire length (though it’s not required). So the first picture is illegal because there is no backing at the bottom end.
If a bumper segment is the ]-shape, then yes, your diagram shown would qualify; 1/2" at each end, within 1/4" of the corner, and no gaps wider than 8". If a segment is one side, then there does not appear to be 1/2" of support at the corner ends of the front and rear segments.
Looking at the usage of segment in the rules, it appears to be each side. Look particularly at R31f:
optionally use metal brackets (i.e. angle or sheet metal) to attach BUMPER segments to each other (see Figure 10-5).
So that two straight pieces attached with an angle are separate segments. Also, the phrasing of R33 implies that the end of the segment includes the corner:
BUMPERS must be supported by the structure/frame of the ROBOT (see Figure 10-8). To be considered supported, a minimum of ½ in. (~13 mm) at each end of each BUMPER wood segment must be backed by the FRAME PERIMETER (≤¼ in. gap). “Ends” exclude hard BUMPER parts which extend past the FRAME PERIMETER permitted by R31-B. Additionally, any gap between the backing material and the frame:
As such, it appears that you need another 3/8" or so of frame perimeter extending from each corner across the front/back, though if you really do mean that the frame cap is greater than 1/2", then you’d be good to go.
The idea was that the side bumper rail extends to meet the front and back bumper segments. The rail would be 1x1" tubing, so the front/back bumper segments would be supported by 1" in each corner. If I’m misunderstanding your concern, can you clarify?
Sorry, I probably should have explained the diagram. The two drawings are of the same robot chassis. The top picture is a front view and the bottom one is a top view.
Assuming the blue parts are bumber assemblies (including wood backing) and the gray parts are robot frame, not bumper hard parts, then yes they are legal.
One confusing part is what I read to be the same dimensions, you have one as < 6 and one as > 6
Sorry, the bottom < 6" should be < 8" (i.e. doesn’t exceed the support gap limit). You’re correct about the blue being bumper and gray being frame. I guess I should have gone over my diagrams a few more times before posting.
Just to clarify my understanding… the top diagram, showing the front view, is a cross section of the bumper mount, sliced at the location of one of the axles. The top view shows supports outside the wheelbase where the bumper is presumably supported along it’s entire height, rather than just at the top edge?
I’m probably being a bit pedantic here… I don’t think you’ve designed a bumper that is only supported along the top 1/2" or so… it would be very difficult to build a sturdy bumper that way… just wanted to make sure that the bottom edge of the bumper was supported, too… lest it bend inwards after being hit down low.
You’re correct about your understanding of the drawing. The bumper here is only supported from the top inch on the sides, and from the bottom 2" on the front/back. This isn’t actually the design of our robot, just a gedankenexperiment to see if this idea is legal. If I were making it in real life, I would definitely make sure that however the bumper is mounted it can withstand hits from all angles.
Good now. Not always easy to tell if just a mistake or a major misunderstanding. Wouldn’t want you or another team to get a nasty surprise during inspection - rebuilding bumpers isn’t fun. Cheers.
Just that those side rails don’t look 1/2" wide, much less 1" wide, unless you have enormous wheels and break frame perimeter rules. If that’s 1" tubing that goes to the bumpers fore and aft, you should be OK.
OK, There are multiple rules that apply to this question. The 6" minimum length is measured along the frame, not the length of the bumper segment or backing material. When a bumper segment is mounted, the supporting frame segment must be a minimum of 1/2" wide at each end of the segment (to satisfy the design of the kit chassis) and also satisfy a minimum of 8" between supports. So the 6" bumper segment at the corner must be supported at both ends with a minimum frame support of 1/2". No end of a bumper segment(s) may be unsupported.
