This fall, at the Battle of The Bay, we saw something that was truly remarkable (well, many things actually, but this one is the subject of this thread). One team (we forget who) had bumper fabric that rolled up/down to change color. It was kind of like reversible bumpers, but one color was essentially permanently attached and rolled down (or up, I forget which) then velcroed to secure the color for the match.
We want to emulate that this year and have a few questions.
Last year there was a rule that allowed for the corners of your bumper to be any color. This made the above mechanism much simpler. We have looked through the rules and not found this rule, but also not found anything prohibiting it (it is possible we missed it). Is it allowed to have the corners show the under-laying fabric (red) when we are blue? We think the answer is no, but want to be sure.
Is it allowable to have the second-layer color (blue) rolled-up and secured behind (or on top) of the backing material either above or below where the frame meets the backing of the bumper (probably not between)?
Has anyone tried this and come away with some advice to share?
Our initial troubleshooting thoughts are, if #1 is not allowed to have four corners to attach under the second layer, so it will be sandwiched and secured when the bumpers are blue (our default will be red, self-fulfilling prophesy and all), they will be held-on on all sides.
Maybe we need to employ a non-velcro solution (zip ties and grommets?) to ensure the blue fabric remains rolled up when the bumpers are red no matter how hard we get hit.
Thank you, that does help, but unless I am reading it wrong, that does not explicitly answer 1 or 2.
…narrow areas of underlying fabric exposed at seams, corners, or folds [are allowable].
For 1, when they mention corners, are they talking about the corners of the robot/ bumper, the corners of the fabric, or both?
For 2, They do not talk about whether hidden fabric that is stowed (assuming it remains so) will be a violation of bumper rules or robot perimeter rules. Especially if we want to use zip ties to secure them (although, I just realized we can use staples instead of eyes to secure the zip ties to the bumper backer material (we are using plywood).
We do know that weight could become the problem here.
We also make these bumpers every year. Below is a photo of our bumpers in 2016. You can clearly see the opposing color on the corner of the bumper.
And This is what the rule stated (in 2016)
The cloth must completely enclose all exterior surfaces of the wood and pool noodle material when the BUMPER is installed on the ROBOT. The fabric covering the BUMPERS must be a solid Red or Blue in color. The only markings permitted on the BUMPER fabric cover are the Team number (see R28) and hook-and-loop backed by the hard parts of the BUMPER.
I was worried about it at the time but we passed inspection just fine. As they have now included the wording about the corners, I think you will be ok. But you can always Q&A to verify. Just make sure you word the question clearly so they don’t fall back on “specific robot design”.
The search term you are looking for is “reversible bumpers.”
We use them, and they are really a big hit with the drive team. Not so much of a hit with the mentor who makes our bumpers each year, but it’s a good way to save time in the pits between matches.
Our bumpers use a combination of velcro and shock cord, and some very careful planning, measuring, cutting, folding, and sewing. It’s more work than making two sets of bumpers, but we can chameleon in under a minute.
Here’s a nice old thread about them (not ours) with pictures.
Reversible bumpers are allowed (R408D allows multiple layers of cloth) and convenient, but more involved to fabricate. If not executed well and a flap exposes the wrong color you are at risk of losing a match due to bumpers (G104 Violation Disabled).
If you are going to be at Bedford for Week 0, I would bring at least a mockup with you. There will likely be some of my fellow local robot inspectors there who can give you opinions on what you’re trying to do and how best to do it. I have plans to get there at some point in the day but I’m likely double booked so I can’t guarantee when I will get there.
Remember the bumper rules are very strict. They tell you how to make them, and deviating from that can result in great struggle at competition. Asking questions here is great, but nothing said here is going to be binding at your competition. The only way to get a real answer is to ask on the Q&A!
The rules last year were significantly loosened. As everyone was playing at home, specifics like bumper color really didn’t matter. This year the rules are back to what they traditionally have been. So don’t base decisions on what was legal last year! R405 is what regulates bumper color, and the exception in D is your only exception for showing the wrong color. D lists “narrow areas”. To me, this means a small area or strip (probably 1" or less) between two pieces of fabric that are folded up/down to change the color. A significant section, like the end of the bumper at an opening, should really be covered. When teams leave those end parts the wrong color, that’s a section the size of my hand - i can’t really call that a “narrow area”.
I have never seen this before. I would encourage you to ask on the Q&A, because it would make reversible bumpers significantly easier to make. My reading of the rules, particularly 408 D (which allows multiple layers) and the referenced figure 9-7, says no. A rolled up section of fabric would be a significant deviation from the provided cross-section, with no clear exception for it listed in the rules.
We’ve made reversible bumpers before, with the more traditional seam through the middle and a flap going up/down. Velcro can work, but it can also come loose. Making them takes significantly more time and effort than making two sets of bumpers - your time is likely better spent finding a quick and easy way to change bumpers. The rules say 2 people in 5 minutes. Swapping bumpers with 2 people in 30 seconds isn’t too hard to accomplish!
Thank you all for your replies. This is great info. A few quick responses.
@dheadley That is a wonderful idea. We are not signing up for Day0 in Bedofrd as I have a prior commitment. However, it is a good resource. We may have a contingent attend. So, a mmockup is not out of the question.
@Jon_Stratis I may ask in Q&A. I think that would alleviate potential concern and/or stress.
We have actually done this already. Our solution is 1/4 20 threaded posts attached to the robot with a block nut under the frame, and an 80/20 slide in over the frame. We use the Andymark peanut brackets on the bumper.
The problem we are trying to solve is dealing with bumpers in the Pit, on the cart, in and in our limited storage space at home.
This may not be worth it in the end, but we thought we would explore the feasibility.
We’ve been using reversible bumpers for several years. Saves a ton of time at competition. We use snaps to hold ours in place on the top or bottom side of the bumper. It’s essentially sewing two layers of fabric together, making a T shape. The left and right of the T are different colors, but the vertical is double sided and flips one way or the other.
Thank you. Did this require more fabric? It seems like it does not, but I want to be aware of this now if it will. I think we are leaning toward going with traditional reversible bumpers for sake of ease of the inspection process.
I have not been directly involved in making them, but no they don’t require any additional fabric. We’ve never had any issues with them about inspection either. At many events we’re the first ones done with inspection.