# Round Bumpers?

Is there a legal way to make a round bumper? In some years as to robot size all that is specified is something like 120in circumference that could allow for some or all of it to be round. Could not find in any year something for a round robot. Lets go extreme - asssume a circular robot frame. Now you can bend plywood to a degree. 3/4 in is tough to bend but 1/4 in not so much so could one laminate 3 ea 1/4 in bent plywood pieces together? after all plywood is sheets of wood laminated together so that would be then a DIY piece of plywood. The pool noodles and cloth would be no problem. Just as I could not find something (maybe I missed it) that said the robot has to be a poligon with no more than X sides and each side measuring at least xx in. We had an octagonal frame a few years ago. So how about a round frame and bumpers?

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Here is an example round robot:
https://www.thebluealliance.com/team/3574/2013

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Is a round bumper theoretically possible? Sure. Is it actually feasible? Not really. 3 pieces of 1/4â€ť plywood is not a single piece of 3/4â€ť plywood, which is what the rules require.

That being said, whatâ€™s the big difference between a true circle and a 10- or even 20-agon frame?

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Question then would be if 3 pieces of 1/4 in plywood would make 1 piece of 3/4 in plywood and how would you tell the difference as the definition of plywood is sheets of wood glued together with alternating grain. So gluing 3 pieces of 1/4 in plywood together would make a 3/4in plywood by definition. Or even taking 3 pieces of 1/4 in any wood glued together would be plywood by definition if the grain alternates. As for a 20agon - possible as 20x6 = 120 but a circle would be cooler then

Just musing on a Sat. morning

Cant seem to find a pic

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â€śplywood or solid robust woodâ€ť is the wording of the bumper rule. I donâ€™t view that as mandating the use of plywood only. Plausible argument could be made that bentwood lamination meets the criteria of solid robust woodâ€¦

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Why would you want round bumpers, are octogones not good enough for you?

Its a theoretical question atm and one of feasability and how to do it if one would want/need to. Its born from the idea how to possibly have the biggest volume/area within the dimensions and a circle give the biggest area to its circumference and it probably would never be a perfect circle as one still would have to mound some wheels etc Plus a round bumper could be helpful twisting out of a pin possibly or make it tougher to pin someone

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Nonagons are where itâ€™s at. 100% of nonagonal robots have won Einstein last I heard.

Back the the original question, thereâ€™s nothing that I can find saying you canâ€™t steam the wood to get it soft and bend it around a form or your robot. Thereâ€™s actually been some discussion on that in days of yore, if the threads can be dug up.

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We did a round robot in 2014, with one continuous bumper segment. We did the 3 sections on 1/4 in plywood to make them.

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If a full circle bumper isnt feasible, try something like 971â€™s 2014 robot.

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Cool - that was an awsome year

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OK, there is a few items here. For the circular robot frame, bumpers rules specify that bumpers must cover both sides of every corner of the robot frame. Therefore a circular robot is considered to be an infinite number of corners and needs to be completely covered with bumper.
Three pieces of 1/4" plywood is most defnitely not the same as 3/4" plywood. Anyone who has done this in the past and was able to get by inspections, consider yourself lucky. The GDC was actually vocal about this in the 2019 season.
While there has not been any Q&A about this recently, kerfing one side of the plywood and bending into the shape of the robot frame has been allowed in the past. That is no guarantee that future seasons will allow this. Of course there are right ways to do things and wrong ways to do things. Each implementation will need to be examined by the LRI on site to insure compliance.
As to the functionality of round robots, each team should make their own design decisions. Round designs have proven competitive in some past games but remember that some of those games were pre-bumper. Some of the criteria in your design should be the wheelbase compared to bumper, the height of the center of robot mass with regard to driving stability and the game itself.

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Isnâ€™t plywood defined as thin layers of wood glued together? Would teams be allowed to manufacture their own plywood from single ply stock? I donâ€™t plan on ever doing this because it violates my personal rule on overcomplicating simple things, but I canâ€™t see the distinction between 3x 1/4" ply and 3/4" ply.

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R31. BUMPERS must be constructed as follows (see Figure 10-6):
A. be backed by Âľ in. (nominal) thick (~19mm) by 5 in. Â± Â˝ in. (~127 mm Â± 12.7 mm) tall plywood or solid, robust wood.

In other words: Robust wood consisting of solid or ply construction, 3/4" thick.

Doesnâ€™t 3/4 solid pine count?

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To expand on thisâ€¦ kerf-cut plywood has been allowed but custom plywood layups are illegal?

@Al_Skierkiewicz can you shed some light onto why the decisions were made this way? Any reasonable layup of 3x1/4 plywood (or some layers of thickness equivalent to 3/4in plywood) would be much stronger than kerf-cut 3/4in plywood, all else being equal. Why would an arguably more-robust solution be ruled illegal?

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I can only guess but I know that the plys are thicker on 3/4" than on 1/4". (Unless you are looking at furniture or marine grades which are prohibitively expensive for bumpers.)

Thinner plys make stronger plywood.

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