Bumper Design
 

Every year we put off making bumpers to the last week of the season, slapping them together before we get to the competition, sometimes stapling them on the bus. Furthermore, they often aren't well integrated into the frame and take a long time to change between matches. We don't really like bumper covers as they tend to look rather poor.

I was wondering how other teams deal with creating bumpers that are easy to take on and off between matches and stay on sturdily during them. Specifically I'm looking for mounting hardware that others may have worked with that is good. Usually we use wing nuts and bolts which are quite finicky.

Thanks in advance!

Re: Bumper Design
 

We put C-shaped brackets on the back, sized to fit neatly over the frame rails with no slack. We drill a vertical hole all the way through each bracket and rail. Then we put a clevis pin or hitch pin through to lock it and latch the pin so it doesn't fall out if the robot is inverted or takes an upward hit to the bumpers. Solid connection, rapid installation and removal (as long as we put each bumper assembly on the correct side for the holes to line up).

Re: Bumper Design
 

Last year we designed our bumpers to be held in place by bolts fastened by some quick release pins,https://encrypted-tbn2.gstatic.com/i...kQsVL_cfhEVPyg
something like that, and we were able to change them pretty quickly once we got the hang of it..

Re: Bumper Design
 

People have suggested quarter turn fasteners before, similar to the fasteners used in race cars.

Re: Bumper Design
 

We essentially permanently mount our bumpers (we can take them off if needed). Instead of switching them we have it so we sow the fabric so we can just flip it over. It takes seconds and looks much better than a cover.

Re: Bumper Design
 

^ can you post a pic, I am not following the concept. Thanks

We also use the C channel on the back, over a 1" frame rail, then a pin with a clasp that you would see on tractor implements.

Re: Bumper Design
 

I believe we do the same essentially

Re: Bumper Design
 

Our team has been thinking on how to do something similar; however, we're not entirely sure on how to go about it. Is there any way you could post a picture, or a diagram of how your flip design for your bumper works?

Re: Bumper Design
 

I believe this is what they're talking about.

Re: Bumper Design
 

K-Botics 2809 Reversible Bumpers White Paper

My unbiased opinion would be to start here :rolleyes:

Re: Bumper Design
 

Something that also works rather well is to have connected bumper sections connected via a hinge.

For example, on our 2012 off season robot, we had a cutout in the front of the C-Frame, to pick up the balls. our bumpers were in two parts, each covering one long side, one short bit at the front of the robot and half of the back.

The connections between them were hinged. That enabled us to bend the outer two pieces of the bumper out a bit more, making it far easier (and less frustrating :) ) to put on.

Re: Bumper Design
 

Hinges can be tricky, as far as inspection goes. in 2008, we used hinges to hold our smallest pieces on (WAY less than 8", back then it was legal), and it took some convincing that they were mounting hardware. It would have hurt to redesign the bumper mount in the pits.

I'd like to get inspector opinions on hinged bumpers. (To be absolutely clear, not Articulating bumpers, just bumpers connected together at the hinge to make them easier to fold around the robot.)

Re: Bumper Design
 

The first thing to watch out for is whether those hinges may be counted as part of the bumper, part of the main robot itself, and/or a separate thing. (The rule refers to "any fasteners and/or structures that attach [bumpers] to the ROBOT".) The rules are ambiguous on this point, but I'd tend to give a team the benefit of the doubt if they interpreted the rule in either of the first two ways.¹ Confusingly, "removable fasteners" are explicitly part of the bumpers.

A related issue is whether the bumpers are part of the robot—this is complicated and annoying because of the different senses of the word robot, but once again, given the ambiguity, I'd give the team the benefit of any reasonable interpretation.

The current rules call for "a rigid fastening system to form a tight, robust connection to the main structure/frame [of the robot]". Many sets of hinges could satisfy this, installed correctly. It doesn't have to be a specific type of mounting hardware anymore (threaded fasteners were once specified).

With regard to bumper articulation, I interpret that as meaning that to pass inspection, and when on the field, articulation must be prevented. However, I reject the notion that bumper articulation (e.g. via hinges) during assembly of the robot is prohibited. (By definition, every robot is illegal when you're not finished installing the bumpers.)

¹ If you rule it legal as part of the robot or bumper, it counts toward that assembly's weight and size. Inspectors often need latitude to rule it one or the other on a case-by-case basis, to avoid frame perimeter and bumper hard part surgery.

Re: Bumper Design
 

That's just it. Since they attach bumpers to other bumpers, it could be argued that they are not "fasteners and/or structures that attach [bumpers] to the ROBOT"

I like them for keeping the bumpers together in more complicated bumper setups. I haven't used them as such since 2008, though.

Re: Bumper Design
 

Using hinges to hold bumper sections together at a corner is an acceptable method and the hinges and pins must be weighed with the bumper. Using this type of hardware keeps adjacent sections together especially if you are only using the minimum bumper sections at the corners of your robot.

Re: Bumper Design
 

We've used K-Botics' reversible bumper design for a couple years and found it to be very easy to use at competition. They do require the talents of a good seamster (androgynous version of seamstress?).
AndyMark now offers an entire bumper kit as well as just the hardware to fit over the C-Channel if you're using kitframe or something like it.

Re: Bumper Design
 

Our robot is made out of extruded aluminum for the chassis. We slide bolts into the front and side, then put a piece of angled aluminum on the back of our bumpers. We slide the things on with the right colors, then use home-made long bolts with a hexagon head, tightening it down with ratchets. They have never come off.

Another hint, to save time with swapping bumpers one year, we made bumpers with a flap in the middle. If we were red, it was one way. When we went to blue, we simply unvelcroed the flap, and put it to the other side, showing blue.

Re: Bumper Design
 

Thank you for the picture, it is greatly appreciated!

Re: Bumper Design
 

Our team normally uses C-channel on the back of the bumper and pins to hold it to the chassis. (We use aluminum tubing) Also, we have pretty much perfected the reversible bumper fabric. Switching from red to blue and vice versa is super simple with the system we use.