The age old question - bumper mounting

[ksafin]

Hey all.

We've suffered from difficult-to-mount bumpers for the past two years and wanted some input.

How does your team do it? Are there great ways to do it?

ALSO, what's the best way of making bumpers - IE, make each side a separate piece? Make the whole thing somehow 1 unit? Make a U-shape that's 3 sides to slide on, and then finish off by mounting the last side? What has the best balance of aesthetic appeal and ease-of-mounting?

As for mounting, I keep seeing something like a shallow aluminum c shape onto which bumpers slide onto, which I can't for the life of me understand!

Thanks.

[Jay O'Donnell]

What we've done the past few years is bolted some small pieces of c-channel with a hole onto the back of our bumpers, and then put the small pieces of c-channel on top of our frame, line up the c-channel holes with holes on our frame, and put a pin through them. As for amount of sides with separate bumpers, two years ago we used one for each for each side, and this year we made one set to fit on all sides. There really wasn't too much of a noticeable difference between the two, other than it took more time to make the singular bumper than the separate ones.

[yash101]

Though I haven't seen how one works, bumpers with a quick release seem quite nice because changing bumpers can be done with no or less tools!

MAKE SURE THE BUMPERS DONT FALL OFF IN THE MIDDLE OF A MATCH!!!

[Abhishek R]

We usually have bolts sticking up from the frame of the robot and then holes in the bumper mounts so we basically just drop the bumpers down over the robot and secure it with wingnuts. Combined with the reversible fabric colors, it takes about 30 seconds to switch/take-off the bumpers.

It also takes no tools at all to remove or put on.

[Whippet]

We always mount our bumpers on 90º angle brackets directly to the top of the c-channel using quick release pins. When we use this system, we can change bumpers in around thirty seconds by simply pulling the pins out, kicking the robot to make the bumpers fall off, line up the other set, and slide the pins back in. The pins are strong enough to keep the bumpers on the robot even when it's upside down (we use the variety with a ball bearing at the bottom of the pin), but easy enough to remove that they're not too much of a hassle for us to hate changing them.

EDIT: These are the pins we use.

[Anupam Goli]

For this year's game, our original plan was to have 1 wrap-around bumper fall into place and snap on, making a secure fit. However, the quick release system didn't end up working as the pins we ordered at the time were too short.

For simplicity's sake, we decided to use just add two pieces of L-angle aluminum to the back of the bumper, mounted such that when the bumper came down on the robot, the bumper would be resting on top of the drivetrain rails. We then used wing screws and some 8020 drop-in nuts to secure the bumper in place.

[Mr. Lim]

We've used a 2-pin quick release system for the last 2 years as per the pictures in this post:

http://www.chiefdelphi.com/forums/sh...4&postcount=87

[Dave McLaughlin]

For the last few seasons 1983 has recessed our bumper backing into the frame and then pop riveted through the top and bottom to secure it. We think that the end result is not only aesthetically clean, but it adds to the structure of the frame. The recess is created by extending the upper and lower sheer panels past the vertical walls of the frame. If you look closely you can see the thru holes for the rivets in the attached picture.

http://team1983.files.wordpress.com/.../wp_001144.jpg

[Oblarg]

80/20 angle brackets (the small type) attached directly to the frame have always been the standard method on 449, with the bumpers mounting directly through them via. wing nuts. Easy to set up, and it works well.

Last year, 4464 mounted our bumpers through holes in the c-base using washers and wing nuts, but this was a pain and I hope we don't do it again.

Both teams used separate bumpers for each straight run on the frame perimeter, and that's worked well enough that I don't see any reason why we'd change it. Corner bumpers just seem harder to make.

I am proud to report that I have never, ever seen a bumper on one of our robots fall off during a match.

[MrBasse]

I still like the added structure of having a solid full wrap bumper with no gaps. Here is our take on the quick change color set up. Just sew a loop in and fish 8 feet of elastic through, a few hog rings later and never look back.

[cmrnpizzo14]

We usually have had a C-Channel chassis so we mount vertical 80/20 channel pieces periodically around the perimeter. These pieces are only several inches high and have a thumb screw with the part you would grasp facing the inside of the robot. The bumpers have 14-20 buttonhead bolts screwed into them that stick out just enough to drop them into the 80/20 sections. Usually works pretty well, sometimes we have to use a hammer to give the bumper a little motivation.

As for our actual bumpers, we usually make 2 sets of 2 bumpers. Usually right/left or front/back depending on our robot dimensions or if we have to have a gap in our bumpers that year.

[mmcewen]

We drilled holes through the backing plywood and glued pins in to it. The pins line up with holes in the robot chassis and are fastened with small wire pins.
Our only problem was reaching the pins in the middle on our shooter side. It's super quick but only if you can reach your hand in the right spaces.

[bachster]

Originally Posted by Dave McLaughlin

For the last few seasons 1983 has recessed our bumper backing into the frame and then pop riveted through the top and bottom to secure it. We think that the end result is not only aesthetically clean, but it adds to the structure of the frame. The recess is created by extending the upper and lower sheer panels past the vertical walls of the frame. If you look closely you can see the thru holes for the rivets in the attached picture.

http://team1983.files.wordpress.com/.../wp_001144.jpg

Dave, this looks like a very slick way to attach bumpers, but my initial reaction is that it would be in violation of R21-F (must attach to the FRAME PERIMETER of the ROBOT ...) and/or 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...)

Since your FRAME PERIMETER (definition copied below for reference) is the top/bottom horizontal plate, it seems your BUMPERS are backed by an interior part of the robot, not the FRAME PERIMETER. Alternately, if you intend to define your FRAME PERIMETER as the vertical face which backs the bumpers, then the robot is in violation of the STARTING CONFIGURATION requirement.

Can you (or any experienced inspectors) help me understand how this attachment method is legal?


FRAME PERIMETER: the polygon defined by the outer-most set of exterior vertices on the ROBOT (without the BUMPERS attached) that are within the BUMPER ZONE. To determine the FRAME PERIMETER, wrap a piece of string around the ROBOT at the level of the BUMPER ZONE - the string describes this polygon.

[dellagd]

We just attach them in some solid yet semi-removable way. We dont actually ever take them off in competition because we just use reversible fabric on the bumpers. SOOOO much easier to just pull some velcro and flip the fabric instead of taking the whole thing off. We actually just did it in que.

[Tristan Lall]

Design your bumpers so that each segment is removable by one person in less than 10 s, yet won't shift or fall off during a match. This is easy using a locking pin system (if you pay close attention to hole tolerances and alignment), but a bit harder if using threaded fasteners (try wing screws and threaded inserts for woodworking).

For bonus points, consider using the bumpers as robot structure (plywood can be quite strong). In that circumstance, a little extra effort to remove the bumpers (like 60 s per segment) is perhaps justifiable.