Need help with bumpers

[=Martin=Taylor=]

We had tiny flanges on our bumpers last year that locked into our 80/20 frame rails. Each bumper was attached with only ONE bolt. Never had a problem taking them on or off.

A crude picture is attached. You can see the three flanges on the left bumper.

[Gdeaver]

One thought on bumpers and thier mounting. The plywood and aluminum frame can be a stuctural part of the robot. The mounting can be very critical if a team wants to integrat the bumps into the frame as a structural member.

[Jeff K.]

We used blocks of abs that were mounted to the back of the plywood with some machine screws. They fit into 2x1 aluminum tubing we welded onto the side of the chassis and then we drilled a hole vertically through it all and held it in with a clevis pin and a hairpin cotter pin. For the front and back, we drilled 2 holes that the pins went through, so the pin took the place of the bolt. Looked cleaner and was easier to remove for doing maintenance and inspection. Didn't have any problems and it held it nice and snug.

[Mike Martus]

Caution!

Bumpers have specific materials, specifications and mounting rules.
It is very important to read the section of the manual that covers this.
Violations will not pass inspection.

Hey... there may be changes for 2008, who knows?

[EricH]

Originally Posted by Mike Martus

Caution!

Bumpers have specific materials, specifications and mounting rules.
It is very important to read the section of the manual that covers this.
Violations will not pass inspection.

Hey... there may be changes for 2008, who knows?

Unless you make custom bumpers, in which case you need to have them fit in the box and 120 pounds (or whatever it is) weight limit and you may as well make them an integral part of the robot. You still need to make sure to have them qualify as bumpers, though.

[Blue_Mist]

We weld our aluminum frame together and bolt the bumpers directly onto the frame. We use bumpers on sides only since the front and back are occupied, two bolts and two nuts per side. The bumper nuts are tightened before every match and checked after every match. Finger-tight for demos, since that's when things go wrong, and wrench-tight for matches despite things going wrong, since that's when the bumpers are actually needed. We use regular nuts because they need to come off regularly for robot repairs. The bumpers are easy to remove and very sturdy.

[Jeff K.]

Originally Posted by Mike Martus

Caution!

Bumpers have specific materials, specifications and mounting rules.
It is very important to read the section of the manual that covers this.
Violations will not pass inspection.

Hey... there may be changes for 2008, who knows?

The inspectors said the blocks were just ways of mounting it, and it did not exceed the 15 lb weight limit or the 3oz/in^2 limit. They were more efficient, and the inspectors and judges like the design.

[dtengineering]

If you are using the KOP frame we had good luck with a technique that is probably in the CD image archive somewhere... at least that is where i think we got the idea from.

Use an eyebolt. If you pick on the right size (1/4" seems to work nicely) you can just run a bolt through the KOP frame rails and eye of the eyebolt to hold it together.

To screw the eyebolt into the bumper we took a small piece of 1/4" band iron, drilled and tapped a hole for the eyebolt, along with a couple of small screw holes.

We drilled a hole in the plywood for the eyebolt to pass through, then screwed the band iron into place on the inside of the bumper.

This worked well.

Jason

[joeweber]

I was thinking of velcro, but there are spacific rules on how it should be bolted on. My question to those rules are: we want to build a round robot, can we make our bumpers in a circle? Making our own plywood in a curve would not be a problem. How far outside the robot frame can the plywood be mounted? I know that the bumpers can only be so thick but dose it have to be up tight to the robot?

[M. Mellott]

Last year, with 4 seperate bumpers, we used 1/4-20 carriage bolts (large, smooth button head backed by a square shank before the threads begin) through a thru-hole in the spec-size plywood--4 bolts for the longer sides, 2 for the front/back. The square shank bites into the plywood and keeps the bolt from turning while being tightened. The bolts ran through holes drilled into the side frame members (1.5"x1.5" welded aluminum tubing frame) and fastened by wing nuts that are hand tightened (i.e. no tools). We used lexan panels for side shielding on the base frame held on by velcro, which allowed us to rip off the panels and have easy access to the wing nuts for quick removal of the bumpers. We usually checked between matched to make sure none of the wing nuts loosened as part of our pre-match checklist. There were some doubters at first on the wing nuts, thinking they would loosen and fall off during a match, but we didn't loose a bumper (or a nut) all season. The only issue we had was placing the bumpers back on and getting 4 bolts through the blind holes on the inside of the frame rail--takes a little practie to do it quickly.

[EricH]

Originally Posted by M. Mellott

Last year, with 4 seperate bumpers, we used 1/4-20 carriage bolts (large, smooth button head backed by a square shank before the threads begin) through a thru-hole in the spec-size plywood--4 bolts for the longer sides, 2 for the front/back. The square shank bites into the plywood and keeps the bolt from turning while being tightened. The bolts ran through holes drilled into the side frame members (1.5"x1.5" welded aluminum tubing frame) and fastened by wing nuts that are hand tightened (i.e. no tools). [. . .]The only issue we had was placing the bumpers back on and getting 4 bolts through the blind holes on the inside of the frame rail--takes a little practie to do it quickly.

We had the same system, but used two on each of the 5 bumpers (one per side, two for the front). We also labeled the bumpers to show where they went and which way. Took 5-10 minutes, maybe 15. No wing nuts though.

[popo308]

We originally had a nice bumper mounting system but then we realized the bumpers could not go off the group with are robot. So we mounted them to the bottom of the legs. Still a pretty good system but then we ended up talking off are lifts for a better system and we really didn't have time to prepare anything else so are last system was some wood screws through the frame rail into the bumper... It worked but it was kind of just thrown on there so next year hopefully we can get a system down good.

[Al Skierkiewicz]

The 2007 rules do not specifically address a round robot base. In the robot section of the rules, Rule 37 gets very specific about bumper design. Those bumpers that meet the criteria may be weighed separately from the robot weight. Those bumpers that do not, cannot qualify for the exclusion and must be weighed with the robot. I would put this question to the Q&A as soon after kickoff as you can IF you still plan to use a round base after the game is announced. Decisions made on robot design before kickoff may not be the best fit for game play after kickoff.