Best methods of bumper mounting?

[notmattlythgoe]

Originally Posted by JesseK

We used Rivnuts this year. In 55 matches and approximately 60 bumper swaps (including practice/etc), we stripped 3 of the Rivnuts. The last time one stripped, removal of the rivnut caused a bigger hole in the frame which then wouldn't accept a new rivnut. So we had to drill through and put in a through-bolt.

Next year, we may go to what 2363 had - see attached.

Previously the pins were vertically mounted, but I was much more pleased with the horizontal mount this year. Much sturdier.

[Chris is me]

Originally Posted by sanddrag

The 1" limit in the picture is placed over the inside and outside surfaces of the bumper plywood.

This isn't correct - the 1" limit is from the frame perimeter outward (away from the robot), there's no limit on how far inside the frame perimeter you can go.

[evoluti1]

Originally Posted by philso

There have been many different excellent attachment methods mentioned in this thread. The most important thing to do is to pick one and design it in along with the rest of the robot rather than leave it as an afterthought.

THIS is the most important advice. Assuming your latches/pins are strong enough, a well-integrated design will have a much bigger impact on reliability and ease of use than which particular pin you buy.

If your frame tweaks and you end up needing a hammer to get your bumpers on and off, all of a sudden you won't care that you can remove your latches in 1 second instead of 2 seconds. Be sure your frame is strong and won't permanently parallelogram or deform when you get hit. A bellypan, be it plywood, polycarbonate, or laser-cut aluminum helps a lot with this. It doesn't have to be sophisticated.

Mount bumpers such that impacts get distributed along the length of horizontal member, rather than being concentrated at attachment points. If you're running WCD, you may need to design an additional rail above your wheels to accomplish this.

[suttonrc]

Our team tried out these snap slide latches for the 2016 game and had a good amount of success with them.
http://www.mcmaster.com/#standard-draw-latches/=12g6itm
You bolt the pin to the top of your drive base frame and mount a piece of angle aluminum to the inside surface of your bumpers to mount the latch.
No tools necessary to take on or off the bumpers, no nuts, bolts, pins etc. to drop. Mounts and unmounts bumpers in a matter of seconds.

[ollien]

Originally Posted by suttonrc

Our team tried out these snap slide latches for the 2016 game and had a good amount of success with them.
http://www.mcmaster.com/#standard-draw-latches/=12g6itm
You bolt the pin to the top of your drive base frame and mount a piece of angle aluminum to the inside surface of your bumpers to mount the latch.
No tools necessary to take on or off the bumpers, no nuts, bolts, pins etc. to drop. Mounts and unmounts bumpers in a matter of seconds.

Which item specifically? You linked to the general McMaster page for draw latches.

[philso]

Originally Posted by evoluti1

THIS is the most important advice. Assuming your latches/pins are strong enough, a well-integrated design will have a much bigger impact on reliability and ease of use than which particular pin you buy.

If your frame tweaks and you end up needing a hammer to get your bumpers on and off, all of a sudden you won't care that you can remove your latches in 1 second instead of 2 seconds. Be sure your frame is strong and won't permanently parallelogram or deform when you get hit. A bellypan, be it plywood, polycarbonate, or laser-cut aluminum helps a lot with this. It doesn't have to be sophisticated.

Mount bumpers such that impacts get distributed along the length of horizontal member, rather than being concentrated at attachment points. If you're running WCD, you may need to design an additional rail above your wheels to accomplish this.

Even if you use the same attachment system that worked well for another team but left the bumper design as an afterthought, it is likely that attachment system will not work as well for you.

The ones we used this year were part of the CAD and untrained students could get a set on or off within two minutes on the first try.

The rest of Evoluti1's advice is also really good, especially when there is a lot of defense to be played.

[Bryce2471]

I think 2471's bumpers this year should be contenders for "best bumpers" and "best bumper mounting method." Here are some pictures of the mounting system and the bumpers themselves after several intense competitions:
https://scontent.fsnc1-1.fna.fbcdn.n...4f&oe=579B762B
https://scontent.fsnc1-1.fna.fbcdn.n...0a&oe=57E0D1C9
https://scontent.fsnc1-1.fna.fbcdn.n...4e&oe=579F2BAC

The bumpers slid on from the top. Quarter inch bolts fit into slots in the drive plates and plastic latches clicked around the front and back frame rails. A couple of people could remove or attach a set of bumpers in less than ten seconds.

Also, a set of these bumpers was stronger than most robots' frames!

[suttonrc]

Originally Posted by suttonrc

Our team tried out these snap slide latches for the 2016 game and had a good amount of success with them.
http://www.mcmaster.com/#standard-draw-latches/=12g6itm
You bolt the pin to the top of your drive base frame and mount a piece of angle aluminum to the inside surface of your bumpers to mount the latch.
No tools necessary to take on or off the bumpers, no nuts, bolts, pins etc. to drop. Mounts and unmounts bumpers in a matter of seconds.

Originally Posted by ollien

Which item specifically? You linked to the general McMaster page for draw latches.

Whoops! This link should be more specific:
http://www.mcmaster.com/#1872a72/=12gougp

[SpoonMechanic]

We used cleco clamps. Do not use clecos for a game as violent as Stronghold. Actually, we probably won't use them even if there's not a lot of contact in any future game. Our bumpers fell off.

[bmoore]

Originally Posted by PAR_WIG1350

The obvious response to this is to use the right bumper as the attachment mechanism for the left bumper.

About that.... 2502's bumpers in 2014 were very interesting. Our electronics, drive modules, and just about everything else were super compact in the robot. The original plan was just to put bolts in the bumper, put the other side of those bolts through the frame, and then put nuts on the back to hold the bumpers on. Except that we couldn't reach the bolts to put nuts on the back. So instead, we used the bolts merely as a locators and strapped the bumpers to each other. So we ran webbing through our robot and tensioned it so the bumpers couldn't pull away from each other. Needless to say, the inspectors didn't like us very much.

TO CLARIFY: I DO NOT RECOMMEND THIS SYSTEM OF ATTACHMENT! It took upwards of 10 minutes to put the bumpers on and the only reason it didn't screw us over, especially in elimination matches, was because we had reversible bumpers. It was just a little bit hilarious so I thought I'd share.

This year, we had pieces of angle with holes drilled in them attached to the bumpers. Our frame was 1x2 tubing. We put pins through the holes in the angle and through the frame. It worked well, but they could have been a little more secure. Definitely paying attention to this thread to find ideas for next year!

[bstew]

Originally Posted by bmoore

It took upwards of 10 minutes to put the bumpers on.

How did these even pass inspection? You seem to indicate they took more than twice the guideline time to remove. According to the 2014 game manual:

Originally Posted by 4.6.7 R25

BUMPERS (the entire BUMPER, not just the cover) must be designed for quick and easy installation and removal.

[bmoore]

Originally Posted by bstew

How did these even pass inspection? You seem to indicate they took more than twice the guideline time to remove. According to the 2014 game manual:

It's a loose rule. We could also get them off very quickly, it just took a long time to put them on. The rule is phrased as "removable by two people in fewer than five minutes." We could remove them in about 45 seconds. It was a nitpicky way to get around the rules to be sure, but we really didn't even get questioned on it. They were secure, that's the important thing to most inspectors.