Re: Bumper Attachment for Rapid Removal
 

For the rookies here and those working with bumpers for the first time in the coming weeks...
The GDC wrote very specific rules for bumpers in both 2008 and 2009.
The rules are not open for interpretation by inspectors and the GDC believes the rules to be clear enough for compliance and understanding by all teams.
The bumper rules are intended to minimize robot damage by insuring that any robot to robot or robot to field interaction take place only through the soft parts of the bumper.
I would suggest that teams take some time this week and review the 2009 Q&A on bumpers and the bumper rules in the robot section of the 2009 manual. It will help you in the coming weeks to understand whatever changes may be introduced by the 2010 manual.

Re: Bumper Attachment for Rapid Removal
 

What our team has done, is to use 3/4" x 3/4" ( 1/8" wall ) square aluminum tubing, for the structure of the chassis, then use 1/16" aluminum U-channel
( which is 3/4" wide and 1/2" deep ) to fit onto the tubing. 2 small pieces, about 2" long are placed on the bumper board, inside, so that it is locked into place vertically, and then 2 pieces are placed to lock into the vertical structural components, to keep the bumper from moving forward and backward. We then simply drill 4 clearance holes for the nylon bolts, washers, and wingnuts ( # 10-32 ) that will hold them in place. Our bumper weight, last season was around 10 pounds, easily within specs.

Re: Bumper Attachment for Rapid Removal
 

Was chatting with RC last night and we also came up with cotter pins + clevis pins as a cheap alternative to another solution. You can just buy steel clevis pins from mcmastercarr since the weight goes with the bumpers and for the most part bumpers seem to be underweight.

http://www.mcmaster.com/#clevis-pins/=57qrqv

Then just pick your style of cotter pin to secure the other end http://www.mcmaster.com/#cotter-pins/=57qrx2

Now for the expensive solution.

http://www.mcmaster.com/#aluminum-qu...e-pins/=57qs26

Quick release pins, push button yank out.

Downside is they are about 20 bucks a piece though theoretically you need just 1 per bumper right in the middle of the span if your bumpers are secure enough they shouldn't be able to bend up at the edges if they get yanked.

Re: Bumper Attachment for Rapid Removal
 

This is very similar to what we did for 2009, and it worked fairly well for us. The bracket may have been the AM one, but I didn't make the bumpers, so I'm not sure. However, we had some issues with getting a few of the pins in - issues with lining up the brackets with the frame exactly, and a few of the pins had to be pushed in at EXACTLY the right angle...while using a hammer. If the pins had gone in a bit more smoothly, we would have had a much easier time. I have the feeling that we'll also be modifying our system this year (game pending), but the pins are much easier than what we've used in the past, so we might just stick with them.

Re: Bumper Attachment for Rapid Removal
 

I have a feeling our team will use Pins this year if we can, getting bolts out of a cramped robot to release the bumpers is not a fun experience, the first year was awful, last year was mildly better.

Re: Bumper Attachment for Rapid Removal
 

I know that last year sense our robot was made with 80/20 And we had vertical piece of it on each corner we found bolts that fit into the slots and Just mounted the bolts into the bumper back. This allowed us to just slide the bumpers on and off.

-Rion

Re: Bumper Attachment for Rapid Removal
 

Here is a vid from a proof of concept that we did in 2008.
Our 2009 robot used a shoulder-bolt form a lawnmower axel with the hex ground down. This proved quick and simple.

Re: Bumper Attachment for Rapid Removal
 

There's two good ways to do this that I can think of.

The first is if you have a reasonably solid frame, 1/4in thick or more, solid bar chassis (like 675 uses... a lot...). You could have matching holes in the frame and bumpers, tap the holes in the frame (or maybe weld on matching-thread nuts to the inside of the frame, assuming you're using weldable materials). Then what you do is get bolts that are just longer than the combined thickness of the frame member, nut if applicable, and bumper, and use that. Installation/removal is quick and easy, especially if you've got a socket driver on a power drill.

The second option should work for pretty much any frame. Pins. Do the same thing as above; holes in both the bumpers and frame members in matching place, or you could press or bolt in the male pin to the bumper. You can use either bolts or machined pins. Bolts will be cheaper but harder to drill a hole through. I really suggest using a drill press and a vice for this. Trying to drill something small while holding both things in your hand... bad idea.

Anywho, so what you do is once you've got your holes drilled and your pin ready, you mock it up on the chassis, and mark where to drill your hole. pull it apart, drill the hole, and put it back together with a cotter pin through the hole. For extra strength, put an appropriately sized washer in between the cotter pin and the frame member.

I can't guarantee either of those will conform to FIRST rules (depends on how you design them, honestly), but that's on you. Option #2 will be quicker to get on or off. Both are pretty quick though.

Re: Bumper Attachment for Rapid Removal
 

This is more or less what 973 used to do, and now does. We have been happy with both methods with the exception of losing pins.

Re: Bumper Attachment for Rapid Removal
 

Idea for preventing that, taken from race cars;

http://www.irvansmith.com/scart/hood..._term=HOD-2001

Something like that. Thin cable, one side with the pin, the other bolted down to the chassis. No worry of losing pins, they'll be attached to the frame via cable. Pull the pin out, take off the bumpers, and get to work. no worries about trying to find the pin afterwords.

Re: Bumper Attachment for Rapid Removal
 

Yup, we made lanyards after those issues.

Re: Bumper Attachment for Rapid Removal
 

We've been using a similar method since 2007. Like Adam and 973, we've had problems losing pins. We've been very happy with it and it's made many inspections much faster...

If we use bumpers this year I think we'll use a lanyard attached to the bumper to make sure we don't lose the quick release pin.