Whats the Best way to do Bumpers?
 

During our Monday meeting my team got to talking about last years bumpers. We concluded that although our bumpers worked quite well, there were better ways to do them. I was charged with finding a past thread on the subject if one existed, and starting a new thread in the event that it didn't. I didn't see one so here goes...

I'm basically wondering:

1: How did your team do your bumper mounting or otherwise? (I know there is that very cool flip method.)

2: What was the best bumper mounting you saw during the season, I'm talking about either functionality or looks. (on the killer bees we're all about looking good:p.)


To get the discussion rolling: my team made pretty standard bumpers which attached to the frame via 1" aluminum L bracket and some... I'll call them easy bolts for lack of a better term as they could be screwed and unscrewed quickly be hand. However, we had 8 different bumper parts which were kind of cumbersome. (4 red 4 blue)


Thanks in advance, this will be a great help.

Re: Whats the Best way to do Bumpers?
 

We used 2 L-brackets per attachment point (2 or 3 points on each bumper). There were holes drilled through the outward part of the L-brackets as well as through our robot's frame. To attach the bumpers, they were placed on the frame and then pins (basically these) were placed through the holes so that the pin went in the top bracket, through the frame, and out the bottom bracket.

For color of bumpers, we attached snap buttons to the bumper and to our blue fabric, which allowed us to go from blue to red almost instantly with one person per bumper (red to blue was obviously harder).

This system allowed us to switch from red to blue in < 3 minutes with a 4 person crew. Took one person to remove each bumper (we had 4), then each person could attach the blue fabric, then it would take 2 people to put each bumper back on (one pushing it in, the other placing the pins).

Re: Whats the Best way to do Bumpers?
 

If you are using the kit frame material, I highly recommend the bumper brackets that are sold by AndyMark. They slide right over the frame rails and you drop a hitch pin or bolt through the holes. About 30 seconds to remove or replace a bumper. They are not cheap, especially if you are making 2 sets of bumpers, but are worth the investment.

The same technique can be used for non-kit frame rail materials, if you have access to a metal brake or a sponsor that can bend you some. One of my teams did that a couple years ago with great results. Or find some channel the right size and use that. That can also be done with the kit frame.

I'm not a big fan of permanently attached bumpers, I strongly recomend a solid, well thought out method that allows them to be removed and replaced easily. Keep in mind that the rules recommend that one person should be able to do the task in under 10 minutes. Also keep in mind that the bumpers have to be off the robot for weighing and sizing. You would not believe the number of robots that it takes an hour to try and put the bumpers back on.

When I give seminars, I emphasize that the bumpers need to be part of the design from the beginning, not something that is hacked on to the robot on ship day or at the regional. It's very obvious when inspecting a robot if this was the case or not. If you pay attention to what you are doing, that 3/4" slab of plywood can provide a lot of structural integrity to a lighter weight frame.

Also, if you are only going to have one set of bumpers, and looking good is important to you :) , making slip covers for each bumper that attach with snaps or velcro and fit snugly is strongly recommended. The elastic covers that were available last year came loose or got pulled off due to robot-to-robot interaction. Saw some penalties due to the bumper cover hanging down below the bumper zone. Duct tape and/or cable ties are not an acceptable method of trying to hold the cover back on. I know it's a pain to have to store them in the pit, but I recommend having two sets so you don't have to worry about covers coming off.

Re: Whats the Best way to do Bumpers?
 

This past season we made two sets of bumpers. We put threaded inserts into the plywood. Then we attached the bumpers to the robot with thumb screws.

We attached the fabric to our bumpers with staples. We find that this works best. After we staple one side of the bumper we pull the fabric tight( a 2 person job) and staple it while gradually moving down to the ends of the bumpers. this leaves us with bumpers that are very tight. We like test them by flicking them if it is wrapped tight enough, you will hear a subtle drum like sound.

Unfortunately Im not sure what the best bumper design is that I've seen, there are alot of methods that have the same result.

Re: Whats the Best way to do Bumpers?
 

our bumpers this year used wing nuts to attach, 2 people could change the colors in less than 45 seconds

Re: Whats the Best way to do Bumpers?
 

Our bumper design worked our extremely well for us this past year. We took some 3" angle brackets(placed in the corners) and screwed all four sides of our bumpers together in the permanent shape of the frame perimeter. We then added 1" angle brackets to attach our bumpers to the chassis. To put the bumpers on the robot, we would just slide the bumpers over the top, like how somebody would put on a t-shirt. To fasten, we drilled a hole in the 1" angle bracket and the chassis. We dropped a bolt with a loop of surgical tubing attached near the bolt head and looped the surgical tubing around the other end of the bolt. We did this on all four sides and it worked perfectly. With four students, we were able to change our bumpers in about 30 seconds.

The best bumper design that I saw this year were the ones with the folding fabric. They had Velcro on the top and bottom of the bumpers, and they would peel one side off and fold it(the seam ran horizontally along the middle of the bumper) to the other side, which was the opposite color.

Re: Whats the Best way to do Bumpers?
 

My team used 80/20 stantions mounted to the kit rails and screwheads coming out of the plywood to fit into the 80/20. It was very secure and allowed for easy removal. For covers, we made a set that velcro'ed to the acutal bumpers. It was sturdy as well, but it might lack the visual wow factor you are looking for

Re: Whats the Best way to do Bumpers?
 

We did the flip method with Velcro and to attach to the frame we used threaded rod type things that stuck in the wood and we put wing nuts on them. Very Sturdy and Easily removable for Weigh in.

Re: Whats the Best way to do Bumpers?
 

I thought our 2010 robot's bumper worked pretty well. One of our mentor took some time to cut and sew a red cloth cover for the main bumper, it was attached by two staples on the back I think. We had velcro and a blue cover since we didn't want to spend the time and resource to make another set that has to be reattached on and off during competition.

We had holes drilled into the robot and had bolts attached to the inside of the bumper so a wingnut could be fastened onto it and hold the bumper in place.

The blue cover wasn't asthetically nice to have on, and putting velcros on the red bumper probably didn't help, but we encountered no problems with it.

Re: Whats the Best way to do Bumpers?
 

We had two sets of bumpers, with a very similar attachment method to this. We used the same pins, but used 1" ID C stock and put that around 1" x 2" tube stock. We then drilled a hole through both pieces of metal, through all 4 walls. We then dropped the pin through the hole. We could take a bumper off in 5 seconds, and put another one on in 15 seconds. If we have bumpers again next year, that's how we are going to do it again.

Re: Whats the Best way to do Bumpers?
 

All these methods work well. BUT, the VERY BEST way to construct and mount bumpers is in strict accordance with the 2011 FRC Manual. ::rtm::

Re: Whats the Best way to do Bumpers?
 

Team 148 had a one-piece bumper (1 red and 1 blue), that fit perfectly over the frame of their robot. I watched them change it out, and it only took them about a minute to do it. It was also made out of a very slick material, so it would 'slip' off an opponent's bumper.

Very cool!

Re: Whats the Best way to do Bumpers?
 

Best or easiest? I'd go with easiest for bumpers any day.

Our team attached our four bumpers together with angle brackets to make one large bumper and then had corner plates that laid horizontal to the top of the robot frame and attached to the robot with wing nuts. Took 2-4 students around 20-30 seconds to install.

Re: Whats the Best way to do Bumpers?
 

Team 118 also had a one-piece (see photo).

The cool thing about them, was that they brought extras, and were giving them to teams that had not done their bumpers at Lonestar. They brought a big stack of them, but by the end of Thursday, they were all gone.

Re: Whats the Best way to do Bumpers?
 

This past year we used the flip method to change our bumpers which worked out pretty awesomely. Luckily we had a talented seamstress on the team that made the bumper covers for us that worked excellently all season.

As for mounting them, we used L brackets to hug the 1" box tubing that ran around the frame perimeter of our robot. We then just dropped a pin through the L brackets and the box beam. Took ~1 minute to remove all the bumpers from the robot.


Another cool thing we did in 2009 was use the same clips that hold brooms to a wall to hold the front bumpers to our robot. This was part of the rule that required 6" of bumper to be backed by a solid frame member. Because our robot had a wide intake in the front we wanted to minimize the bumper/frame member required to do this. Below is what we ended up with. It worked out great, we never had a bumper fall off and they were literally snap on and snap off.



-Brando

Re: Whats the Best way to do Bumpers?
 

Always a good reminder! Don't count your chickens until they hatch and don't make firm plans for a bumper design until the game rules are released!

This is Team 1511's approach as well. Easy on, easy off!

(emphasis mine)

You can't say enough about the talented seamstresses / seamsters who sewed fitted covers and flip bumpers this past year. As the person running the sewing machine for our team, my firm belief is that although the flip bumpers looked awesome, given the chance to do it again, our team would have two sets of bumpers.

Re: Whats the Best way to do Bumpers?
 

I agree completely. It took me way to long to do the reversible cover. We loved having it but I'm not sure I would want to spend the time making it again.

Also we used ball lock pins from McMaster to hold our bumpers on the last 2 years. thay are the easiest thing we've found.

Re: Whats the Best way to do Bumpers?
 

I did not run the sewing machine so I cannot speak on how difficult it actually was (although I know our seamstress spent a considerable amount of time on it). I did really enjoy having the flip as opposed to an additional set though. I guess that will be one of the discussions we have next season, assuming similar bumper rules. If FIRST does go with similar bumper rules for 2011, it may be worthwhile to look into having the flip covers mass produced.

-Brando

Re: Whats the Best way to do Bumpers?
 

If team 811 needed a set, they could have kept the numbers on.

Re: Whats the Best way to do Bumpers?
 

You want to get me a copy of this rule book? :rolleyes:

Re: Whats the Best way to do Bumpers?
 

Can do, but due to circumstances beyond our control, it will not get to you before January. It will have the bumper instructions, though.

Re: Whats the Best way to do Bumpers?
 

We countersunk 2 "U" chanels into the plywood for the bumpers than wraped the fabric around it. The "U" chanels slipped over the frame we than slipped eye bolts through drilled holes and install wing nuts. This allowed us to remove and install with out tools.

I wonder if we can use the same bumpers for next year? That would save some money and work.

Re: Whats the Best way to do Bumpers?
 

Was the bumper necessary every year? or was it just last year? Was the bumper as limited as last year was?

Re: Whats the Best way to do Bumpers?
 

Bumpers are required and have been since 2008. They were optional in 2006 and 2007. You must use the pattern given in the rules, and yes, they are that limited, though openings are typically allowed.

Re: Whats the Best way to do Bumpers?
 

We were a wing-nut bumper team this year as well. It started out very fast and got progressively more difficult as our additional functionality started blocking hand access. Still a clean and simple system and much better than some of our previous methods.

My favorite technique? Probably these guys. Then again, it's hard to beat the Thunder Chickens and their rivets.

Re: Whats the Best way to do Bumpers?
 

As far as construction, we just took the wood, glued on pool noodles, put the fabric around it, and stapled on the back end.

For mounting, we used 254's slick idea of codder pins. Took us about 10 seconds to replace a single bumper (total of 4 bumpers). After one competition, we made it a requirement that each drive team member carry an extra codder pin on them at all times :D

Re: Whats the Best way to do Bumpers?
 

Chances are, you won't be allowed to. They'd be fabricated items used on a previous robot, thus not allowed under the 2010 rule <R35>. Assuming that the 2011 rulebook has the same rule, which is in fact a pretty safe bet (it's been in the rules for as long as I can remember), then no use of this year's bumpers would be allowed.

Also note that robot design plays a factor; your robot design next year may not call for bumpers all around the perimeter.

Standard disclaimer: I am not on the GDC, and therefore have no knowledge of the game, and this is an unofficial forum, so this is not to be construed as an official statement in any way, shape or form.

Re: Whats the Best way to do Bumpers?
 

Even if the rules would allow reuse of the bumpers, you'd be wise to look at making a new set. They get pretty beat up over the course of a year, especially if you go to several events and off-season events. The pool noodles begin to compress, and the wood starts to splinter and even crack. Besides, don't you want a fresh look for your new robot each year?

Re: Whats the Best way to do Bumpers?
 

As far as bumper construction, we made ours according to the guidelines set forth in the manual. (I know, suprise :P)

For attachment we made brackets out of aluminum "U" channel that could slip over our frame without much effort. From there we used 1/4" Push Pins from McMaster similar to part number 92384A036. We found that these worked excellently and almost never came loose during competition. The only drawback is that they're pretty expensive at ~$20 a piece.

Re: Whats the Best way to do Bumpers?
 

$$$ Yikes!!!

If you need more pins take a look at 98320A135.

They should be a direct replacement for a lot less. $1.39 / piece. I've used them on 3 robots over the last 2 seasons without issue.

Re: Whats the Best way to do Bumpers?
 

we used aluminum c-channel that fit over the KOP frame c-channel. There were two small (about an inch to inch and a half) pieces on each bumper. We attached the bumpers with cotter pins, so if you pulled directly up, they would come out, but only if you pull directly up. We had 8 pieces, the 4 red, 4 blue, yet it only took about 3 minutes for one person to change all the bumpers (handy when we came directly from one match to the queue, one team member met before the queue, and we pulled off the old bumpers, and put the new bumpers on in the queue.)

Re: Whats the Best way to do Bumpers?
 

We used similar pins at a similar price. Remember they are COTS though so buy them once and reuse them. We've used the same pins for 2 years now. Also the cost doesn't count toward your $3500 limit so build budget shouldn't affect your decision.

Re: Whats the Best way to do Bumpers?
 

The advantage of them over sprung ball locks is their locking ability. Allows a wider amount of bumper mount variety knowing the pin itself can handle axial load.

Re: Whats the Best way to do Bumpers?
 

Like most teams- brackets that "sandwhich" the frame. Some holes and these pins for $3 each.

http://www.harborfreight.com/square-...pin-96281.html

One big change I plan for this year is to have handles to lift our robot. The last 3 years the students lift by the bumpers. After a day or two the brackets are bent, holes don't line up, and it becomes a pain to remove and replace the bumpers. Bumpers strong enough for competition are not strong enough to be a lifting point.

Troy

Re: Whats the Best way to do Bumpers?
 

No problem, the added flexibility of the cracked plywood compensates for the compressed noodles.;)

But in all seriousness, if the inside of the bumpers could slide out of the fabric, then at least the fabric could be reused for probably one extra season.

Re: Whats the Best way to do Bumpers?
 

So, we had a disasterous bumper year in 2008. Bumpers were an afterthought. In the last 30 minutes of build season. They worked, but could not be removed or installed in my life-time.

Starting 2009 we had a bumper mentor (most serene bumper guru - Mike Rizzo). The bumper mentor did other stuff besides the bumpers, BUT HE OWNED THE BUMPERS. A huge improvement.

In 2010, bumper design was first-of-mind during robot design (the opposite of an afterthought). Bumper change requires about a minute.

Our bumpers have male 5/16" bolts extending from them. They are as symmetric as possible and marked for proper installation. Wing nuts secure the bumpers to the chassis. We bring lots of spare wing nuts.

Key points:
1) we have a responsible mentor w/ students
2) bumpers & mounts are designed robot components from a very early stage

Re: Whats the Best way to do Bumpers?
 

What type of fabric did everyone use for their bumpers? I don't really know where to get started on this one.

Re: Whats the Best way to do Bumpers?
 

Most teams use 1000 Denier Cordura or a similar ripstop Nylon fabric. In past years a sample of this fabric has been included in the kit.

Here is one source for this fabric:
http://www.seattlefabrics.com/nylons.html#fc1

Re: Whats the Best way to do Bumpers?
 

Brendan, Marc, et al,

First of all, let me apologize for the length of this post. It is not my intention to rub salt into a wound but rather to give some insight into a process that sometimes appears arbitrary by the field soldiers…

Unfortunately, the one piece bumper design you advocate was ruled illegal last year by the GDC (Official Q&A post: http://forums.usfirst.org/showthread.php?p=39030).

Prior to that post, not only did I consider a one piece bumper legal, but I told many teams to add corner braces to increase support for non-orthogonal bumper impacts during my courtesy inspections at a local pre-ship scrimmage in February (I was Lead Inspector at two Regionals last year).

After that Q&A post this subject was debated by other LRIs on a weekly conference call.

I even made a behind the scenes appeal to the GDC via the Deputy FRC Director. I persuaded him to advocate our (mine and a few other LRIs) position with reasons why corner supports should be considered both desirable and legal along with some illusory drawings (one in attached). His reply was as follows:

I imagine that this design nuance eluded many teams and I imagine that many inspectors missed enforcement as it was pretty far down on our priority list (namely, get the teams on the field fairly and safely).

Regardless, it could be misleading and/or detrimental to teams, looking to his forum for guidance, to advocate corner bracing on bumpers… At least until the 2011 rules come out (I hope).

JMHO.

Mike

Re: Whats the Best way to do Bumpers?
 

Same here. It was quick and did the task extremely well.