I figured in light of Frank recently confirming the return of bumpers, I would see what other teams have done in the past that has worked, and maybe what has not worked regarding good bumpers. For 2014, 1073 used hinges , some c-channel, and a few pins that we could swap out fairly quickly. The only problem was that the hinges weren’t all that great, and IIRC, they were constantly loose.
I know that either 1114 or 254 (I cant remember) uses a special low friction material to slide by opponents during pin-holds.
I believe 254 uses sailcloth or something similar.
The biggest thing with bumpers is to get the fabric nice and tight. What some teams will do is to staple (or otherwise secure) one side of the fabric, then have several people stretch it over the noodles and hold it while someone staples the other side down.
Tape your noodles in place before you wrap the bumper. This helps a lot in the assembly process and especially helps prevent sagging noodles.
Staple one side, then stretch the fabric as tight as you can before stapling the other side. Any amount of sag in the bumper is bad.
Remember that your bumpers can (by 2014 and previous rules) weigh up to 20 pounds, and there’s no reason you can’t make your structure that you use to mount the bumpers as beefy as you would like.
For reference, our standard set of plywood bumpers mounted with wood tee nuts weigh somewhere around 12 lbs, so there is a lot of room to grow.
The Lunatecs have recently made reversible bumpers out of thick fabric and velcro. Basically the red and blue fabric is sewn together on one side and then again in the middle. The free ends are then stapled to the backboard. Volia, you add velcro and you have a single set of bumpers that can be used for both (or all 3:eek:) alliances.
Another trick used to get the bumpers tight is to compress them before stapling. Some teams report using a custom device they made, but we just used our three large (10"?) c-clamps and a table top, and do one edge at a time.
Securing bumpers them with angle brackets works well, as long as you have an inch or more of bumper above the top of your frame perimeter. Mount two bolts to each side of the chassis facing up (should be easy with the KoP chassis; just use the holes already there), drop the bumpers over the robot into place, and secure with a second nut on each bolt. (Wing nuts or power nut driver recommended). Rivet nuts mounted in the frame and (captive?) bolts passing through the bumper’s brackets could probably also be used for this, but we haven’t tried it.
This^
It’s more work during the build, but it is so worth it at competitions.
You will need a heavy duty sewing machine to work with the sailcloth.
Totally agree with reversible bumpers. Why have a quick change bumper when you can just flip the color around even faster.
By the 2014 rules (and specifically the Q&A), pre-compressing your bumper noodles as you assemble them isn’t legal. I’ll find the actual rule after work, but I remember this being shown / proposed in a CD thread in 2014 and a Q&A ruling came in declaring it illegal. Sorry for the vagueness.
Team 74 did the same thing in 2014. It was pretty convienient at competitions.
In my mind the reversible bumpers and bumper covers teams have produced in the past never looks as “polished” as separate well made bumper sets. The key to good looking bumpers? Pick quality materials (plywood, noodles, and fabric) and take your time.
Yes. Plywood. Get the good, sanded both sides stuff, not the sheathing grade that is rough. It’s only a few dollars more.
In 2014, someone decided hardwood planks (oak or maple, I think) would be suitable. They ended up splitting along the grain in several places.
From 2014:
Q302
Q.R21 C states that teams should use a pair of 2.5" pool noodles. Does that requirement refer to the pool noodle’s size when on the robot, the pool noodles size when purchased, or both? Is compressing pool noodles legal?
A.1) Both. 2) No.
Please note that while previous answers like this may provide guidance on the general thinking towards a rule area, unless/until it’s asked for this season, there is no official ruling that applies for this year. Which means you may or may not be flagged for it by an inspector if it’s not crystal clear in the rules/q&a for this year.
Sure, separate sets may look a little better than reversible bumpers (and everything looks better than bumper covers!), but honestly, the convenience factor more than makes up for any slight visual difference between them, assuming they are both well made.
A few years back we had a huge issue with our state championship and teams bumpers. With only 30 teams at the event, you were queueing after only being in your pit for about 10 minutes. Teams with separate bumper sets had a lot of trouble making that turn around time… And let’s face it, you want to spend that time on robot improvements, not changing your bumpers!. Good reversible bumpers look good and can be changed by one person in under a minute while standing in the queueing line. You just can’t beat that!
Why used sanded material when the other material works just as well and you’ll be covering it up? That’s like using high polished material when you plan on painting it anyway. Price difference is small ($19.18 vs $26.58) but I just don’t see the point, does smooth plywood hold staples better than rough plywood?
And I think the rules have specified plywood for as long as I’ve been making bumpers, so hardwood shouldn’t even be considered anyway. Plywood will take an impact better due to the crossing grain structure over hardwood, the results of hardwood would be exactly what you stated.
Solid wood became legal in 2013 or 2014. A typical 1x6 is perfectly legal and effective bumper material and teams don’t even have to cut it to width. (bumper heights are ±0.5“). We used 1x6s in 2014 and didn’t have any splitting problems. We played at 2 regionals, champs, and 5 off season events, plus demonstrations and we haven’t broke any wood and our 2014 drive train had a lot of power behind it. We also used the full 20lbs for our bumpers each set weighed over 19.5lbs, with a sheet metal frame covering the top edge and 1/8" aluminum L on bottom edge.
Just like you would design a component of your robot, design your bumpers to be quick change.
This is a requirement on 2826 for bumpers. 1 or 2 people need to be able to replace the bumpers in 1 min.
This requirement can be met several ways and reversible is one of them but I have yet to find a set of reversible bumpers that I would be willing to put on 2826’s robot.
There will be more than twice the usual number of teams at events this year who will need help with bumpers: rookies last year didn’t need bumpers, after all.
Hmm, 6" bumper height is much desired in some cases, IMO. I’ll have to look into this.
They will be 5.5" since a 1x6 is actually (3/4" x 5 1/2")
From the 2014 manual
4.6.3 R21
A. be backed by ¾ in. (nominal) thick by 5 in. (± ½ in) tall plywood or solid, robust wood. Small clearance pockets
and/or access holes in the plywood backing are permitted, as long as they do not significantly affect the structural
integrity of the BUMPER.
Particle board or chipboard is not likely to survive the rigors of FRC gameplay and thus not compliant with R21-A.
Also when talking about compressing the noodles.
To assist in applying the fabric covering, fasteners may be used to attach the pool noodles
to the wood backing, so long as the cross section of Figure 4-8 is not significantly altered (e.g. tape compressing the
pool noodles).