Bumper bracket and weight considerations

[AdamHeard]

Originally Posted by Greg Needel

I wish we could go back to making bumpers optional. While there are many advantages to having them I can think of just as many not to have them. I wish it was a choice instead of a requirement, then people could attach them legally or not at all and still be fine.

Exactly.

Many teams are capable of choosing to not use bumpers, and as a consequence building a robot that has to withstand an impact with another nonbumpered robot.

[waialua359]

If bumpers become optional, then no rule should be in place on how to make them exactly. In 2006, I believe they were optional, BUT, if you used them, it had to be according to FIRST specs. I dont see why if you gain no competitive advantage (within 120lbs that year) with them. We made our own type and had to remove them.
If we have the liberty of creating our robot how we want, why cant we make our own provisions for protecting our bot (following the robot construction rules)?

[Jeff Pahl]

Originally Posted by Wayne C.

Consider this more- if you built the bumpers exactly to the specs in the rule book last year they could not make the specified weight.

I had the interesting experience last year of inspecting at events on opposite sides of the US (Peachtree [GA] and Minnesota) and also at the Championship.

I observed that plywood does not have the same density, depending on the source. Different parts of the country, it is made from different woods which affect the weight. Of course, the moisture content can make a difference, too.

One of my least favorite parts of inspecting last year was having to try to explain to teams that fact. You would have one team with a set of bumpers that fully wrapped the bot that would just make the 15 lbs, and the next team would be at 15 lbs with only three sides. I had teams tell me that it was impossible to build 4 sides of bumpers that met the rules and the weight, but I also saw many teams that managed to do just that.

And I had a discussion with Russ Bevis, the Chief Inspector for FIRST, about this very subject at the Championship.

I'm not going to touch the attachment discussion, that subject still makes my blood pressure rise...

[R.C.]

Originally Posted by waialua359

If bumpers become optional, then no rule should be in place on how to make them exactly. In 2006, I believe they were optional, BUT, if you used them, it had to be according to FIRST specs. I dont see why if you gain no competitive advantage (within 120lbs that year) with them. We made our own type and had to remove them.
If we have the liberty of creating our robot how we want, why cant we make our own provisions for protecting our bot (following the robot construction rules)?

Point well proven. I kinda liked it without bumpers, the bot looked liked it had a world war when it came back after the comps.

[dtengineering]

While I have forgotten some of the minuitae of the rules, and didn't find the confirmation to this even after following Richard's very helpful links to the Q&A (I didn't exactly knock myself out doing it.. the season IS over, after all), I believe that the mounting brackets would not only have to be weighed with the robot, but also sized with the robot, as they are not, technically, part of the bumper.

On the issue of building and inspecting robots to meet the bumper specifications... the rules were pretty clear. If you just followed the rules, you wouldn't have any problems. This does require reading the rules, following the Q&A, and recognizing that no matter how brilliant your particular design is, that it is not brilliant in an FRC competition context if it is not FRC legal.

It is disappointing, but not surprising... especially for teams that followed the rules very carefully... to see other teams pass inspection with bumpers that fall outside the specs. This obviously happened at regionals, because when I was doing tech inspection on Galileo, our team of inspectors found several bumpers that did not meet FRC rules. The most common violation was that the plywood had holes in it other than those used for fasteners, but I also came across a team using 5/8" MDF instead of plywood. There were, quite possibly, one or two that slipped past us in Atlanta, too, but we tried... really, really tried... to make sure that every robot was competing on a level, FRC-legal footing by Friday morning.

And I have to add, just for Cory, who felt that their time spent making their bumpers legal was wasted, that it most definitely was not. I remember looking at their robot (it is a beautiful machine) and had I noticed bumper configuration that was not "spec", they would have been having a conversation with the lead tech inspector over what they would have to do to make it legal.

Most tech inspectors are or have been builders, coaches and/or mentors, too. The only thing more painful than seeing a robot not pass tech on a "technicality" that "doesn't affect performance", (please don't even try that argument with a tech inspector... they don't make the rules!) is missing the violation and ignoring the hard work that all the other teams did to comply with the rules.

Just a few thoughts...

Jason

P.S. Ever tried finding pool noodles in Canada in winter? Now we stock up in the fall.

[R.C.]

Originally Posted by dtengineering

P.S. Ever tried finding pool noodles in Canada in winter? Now we stock up in the fall.

Yes, a fellow team told me about it and they got some from us. Funny.

[MrForbes]

Originally Posted by Jeff Pahl

I observed that plywood does not have the same density, depending on the source. Different parts of the country, it is made from different woods which affect the weight. Of course, the moisture content can make a difference, too.

That is something I had not considered...we seem to get the dry, light stuff!

[Al Skierkiewicz]

Everyone,
I can tell you that there has been a lot of discussion over the bumper design and rules. We all have to wait until the robot manual is released to know for sure if there is any change. The rule on bumper design should make all bumpers fairly alike but I can tell you, I saw almost as many bumper designs as I saw robots in the years since the bumper rule was included. As other have pointed out, R08 stated
"STANDARD BUMPERS must be
attached to the ROBOT with a boltand-
fastener system to form a
rigid, robust connection to the
ROBOT structure (i.e. not attached
with Velcro!)."

[Cory]

Originally Posted by dtengineering

And I have to add, just for Cory, who felt that their time spent making their bumpers legal was wasted, that it most definitely was not. I remember looking at their robot (it is a beautiful machine) and had I noticed bumper configuration that was not "spec", they would have been having a conversation with the lead tech inspector over what they would have to do to make it legal.

I completely agree. I meant that I felt we wasted our time coming up with a legal solution that wasn't terrible, when we could have spent a lot less time and come up with a much better mounting system, if the rules were slightly relaxed.

[Qbranch]

We've used bumper-side brackets these past two years and used tent stakes to install/uninstall them.

2006: Side bumper mounts were FDM, front mounts sheet aluminum, rear mounts plate aluminum

2007 (bad year for us): FDM brackets all the way around

2008 (good year for us): FDM with bracket mating areas built in to the unibody.

-q

[M. Mellott]

Last year, we used eyebolts attached to the back of our bumpers that laid flat on our square tubing frame onto permanently-mounted bolts sticking up from the frame, with wing nuts over top of the eyebolts to hold them solid. They were simple, held the bumpers very well, and were easy to remove. Even with our full-circumference bumpers, we've never had a bumper weight issue.

Personally, I like using the bumpers, not only for protecting robots, but it also adds an additional 13-15 lbs. of free weight down low to help lower the CG of a tall robot.

[vivek16]

I guess one of the things about custom bumpers is that bumpers right now can have a larger footprint than the bot itself. So, custom bumpers may alter the rules somewhat about the foot print.

-Vivek

p.s. we have alway had under weight bumpers with 3/4" plywood.