Re: Non-sagging Bumpers Q&A Response
 

You're correct. I could have sworn that they'd addressed that in a past year, so I compared the current diagram to Figure 8-1 in <R37> from 2007. The old diagram made reference to staples and glue as possible options, and the Q&A of that year stated that either was acceptable in lieu of angle.

At some more recent date, they omitted that reference to staples/glue from the diagram (apparently in 2009, when clamping angle was no longer "optional" according to the rules), while maintaining the requirement that bumpers be constructed per the diagram. Aluminum angle was specified as optional in later years, but legal alternatives are no longer specified. It's worth a Q&A, and will presumably be the uncontroversial subject of an update to R21E.

Re: Non-sagging Bumpers Q&A Response
 

Martin,
The Q&A people do watch CD. Your point has been made and no, it is not taken as bad attitude.

Re: Non-sagging Bumpers Q&A Response
 

Al, correct me if I'm wrong but you seem to be saying that compressing the pool noodles is a bad thing. What rule does that violate? Other than the newly understood attachment ban. Pre-compressing noodles, like 971 does, seems completely within the rule set to me, assuming the team uses nothing but fabric, pool noodles, and wood.

Re: Non-sagging Bumpers Q&A Response
 

Allen,
The team used the tape to make the 2.5" noodle about 3/4".

Re: Non-sagging Bumpers Q&A Response
 

If a team did that with only fabric, would it be illegal? I don't think it would.

Re: Non-sagging Bumpers Q&A Response
 

If the pool noodles are compressed such that they appear to be (significantly) less than 2.5" in diameter (per R21C), then you could have problems with your inspector. In other words, when all is said and done, if I hold a tape measure up to your bumpers, I should be able to say "Yup, that looks like you used approximately 2 ½ in. round, petal, or hex pool noodles". If I do that test and I say "Hmm, it looks like your pool noodles are only 1.5" in diameter..." then you have a problem. At that point, you have to prove to me that you actually used 2.5" pool noodles, which means disassembling your bumpers, decompressing the noodles, and hoping they pop back out to somewhere close to 2.5". Then you get to sit there and explain to me why you compressed them and attempt to provide proof that compressing them doesn't compromise safety on the field or compromise the intended robot-robot or robot-field interaction that bumpers are designed to help protect. All in all, it will just make things much more painful for a team that attempts to compress their noodles.

Note that this isn't about a little pre-compression that you can do to get the fabric on then have the pool noodles expand to make everything firm - in that case I would expect the noodles would be "approximately 2 ½ in" when all was said and done. This would come into play for a team that, for example, flattened their pool noodles permanently in order to make their pickup mechanism work better (if having smaller bumpers in either the horizontal or vertical dimensions were required to make that particular mechanism work). These would be the type of bumpers that an LRI would spot from across a room and think "those don't look right".

Re: Non-sagging Bumpers Q&A Response
 

This makes sense to me. The problem is that the Q&A ruling doesn't seem to link to this reasoning in a particularly clear fashion. It's very easy (and possible) to use tape but not compress the bumpers severely, just like it would be possible to use fabric to heavily compress the bumpers. If this is the intent, the better option (IMO) would be to revise R21-C to read that the cushion material must extend to a minimum of 2-1/4" (or whatever number you want) and a maximum of 2-1/2". Right now it only gives an upper limit.

Saying you can't use tape is a rather indirect and ineffective way to achieve the result of not having severely compressed bumpers. Now, the Q&A question asked about tape specifically, but I feel like a revised response would be in order if the actual intent is to prevent severe bumper pre-compression.

I think that they may also be trying to avoid a team finding a particularly hard tape and wrapping the entire bumper with them underneath the fabric to change the way the bumpers respond. I think a more clear response would be something like:

"Small amounts of soft, flexible tape may be used to secure pool noodles to the wood backing to aid in assembly. Tape markings should not be visible from the outside of the cloth on completed bumper assemblies. Pool noodles must remain close to the 2-1/2" nominal diameter".

This gives teams a way to build their bumpers better, within the intent of the rules, and limits the tape's ability to be used for any competitive advantage or create an unsafe condition. It also gives the inspectors grounds to disqualify bumpers if it appears they are not using it for something other than an assembly aid, without being overly strict. It still relies on the inspector's judgement, but it becomes easier to judge the intention of the team.

Re: Non-sagging Bumpers Q&A Response
 

That rule makes complete sense but that is not the current rule, it doesn't say anything about the state of the noodle upon mounting it to the wood. I don't see how an inspector could demand that any team open the bumpers, especially if they had a sample made or any other way to prove that they used 2.5" pool noodles. There should be a defined edge, since it already been shown in this thread that having tighter bumpers is an advantage.

Even a rule that said "pool noodles should not be heavily compressed" would be good enough validation for me to be able to enforce that at an event, but currently I don't think I can enforce that interpretation.

Re: Non-sagging Bumpers Q&A Response
 

Remember when everyone complained that the bumper rules were too complex, and that they should be simplified?

Re: Non-sagging Bumpers Q&A Response
 

We've always tacked the pool noodles onto the plywood with hot glue. That's not tape, shrink wrap or an other soft material, but I'm getting the impression that its generally in the same category since it is securing the pool noodles to the plywood under the fabric.

Is this really not ok? I really though that was how everyone did it! We've helped a gazillion teams through the years build bumpers! This might ruin my day! :ahh:

Re: Non-sagging Bumpers Q&A Response
 

A team at our regional used their bumper fabric (not tape) to squish their bumpers in about 0.5" to get their climber working well. They were not allowed to compete with bumper like this even though no rule was shown to the team as to why is was illegal.

As far as I can tell, the only thing an inspector can call you out on for squishing your noodles to 0.25" thick is that it might be unsafe. However, this is kind of subjective.

If the GDC gives us simple rules that make sense (ie, don't squish the bumpers), teams won't try to "lawyer" the rules. If they give us nonsense rules and responses (speed racer in 08, 118 in 2012, unclear on angled bumpers in 2013, bumper fastening in 2014...), then expect to see teams try to get around the rules.

Re: Non-sagging Bumpers Q&A Response
 

Just a note... My response about pool noodle compression wasn't intended to be part of the "Great Tape debate of 2014" :) I was just replying to AllenGregoryIV's question about what rule pool noodle compression violated.

Re: Non-sagging Bumpers Q&A Response
 

In the bumper diagram the angle is listed as optional.
Since the angle is optional, there is another unspecified legal method for attaching the fabric to the plywood. I am going with staples without further official guidance

Re: Non-sagging Bumpers Q&A Response
 

To avoid misinterpretation and rule bending I think that rule references and/or rule intent should be included in any answers given by the Q&A people.

Re: Non-sagging Bumpers Q&A Response
 

This is a whole lot of debate about nothing. Yes we all want nice looking bumpers and we all need legal bumpers. Make your grandma proud, build them to spec. Don't worry about what was in the 2007/2008/2009/200x rules, we are in 2014 now.

Thank you to everyone who provided their methods of making bumpers, I'm sure someone will appreciate it. Several small things (like using a string then pulling it out) are crafty, creative, and something I never would have thought of (and legal in every sense of the word.

Can we just let this be? We spend 6 weeks creating a 150 lb metal robot, take pride in this as well as your bumpers but don't worry too much about the use of tape. Try and remember that the robot is just the vehicle too, FIRST is about much more than robots (and bumpers).