Re: Fasteners extending outside the FRAME PERIMETER
 

I still can't understand why teams don't just build their robots an inch smaller than the sizing box. All this debate over bolt heads sticking out is just silly.
The rule should read like this:
"We're bringing a box with these dimensions. You better be sure ALL of your robot fits in it"

Re: Fasteners extending outside the FRAME PERIMETER
 

Once again, this issue is NOT ABOUT the sizing box.

This issue could affect a 12"x12" robot. If the frame has an upper level in the bumper zone that is 12"x12" and a lower level that is 12"x12" below the bumper zone any fasteners sticking out of the lower frame are illegal per <R16>.

The very, very bad thing is that if fasteners stick out both inside and outside the bumper zone you were legal before Team Update 6 and now you're not. Making such a ruling at the end of week 3 is frankly unacceptable.

Re: Fasteners extending outside the FRAME PERIMETER
 

Paul,
What part of rule <R16> did the GDC screw up?

<R16> During normal operation no part of the ROBOT shall extend outside the vertical projection of the FRAME PERIMETER, except as permitted by Rule <G30>.

They gave us some freedom to have screw heads under the bumper but we had no right to expect that this would extend outside this space. There was a question, it was answered relatively fast and while there is time to work around it if you have to.

I don't see how we can blame the GDC.

Joe J.

Re: Fasteners extending outside the FRAME PERIMETER
 

I guess I didn't fully understand the issue. So, to make this theoretical 12x12 team described above compliant, they would need to make their upper level say, 13x13?

Re: Fasteners extending outside the FRAME PERIMETER
 

Exactly. Or somehow modify things so the bottom fasteners don't stick out.

Re: Fasteners extending outside the FRAME PERIMETER
 

Joe,

Prior to update 6, the fasteners, etc within the bumper zone defined my frame perimeter. After update 6 & 7 they did not. What this means is that all of us who made sure the bolt heads within the bumper zone stuck out more than the bolt heads below the bumper zone to be within the rules are now illegal and it is the start of week 4.

In short, our robot was legal on Thursday, and now it is not. How can you not see a problem with that?

Even more ridiculous, if I have a sheet metal drive base and I have rivets all over it to hold it together, this update makes the rivets below the bumper zone illegal.

Ridiculous

Re: Fasteners extending outside the FRAME PERIMETER
 

I guess if you have your bumper mounting parts of the sheet metal chassis a quarter inch out from the rest of it, you could still rivet it.

I share your frustrations, though, despite no changes being needed for my team's robot. This isn't an acceptable week 4 change.

Re: Fasteners extending outside the FRAME PERIMETER
 

Paul, I see exactly where you are coming from now that I understand the issue. This is a design-altering rules change, not just a clarification. Perhaps they should make it so bolt heads may be excluded, at the discretion of the team.

Re: Fasteners extending outside the FRAME PERIMETER
 

You are right about the idea that if you line up rivet or bolt heads or whatever. I missed/forgot that (I say forgot because I knew it at one point but not at another). I apologize to you, Paul, for not understanding your point of view.

As to the rivets below the bumper zone, unless they were lined up with ones in the bumper zone then they would have always been illegal. Am I right on this?

I see at least 3 possible paths.

1. First, FIRST could realize that they were trying to do one thing and (perhaps) did another instead (by taking away the heads on the bumper zone they took away the head below it) and go to a mixed definition that allows for your heads to be legal as long as they are below heads in the bumper zone but for bumper mounts to be secure.
2. Second, FIRST could allow all fasten heads to count for robot overall size but not for extending beyond the FRAME PERIMETER
3. Third, Teams could mount a small (hopefully light) spacer on the robot at the bumper zone that spaces the FRAME PERIMETER over the tops of the fastners.

I think 2 is the most reasonable given where we are. I don't think they are going to go for it. I suppose 3 is the safest bet because it is in the team's control.

Joe J.

Re: Fasteners extending outside the FRAME PERIMETER
 

This seems like a pretty good summary of the options at this point.

Our team is hoping for #2 and planning for #3.

Re: Fasteners extending outside the FRAME PERIMETER
 

I guess it's not a quick fix, but perhaps teams whose robots break this new rule change could slap some material over their bumper zone to make it thicker? i.e. 4 thin pieces of lexan as long and wide as the bumper or something, with holes for the bolt heads, that makes the bumper perimeter thicker. It's easier than redesigning a drivetrain because rivets or bolts stick out.

Re: Fasteners extending outside the FRAME PERIMETER
 

Wow update 7 is frustrating... so this means our screw heads and washers keeping our drive shafts in are now illegal, great.

Yea I know is some sort of wording this was always illegal, but I don't undersand why FIRST would go to the effort, in week 4, to define how we must design the area beneath our bumpers in such a specific way. In all honesty this is a very unenforceable rule defined so late in the season, that some 'elite' teams are going to have a tough time meeting. I feel sorry for teams who built their frame out of sheet metal and rivits. These rulings makes me think that the GDC didn't even consider the realistic consequences of this definition, and how unenforceable it will be.

Re: Fasteners extending outside the FRAME PERIMETER
 

Recognizing this gray area in the rules, we always knew that we could glue on a spacer in the bumper zone to exceed the extension of any fasteners (in our case welds) lower down on the robot. At this point it looks like this is what we will have to do and we will need to make it weigh as little as possible.

Any suggestions for a suitably light spacer material?

Eugene

Re: Fasteners extending outside the FRAME PERIMETER
 

Eugene,

ABS or Delrin works great as a light spacer material. If you want something easier to find use pvc.

-RC

Re: Fasteners extending outside the FRAME PERIMETER
 

Well this make sheet metal designs a bit more difficult... back to the old flat head bolts with PEM nut option.


For those which cannot change their fasteners to flat head bolts, here's the McMaster part number that I think will save a lot of teams this year: 8782K12

1" wide x 1/4" thick polypropylene strips at $0.53/foot. Polypropylene is among the lightest and cheapest commonly available plastics, but even still, installing this strip around the outside of your robot perimeter will add just over a pound.

For comparison, using a 1/4" x 1" strip of Lexan will add over 1.3 pounds.