We have some old plexiglass that has our team number on it and we were going to mount that on the robot. Do we also need to put the team number on the bumpers?
I was curious since on the 2011 FRC inspection checklist for Logomotion mentions:
“Team number displayed with 4” tall x 3/4" stroke, on the bumpers, 4 locations at approximately 90 deg spacing, in contrasting color or background."
Thank you:)
Yes, it needs to be on your bumpers, both the red and blue.
And for the contrasting color, as a scout/scouting mentor, I strongly recommend something in the white/silver/bright yellow range. Black lettering looks fine close up, but it’s nearly unreadable in the stands.
Yes! We have used a bright white color, and it looks fine on both red and blue bumpers.
If you do use black letters, at least put a thin white outline around them.
If the piece of plexiglass with the team number was fabricated prior to this year’s kickoff, you aren’t allowed to use it on your robot. ::rtm::
Is it really plexiglass or lexan? I wouldn’t recommend using plexiglass on a robot: it will shatter upon impact.
It is plexiglass and we still need to cut it.
Why are you creating room for interpretation when there isn’t any?
Jane
Plexiglass, AKA acrylic, shatters on impact. I’ve seen it happen, back in 2005 (and the robot that did the shattering drove up a steep angle to do it). That’s why it’s not recommended in any areas on the robot where it might get hit.
You may be thinking of polycarbonate, AKA Lexan, which doesn’t shatter nearly as easily.
Well, the plexiglass will be located about 2-4ft off the ground. It will be connected the Arm frame which Doesn’t hit something on impact >…<
I have seen supposedly safe plexi shattered.
There is no safe place on a FRC robot.
Yep. That acrylic I mentioned earlier–the impact was at about 3.5-4 feet up. The “ramp” that was gone up could slow or stop a robot pretty well-- except that one. The other 3 sides of the tower shielding (running between arm supports) were Lexan and survived the rest of the season, as did the replacement Lexan panel.
The best place for acrylic is the trash can. There is never a situation on your robot where it would be a better choice than polycarbonate.
This isn’t an interpretation. It’s a reading of the rule:
<R09> Teams shall display their team number on the BUMPERS in four locations at approximately 90° intervals around the perimeter of the ROBOT. The numerals must be at least 4” high, at least in ¾” stroke width and in a contrasting color from its background. Team Numbers must be clearly visible from a distance of not less than 100 feet, so that judges, referees, and announcers can easily identify competing ROBOTS.
See how many times “must” and “shall” appear? You have to do it - numbers on the BUMPER, regardless of wherever else on the ROBOT they appear. Period.
Let this be your guide… I predict 50% of the robots on the field will have an arm for scoring at least the center rows. That means at least one robot on the opposite alliance in every match will have extensions beyond their frame perimeter. Those arms will reach over six feet and can contact your plastic signage.
For the past, what, 3 years now, we have used plexi for the electrical box, becouse it doesn’t bend under load. Never had a problem. Asides from that, true, lexan is much more resilient under shock.
Back in the 90’s, Plexiglass was explicitly forbidden on the robot by rule. When the ban was lifted, I bought a small sheet at the HD for an electrical panel. When it shattered during routine tooling, we went back to polycarb and never looked back.
No team I have ever mentored has ever had Plexiglass on their robot.
To the original poster: If the rules don’t persuade you, note this quote from this document:
Team number displayed with 4” tall x ¾” stroke, on the bumpers, 4 locations at approximately 90 deg spacing, in contrasting color or background.<R9>
Without the team number on the bumpers as specified, you will not pass inspection.
Regards,
Mike
It’s more than just that. Simple vibrations will crack the acrylic where the bolts go through to mount it to your backing. Acrylic is not acceptable for a FIRST robot under any circumstances. If I won’t use it in my computer for waterblock tops (where there is negligible vibrations and no movement), you definitely shouldn’t ever use it on a FIRST robot.
Theres a few companies (Thermaltake) that used to make waterblocks with acrylic tops and meager 10°C changes to the acrylic along with the pressure the barbs put onto the threadings to maintain a watertight seal caused many of these blocks to crack and leak water over the users video cards and motherboards.
I find it interesting that this post has turned into a post on acrylic vs polycarbonate.
With students, I normally do the “vise test” . .
Give a student (with safety glasses of course) a small piece of polycarb and tell them to smack it against the vise.
Then give them a piece of acrylic and tell them to do the same thing.
That’ll teach em. 
(and yes, you need to put your numbers on your bumpers . . silver Sharpie works GREAT!
http://www.amazon.com/Sharpie-MARKER-SHARPIE-METALLIC-SR/dp/B001GXFNYI)
We used plexi (acrylic) to make a mounting bracket for our C-Rio, since we have access to a laser cutter, which can’t cut polycarb. It allowed us to precisely “drill” the holes for the bottom of the C-Rio, and mount it in a way that it won’t crack.
But then we took it off for weight and made a smaller bracket by hand out of polycarb 
Is there any difference between “plexiglass” and “acrylic”? I have seen stuff marketed as “plexiglass” that was very brittle and virtually impossible to drill holes in without cracking. We have had decent success with “acrylic” sheet (as marketed by Ace Hardware), for non-structural, flat panels that are well supported along the edges. It drills fairly well, and is quite flexible, but will break before it bends. In 2009 we had 3 large panels (30" x 44") of the stuff and they held up very well despite impacts that bent the supporting structure (yeah, I know - that was Lunacy and there weren’t arms and impacts weren’t like they are on carpet).
We have three small, non-structural panels of it on the robot this year (because I had a tightwad moment and it was in stock), and we are taking bets about how long it holds up. Will replace any broken sections with Lexan, though.