I’m still investigating a few things for this year’s robot, one of them being protective side panels for the robot’s frame (which will be kitbot, if that helps you visualize it). We’re investing in a pair of AndyMarks this year, and I have this recurring fear that those gold side plates will become a big “HIT ROBOT HERE” sign. (Sort of like how your feet always get stepped on right after you buy a new pair of sneakers.) In the interest of giving the sponsor logos the same protection (except theirs would be more “SCRAPE ROBOT HERE”), I’m looking at lexan for this particular job.
For those who’ve done similar things before, what thickness of lexan were you using? Did it hold up reasonably well?
We have used 1/16" for places where the lexan has been supported by the robot’s frame behind it in case it gets hit, and 1/4" or larger where we need some support.
Both thicknesses have never been punctured on our robots, but they get scraped up pretty well.
As long as it’s properly attached and supported, Lexan as thin as 1/16" may protect you. 3/32 or 1/8" is a safer bet though. I would not recommend using anything thicker than that unless it is really unsupported, or protecting something that’s gonna be chewed on. The weight penalty is not necessary, as something thinner will do the same job. More often than not, you’ll see the lexan pull, deform and bend instead of simply breaking, and if the shield fails, it’ll be because of attachment failure. We’ve bent 1/4"-20 bolts 90* while the Lexan mostly deforms around the bend.
It’s hard to make it really fail. Although, as said before, it will get scratched up as time wears on, but almost entirely it will be due to robot contact, not incidental out-of-match wear.
I’ll second Andrew Blair’s comments. I have never seen a piece of lexan actually fail outright. I’ve seen it get bent or deformed slightly. So unless you need structural rigidity out of it keep it very thin and you’ll do fine.
One suggestion is to arc it over the part of your robot that you want to protect. The shape of the lexan will help it deflect and absorb blows. The bowed shape also makes it stiffer than if it was layed flat over a hole.
Last year our team built allmost all of the robot out of 1/4 in pollycarbonate expect for the frame. It was verry heavy and you do not need it that thick if you structure it correctly. This year were building every thing out of 1/8 in pollycarbonate. So I would recenmend 1/8 in.
if you have a full frame for it go 1/16, especially if its a large area you have to cover. its cheaper, lighter, and usually just as effective. The only time our team uses 1/8 is to cover our electrical panel, or where there`s one side with no framing.
weve covered huge areas and just attached it with velcro, and even some of the toughest blows have not gone through. (I dont know if velcro is still legal… anyone?)
only thing to think of is maybe bringing a spare just in case.
Lexan is a great material but it’s heavy, really heavy. A few alternatives I’ve seen several teams use over the years is a Green House like, Corrugated Polycarbonate Material, lightweight with a bit more stiffness. Off the top of my head 173 and 1126 are 2 successful teams that have used the material extensively.
1/16" is plenty for scrape protection, especially if supported.
For impact protection, thicker is better - BUT aren’t you guys thinking about bumpers for this year? If so, let THEM be your side protection.
Although they must be made from 3/4" plywood, you don’t want CDX (the plain builder’s plywood) — use hardwood plywood (not the luan stuff Home Depot sells, but Maple, Birch or Oak, also known as marine plywood or aviation plywood) as it is really strong - I mean realllly strong. And, there’s no weight*!!
Don
*well, not included with the robot, and enough to surround your entire bot won’t exceed 15 pounds either…
At the Ruckus, GRR put 1/4" polycarb on the sides of the robots. We could kick, punch, launch tools, etc. at them all day long and nothing would happen. Remember, you’ll need to make sure the lexan/polycarb is securely fastened in many different points if you want it to work properly and to its potential.