Plexiglass
 

Is it allowed or not? I dont see it anywhere in the manual that you can't. And if the side of the toughbox is plexiglass I dont see why we cant use it.

Our electrical team originally had all of our electrical equipment on a metal cage whem mechanical said to was to heavy and handed us plexiglass.

Re: Plexiglass
 

Basically, as long as a structural material like plexiglass is not specifically prohibited in the manual, it is allowed. Depending on your application, polycarbonite/lexan might be a better choice, however.

Re: Plexiglass
 

yep you can use it ;)

Re: Plexiglass
 

I would go with lexan, it's much stiffer and quite strong. You can get it at home depot. If you really want to go big, you could use ABS plastic from mcmaster or something. But it's a bit expensive.

Re: Plexiglass
 

we've used both lexan and plexi in the past and we found its brittal and heavy last year we used 1/8" ply wood its light and easy!

Re: Plexiglass
 

Real Plexiglass is acrylic, it is not that strong and it does break and sdhatter. Polycarbonate (Lexan) is very strong and doesn't shatter - it costs more, but is a better choice.

They look the same (almost) but are very different materials. Both are legal.

Don

Re: Plexiglass
 

I would use 1/4" plywood if I were you. It's cheap and easy to work with. Plexiglass, while tough and cool, has a tendency to crack when you're working on it. We also tried using sheet polycarbonate, and the stuff just cracked and shredded like no other. However, because it was cheap, we just got huge sheets of the stuff.

Re: Plexiglass
 

We just got done cutting and assembling our electrical panel on acrylic. Very cool I must say.

Re: Plexiglass
 

Acrylic/Plexiglass is pretty much the bane of my existance when doing electrical work. Thin acrylic shatters when drilling (except when drilling with fine-toothed holesaws... that's the only thing I have found doesn't shatter it), it shatters when cutting, it shatters when bolting, and it shatters when you look at it the wrong way. We used a lot of 1/8" acrylic on our 2006 robot (hopper walls, electrical board, and a few other things), and most of us decided never to use it ever again. Polycarb/Lexan is much easier to work with. It still shatters if you drill it really funkily or tighten a bolt too much, but it is nowhere near as bad as acrylic. I have even pop riveted 1/8" polycarb (which, I imagine, puts a lot of force on it) with no problems. Just use polycarb instead of acrylic, the cost difference isn't that bad, and it is much easier to work with.

Re: Plexiglass
 

We used 1/4 in. ABS last year. That was a bit of overkill. However, I really liked the ABS because you can treat it like you would most any other material. We band sawed and drilled and it never showed the slightest crack. It's pretty expensive stuff though.

Re: Plexiglass
 

Acyrilic is perfectly legal to use (follow the flow chart!). However, as others have stated, it's not exactly an ideal material. Polycarbonate (lexan) is just as easy to work with and less likely to shatter or spiderweb on you.

Acyrlic does have one fantastic property- using a torch you can flame the edges. This finishes them off removing any tooling marks, rounding the edges and restoring it's clarity. It makes parts look much more professional. Since that is a pretty minor consideration in FIRST, I'd focus on using polycarb. if you are set on using a plastic as a base.

In place of either material, I would suggest either plywood or, if you want to get fancy, my new favorite material, garolite. Garolite is a cloth and resin based composite, sort of like fiberglass. It is very rigid, easy to work with and transparent to radio. It's used in some PCB's. McMaster has it in various grades, sizes and thicknesses. It's more expensive then plywood and comparable to polycarbonate. It is in between plywood and polycarbonate for toughness, but beats them both in rigidity. This means you can get away with a very thin, and thus lightweight, sheet. 3/32 or 1/8 would be fine, I think, depending on the overall size.

-Andy A.

Re: Plexiglass
 

Whether you use acrylic (Plexiglass) or polycarbonate (Lexan) I would suggest that when drilling holes in it that you re-grind your drill bits to make them "pointier" than a typical jobbers drill (about 60 degrees sounds right). Alternatively you can purchase specially ground drill bits for plastics. Yes, you can drill the plastics with a standard bit, but the pointier bits cut nicer and reduce the likelihood of cracking in plexiglass.

We use lexan extensively on our robots and have found it formable and durable. Plexiglass tends to be subject to cracking if you don't baby it carefully, while you can bend and fold lexan just like you can sheet metal.

We have also used a plywood, and recommend baltic birch, but... of course... you can't see through it.

Jason

Re: Plexiglass
 

Question; Would not starting your hole with the smallest drill bit you have and working your way up to the hole size you want by redrilling with with the next size bit up also lessen the chance of cracking the Plexiglass ?

Re: Plexiglass
 

Probably, but unless you really need the flexibility of plexi, I'd go for lexan.

Re: Plexiglass
 

For those of you drilling acrylic / plexi / lexan, they make special bits specifically for the application. The only difference these bits really have is that they have a much more angled or "pointier" end. If you have an old set of bits around and a bench grinder you can quickly grind them so you have a set of plexi-bits. :)