This past Saturday my team and I attended the Warren II qualifier. When we went to inspection, everything checked out. We were about to sign off when a referee came up to do a last minute inspection. He told us that our plastic was illegal to use due to thickness and it not being lexan and that we needed to take it off before we could compete.
What I’d like to know is where can I get vex legal lexan? Where do your teams generally get it from? We’d like the thickest allowed by vex (.065 I believe?) Without it being overly expensive.
On an off note, what are the physical differences between .07 plexiglass and .065 lexan? As in: does it bend more? Does it crack often? Is it easier to use?
Since you appear to be in Indiana I would suggest Andymark as the source of the polycarbonate. It is a little larger than you need at 24"x24" but there is always a need for this stuff. Andymark has both .03 and .06 thickness - the larger size coming in a “smoke” color which is kind of nice.
I order today and get it tomorrow to Wisconsin - they have a great shipping department.
We always buy our polycarb from Amazon for $8 w/Prime shipping (if applicable). I can believe the thickness issue, but lexan is not the only plastic you can use. What plastic were you using?
Our team was seriously considering getting a Delrin sheet, as it’s supposedly more durable than polycarbonate. That being said, our intake last year could hold many, many sacks on a metal-reinforced polycarbonate tray
You’ve had lots of good advice here about where to get the Lexan, but not a lot of information about how it is different from Plexiglas.
To begin with Lexan and Plexiglas are trade names. Lexan is actually a polymer known as “Polycarbonate” while Plexiglas is a polymer known as “Acrylic”… or, more specifically, “Poly meth methacrylate”.
As the different chemical names suggest, the long-chain hydrocarbon… the polymer… that makes the plastic is quite a bit different for both materials. Acrylic tends to be harder and more brittle, while polycarbonate is much more ductile… it can absorb impacts without shattering. Acrylic isn’t so good in this regard, which is why it doesn’t fit the definition of “non-shattering plastic” in the VEX rule book.
When you get your hands on some Lexan, try the following tests and you’ll see the difference between them very clearly:
Use a pair of pliers (bigger is better) to grasp the corner of an piece of each plastic. Bend the plastic to a right angle with the pliers. The one that bends is Polycarbonate… the one that snaps is Acrylic. You can also try this using a sheet metal brake (bending tool in the metal shop, if you’re not familiar with it). Polycarbonate can actually be cut and folded… cold… just like sheet metal. Good luck trying that with acrylic!
Take a sharp knife and try to shave a thin slice off the edge of a piece of each plastic. The acrylic will chatter and be hard to cut… the Polycarbonate will slice… not really easily, perhaps… it is tough stuff… but there will be a very noticable difference.
Drill four, 1/8" diameter holes fairly close to each other. If the acrylic doesn’t crack immediately, congratulate yourself on your drilling technique (you’ve probably ground your drill bit down to make it better suited for drilling acrylic) and then try flexing the piece. Cracks will begin to form between the drill holes. The polycarbonate won’t really be any worse for the wear.
So… why is acrylic so popular? It is reasonably hard, it is more impact resistant than glass (and in thick sections can be reasonably impact resistant in general) and has excellent optical properties. It transmits a great percentage of the light that hits it than polycarbonate, making it a better material for applications where people need to see through the sheet… like the protective “glass” in hockey rinks. It is also, last time I looked, less expensive than polycarbonate.