I have some 1 1/2 plexiglass a friend gave to me that I would like to experiment with on the laser. However, it does not have the protective coating that usually comes on other plexiglass. Is it ok to use? I’m only looking to do some detailed etching into it.
The coating is mainly to protect it during transit, but it does have the function of keeping the soot generated in the cutting operation from settling on the surface. You’ll often see people working with scraps which don’t have the coating on them. You may find you have to clean your work afterward.
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Use some blue painter's tape instead. Or use paper ansctape it down with painter's tape. Depending on the size of the cuts.
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First off, make sure that plastic is an approved material before cutting it on the laser. For example, acrylic is fine, but polycarbonate is not; both are commonly sold as plexiglass. Unfortunately, I’m not the best person to ask how to identify which plastic it is.
If there’s no film/paper on either side, I recommend using soap film on both sides to prevent the vaporized plastic and dust from bonding near your cuts. Wash the parts off with water after you’re done cutting. Even with soap film applied to the bottom, you’ll probably still get pockmarks from grid reflections. The paper that’s usually on both sides of the acrylic helps lessen those marks. If you have any wood or thick paper you can lay down beneath the plastic as a sacrificial layer, it should help. Just don’t use anything with a finish on it, as you may discover it leaves behind a haze or sort of glues your new plastic parts to the paper/wood.
My guide, for reference on the soap film thing (Credit to Haley for showing me the technique in the first place): http://likemagicappears.com/2014/02/07/laser-cutter-tips/
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This is a great set of tips! Thanks much to you (and Haley) for pointing them out. Thanks, Chris
Plexiglass will flex easily, acrylic is very rigid. Not sure if that’s the best way to tell them apart, but it works for me.
I use pliers to check if clear plastic is acrylic or polycarbonate. Take the pliers and grab a corner and hold on tight. Grab near the corner with the other hand (wear gloves!). Bend just the corner with the pliers until either the acrylic snaps off cleanly into a shard or it bends and the crease becomes opaque. If it snaps clean off with no cloudiness it’s acrylic. If it bends and becomes opaque at the crease it’s polycarbonate.
Do not cut polycarbonate on the laser. The fumes are very bad and even if the fumes weren’t bad it cuts like crap. If you have any doubts about what material you’re dealing with ask someone on the laser committee. I’ll be at the space tonight if you need the material checked out.
The material I have is 1.5" think. It came from a former bank my friend was helping remodel. What time will you be up there tonight? I’ll bring it up so you can check it out.
If it’s over an inch thick, & came from a bank, it’s probably polycarbonate (Lexan) “bulletproof glass”.
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If it’s from a bank it’s polycarbonate and shouldn’t be cut with the laser.
Fair enough. Well then maybe I’ll just take my butt over to the cnc whenever it becomes ready!