I have seen a lot of people talking about how acrylic shouldn’t be used. I know it is weak, but is it okay to use it purely for aesthetics or is it still too fragile to be used on a robot?
Purely aesthetics, you could probably get away with it for a bit, if you get it thick enough.
Especially if your aesthetic includes cracks through the acrylic.
Polycarb seems like it’s a bit cheaper, and it won’t crack. About the only advantage to acrylic might be causing your opponents to get yellow-carded.
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My team used it last year but in some pretty low impact spots, it worked decently and only one panel cracked somehow. The main reason I want to use acrylic is because of the color options.
I now introduce you to the wonders of spray paint and wraps and other methods of changing material colors.
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The sole reason one would use acrylic, I’d say, is because it’s easy to cut with a laser. You can get some really nice aesthetic designs with laser cut acrylic parts overlayed onto other materials. We use acrylic in our custom driver stations and etched panels on the robot’s sponsor panel (2-layer dual color acrylic). If properly backed or covered in clear tape, it won’t cause problems even if it shatters.
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…vinyl design over polycarbonate?
(A dedicated vinyl cutting machine is better than a laser, of course. Cricut’s hardware is fine but definitely get Sisor(?) EasyWeed or another higher end vinyl instead of the cricut brand vinyl)
For a driver station or cart, yes, acrylic is fine.
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Lots of different ways to do it. I literally own a side business that designs/makes custom things out of acrylic, so I have a lot more laying around and find more ways to use it than others may.
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We had an .25" acrilyc sponsor panel in the early season this year. It was hit by an intake and exploded.
We did basically an acrylic robot in 2023… As you would expect we had some issues, but it did survive a full district event and the way it was designed we could have made spares, but ultimately we made an aluminum replacement.
Backstory: We received a donation of Hockey Rink Wall acrylic that is 1 inch thick. They came in giant slabs that we tried to make use of over several years. We started mostly with prototyping parts, some final pillow blocks, bumper clips, etc. We decided to be brave and trust the strength and thickness to provide a good base.
One of our sponsors had a machine big enough to cut a unibody baseplate with mounting holes, ridging, etc. We tested it out at the lab extensively, did solo drive practice, but didn’t week 0 or scrimmage at all. All seemed well, but when we got to the end of the event and started to do our ‘whats needed before next competition’ info gathering we found 4 cracks ranging in size.
The issue is with a unibody chassis it’s all or nothing… So we knew no matter what it was time to remake another baseplate. We had and still do have plenty of that acrylic stock, we had time and the ability but once we found that weakness still carried through to the very best case acrylic… Why go down that road again and have to make possibly a third or fourth chassis that year. One more time and metal was the right answer. That also let us make it thinner and weigh less
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I have never seen Lexan cheaper than Plexiglas. Has something changed?
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We’ve used laser engraved acrylic with our logo on it, looked sick, but If you couldn’t take the piece off the robot with no harm done, stay away from acrylic.
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Acrylic is also great choice to laser cut for use as a template for something like a router (with a template bushing). I should also note that fiberboard is much cheaper for this but the durability is an issue after a few uses. I do this often at work to cut polycarbonate since we don’t yet have a CNC router, and for my woodworking projects at home.
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I checked McMaster before saying that. Current rates seem to be lower on polycarb.
YMMV.
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This is true, but I also have seen acrylic decorations shatter. It was probably too thin, but the clean up was not enjoyable for anyone and the kids seemed sad their decorations broke. 
I would advise decorating with a different material.
Acrylic on robots.
Don’t.
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I generally steer teams away from using acrylic as it produces little slivers when it cracks. Nothing worse than trying to kneel down on the playing field to work on your robot and find a sliver sticking out of your knee. just my two cents.
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Look at izod impact strength to compare how they might behave in collisions. Acrylic is one of the worst plastics for impact strength.
https://www.curbellplastics.com/resource-library/material-selection-tools/plastic-properties-table/
PC, PETG, Nylon, ABS, and PEs will all do better.
Fwiw the front air dam, wheel flares, radiator ducting, and splitter mount on my race car are all ABS and have withstood high and low speed impacts with all sorts of things. I chose ABS specifically because of the cost:impact strength ratio.
On robots we use a lot of PC for final components that will see impact loads. It is simply one of the best plastics for impacts, and the izod impact data reflects that. This HSV shows how much PC intake parts can deform during impacts without failure.
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We had a team at PCH Charleston last year who built their electrical panel out of acrylic. Well, they weren’t sure when I inspected them but I expressed caution for all the reasons explained above.
Sure enough, they played D against us in a match, shattered the electronics panel five ways to Friday…and their next match was with us. We quickly went to the machine shop to chop to size my favorite source of cheap, field-expedient HDPE (we always keep a couple in our pit for emergencies), shoved it under the acrylic panel for lack of time, and they made the match.
I hope they hit a Sam’s Club sometime since last March.
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I’m curious what y’all think about prototyping with acrylic vs something like plywood? I inherited about 10 sheets of 1/4"x24"x48" that were supposed to be for our district’s covid shields, and I’m considering having the team use them to prototype mechanisms rather than using 1/4" plywood as we usually do. I’m concerned 1) if it will be a safety hazard by shattering just while just prototyping mechanisms and 2) that it might get accidentally confused with polycarb later in the season and make it’s way into a robot while I’m not looking. I hate wasting it while it just sits back there, and I like that we could cut it with the laser cutter as well as our routers, but I don’t want to use it if it’ll end up hurting the team more than help.
Some thoughts:
Templates seem more goof-resistant. Perhaps stencils for your bumper numbers, if you haven’t dialed that in? Or make sponsor thank-you plaques out of it?
If you do use them in prototypes, I’d do two things:
- Etch “THIS IS ACRYLIC DON’T PUT THIS ON THE ROBOT” on the acrylic parts. If you have freshmen leading the effort, “PUT THIS ACRYLIC ON THE ROBOT AND HAVE OHIO RIZZ FR FR YEET” is also acceptable.
- Some clear packing tape should help keep all the cracked parts together if (when) they crack. Won’t save you from a full speed whack against field truss, but I think you’ve got more sense than that.
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