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Re: Polycarbonate vs. Aluminum
Just a reminder, if your intake is made of polycarb, it will probably deflect some. And if that deflection makes your robot exceed the maximum size constraints (of which there are two possible combinations), you theoretically could get flagged for violating G04. I'm not advocating for aluminum over polycarb, but do be aware that they each come with their own set of challenges, and this is one of them.
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Re: Polycarbonate vs. Aluminum
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Bonus points if you can show the residual stress fields in the plastic. |
Re: Polycarbonate vs. Aluminum
Thank you everyone for the input thus far, all of this has been helpful for us and we will take this information into account.
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Re: Polycarbonate vs. Aluminum
Okay, so, guess what snapped in my hand this evening?
A piece of 1/16" polycarbonate that we'd bent on the break. We've been doing it for years with no problems, and have played some awfully aggressive games with pieces made like this, without any problems. It took almost no effort to break. It was, mind, bent much farther than 90 degrees, and I'd warned my students that this might be a problem. So as with most things, you might want to try things for yourself before implementing them based on advice from some internet blowhard (i.e. me). |
Re: Polycarbonate vs. Aluminum
Another poly-card intake from 2014, MORE Robotics.
https://www.thebluealliance.com/team/1714/2014 This one freaked me out a little when I first saw it, not because of the design, but I had never seen a polycarb intake of that scale before, it had significant wobble but worked just fine. |
Re: Polycarbonate vs. Aluminum
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Re: Polycarbonate vs. Aluminum
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Re: Polycarbonate vs. Aluminum
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Of course, this is a very different use case than an outside-frame intake, but my point is mainly that what you can get away with depends on use context and runtime. FRC teams can and do get away with doing a lot of objectively awful things to our robots. |
Re: Polycarbonate vs. Aluminum
Thanks s_forbes!
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However, I reserve the right to be skeptical. I'd rather see one example in practice than a dozen people insisting something is okay without any tangible proof. |
Re: Polycarbonate vs. Aluminum
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Here is the only picture of one of the Cold bent parts I have on my phone. https://drive.google.com/file/d/0B5V...ew?usp=sharing I apologize for the google drive upload. I'm at school ;). If you want any more pictures of parts Ill take more when I can get into the lab after school. |
Re: Polycarbonate vs. Aluminum
We have a few scraps in the shop. I'll bend some up and post a picture today.
We do cold bends on non crucial parts. Things we want to have survive for a long time we heat bend. |
Re: Polycarbonate vs. Aluminum
Don't confuse polycarb with Acrylic. People do it all the time because they look the same but drastically different properties. Acrylic will shatter and crack. Poly is the same stuff bulletproof windows in banks are made from.
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Re: Polycarbonate vs. Aluminum
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EDIT: apologies, it was only explicitly stated once, now I look like a hypocrite... |
Re: Polycarbonate vs. Aluminum
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I think polycarbonate intakes are great, but you need to ensure it is functional under defense with the added flexibility (though this is really applicable to any intake). |
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