Metal Plate Weigh Reduction Through Trussing

Our team competed at a week 1 event with a 4-bar harvester made primarily of polycarb. While it was successful, we had a few snapped bars throughout the season and are re-fabricating the parts out of sheet metal. In order to save weight on our robot, we plan on trussing the plates and metal side plates of the shooter.

Unfortunately, our team has no experience with this. I am wondering if anyone has any advice or insight of how to design them in a smart and efficient way in CAD?

Edit: I have confirmed the arms were made of acrylic and not poly and that change will be made. However, we still are going to truss other plates on our robot including a modified version of the Greyt Shooter.

Using aluminum is gonna make the issue worse as when you’re hit, the piece is going to stay bent. Seeing as it snapped, I’m assuming you used acrylic rather than polycarb.

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We probably did. Manufactured with what we had in the lab and my assumption was that it was polycarb at first but now that makes sense.

My team has a number of CAD videos on our youtube channel. One series goes through the process of designing a sheet metal drivetrain. The final part shows how to CAD the lightening patterns: https://youtu.be/qZW9MKGitoM

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Put a piece of the material in a vise with about an inch sticking out. Grab the part sticking out with a large pair of pliers and try to bend it. If you get a nice sharp bend along the top of the vise jaw, you most likely have polycarb. If it snaps or shatters, you don’t have polycarb.

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