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Especially proud of learning to integrate components from other sources properly. SG-90 servo motors are now in the design (random open-source), as well as a ball joint from McMaster-Carr
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I'm still astounded by how I can do all this insanely powerful engineering design work for free, and my only cost is materials and time.
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The turnbuckle was the hardest thing I've had to model. 2 ball joints at either end of a variable length rod... I left out the screw constraint and the lock nuts. Made it cylindrical joints instead.
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And FINALLY, the full assembly is sorta done with all major linkages and joints represented. It was a bitch to get this right... there's like 6 ball joints, and 5 pin joints here.
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The thing is, attaching the 2 turnbuckles would immediately mangle the assembly into a weird train wreck. Since the geometry is coarse, all lengths are rough approximations, and OnShape doesn't allow ball joints to be constrained, the constraint solver creates pretzels.
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And initially I had the turnbuckles set too long, so the thing would really contort. So I suppressed one end of each turnbuckle, rearranged the whole thing to look right, then manually adjusted the turnbuckle lengths and positions to be approximately right...
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Then I unsuppressed end connections and the solver "found" the nearby solution and didn't pretzelize the design. Then I used the measuring tool to measure the turnbuckle length, and went back to the part subassembly and constrained cylindrical joint to be a few mm around that.
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Effectively, instead of solving a hard 3d geometry problem to compute the right nominal length, I found it "experimentally" in the 3d CAD design. Now I have everything close enough that I can do projections and back out final actual geometry. 😎 🥳
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