r/MechanicalDesign

I'm making a small, 6-axis 3D-printed robot arm using a mix of MG996R and SG90 servos. For the joints, I've been designing the printed parts to wrap around the servo horns, like in this photo: https://imgur.com/a/v871Zqf

Is this considered a good approach, or is there a more reliable method for attaching servo horns to 3D-printed parts? Any advice or examples from your own builds would be appreciated.

I’m 3D printing 2 parts that thread together and hold internal water pressure (40-60PSI) so I’ve added an O ring but am struggling to get it water tight. The parts themselves are not leaking, I’ve got plenty of walls/top and bottom layers/correct settings, it’s just in the seal. I’m currently printing the O ring using 85a TPU for iteration’s sake and would like to avoid buying a nitrile/silicone set until I know my design is correct. I’m sanding the seal face with fine grit sand paper to make sure it’s smoother than a typical 3DP top layer, but I can’t evenly sand the gland or shoulder on the top side since it’s all inside the female threads. 3”id 0.125”cs 3.25”od 85a TPU ring, gland is 0.185” wide and 0.09” deep with 0.3125” radius, do these numbers sound decent/anything obvious I’ve missed? I know 3D printing isn’t ideal for this but I can start buying parts when I get it close…

I have an STL file of a patient’s hand/wrist from a 3D scan and I need to design a custom-fit wrist splint with a Voronoi pattern for 3D printing (similar to attached image — you know, the breathable lattice type). SolidWorks feels like complete overkill and a nightmare for organic geometry like this. What’s the best software/workflow for this?

I'm designing a passive water cannon deflector for riot control vehicles. It's meant to be attached by protesters directly to the nozzle using a one-way, snap-fit mechanism and no tools required. The deflector redirects the water stream upward using a fixed 45° plate. I'm open to all criticism on the concept, mechanics, and material choices. Thank you.