I just got ten of these ball joints. I figured out that I needed four of them for the sculpture, but now I just need two. These are very cool, so I’ll need to figure out how to use a few more. The pen shows the size. These are bigger than what you might find in a radio controlled car, plane, or helicopter.

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Ball Joint and Ball Point Pen

Here’s the latest plan. I still need to rotate the top structure 90 degrees, but I’ve moved things around so that I can see the timing of the top ball pickup, while also seeing the crank shaft closer to its final position. There is an extra arm on the top to help me build the crank shaft and pickup arm all with the correct angles, but the sculpture won’t actually have two arms on top.

Design Animation