I haven't seen the gantry I designed for Sisyphish used elsewhere. It's a modified version of polar gantries, and it uses a rotating arm for rho (linear) positioning and a spur gear for theta positioning. The gantry is built with a combination of Waterjet Delrin and FDM printed components, with a few rods and pins for part indexing. Two stepper motors drive the gantry.  You can learn more about how this was built at my portfolio website. 

     The motor driver is an Einsy Rambo which I chose because it has TMC drivers on board which support StallGuard. This enables me to home the rho axis without the need for hardware endstops. One challenge with designing this gantry was eliminating wires routing to any of the rotational stages as that would necessitate adding slip rings to the design. 

     The Einsy Rambo uses a Raspberry Pi running Octoprint as a host. I can upload my modified polar gcode files to the octopi server and run the machine headless. Paths for this machine are made using Sandify. Sandify outputs a file with a theta rho coordinate pair, and a script that I wrote manipulates it into gcode that’s usable on Sisyphish.

    The most important feature of the project, the livestock, are Taiwan Bee Shrimp. These are among the most colorful of the Caridina and Neocaridina shrimp families. The main benefit is that they can breed with differently colored shrimp without losing their coloration over generations.

     As well as this project ended up, I’m not sure that I’m going to keep this tank going, and I’ll probably make a new tank for the Bee Shrimp. The main challenge with this tank is fairly simple; shrimp poop. I was hoping the volume wouldn’t be quite as significant, and I was also hoping that biological filtration would quickly result in the poop fully decomposing. I was incorrect on both fronts, and the sand at the bottom quickly loses its luster due to a surplus of shrimp poop.

     I’m really happy with how this came out, but the maintenance required to keep it clean will likely motivate me to move towards a more conventional setup. Maybe I’ll come up with a more sustainable way to mix mechanics and fish in the future.