While the body is still made to be 3D printed, the redesign removes the dependency and inefficiency off single use CO2 cartridges and instead uses two counter-rotating flywheels, powered by FA-130 DC motors, to fling pellets (moss/water capsules, simulated with 6mm BBs) forward and down into tillable soil. Because the system runs on battery power rather than a pressurized gas cartridge, it can fire continuously and repeatedly without requiring the robot to return to base for a reload between every few shots while being cheaper, lighter, and more sustainable then the previous firing system. Next steps include tuning the spacing between the custom flywheels more maximum launch velocity and integration with the movement system as well as testing the optimal launch rate of the moss pellets/BBs.

In terms of materials, PLA would be used for all 3D printed components, as it holds tight tolerances well , which is needed for the BB channel and flywheel gap, and is cheap and fast to iterate on, which is better for testing. It's not viable as a final material, though: PLA is brittle under repeated impact, softens at low temperatures, and wears poorly at points of frictional contact. This is significant for parts expected to survive sustained field use and "eventual" Martian atmospheric extremes. For the barrel and flywheel-bay walls, which see the most wear, a move to PETG would be ideal, as it offers better layer adhesion, impact resistance, and toughness while still being easily printable. Post-processing includes heat-set brass inserts at the motor and servo mounting points. If this went to true mass production, the biggest change would be moving from FDM to injection molded housings something like ABS for tighter tolerances and faster production.

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Jonathan BrooksJB

Spider Mine to Tank of Creation (Firing System)

Evohome V2