#video on #3D-printing pneumatic logic display #mechanisms (incorrectly described as #fluidics) with FDM and silicone membrane to get 8×8 bistable pixels, which he can play Snake on. Each pixel has a single pneumatic vacuum valve (“transistor”) which permits vacuum to the display only when there is vacuum on both the column channel (providing the air current) and the row channel (opening the valve). To get airtight channels with FDM he prints slow, hot, and overextruded, which still wouldn’t give you the wall smoothness you need for fluidics. The multiplexing is rather slow because he’s driving the rather voluminous channels with solenoid-driven valves, getting speeds more like 8Hz than the 10kHz or so normally achieved with fluidics. The platinum-cured 25A silicone membrane’s smooth surface comes from the air-exposed surface of the silicone in a mold carefully leveled with a 2-dimensional bubble level; he tried using a different, commercially-made silicone membrane for the logic surface, but it had to be smooth and flat on both sides, and the commercial silicone sheet wasn’t smooth enough, so he cast his own with glass as the mold on the bottom side. To get the warped bottom surface of the 3-D print to be flat enough to seal well, he sealed it against glass in a vacuum bag and then annealed the assembly at 60° for several hours. Tiny raised concentric rings around the holes that have to make contact with the silicone membrane hopefully make the system more robust against small deviations from flatness. He 3-D prints Luer lock adapters for standard medical tubing, which connect to the logic board with O-rings. I feel like you could probably Charlieplex with this pneumatic-logic approach, and with silicone you might even get a reasonable lifespan, especially with less extreme flexions than the ones he demonstrates in the video. Amusing note: to speed up display updates, he seems to activate multiple rows simultaneously when their contents are identical, an approach which might work for other kinds of multiplexed #displays.
on 02026-08-24#fluidics for pumping in #molten-salt #nuclear-reactors (just an abstract)
on 02025-08-24