[introduction] cad/cam, modeling, software
[press fit structure] laser cutter, vinyl cutter, plasma cutter/router
[printed circuit boards] pcb fabrication, board stuffing -
[cables] making molex<->serial and soic8<->parallel cables
[hello world] microcontroller programmingS
[coffee or tea] 3d scanning and printing
[input devices] sensors, instrumentation, light, sound, temperature, position, proximity-
[flexures] waterjet cutter, CNC milling and turning
[output devices] LEDs, OLDEs, LCDs, video, speakers, motors
[pdms] molding, forming, and casting
[LED array] With the final project in mind, I decided to work on an LED array cast in Polydimethylsiloxane, aka PDMS. PDMS is the most widely used silicon-based organic polymer, and is particularly known for its unusual rheological (or flow) properties. It is optically clear, and is generally considered to be inert, non-toxic and non-flammable. PDMS has been assigned CAS number 63148-62-9, and is occasionally called dimethicone. It is one of several types of silicone oil. - Wikipedia entry It's important to thoroughly mix both parts of the PDMS solution (10:1). I made a homemade wisk by spinning a piece of 1/8" wire and using it as a drill bit. Once it was mixed, I used a pressure chamber to de-air the concoction. To complete the casting, I baked all three parts (MDF, PMS, LEDs) together in an oven at 80 degrees Celcius for 2 hours. An alternative would've been to just let it sit over night, but I had little time to waste. For this component I CNC routed a mold out of MDF to house the liquid PDMS and the suspended LED array. The dimensions of the mold correspond to the dimensions of the cavity in the frame of the chair. Eventually, each LED terminal pin will be wired in parallel to a power source on one side, and a plastic tube on the other. When salt water is pumped into the tube, thus inundating the exposed wires, a circuit will be completed and each successive LED will illuminate. |
