#video of die-sink #EDM #machining in diesel fuel using an Arduino, a MOSFET for PWM, a halogen worklight in series to limit current, and a stepper motor. #TheIdahoanShow reports that motor oil, WD-40, and canola oil also work, and aluminum and brass (such as a cartridge case) both work well as electrode materials, but TIG welder electrodes tended to stick and not cut very well. Stainless “kind of worked”. His demo was to cut a plus-sign-shaped hole into a chunk of old file. #bootstrapping #DIY #jugaad #manufacturing
#PDF #paper covering the #history of #PAKE #protocol development in #cryptography up to 02021, including the known vulnerabilities in #SRP.
#video by #AndysMachines on #EDM #machining, using an RC circuit to limit the energy of each spark and an IGBT to switch it, with 20μs on and 180μs off time (5kHz 10%), 60V, a 100μF electrolytic cap (which gets too hot), a heating element to limit the cap’s inrush current, a 3mm brass electrode cutting aluminum, and just distilled water for the dielectric. He makes it through 1mm of aluminum in 23 seconds, 18mm³/minute. #electronics #manufacturing #bootstrapping
#machining #video by #AndysMachines on his die-sink #EDM #machining #manufacturing setup. He’s using an aquariump pump to circulate his distilled-water electrolyte through a coffee filter, which needs changing often. He switched to a photo-flash 160μF capacitor for his IGBT-triggered 60V sparks (averaging around 50V). The #electronics use two DRV8825 stepper drivers, though they have trouble with the noise; the die advances when the current averages below an adjustable limit of 2.5 amps, and then there are periodic retractions to permit better flushing. He measures the capacitor voltage with a voltage divider to estimate the current. #bootstrapping
another #machining #video, by #My-Engines, on die-sink #EDM based on Ben Fleming’s book, using varying sizes of capacitors in an RC setup (16μF, 32μF, 192μF) with the lower capacitances giving a finer finish. He has some detergent (“wetting agent”) in his water electrolyte, presumably an nonionic surfactant (he says his tap water works better than deionized or distilled). However, though big electrodes worked fine, his thin copper and brass sheet electrodes eroded too rapidly, and he wasn’t able to get a stable “burn” out of either them or graphite. Lamp oil worked better than vegetable oil or water for him. #electronics #bootstrapping
another #My-Engines #DIY #EDM #machining #video. Finally he got his pulse EDM working. He had blown the protection diodes and the pulse transistors in the #electronics. His numerous 25Ω power resistors were inadequately heatsinked. He found that long on-times were the key to low electrode wear, backwards from what I would have expected. Sadly he doesn’t say anything about his parameters (voltage, current, frequency, duty cycle) or circuit design. Looks like he’s at about 5kHz. He’s using a diesel fuel pump to circulate his lamp-oil electrolyte (kerosene) through water filters.
#video about changing over a (bulk cargo?) ship from maritime very low sulfur fuel oil (VLSFO, ≤0.5% sulfur, 180–380cSt at 50°, service tank temperature 90–95°, injection temperature 130–140° for 12–13 cSt viscosity) to low-sulfur marine gas oil (LSMGO, US$674/tonne at the moment, according to Ship & Bunker’s Singapore bunker prices chart, while VLSFO is only $672/mt) in order to reduce SO₂ emissions to enter the North Sea SECA zone. It’s remarkable to me to see such an in-depth explanation of how to run a container ship on YouTube.