#video of #Rack-Robotics’s DIY wire #EDM #machining rig, including #manufacturing it with #3D-printing from carbon-fiber-filled PLA; the power supply here is their “Powercore V2”, which is 200 watts at 70 Vdc output with “up to” 90% efficiency for US$400. He uses a jug of distilled water from the store. He says the Powercore is “expecting a 1Ω resistance”, so it doesn’t shock him when he puts his hand in the circuit, though I notice he doesn’t connect it across his two hands. He says the wire’s outer coating is zinc, not tin as I had guessed. He says the water circulation is 100 “psi”, and it seems to be moving at a pretty good clip parallel to the wire. He touts ±100μm tolerances on the current revision, which sounds pretty shitty for wire EDM, and for the next revision they’re still only targeting 50μm, so they’re really trying for the rapid prototyping market here, not the traditional ultra-precision market of wire EDM. The motors (“hybrid” steppers) are kept out of the water, using only mechanical linkages to move the toolhead and tension the wire underneath the water. They dunk it in a 10-“gallon” aquarium to hold the water. They’ve moved to Colorado Springs and gotten funded. (This video is from this week.) 180 watts output at 5kHz implies 36 millijoules per spark, which implies about a 14μF output capacitor.
on 02024-05-17#video of #manufacturing a DIY wire #EDM for #machining; basically an ad for #Rack-Robotics’s (rackrobo.io) maybe-someday-open-source Wire Tool replacement hotend to turn any 24-volt 3-D printer into an EDM machine with 300μm brass wire, which looks silver, so maybe it’s tinned. Not sure how the filtration and feedback works, which seems like almost the most important part? He never mentions filtering. Also demonstrates hand-carving a 600μm aluminum plate with a 1.5mm brass rod electrode, which ought to be impossible because it should short out to the workpiece when you’re holding it in your hand, but actually it works fine. Gets up to 100mm/minute with the wire on the 600μm aluminum, or 20mm/minute in 3mm aluminum, while steel is 4½ times slower, while titanium is only 2–2½ times slower than aluminum. The power supply (“Powercore V1”) goes up to 72 volts, but the demo is all at 65 volts; he says the hard part is actually the power supply, which is “high voltage” (ha!), high power, 5000 Hz. This is at #rmrrf which I think is the Rocky Mountain RepRap Fest.
on 02024-05-17