When you see something made of metal that seems like it would be impossible to manufacture, possibilities are great it was made with some range of electrical discharge machining. EDM is the technique of option for hard-to-machine metals, high aspect ratio hole drilling, and precise surface completes that let mating parts slip together with nearly zero clearance. The difficulty is, EDM is a bit fussy, and as a result hasn’t made many inroads to the house shop.
[Action BOX] aims to modification that with a diy cable EDM machine. In cable EDM, a fine brass cable is utilized as an electrode to slowly erode metal in a dielectric bath. The cable is consumable, and has to constantly move from a supply spool with the workpiece and onto a takeup spool. most of the build shown in the video below is concerned with the wire-handling mechanism, which is prototyped from 3D-printed parts and a heck of a great deal of rollers and bearings. preserving the appropriate tension on the cable is critical, so a servo-controlled brake is fitted to the drivetrain, which itself is powered by a closed-loop stepper. tension is determined by a pair of strain gauges and Arduinos, which manage the setting of the shaft brake servo and the speed of the motor on the takeup spool.
Unfortunately, in testing this configuration proved to online as much as EDM’s fussy reputation. The brass cable kept breaking as soon as cutting started, and [Action BOX] never made any actual cuts. There’s definitely promise, though, and we’re looking ahead to developments. For more on EDM theory, inspect out [Ben Krasnow]’s look at EDM hole-drilling.
[Alen] sent in the tip for this one. Thanks!