I have started to play around with EDM. The intention is to make an EDM "grinder" to profile tool steel and possibly carbide cutting tools using CNC-turned profiles.
At the moment I am using a cobbled-together XY table with a couple of STMBL drives. One of the STMBL analogue inputs is used to measure the current through the gap. (ie using the voltage across the resistor that a capacitor is charged through). Then a PID controller tries to achieve a target current by adjusting the adaptive feed pin. I think that it shows promise, but only partly works. I am using a 50R resistor and a 1000uF capacitor. I suspect that this is too high on both counts. I am working at 40V and it seems that the tool welds to the work too readily. I suspect that I would get different results if I controlled to the gap voltage, rather than charging resistor voltage. And probably better still with some sort of signal processing on that voltage. What combination of R, C and V would be typical for a servo-controlled eroder? I imagine it might be different to a "doorbell" style one. Current set up: https://youtu.be/nxpmEFnmK-A -- atp "A motorcycle is a bicycle with a pandemonium attachment and is designed for the especial use of mechanical geniuses, daredevils and lunatics." — George Fitch, Atlanta Constitution Newspaper, 1912 _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
