Re: EDM stuff from Electronics 101
2005-07-08 by Curtis Richards
Dave Mucha wrote: >Hi Kurt, > >I noticed you posts on the Yahoo group Electronics-101 and was >wondering just how far you were able to get ? > >Did you make the power supply from Garden of EDM ? > >I know many people have discussed it and some have said it was too >complex, but I don't know anyone that actually made the circuit (and >admited it) > >I am fastenated by EDM and made a simple RC type. It took so long to >cut, I only use it as a last restort. Much too slow for PCB work. > >Dave > > > > > Hi Dave, I've been hacking around with the PCB EDM idea for a little more than a year. I initially used salvaged printer parts in the hope that I could simplify the software and "print" the PCB. Using PCL commands to "print" or burn one dot on the board at a time works, but is hideously slow. Using a plotter also adds complications in area of the pulse return path. I have had success lately using a gantry style machine with raster scan software. I can burn a 8.5 inch by 11 inch single sided board in under 45 minutes. Still slow but good enough for prototyping. I have been using the latest update of "Garden of EDM" without problems, but it is over powered for PCB work and I am in the process of a redesign using Mosfets instead of IGBTs and a PIC for control The RC or relaxation systems are way too slow and too hard to control for gap voltage. I'm working on a PIC system that will use voltage feedback to control a stepper/leadscrew to maintain the gap. My current system uses A3967SLBs for stepper drivers ($3.14 per axis! ) and a LPC2138 for a system controller. The ARM chip takes a JPEG image from a scanner or CAD program and outputs the correct pulses to burn the image onto a PCB one line at a time. The resolution is determined by the x-axis increment in the gantry movement. I'm working on a new design that I think will be "ready for prime time" or at least publication on the Web! It will use the A3967SLBs for the steppers, a PIC for EDM pulser and an old PC for system control ( ala EMC ) so that anyone wishing to work with the system won't be tied to the Forth programming language that I am now using. I'm thinking of something along the lines of a hardware version of a Sourceforge project 8-) . At this moment I'm looking at digital cameras in order to put some pictures in the Photos section of Homebuilt_PCBs. Further details to follow ( when I get a handle on photography :-) ! ) -- Curtis W Richards -- "The natural progress of things is for liberty to yield and government to gain ground." --Thomas Jefferson