Using welder as power source for ECM

I believe that a transformer-based CV machine is basically a transformer with a big capacitor bank. At any rate, my wirefeed has a bunch of honkers in it. CC stick machines I believe have transformers that are wound to maximize inductance. But either would work fine if you aren't suddenly varying the load. The reason stick machines are CC is that if the weldor varies the arc the current will try to stay as much as possible the same so the weld doesn't vary as much. For a fairly constant load, I'd imagine either would work OK. What kind of current and voltage are you looking for?

GWE

Unless you mean "Electrical Discharge Machining", or EDM, you've been seriously disinformed. Electro-etching takes milliamperes at less than ten volts. You could do it with a couple of flashlight batteries. If you're really talking about electro-etching, then I might suggest that you might do a little studying on the subject.

Electrical Discharge Machining, on the other hand, is one of the things that drops my jaw in awe, and could, conceivably, take the kind of power that's necessary for real welding. Thanks, Rich

" The ECM process requires low voltage DC. Voltages from 5v to 15 v are usually used but may go as high as 30 v in certain cases. Currents from 100 to 20,000 amp are being used with even higher currents being considered for the future.

A welder would have a higher voltage than you need, but might work for doing some experimenting. You might also consider Microwave Oven transformers with a rewound secondary.

Dan

another source is the group:

I ran an EDM machine many years ago, voltage was under 30V, don't know the amps but it wasn't on the order of 100A or more. The power supply charged a capacitor which then discharged as a spark between electrode and work piece with a flow of electrolyte to wash away the tiny bit of material removed by each spark. We used pieces of copper tubing as the electrode to burn out 'high speed" alloy tools like taps that had seized in a work piece. EDM removed the hard tool steel as easily as mild steel and allowed us to salvage a piece with lots of materials and labor invested in it. Slow but the only option was to cut out the damaged area, weld in a repair, and then turn, drill and tap, bore and ream, etc to replace what was lost. Grove Valve & Regulator, gone now but we made the valves for the Alaska pipeline.

See Radio Shack if you're looking for electrochemical etching or chemical etching similar to the process used for circuit boards. They used to sell kits of tape and "resist" pens to protect the copper plating on a circuit board that you want to keep, then use acid to remove the rest of the material.

Rich Grise wrote:

At this point, I would guess somewhere between 10 and 50 V, and probably 5-10A as a minimum, possibly much more depending on how much area needs to be etched (and how patient I am). I expect some experimentation will be involved. I may end up needing a step down transformer to get the voltage in the right range.

Bert

Those numbers seem in line with the info I've run across so far. The industrial machines run with very small (sub-mm) gaps between electrode and work. My setup will be a bit cruder with a substantially larger gap, so I imagine I'll need to bump up the voltage quite a bit. And I'll be working at lower currents, at least initially -- until I get a handle on the process -- but I should still end up with much higher material removal rates than during my earlier experiments with a 12V/6A battery charger. I'll keep the microwave transformer in mind in case the welder doesn't work out. Thanks.

Bert

replying to Bert, Nick wrote: Hi, just wondering how your trials worked out?