Really, the electric arc furnace seems to be very appealing:
1. Cheap to build (old welder + carbon electrodes + crucible)
2. Melts steel
3. Melts just about anything
In particular, it seems to solve a gap we hobbyists have -- we can melt aluminum and brass, but nothing much hotter. A lot of us, myself included, would love to melt steel and iron to make simple castings. It's a perfect complimient to the CNC hobby.
For instance, cut a foam pattern on the CNC router, slip coat with drywall compound, pour yourself a cast iron widget and finish machine on your CNC. There, we've come full circle with the hobby.
In any case, casting steel and iron sounds like fun. Heavy castings have a satisfying feel and may serve structural applications that our typical aluminum castings just won't.
That brings me to a question. What is the drawback to melting steel or iron this way? Do the carbon electrodes leave too much carbon in the steel soup? Do castings from this process have questionalble strength? Does it require argon or some other inert gas?
I already figured that the UV radiation would be bad... so that needs to be contained in the crucible. Are there other drawbacks? Does it not scale well for small home foundries?
So, I invite any answers or experience you folks can offer. Even more questions. Give a shout out if you're interested in a DIY arc furnace.
Wouldn't it be great to have the equivalent of JRGO plans for an arc furnace?
Did it when I was a kid only a small 4KW input furnace, power is what you need and lots of it, at a guess 10Kw for a few Kg melt, If you can get one of the large flux cored or sub arc wire feeders lincoln ln7 comes to mind and a roll of scrap fence wire, getting a crucible full of iron is doable, preheat with gas then start the wire feed, need to water cool the contact tip and seal the furnace, argon or CO2 blanket would be ideal (careful the CO2 will become CO +O2). As for a power source any heavy duty MIG, I have a DC600 which would work fine 100% duty @ 600A
Light duty home welder, forget it, most have only 20% duty or so at 140A, AC welders need considerable power factor correction to get the full KW out of your supply Industrial duty machines are usually rated at 60% duty so a 300 or 400 amp machine will be fine for most use. US users are lucky in this respect in that 240V high power welders are common as are 240V supplies, in Australia they are usually 415V requiring 2 or 3 phase power.
In short a MiG power source will work fine as a consumable electrode arc furnace power source and a electrode power source will work fine as a carbon electrode power source. Visit the local scrap yard or clearance auction for a power source. Call a carbon supplier for graphite electrodes. Water cool the electrode clamps, they get very hot otherwise