I have seen some videos on Youtube depicting a crucible in which the user sticks a single carbon electrode to melt the contents of the crucible which was cast iron.
I tried it by making a steel bar with a ring in it in which the crucible fits and shaved the glazing off the crucible somewhat to enable proper contact. Admitted, it is an old one used earlier for melting cast iron in a propane furnace.
I connected the cathode (the clamp) of the DC welder (max 200 A) and a carbon rod to the anode (where the welding stick normally has to be attached). After some fizzling around, shaving crucible, I managed to melt a tiny amount (10-20g) of cast iron in a few seconds, but later the crucible started arcing outside between the steel ring and the crucible, even almost melting a piece out of the ring. Moving and tightening did not help: it persisted arcing on the outside. The current was set to 100 A.
Here a very short 4 seconds clip what happened : http://www.metallab.net/clips/crucible-eaf.mp4
Does somebody have experience with this ?