Graphite electrode is nothing more than a sharp graphite rod, taken from a pile, subject to a support conductor of the current, copper tube, and at a reasonable distance a plastic handle, PVC tube. The handle should be far enough away so that it does not reach so much heat to soften it. Anyway it is clear that PVC is the worst plastic that can be used for this but it was there.
This is a sheet metal welder for almost any metal. It does not require input of material and practically does not admit it unless they are very thin rods. It is not about electric arc welding. What melts the metal is the graphite tip that shortly turns to bright white. What is heated by the current is graphite, not metal, Graphite electrode because the first one has a much greater resistance and dissipates most of the power. It is important that the graphite tip is sharp for two reasons:
The finer the point of contact between the material and the tip more resistance to current and more temperature reach. If it is too thick, heat is transmitted easily from the tip to the soldering iron and a large part of it dissipates without reaching the necessary temperature. The soldering iron only works if it concentrates most of the power at the point to be soldered. Everything has to be thought for that.
The truth is that to have been done in 10 minutes, nothing else came up with the idea, it was pretty good. The way to hold the Graphite electrode was the idea of a friend and is interesting for its simplicity. It involves making two cuts on the edge of the tube longitudinally dividing it into 4 more or less equal parts. Two of them are eliminated and the tube is left with two tabs. Each one is tightened with pliers to give it a round shape and it adapts to the bar and then approaches each other. You are looking for a large brass nut that snaps into place and, without the rod; you turn the nut with force, making a thread in the copper. Then open, put the bar and do the same again and is perfectly subject. This system allows changing the bar quickly, adjusting its position, and providing a good electrical contact.
Graphite electrodes are mainly used in electric arc furnace. They are presently the only products available that have the high levels of electrical conductivity and the capability of sustaining the extremely high levels of heat generated in EAF. Graphite electrodes are also used to refine steel in ladle furnaces and in other smelting processes. Graphite electrodes are divided into 4 Types: RP Graphite electrodes, HP Graphite electrodes, SHP Graphite electrodes, UHP Graphite electrodes.
Diameter and length for all grades:
Machining Dimension of Electrode and Nipple：