Abstract: An electrode for use in a rotary electrical discharge machining (EDM) device for producing at least one curved hole in an article includes at least one curved tooth. The curved tooth lies in a plane. A perpendicular line to that plane is parallel to the axis of rotation on the rotary EDM device. At least one curved cooling hole is machined in the article.

Abstract: A helically fluted deep hole cathode which is fabricated by helically winding at least one thread member around a dielectrically coated cathode tube and then applying a layer of electrical insulation over the tube and thread member so wound and wherein, preferably, the helical flutes commence about the distance of the diameter of the electrode tip from the tip and are selectively formed or machined after forming to have a flute diameter approximately .001 inch to .002 inch smaller than the diameter of the hole to be cut so that the flutes support the electrodes in the deep hole during the cutting operation and provide an egress route for the electrolyte and removed workpiece material to depart the hole area during the hole drilling process.