Abstract: A method of forming a shape such as a groove by inserting a stick-like electrode during electric discharge machining to form a first deep opening, retracting the electrode, repeatedly shifting the location of the electrode and inserting the electrode while electric discharge machining to connect adjacent deep openings.

Abstract: A method for forming a master die from a conductive material using electrical discharge machining. The conductive material is created to have a plurality of dimples that are non-circular in a direction perpendicular to the spherical surface of a conductive material and/or in a vertical cross section. The plurality of dimples being formed by electric discharge machining using an electrode that is moved in a direction perpendicular to the surface of the material.

Abstract: Apparatus for fusing electric motor parts (e.g., fusing electric motor armature coil leads to the commutator of the armature) includes positive control of the elements which move to perform the fusing cycle so that the fusing cycle stroke can begin at any desired location. This facilitates shortening the stroke and making it constant despite changes or deviations in the workpieces being fused. It also facilitates withdrawal of the fusing head to a location which is more remote from the workpiece when the fusing electrode is to be changed due to wear. In fusing machines having a rotating turret which carries several fusing electrodes, the mass of the moving parts is reduced by mounting the actuator which reciprocates the turret on the frame of the machine, and by deriving the motion required to rotate the turret from the reciprocation rather than from a separate actuator.

Abstract: An electric discharge contour machining method in which a plurality of rod-shaped portions having different outer diameters on one rod-shaped electrode are used to machine the contour shape of a workpiece. The workpiece is selectively machined in any of a plurality of contours by the single electrode having an optimum electrode diameter for each selected contour. Specifically, the method uses one rod-shaped electrode having a plurality of rod-shaped portions, each portion having a different outer diameter such that the workpiece contour having a small inner corner of first radius R is machined by the electrode portion having a small outer diameter and the workpiece contour having a large inner corner of second radius R is machined by the electrode portion having a large outer diameter.