Abstract: An apparatus for shaping a three-dimensional workpiece by inducing the following relative motions between an abrading die member and the workpiece: a feed motion, periodical retract and advance motions in a z-direction, and a planetary or orbital motion in the x and y directions. The mechanism which generates the planetary or orbital motion is provided with means for infinitely adjusting the eccentricity of this motion and is provided with means for selectively and releasably fixing the chosen amount of eccentricity. An assembly is provided to adapt the following process values to conditions within a gap between the die and the workpiece such that the abrading process is optimized: (i) feed pressure between the die and the workpiece during an abrading period of a work cycle; (ii) speed of the feed motion; and (iii) speeds of periodical retract and advance motions.

Abstract: An electrode mounting plate having a flat face adhesively bonded to a graphite electrode and an opposite face forming a trough with reinforcing ribs, the trough being covered in use by the mounting plate of the spark machining apparatus to define a chamber communicating with the dielectric circulation system of the apparatus. Flow passages for the dielectric fluid are formed by drilling holes through the mounted electrode and the flat face of the electrode mounting plate.

Abstract: Casting apparatus for use in making intermediate molds for the preparation of tool electrodes comprises a pallette for holding the casting and adjusting devices for ensuring parallelity and correct alignment for the mouldingfaces. There is also vibrator to ensure improved consolidation of the casting material and to provide for degassing.

Abstract: An over or undersize abrasive master mould is used to form tool electrodes by abrading a workpiece using a circular reciprocatory motion. The master mould is made by a casting process which starts with a preformed model, positive or negative, of the exact shape to be machined by the tool electrodes to be made. Positive and negative castings of the model, one of which castings is abrasive, are subjected to a relative circular reciprocatory motion in an abrading operation to provide the correct under or oversize of the master mould, which is then made directly or indirectly from the abraded casting. Casting apparatus for use in the method comprises a pallette for holding the casting and adjusting devices for ensuring parallelity and correct alignment for the moulding faces and there is also disclosed apparatus for the abrading operation in which an error detection system regulates the amplitude of the reciprocatory abrading movement.