Abstract: A forged-steel connecting rod blank is formed with intentional-break zones extending over one or both of the broad crankshaft-eye surfaces of the connecting rod or as crevices formed radially in the inner surface of the large-diameter bore of the eye and running from an upper edge to a web of the material which is ultimately punched out.

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: A workpiece support for supporting multiple workpieces in an immersion bath for spark machining including a stationary workpiece support and an adjustable workpiece support in side by side relation, an electrode holder overlying the supports and carrying a pair of electrodes thereon, the adjustable workpiece support having a pair of cylindrical rollers rotatable on axes eccentric of the cylindrical outer face, a coverplate with openings receiving the outer surfaces of the rollers therethrough, a closed chamber containing gear wheels connected to the rollers for simultaneously turning the eccentric rollers about their rotation axes, and a manual operating apparatus for turning the gear wheel.

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.