The machining of castings requires a different approach to the machining of wrought metal components.
Castings are never totally flat, square, round or straight.
A secondary datum system may be required to define the machining requirements. When a flat face is required, add material to the casting to give a machining allowance. On parts with no obvious location areas for machining, machined lugs should be added for holding the casting. These can be removed completely with a secondary machining operation. Renishaw probes - Micro Metalsmiths machining centres are fitted with Renishaw probes.