Abstract: A tool holder for electric discharge machining includes a block of molded plastic mountable to an EDM tool. The block is shaped to provide locating reference faces adapted to abut a mounting face on an EDM machine and thereby locate the block in a Z-direction on the EDM machine. An electric conductor is embedded in the block and has portions exposed (1) at the faces for electric contact with the mounting face on an EDM machine, and (2) for electric contact with a tool mounted on the block, whereby an electric circuit is completed between the tool and an EDM machine on which the holder is mounted. Finally, the block has a clamp for clamping the block on an EDM machine to urge the reference faces against the mounting face on such machine.