an apparatus is configured for use with an electrode and a cnc machine tool . the apparatus includes a holder configured to hold the electrode in a position projecting outward from the holder , and a pull stud configured to mount the holder on the cnc machine tool . the apparatus further includes a driving mechanism that is operative to provide a motive force , and a coupling configured to couple the holder with the driving mechanism when the holder is not mounted on the cnc machine tool . the holder is configured to transmit the motive force from the coupling to the electrode in the holder to move the electrode outward of the holder .