Abstract: An electrode holder having a replaceable guide through which an electrode extends longitudinally between an inner end operatively associated with an EDM machine and a free end engageable with a working surface of a component to be machined.

Abstract: An electrical discharge machine includes first and second coaxial electrodes and corresponding carriages. A liquid dielectric is channeled between the electrodes and a workpiece which are suitably electrically powered for machining a duplex hole in the workpiece.

Abstract: A system of accurately positioning a manufactured part in a calibrated position, involves positioning the part on a structure. Adjusting the part on the structure such that points on the surface of the part known to be accurate and drilling notches in the part at known locations. Distances from the surface of the part to the structure in `x` and `z` directions, and a rotation angle .theta. are measured. The part is then placed in a fixture having a nest plate with pins which hold the part by the notches thereby defining an axis through the part. A `z` stop is adjusted to the measured `z` distance which stops rotation of the part about the axis between the pins. An `x` stop is set to the measured x distance which stops translation of the part along the axis between the pins. The nest plate is pivotally attached to the base plate allowing the nest plate to rotate with respect to the base plate the rotational angle .theta.. This results in calibrated positioning of the part allowing maximum access to the part.