Cylindrical hole and form centering and drilling device

The present invention relates to an electrical discharge apparatus for machining at least one rectilinear cooling air duct having a flared exhaust orifice in the wall of a hollow blade of a gas turbine engine. The apparatus includes at least one electrode having a given geometry and mounted on a first electrode support arranged to machine the flared exhaust orifice, and means for driving the motion of the electrode support. The electrode comprises a rear end segment that is affixed to the first electrode support. A device for electrical discharge machining at least one rectilinear cooling air passage having a flared opening in the wall of a hollow turbine vane. The device includes at least one forming electrode attached to a first electrode holder and includes a first face provided with a groove for guiding a rectilinear electrode configured to drill the rectilinear part of the air passage, a median portion with a constant section, and a pointed end portion with a section that decreases between the median portion and the point of the forming electrode.