The present invention is directed to machining reforming apparatus for machining electrodes of a resistance welding device. The apparatus comprises a body having an insertion portion for receiving at least one electrode and at least one rotary cutter, the cutter having a cutter portion adapted to extend along a peripheral inclined surface on a front portion of an electrode. A receiving base member is positioned within the body on the axis of rotation of the rotary cutter, wherein the receiving base member is adapted to abut a front end surface of an electrode. The cutter portions are biased radially inward towards an electrode, the biasing device maintaining proper contact between the edge of the cutter and the electrode.