Abstract: An arc welding overlay apparatus that comprises a welding head carriage adapted for movement on a track, an index arm mounted for movement in a direction substantially transverse to the track, a slide mounted for movement in a direction substantially transverse to the index arm, a welding torch mounted to the slide, and means for dispensing a filler material to the welding torch. Feedback means and control means cooperate to indicate and control the movement of the weld head carriage, index arm, electric arc length and the filler dispensing rate. Means are also provided for emergency shutdown of the electric power source.