A control apparatus is coupled to a flame spray gun for controlling the rate of feeding of a rod of heat fusible material through the gun. The control apparatus includes an electric motor adapted to be drivingly coupled to a flame spray gun and being operable in response to application of a D.C. voltage thereto to generate rotary motion to produce and control feeding of a rod of heat fusible material through the flame spray gun, an A.C. to D.C. converter and regulator device for generating and applying the D.C. voltage to the electric motor, a manually adjustable potentiometer connected to the converter and regulator to vary the quantity of D.C. voltage output applied to the electric motor and thereby control the rate of rotary motion produced by the electric motor, a tachometer coupled to the electric motor for sensing the rotary motion produced by the electric motor and, in response thereto, generating a feedback voltage signal representing the rate of rotary motion produced by the electric motor and thereby the rate of feeding of the rod of heat fusible material through the flame spray gun, and a digital display coupled to the tachometer and receiving the feedback signal therefrom, the digital display being adapted to produce a readout of the feed rate in response to the feedback signal.