An automated quill drive assembly is adapted to be retrofit on a milling machine having a frame presenting a quill head and a quill supported on the head for rotation and for relative shiftable movement along a linear axis between retracted and extended positions. The quill head includes a centrally disposed lower lug, a quill feed engagement control lever boss located above and spaced to one side of the lug, and a transmission cover opening located above and spaced to a side of the lug opposite the quill feed engagement control lever boss. The automated quill drive assembly includes a housing adapted to be mounted to the lug, the quill feed engagement control lever boss, and the transmission cover opening, a motor supported on the housing, and a transmission supported on the housing for transmitting automated movement from the motor to the quill to move the quill between the retracted and extended positions. A sensor is provided for continuously sensing the position of the quill as the quill is moved between the retracted and extended positions. The sensor provides an output signal indicative of the position of the quill for both manual and automated movement.