Abstract: A hydraulic drill unit for drilling multimaterial, thick layer stock having a conventional hydraulic drill modified to have its feed controlled by a servo valve and its spindle speed controlled by a servo valve. A linear encoder is attached to the drill to provide an indication of drill position. The linear encoded provides 20,000 forward and reverse pulses per inch, depending upon the direction of travel, which are used to determine net feed rate. The net feed rate signal is compared with a command feed rate to control the feed servo valve. A magnetic pickup is used to provide a pulse signal proportional to RPM. This signal is compared with a command speed signal to control the spindle speed servo valve. Differential pressure transducers are used to measure pressure across the hydraulic feed pistion and the hydraulic drill motor to provide signals which can be used as indications of chip packing or a dull drill.