Abstract: A device for drilling and lining holes in earth bores wherein a casing is intended to be lowered into the bore along with the drilling unit. The drilling unit is mounted on a rotating drill. The drilling unit includes a plurality of cutters which can be arranged in the extended active position or can be retracted to a passive position arranged within the casing of the drilling unit. Drilling fluid through an activating piston repositions the cutters between the passive and the active position. The drilling unit includes a gripping device which contacts a groove in the casing which carries the casing down the bore with the drilling unit. Threaded ribs within the drilling unit act as a pump to maintain down hole drilling fluid pressure. A valve is provided in conjunction with the cutters whereby when the cutters are moved to the active position the valve will open allowing flow of the drilling fluid.