Abstract: An apparatus (10,100) for counterboring a pipe is attached to a pipe end surfacing machine (12) and is comprised of a frame (14) pivotally mounted to a flywheel (16). A cutting tool (50) and guide wheel (72) are attached to said frame (14). Means (91) for positioning the frame so as to locate the guide wheel (72) and cutting tool (50) relative to the pipe for machining is connected between said flywheel and said frame. In operation, the apparatus (10,100) is inserted into said pipe and the cutting tool (50) is positioned to contact the inner surface of the pipe adjacent the end of said pipe. The flywheel is activated and rotates, thereby rotating the cutting tool (50).