Abstract: A well notching tool having an elongated rotary power shaft and a coaxial shell in surrounding relationship therewith. A portion of the exterior shell surface is formed with an upwardly directed taper, and a portion of the exterior surface below the taper is formed with threads. A coaxial bell housing surrounds the shell and has internal threads cooperating with the threads on the shell for relative movement of the bell housing and the shell. The bell housing wall has upwardly directed passageways, and a slip is mounted in each passageway for movement in the passageway when contacted by the taper on the shell. A cutting assembly is located at the lower end of the power shaft to rotate with the power shaft. The cutting assembly includes pivotally mounted cutting tool arms actuated upon rotation of the cutting tool assembly to swing outwardly, and a cutting tool is carried at the end of each arm to cut a notch in the sidewall of a well bore.