a tool for finishing the internal surfaces of revolution in blanks including a casing having a groove on its side surface for accommodating bodies of revolution which are moved by a fluid pressure . a fluid is fed in through channels in the tool casing , the channels putting the groove in communication with the source of fluid under pressure . the groove is surrounded by a cage accommodating working elements which are installed with a provision for contacting the bodies of revolution and colliding with them in the operating tool . during this collision the working elements produce plastic deformation of the machined surface with a force which is somewhat smaller than in the known tools used for the same purpose .