Abstract: A lathe adapted to trim and true the circumference of a rotating cylindrical surface comprising an axially forward plate with a central aperture and a plurality of radially interior and radially exterior apertures, an axial rearward plate with a plurality of radially interior and radially exterior apertures; fixed cylindrical spacers fixedly coupling the forward and the rearward plates, a plurality of threaded cylindrical spindles rotatably supported with respect to the forward and rearward plates with a planetary gear secured with respect to each spindle, a rotatable advancement assembly formed with a rotatable plate and a forwardly facing cylindrical periphery and a tracking ring in meshing contact with the planetary gears whereby rotation of the rotatable plate with respect to the rearward plate will rotate the tracking ring to rotate the planetary gears and the threaded cylindrical spindles, a carriage having two parallel threaded bores in meshing relationship with the threads of spindles for axial moveme