Abstract: A computer-controlled machine for progressively roughing marginal portions of shoe bottoms comprises a tool support arm, on which two rotary roughing brushes are carried side-by-side, and a shoe support between which and the arm relative movement takes place lengthwise, widthwise and heightwise of the shoe bottom. The relative lengthwise movement is fore-and-aft, and the left hand tool is arranged to operate along the right hand side of the shoe bottom as relative movement takes place in one direction, and vice versa in the opposite direction. For effecting such relative lengthwise movement, furthermore, the shoe support is mounted for movement along an arcuate path about an axis extending transversely of the shoe bottom. Conveniently, two shoe supports are provided, arranged side-by-side, the tool support arm being aligned alternately with each shoe support.