Abstract: A machine for sanding anatomically contoured wooden chair seats and the like comprising a pair of laterally spaced sanding belts, each pulley mounted and power driven and each with a generally longitudinal pass adjacent a work station. A chair seat at the work station is mounted on a laterally movable carriage on spaced rails in turn movable upwardly and downwardly to engage the seat with the belt. A pneumatically inflatable resilient back-up member slidably engages the belt on a side opposite the seat and urges the same toward the seat whereby to cause the belt to conform to the contoured seat surface. Entry and exit guide rollers respectively establish angles of attack and separation for the belt relative to the seat surface. The back-up member is adjustably spring mounted and also has a floating spring support.