A wide belt orbiting sander having an improved workpiece conveyor system, wherein a plurality of resiliently biased platen segments are utilized to apply a force against the underside of the upper conveyor flight in oppositely disposed relationship to the sanding heads. The platen includes a number of individual segments, each segment occupying a certain finite portion of the transverse dimension of the conveyor, and with each of the platen segments being mounted for rocking and pivotal motion about both longitudinal and transverse axes. Wide belt sanders equipped with the improved conveyor system of the present invention are capable of handling a wide variety of workpieces including workpieces of variable and varying dimensions.