A blasting apparatus for cleaning and deburring workpieces having a housing defining a blasting chamber therein. A rotary drum within the chamber is supported for rotation about a horizontal axis. A drive effects rotation of the drum through a plurality of angular steps during each revolution. The drum has a plurality of circumferentially spaced compartments opening radially outwardly thereof. A workpiece holder is positioned within each compartment. A housing opening cooperates with the drum, when stationary, to define a station for permitting loading and unloading of workpieces with respect to the holder associated with one compartment. A gun arrangement effects deburring and cleaning of workpieces mounted on the drum. The gun arrangement includes a plurality of nozzles mounted circumferentially so that each nozzle cooperates with a selected compartment and moves axially therealong for treating the workpiece.