The present invention provides a processing assembly for processing edges and angle parts of optimized lath type workpieces which are made from woods, forest products, plastics or similar materials. The processing assembly is one part of a machine for through feeding and comprises a tool unit having processing tools for processing side faces of a front part and/or a back part, the fringe regions and angle part regions thereof in the feeding procedure, a carrying roll which makes sure that the processing tools and the workpieces are separated, rolls along the workpieces are movably fastened relative to the processing tools, a drive apparatus for driving the processing tools. A fastening unit is preferably installed on the assembly and makes the carrying roll parallelly move relative to theprocessing tools, specifically move parallelly with the supporting plane of a workpiece. The fastening unit is driven by a drive element to move.