I have made a simple Plank Thicknesser to dress planks to a consistent thickness after they have been roughly cut on a large saw bench. The setup was pretty easy to build from plywood. The sanding drum spindle was turned from a single piece of hardwood and was mounted in ball bearings housed in the wooden blocks at each end of the spindle. The sanding drum was then covered in a linishing belt glued on with contact cement. The drum is then driven by an electric hand drill. The platform under the drum can be raised and lowered by the adjusting screws to change the thickness of the finished planks.
Below are a couple of drawings of my plank thicknesser showing the components together and in an exploded view. The dimensions are not that important but to give a general idea the plywood used for most parts was 19mm thick. The spindle is about 32mm diameter. The bearings are 32mm diameter. The sanding area under the drum is about 120mm wide. The recesses for the bearings were drilled out with a spade bit in my drill press. The spindle was turned in a home made wood lathe and was trued up when assembled prior to adding the sanding belt.