We are applying a UV finish to a bullnosed plywood edge. We are having a hard time sanding the bullnosed profile smooth enough so that the final finish is smooth. We use two triangular sanding belts with profile sanding blocks. The first is 180 grit and the second is 220 grit. The 220 grit goes with the direction of the feed chain of the shape and sand machine. No matter what we do we don't seem to be able to make a consistent smooth finish so that we don't have to hand sand prior to sending the boards down the UV edge coater. We are running both the shape and sand and the edge coater full time each shift. Does anyone have any suggestions on how to get a smooth sanded edge on bullnosed plywood?
From contributor Y:
Yes, add a 3/4" strip of hardwood to the edge. You can't sand plywood edges deadflat smooth because of the grain running two different directions between sheets of veneers.
Since you are using a belt sander type, you may need to try 320 or even 400 since this is linear action and not orbital (self-canceling) action. Don't use anything that high of a grit on the face, but you don't need to worry about proper adhesion to the plywood edge when sanding super-smooth since it still tends to wick up the finish. I will note though that I have no experience with UV finishes. I suggest you do one with a high grit belt and test it afterward.