This may take some manipulation but the design of the modern vent elbows makes life so much easier for those of us who do home improvement projects, and in fact, it is very hard to find a true 90-degree elbow should you try to find one in the galvanized and aluminum duct or vent pip...
Power sanders smooth wood, sure. But they can do more, like remove loose paint, take the sharp edge off a piece of metal, and round a corner on a post.