we make all of our own dowels. we have found that starting with your square as accurately cut as possible to the final diameter helps, e.g 0.5". then take the care to set up the 1/4" round over so that it is cutting the entire arch and no more. the extra time it takes to set this up accurately is well worth the time saved sanding. then we chuck them into a hand drill (often held in a bench vise, and slide 120 grit up and down until we like it. does not take much if the router is set up well. it will end up around .495" dia.