Once you’ve achieved this stage, it’s easy to get a fully-rounded edge, by doing some light filing, or hand sanding. Some people use a flap wheel at this stage, and it’s great tool, but it takes very good hand control to keep the radius uniform. If you do use a flap wheel, the larger diameters work best, and make sure you use the type that cuts on the edge (similar to the drum sanders) rather than the ones that cut on their face, like a sanding disk. Be sure to hold the flap wheel so it’s cutting ALONG the edge, not ACROSS it! The flap wheel will form a groove where it touches the edge you’re rounding, but this is actually an advantage, since the rounded groove in the flap wheel will help to make your rounded edges more consistent.
Again, if anything goes wrong, and you start losing the consistency of the radius on the edge, careful work with a sharp, half-round file is the best way to correct any hiccups and get back on track. CT