For "fine tuning" of any drilled hole. my favorite tool is a tapered reamer, I think it's also called a plumber's reamer. Five or six flutes, tapers from 1/2" down to 3/16" or so. I use that to touch up the outside of the drilled hole so that the Robart hinge's knuckle fits.

Careful carving with a #11 blade works, too...

--Bill