Remove the burrs from the axle nails.  Gently attach your drill to a vise to create an axle polishing station.  Attach the nail to the drill chuck and run a file over the nail until the burrs have been removed.  Then sand the nail with increasingly fine grits of wet/dry sandpaper.  Start with 400 grit, then move to 500 grit, then to 600 grit, then to 800 grit, then to 1000 grit, then to 1200 grit, then to 1500 grit, then to 2000 grit, then to 2500 grit, then to 3000 grit.  Increasing the grit count gets increasingly fine to give a very fine, finish.