Yes, I use files and fine toothed rasps a lot. Which ones depends on how bad I've allowed the washboarding to become. I usually catch it early. For minimal washboarding, I may use a small 6-8" mill file, or knife file... held askew... for more drastic measures I may use a bigger bastard, or double cut file... then switch to a smaller mill or smooth file. When the surface is even worse, I'll employ my Nicholson #49. I keep all of them and more within arm's reach of the bench vise. It's almost a subconscious thing. Ya grap what ya need, sometimes switching every few seconds without thought. Files and rasps are ultimately cheap and a greater variety makes for better bows.
Another method to cure washboarding is the effective use of good quality sandpaper.... to use stiffer-backed sandpaper... following the file work noted above... cloth backed iron oxide sandpaper is what I use. It doesn't have to be coarse grit, per se.... 100-150 will work great, if it has a spine and is held quite taut between your hands... it will level those osage rings in the dips in seconds. Even the width of the strip you rip off should be conducive to your needs. I'll rip off a wider piece for the limb than I will the dip. ...love my sandpaper. Go then to 200-240 and then 400.... pulling even tighter while pushing down with LESS force, maintaining even more tension on the paper between your hands... sometimes I inadvertently rip the paper in half just because I'm pulling too hard... one hand away from the other... not because I'm pushing down against the bow too hard. Don't let it sink into the softer spring wood. Float the highly tensioned paper over it all, with the grain, parallel with the limbs. This works better than sanding blocks or any hard metal tools I've used.
