I use a cedar board about 3" x 24" and glue or otherwise fasten a 3" x 24" belt sander belt of, as course as I can get, usually 40 grit. I have a handle on one of my boards similar to a plane's handle. A longer sanding belt could be used. I think Chestnut may have used farrier's files (rasps?)to take off the high spots. I work the board at about 45 degrees to the plank across the edges. If I had a flexible longboard I'd try it but I don't.