Filing-Down-Ferrule-Blanks Published January 4, 2013 at 315 × 410 in Making Your Own Bamboo Fly Fishing Rod To best install the ferrule, file down the ends of the blank as it turns on your lathe, using a three- or four- jawed chuck to keep it from moving too much. install the ferrules, he files down the ends as the blank turns on his lathe.