3X Miller-Colburn Bone File 3X Miller-Colburn Bone File BF3X The 3X Miller-Colburn cross-cut bone file is used for final smoothing and shaping of bone with 6.2mm and 4.8mm working ends. Where to Buy x Category Dealer PartnersSales RepresentativeStrategic MarketsSchools RepresentativeAccutron™ Equipment Sales Zip Code Find RepresentativeReset Select a category, input a zip code and click on Find Representative, or explore the complete list here.