The sonication mettled is widely used with surfactants to suspend individual single-walled carbon nanotubes in solution, and it is well known that sonication-induced tube cutting occurs. Recently, it is found out that ultrasonicated nanotubes yield simultaneous separation by tube length and diameter. Nanotubes that have been cut shortest possess the greatest enrichments of large-diameter species. In this study, single-walled carbon nanotubes are cut using a ball milling method. Similar fracture behavior is observed fur the ball milled nanotubes: i.e., large diameter tubes are cut shorter. The ability to separate carbon nanotubes by diameter and length will contribute to tile development of nanotube-based applications.