A method and system for holding fast a workpiece using three or more jaws that are mounted on a chuck base. The chuck base includes corresponding jaw guides, which constrain the movement of a respective jaw toward the center of the workpiece. The jaws collectively move toward the center of the workpiece by tightening a gear that engages was each jaw and is included in the chuck base. Each of said jaws includes 1 or 2 two convex contact regions.