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The ROTA NCR six-jaw power chuck is standardized with diameters to 1,200 mm to offer a solution for thin-walled and easily deformed workpieces, the company says. The lathe chuck is suited in applications in which workpieces with large diameters must be clamped securely and machined with precision such as tube ends for the petrol industry; threads on diamond bore heads; graphite blocks; train wheels; pump and valve housings; gears; and pistons for vessel engines.   The chuck consists of a central chuck piston, which has three inner pendulums positioned at 120 degrees; and each pendulum is connected to two base jaws. The result is that the workpiece is centered between six contact points, which can be adjusted in pairs, allowing the clamping forces to be aligned toward the chuck center. Thus, even pre-machined parts can be centered without deformation of the workpiece, the company says. This arrangement permits roundness of workpieces with conventional jaw clamping.   The chuck is also available with centrifugal force compensation. A standard clamping cylinder is said to be sufficient to actuate the lathe chuck. For certain applications, all six chuck jaws can be moved simultaneously and concentrically. Clamping is achieved by fastening the attachment screw in the piston. According to the company, the chuck is available in sizes of 165, 200, 250, 315, 400, 500, 630, 800, 1,000 and 1,200 mm and can be employed on virtually all lathes.