Large Diameter Air Chucks offer high accuracy and adjustable clamping force for machining large diameter precision and thin-walled work pieces. These chucks are available in three jaws as well as two and six jaw configurations. The large diameter models with extended jaw stroke, air ports on OD of chuck body for stationary applications. The large diameter air chuck with claimed accuracy of less than 0.0001″ TIR, an 18″ diameter sliding-jaw air chuck, it can be operated at a pressure range of 5 - 80 psi. The chuck is counterbalanced to maintain jaw force at high spindle speeds, and the center dust cover can be replaced to provide a 3.40″ diameter counter bore and 3.75″ deep to securely hold workpiece ends.