A device for securing a workpiece to a fixture for performing machining operations includes a tubular, radially expansible mandrel. The mandrel is carried in a passage provided in the fixture and extends into a hole provided in the workpiece. An expander stem is carried within a bore of the mandrel. The stem has an upper end that is tapered for expanding the mandrel. The lower end of the stem is connected to a hydraulic piston. A spring applies an upward force on the mandrel. A hydraulic cylinder moves the stem downwardly, while the spring retains the mandrel in a stationary position until it grips the workpiece. Then, the hydraulic force overcomes the force of the spring to pull the mandrel downward slightly to secure the workpiece to the fixture.