Abstract: A computer interface device for a coordinate measuring machine comprises a trackball that transmits perpendicular movement signals to a computer in response to corresponding perpendicular tangential movement of the trackball. The computer is interconnected with the coordinate measuring machine and normally receives measurement data corresponding to a location of a probe on the computer. The trackball is located adjacent the probe so that a user grasping the probe can manipulate the trackball to transmit data manipulation signals to the computer. Typically, the trackball moves a cursor about the computer screen. A plurality of data entry buttons are included on the interface device and enable the user to execute computer procedures selected by the cursor.

Abstract: A ball bar gauge for evaluating the performance of coordinate measuring machines is disclosed. The gauge consists of a rigid bar having a magnetic chuck at each end. Each magnetic chuck consists of a permanent magnet and six magnetic pole pieces surrounded by a non-magnetic housing. The bar is used with two precision tooling balls which are placed in the chucks at each end of the rod. In each chuck three of the pole pieces are slightly longer than the other three pole pieces to provide a stable three-point contact seat for the associated ball.