Grinding when the wheel axis and the axis of the workpiece contour, in order to ensure the roundness of the sphere. Generally according to the pattern to determine the contour of grinding errors. If the balls appear before the convex surface pattern, indicating that data later this week to participate in the grinding wheel, the center of the wheel below the workpiece center, this time, the center of the wheel should be adjusted so that the center of the workpiece contour, until they are grinding sphere surface was cross-hatch pattern. Its tolerance requirements within the 0.003-0.004mm. Spherical grinding, the wheel frame to be rotated a certain angle, so the dressing wheel bore size adjustment should be completed before the machine. Grinding wheel during grinding blunt, do not need trimming bore, long strip of sand to the end face of wheel dressing, so that both the wheel sharp recovery, but also to ensure the wheel bore size unchanged. Promptly after blunt grinding wheel dressing, in order to facilitate quality assurance process. Since the spherical grinding wheel axis and the axis of the workpiece can not be absolutely high, so that the workpiece will have a small step, the impact accuracy of the workpiece, this case, the top of the sphere of less than 1mm drill a center hole to avoid this.