An elastically guided machine axis with nanometer repeatability

This paper focuses on the on the design and calibration of an elastically guided vertical axis that willbe applied in a small high precision 3D Coordinate Measuring Machine aiming avolumetric uncertainty of 25 nm. The design part of this paper discusses the principles of thissystem, the compensation of the stiffness of the vertical axis in the direction of motion, the weightcompensation method and the design and performance of the axis precision drive system, a Lorentzactuator. In the metrology part of this paper the calibration methods to determine the linearity as wellas motion straightness and axis rotation errors are discussed. Finally first calibration results of this axisshow nanometer repeatability of the probing point over the 4 mm stroke of this axis. The causes of theshort-term variations with a bandwidth of about 10 nm are under investigation. Error compensationmay reduce the residual error of the probing point to the nanometer level.