A new system for measuring the errors of three-axis machines is presented in this paper. It is composed of a planar
encoder system and a magnetic telescoping ball bar. The individual signals of three-axis displacement can be
simultaneous obtained. The errors of the three-axis machines, geometric error, kinematic error, wobble error and
volumetric error, can be effectively measured. The system is characterized by short set up time, low capital requirement,
high measuring speed and high accuracy.