Measurement and compensation of these errors can improve the machining accuracy of a machine tool. Double ball bar is one of the traditional instruments for measuring machine tool errors, whose measurement range depends on the length of the bar since the sensor has a stretching range of only 2 mm. Some extension bars are usually used to extend the measuring range, but each replacement of an extension bar requires recalibration and installation. In this paper, a novel measuring equipment based on telescopic ball bar with an indexing joint (IJ-TBB) is proposed, which has six measuring ranges after a single installation. First, the basic structure and measuring principle of the IJ-TBB are introduced. Then, the effect of structural errors of IJ-TBB on the measurement accuracy is studied. Next, the error amplification characteristic and measurement resolution of the IJ-TBB are analyzed. Finally, an experiment was carried out to validate the accuracy of the IJ-TBB. The results reveal that the IJ-TBB has high precision and high efficiency. It is valuable to extend the measurement range and improve the measurement efficiency of machine tools.
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