Twenty years ago, the largest machine tool positioning errors are lead screw pitch error and thermal expansion error. Now, most of the above errors have been reduced by better lead screw, linear encoder and pitch error compensation. The largest machine tool positioning errors become squareness errors and straightness errors. Hence, to achieve higher 3D volumetric positioning accuracy, all 3 displacement errors, 6 straightness errors and 3 squareness errors have to be measured. Using a conventional laser interferometer to measure these errors is rather difficult and costly. It usually takes days of machine down time and experienced operator to perform these measurements. Furthermore, high-end controllers capable of 3D error compensation are expensive and rare. For these reasons, 3D volumetric calibration has not been widely used.

Recently, Optodyne has developed a new revolutionary laser vector technique for the measurement of 3 D volumetric positioning errors, including 3 displacement errors, 6 straightness errors and 3 squareness errors. All these errors can be measured in a few hours instead of a few days by a conventional laser interferometer. Using this technique, the 3D volumetric positioning errors can be measured and the results can be used to generate positioning error tables compensates the 3D volumetric positioning errors.

Using Optodyne's laser vector technique to measure the 3D errors is much faster and less costly. Also,compensate the part program or G-code makes it unnecessary the need of a high-end controller. Hence,a low cost CNC machine can perform as a high cost machine. Furthermore, calibrating only part volume allows the collection of more compensation points in a smaller volume, resulting in higher accuracy.

However, for most controllers, only the pitch errors of each axis can be compensated. In this case, based on the measured 3D volumetric positioning errors, the part program can be compensated (correct the x, y and z positions) and achieve higher accuracy over the part.