Accuracies of a few micrometres must increasingly more often be achieved for the parts machining using machine tools. In doing so, the heat development during the machining and in the tool holder is not insignificant. The thermal expansion of the spindle during the machining can affect the precision so much that the workpiece no longer meets the requirements. The SGS system developed by Micro-Epsilon is used for compensating for the expansion of the tool spindle. The expansion of the spindle is measured using the eddy current based system and in this way precise workpiece machining is made possible.