Market requires products with increasingly high levels of accuracy, therefore it arises from the quality department the need to measure them with more performing Coordinate Measuring Machines (CMMs). These machines commit errors in carrying out the measurements, because of micro-irregularities of their structure and geometry. Therefore, after the production of a CMM, a procedure called geometrical compensation is carried out: it consists in measuring such imperfections and transforming them into a Compensation Map to be downloaded into the CMM controller. In order to maintain a high-performance level, an accurate error model is necessary to appropriately compensate the data acquired by the machine.