## 5 Conclusions  
As can be seen from the graphs, each characteristic has a different dispersion and position in relation to the tolerance field. This is especially true for the results of the height gauge measurements and the characteristics of the phase shift of the teeth (Figure 14). The question is, could the measurement be influenced by the method of mounting the workpiece? Of course it can, however changing the position of the measured part is not possible due to the fact that in the case of an optical machine, there is no possibility to change the angular position of the quill. In addition, the authors wanted to compare the results for the XY plane for both 3D machines. The linear height gauge is a kind of protection in case the measurement with a CMM is not possible. As the obtained results raise doubts as to the capability of the measurement system, Minitab determined Cg/Cgk values to verify that the system meets the repeatability requirements. For this experiment, the characteristic teeth spacing was selected. Therefore, for the height gauge, the graph and Cg/Cgk indices were obtained, which are shown in Figure 17. For the DEA Global Coordinate Measuring Machine, the results are shown in Figure 19, and for the Werth Scope Check Multisensor Measuring Machine, the results and graphic interpretation are presented in Figure 20.  
The results shown in Figure 17 are out of the specification. For the measurement system to be acceptable, the discrepancy of the results should be within 20% of the available tolerance field. This is required by Procedure I according to the MSA handbook, i.e., Cg, Cgk analysis. The Cg index determines the concentration of the results, and the Cgk index determines the position in relation to the tolerance. The measuring equipment can be used for measurements if the scatter of the results is within 0.2 T. The results went beyond the red lines that define this 0.2 T. The blue lines are the true tolerance lines, which in this case have a value of \(\pm\)0.05. Comparing MPE (maximum permissible error) for the height gauge with MPE for machines, it can be initially stated that the systems should generate similar values obtained from the measurements. The trial has shown that it is completely different. Where do these discrepancies come from? Measuring with the height gauge is done in a completely different way than measuring with the 3D machine. The main difference is that using the measuring machine a coordinate system (alignment) is built, which is recalled each time and provides repeatability. When measuring with the height gauge, a detail has to be mounted each time, and each mounting does not guarantee repeatability. Another factor is undoubtedly measuring in different planes. On the CMM, the workpiece is placed in the XY plane, while when measuring with the height gauge the workpiece is fixed in the ZX plane. Another important factor can be the temperature gradient. The recorded temperature during the measurement was 21 \(\pm\) 0.3 \({}^{\circ}\)C, but there was a variation in time and this aspect should certainly be taken into account and analyzed more extensively. After taking the measurements and performing the analysis, it can be stated with certainty that the operator's influence (AV--appraiser variation) is crucial in the analysis carried out with the use of the height gauge. In the CMM measurement, the measuring points were defined. Both the DEA Global Coordinate Measuring Machine with a contact sensor and the Multisensor Measuring Machine with an optical sensor always collect points in nearly the same place. In the case of the LH-600 height gauge, the location of the measuring points depends on factors such as a perpendicular application of the stylus to the measured element, scanning speed, etc. In machines, these issues are not dependent on the operator. We believe that the discussed topic brings novelty to employees who use various types of equipment available in industry, which are used to qualify products.