The dynamic behaviour of a machine tool influences its accuracy, productivity, reliability and sound emission. For these reasons, efforts are being made to simulate the dynamic behaviour for further optimization steps. In this paper an approach for model updating of a machine tool with many unknown parameters will be presented. It will be shown which degree of accuracy is achievable by using model updating of two models of various machine tools with different state of knowledge of the model parameters. Furthermore, it will be shown that a simplified model of a machine tool can yield comparable results with a complex model both after model updating.