Nowadays, researchers are very interested to investigate the dynamic behavior of thin-walled structures during the machining process due to their broad application in aerospace, automotive industries, etc. One of the main problems in the machining of thin- walled structures is unstable chatter vibrations, which causes poor machined surface quality and decreases the system life span. Therefore, the main aim of this paper is to propose a practical method to solve the chatter instability problem during the milling process of thin- walled components. To this end, rst, the e ects of geometrical parameters like workpiece height, thickness, tool overhang, diameter, and their ratios on the chatter stability are inves- tigated. Based on the mentioned parameters, three-dimensional Stability Lobe Diagrams (SLDs) are presented for the rst time in which one can use the diagrams to switch the unstable machining process to a stable one by changing the values of the system parameters. Finally, the results obtained by the experimental test show that the presented three- dimensional diagrams can be utilized to avoid chatter instability in the milling process.