In milling operations, cutting edge impacts due to the interaction between the cutter and the workpiece excite vibrations. It is possible to distinguish between free, forced and self-excited vibrations. Chatter is a self-excited vibration that can occur in machining processes, and is considered to be a common limitation of productivity and quality. Stability lobes diagrams (SLDs) show the frontier between chatter-free milling operations, i.e. stable dominated by forced vibrations, and operations with chatter, i.e. unstable. These diagrams are usually obtained from impact hammer testing. However, this method requires trained personnel with advanced knowledge and it is not easily applied in engineering studies or operator training. This paper presents an experimental method that allows engineering students and operators-in-training to observe the chatter phenomenon and to distinguish between forced and chatter vibrations and identify process stability diagrams.