Due to its ability to reduce manufacturing costs and time, and the possibility of manufacturing parts with complex geometry, additive manufacturing (AM) in metals is attractive for the industry. The wire and arc additive manufacturing (WAAM) can produce large parts with high deposition rate, surpassing other AM processes. However, for the WAAM process to become truly suitable for engineering applications, it is necessary for the parts to undergo post-processing, since they have an irregular surface. In this sense, this work aims to validate the machining strategy of a hybrid rocket engine nozzle produced by the WAAM. The part was initially manufactured in polymer by material extrusion, with the geometry modified according to the proposed machining strategy. The turning was then performed on a conventional lathe to verify the proposed geometry. The same methodology was applied to a metal part manufactured via WAAM. After the machining and analysis, it was possible to observe that for the polymer part, the validation was satisfactory, once it was possible to obtain the design geometry. During the deposition of the metal part, the heat input caused angular deformation of the substrate, which would be fixed to the lathe, hindering the positioning, and, therefore, there was a variation in the wall thickness of the part at the end of the machining.