The surface roughness in the milling of free-from surfaces, such as convex and concave surfaces, can vary widely due to the changing geometric characteristics of the surface. This variability affects machined part quality by deviating from required tolerances. A methodology has been established to optimize machining parameters in a 3-axis milling machine and to reduce surface roughness for concave and convex AI-7075-T6 aluminum alloy specimens. The Taguchi method is used in the experimental design with an L27 orthogonal array at three levels for each factor. The influence over surface roughness of the factors cutting speed (A), feed rate (B), tool path pattern (C), and depth of cut (D) are analyzed using analysis of variance. Results show that the spiral tool path pattern (factor C, level 2) exhibits statistical significance in determining the final surface roughness for the concave and convex cases. Optimal roughness achieves mean values of 0.256 µm (concave) and 0.248 µm (convex).