We investigate a recently introduced methodology for 5-axis flank computer numerically controlled (CNC) machining, called double-flank milling. Certain geometries, such as curved teeth of spiral bevel gear, admit this approach where the milling tool has tangential contact with the material block on two sides, yielding a more efficient variant of flank milling. To achieve high machining accuracy, the path-planning algorithm, however, does not look only for the path of the tool, but also for the shape of the tool itself. We validate the approach by series of physical experiments using an abrasive custom-shaped milling tool specifically designed for a particular type of a spiral bevel gear. We show the potential of this new methodology in the semifinishing stage of gear manufacturing, where it outperforms traditional ball end milling by an order of magnitude in terms of machining time, while keeping, or even improving, the machining error.