Coming from a tool and die making environment making plastic injection molds and precision manufacturing fixtures for 25 years, machining an arc like this with a single pass with specific sized tool is not the way to it. A single pass with a large cutter will typically result in a poor finish from chatter, rapid tool wear, and material tearing. You will also likely have issues from tool deflection.
I cant say for sure exactly how Speedmaster is doing this and I am not saying that there isn't issues with them. I am saying in a production and precisions machining environment as well a smaller ball mill with the shape being interpolated (3D cutter path) with a highspeed machine will yield the best results for precision, finish, and manufacturability. This will lead to much better tool life, and better consistency across the board.
