An adapter converts a three-axis milling machine to a five-axis milling machine includes two gimbal assemblies. A first gimbal assembly is configured to rotate about a first rotation axis. A second gimbal assembly is rotatably connected to the first gimbal assembly to rotate about a second rotation axis orthogonal to the first rotation axis. A first gimbal positioning system is operable to rotate the first gimbal assembly about the first rotation axis with a rotational movement of a first leadscrew positioned in a first plane orthogonal to the first rotation axis. A second gimbal positioning system is operable to rotate the second gimbal assembly about the second rotation axis with a rotational movement of the second leadscrew positioned in a second plane orthogonal to the second rotation axis. The second gimbal assembly includes a spindle and a motor coupled to the spindle to selectively rotate the spindle.