"In the right hands even dick is a banjo". But C4d isn't good with NURBS. If you have polygonal model, for good machining better way would be retopo from mesh to NURBS using NURBS-oriented software: Alias Design (last years they added Subd functionality and hybrid Subd-NURBS modeling that can help with making proper model from mesh) or Rhinoceros 3D wirh or without retopo plugins (you can find some on "food4rhino". So Rhino is optimal (better price, brilliant functionality and solid amount of plugins).
(if you talking about robot CNC, I suppose it's 5axis machining in the " classical" meaning... It's where is needed NURBS. For 3axis machining can be used mesh models, but in case of big dimensions and high accuracy in the same time the model may be too heavy and calculating the machining paths can be very tricky).
