They're almost certainly not expected to work to anything near the level of precision that these sorts of high-end CNC machines do - judging by the comments in

They're almost certainly not expected to work to anything near the level of precision that these sorts of high-end CNC machines do - judging by the comments in this thread, you're talking about micrometer level precision. They are to 'machine-tools' what your home server is to google's data centres.