Method of and apparatus for measuring separation of casting surfaces

Exemplary embodiments of the invention provide a method of measuring the separation of moving confronting casting surfaces within a casting cavity of a casting apparatus. The method involves attaching at least one separation sensing device to a first one of a pair of confronting casting surfaces outside the casting cavity and then moving the casting surfaces to advance the sensing device(s) through the casting cavity while operating the device(s) to generate signals. The signals are monitored continuously or at regular intervals and converted to distance measurements representing separation of the surfaces at a plurality of positions through the casting cavity. Other exemplary embodiments provide apparatus for carrying out the method, and methods of measuring irregularities of casting belts or the like.