Method and apparatus for testing web bagginess

摘要

A method and portable apparatus to evaluate the planar flatness of a paper sheet comprises a pair of closely spaced horizontal edges secured in relative parallelism. The horizontal edges are separated by about three feet. The horizontal edges define a horizontal reference plane over which a sheet section of paper web is mildly tensioned with the web machine direction of the paper sheet oriented transversely of the edges. Substantially between the horizontal edges but slightly below the horizontal reference by about ⅛ to ½ inch is a comparison line in the form of a wire, for example. A fixture supporting the comparison line provides a plurality of wire-end attachment points. Supporting the horizontal edges are a pair of scissor frames that are held open to a predetermined angle by a compression gusset. Opposite ends of a horizontal edge are secured to respective upper ends of each scissor frame. Against the compression stress on the compression gusset, the scissor frame is drawn by a tensioned guy wire.