Abstract: An expander machine for expanding rotary slit metal webs is of the type having mutually inclined triangular expander arms over which the web is passed forwardly to spread the web and open out the slits to form diamond-shaped meshes. The angle between the arms is made adjustable, and the arms are mounted on a sub-frame which pivots about a longitudinal axis so that when the angle between the arms is adjusted it is possible by tilting the sub-frame to restore the output of expanded web to the horizontal plane. The horizontal delivery of the expanded web facilitates subsequent processing and reduces the risk of damaging frail expanded webs e.g. thin metal foil webs. Advantageous arrangements for gripping the edges of the web and conveying it are disclosed.