A roller feed device (154a, 154b) for a print substrate (127) of non-uniform thickness in a transverse direction relative to a feed axis comprises a first feed unit (154a) and a second feed unit (154b) disposed substantially opposite one another, each feed unit (154a; 154b) having a shaft (205; 236) perpendicular to the feed axis for connection to a drive motor for rotating the shaft (205; 236), and at least one friction roller (220a-220e; 238a-238e) mounted on the shaft (205; 236) in order to be rotated by the shaft (205; 236), the friction rollers (220a-220e; 238a-238e) acting on the print substrate (127) in an operative condition in which the print substrate (127) is interposed between the first feed unit (154a) and the second feed unit (154b), in which the shaft (205) of at least one (154b) of the first and second feed units (154a; 154b) is resiliently deformable by flexure in order to bend according to the thickness of the print substrate (127) in the operative condition.