The machines enable the production of rectangular very compressed bales of straw and hay, carefully squared, easy to remove and to stock up, easy to handly also by hand. All models are equipped with automatic twine knotters. The models “MINI” and “SUPER” are particulary suitable, owing their reduced weight and encombrement, for the use in difficult accessible areas together with low power tractor engines. The models “EXPORT” and “MAGNUM” with their high production output, can be delivered with automatic wire twister.