Abstract: A machine and a method for providing substrate for use in manufacturing of biogas. The machine is provided with an intake for input of moist and dry organic waste to the machine's interior chamber, where the organic waste may contain foreign bodies such as soft packaging, metal, glass, etc., a rotating shaft located in the chamber and provided with at least one tool which has a blunt shape, a stationary part mounted in the chamber acting as the tool's counter-tool, an outlet for milled particles, and an ejector for foreign bodies. The distance between the tool and the stationary part is such that the solid parts are milled into smaller pieces, while a milling effect on softer parts is prevented.