A grinding machine for use in grinding materials, the grinding machine includes a grinder assembly for receiving material. At least one removable hopper is removably positionable on the grinding assembly for dispensing material to the grinder assembly. The removable hopper is positionable on the grinder assembly in a generally non-vertical direction. A passage defined in the hopper is cooperatively positionable in communication with the grinding assembly for allowing movement of material from the hopper to the grinder assembly. A device carried on the hopper is positionable in an open position when the hopper is on the grinder assembly and is positionable in a closed position when the hopper is removed from the grinder assembly.