A grinding machine for grinding foodstuffs, such as meat or the like, includes an orifice plate at the outlet of a grinding head. The orifice plate has collection passages that discharge a mixture of soft material and hard material through the orifice plate. A separator assembly is located downstream of the orifice plate for separating the soft material from the hard material. The separator assembly includes a tapered, perforated separator chamber that receives the mixture of soft material and hard material, in combination with a rotatable separator screw located within the separator chamber. Rotation of the separator screw functions to separate the soft material from the hard material and force the soft material through the perforations in the separator chamber. An adjustment arrangement enables the axial position of the separator screw to be adjusted within the separator chamber.