Abstract: A thresher for grain comprising a rotor and a stator disposed one within the other to define an annular tapered threshing space between them, the rotor and stator having interacting surfaces of generally truncated conical form at least one being lined with resilient material and the other with a friction producing material, the annular space having its larger diameter upwards, the rotor or the stator being axially movable to vary the width of the annular space and loaded to urge the member to decrease the width of the annular space to embed seed part-way into the resilient material to remove the hull from the seed.