How does the rice mill separate chaff, rice grains and sand grains?

The hardness of rice and rice husk is different. The hardness of dried millet is very high, and rice grains and rice husks are easily separated. Generally, the grain size of each variety of rice does not change much. Adjust the width of the inner wheel of the rice mill, and have a spring to control the movable width (just like we can use two boards to "rice mill"). You can separate the rice from the shell. Because the rice husk is in thin strips after separation, rice can be separated by a sieve with thin strips. The mesh of the sieve is strip-shaped and the rice is oval, so the rice can't go down.