Flat burr coffee grinders operate on the principle that coffee beans are driven towards the outer edges of the burrset by the rotation of the moving burr, with the other fixed to the housing.

This grinder concept rotates both burrs in the same direction, but with offset speeds, imparting more centrifugal force on the grounds, increasing grind speeds and reducing “popcorning”, where the grounds bounce away from the burrset edges when they collide with the stationary burr.

The sun gear and planet carrier rotate with a 3:1 ratio and the ring gear is fixed to the housing.