US Patent 10517435 Mill device

A coffee mill 1 to which the present invention is applied includes a milling unit 2 which mills, with an inner blade 8, coffee beans 5, a drive shaft 3 in which one end is cooperatively coupled to the inner blade 8 and in which on the shaft center 23 of the other end, a rectangular shaft portion 21 is formed that has a predetermined twist around at least part of the shaft center in a shaft center direction and that is rectangular in cross section and an operating handle 4 to which a rectangle shaft hole 22 that is rectangular in plan view is open and which is coupled to the drive shaft 3 by externally fitting the rectangular shaft hole 22 to the rectangular shaft portion 21.