The upper millstone contains an iron bar which is embedded in a recess on its underside. In the middle of the bar, there is a slot fitted to hold the upper part of a steel pin, the other part of which, flattened and square, is hammered in a vertical shaft made of oak wood.
The wooden shaft is embedded into the propeller’s body, connecting the millstone with the propeller. It is important to have a firm connection between the upper, iron parts and the wood shaft so that the rotation of the propeller is completely transmitted to the iron bar embedded in the upper millstone.
The propeller consists of a central part, a round body which holds the shaft, and which is fixed by iron hoops and wedges. Some 12-13 paddles are built into the body. The paddles are mutually tightened by a double row of wedges made of laburnum (or golden chain tree) which is a submediterranean shrub that grows in Konavle, and is characterized by its resistance and longevity. The propeller is affixed to a keel.