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How an oil mill works
A water oil mill is powered by an undershot or overshot wheel and is a robust, artisanal structure often idyllically situated on the bank of a brook or small river with sufficient flow velocity. The Oostendorper water mill features an undershot wheel, making it an undershot mill. The most striking feature is the vertical water wheel on the outside, where the flowing water pushes against the lower blades or falls onto them to set the mechanism in motion.
Inside the mill, the rotation of the main shaft is transferred to the heavy internal machinery via an ingenious system of wooden cogwheels. The process begins with the crushing of oilseeds, such as linseed, rapeseed, or canola, beneath two enormous, vertically rotating millstones that roll over a grinding bed. This mechanism is called the roller mill. The resulting seed meal is subsequently heated on a hearth to make the oil more fluid, after which it is scooped into bags. Finally, in the pressing bench, the oil is pressed out of these bags with brute force by means of a hammer which, driven by the rotating shaft, falls rhythmically onto wedges. The result of this intensive process is liquid vegetable oil and the remaining, hard press cakes that traditionally serve as animal feed.
Drie bedrijfsgangen
Olie kan worden geslagen uit vlas-, lijn-, kool-, raap- en hennepzaad en geperst uit onder andere beuken- en walnoten. Dit gebeurt in de volgende drie bedrijfsgangen.
The first stage of operation
The first stage of operation is crushing the seed; this takes place on the roller mill. The roller stones (edge stones) crush the seed into flour. The scraper scrapes the scattered seed back under the roller stones. Once the seed is sufficiently crushed, the oil presser lowers the drain and opens the slide, allowing the flour to fall into the flour bin.
The second stage
The second stage involves heating the seed meal. The heating takes place on the ‘vuister’. This is a stone-built hearth covered with a steel plate. A bottomless pan rests on top of this, in which the seed meal is heated to approximately 40 degrees. If oil is being pressed that is not suitable for consumption, this can also be done up to approximately 80 degrees. Once the seed meal has been heated, the oil presser slides the pan with its contents over the funnels, after which the seed meal falls into the two suspended ‘buulen’ (sacks).
The third stage of the process
The third stage of the process is oil pressing. This oil pressing takes place on the press bench (impact bench). The seed pods are placed between a press board here and then positioned in the press bench. By means of a falling hammer, the striking chisel is driven downwards and into the impact bench. This applies pressure to the seed meal. This liquefies, causing the oil to be pressed out of the pod and collected in containers.
How a striking bench works
Below is a sketch of an oil striking bench in which the parts are named and the operation is explained.
The heated linseed meal from the linseed is fed into two barrels between the driving irons.
- The striking chisel is lifted by spoons on the kingpin and falls onto the striking chisel.
- To build up more pressure, separating pieces can be placed between the striking chisel and the cushions.
- As the striking chisel is struck downwards, the cushions are pushed outwards.
- Due to the pressure on the barrels, the linseed oil is pressed out of the linseed meal, and the linseed oil is collected in bins under the striking bench.
- Pressure of up to 180 bar can be built up. As a result, the striking chisel cannot be loosened manually.
- By striking the loosening hammer downwards with the loosening chisel, space is created. With the weight on the striking chisel, it rises again.
The freshly pressed linseed oil contains a lot of dust from the linseed meal. The linseed oil is allowed to settle for several weeks until clear linseed oil is produced.
The Oostendorp oil mill in pictures
The operation of an oil mill can be seen in the film below. The vater is not yet included here, and will be added soon.
