Grain elevator – the upper part of the mechanism

The top floor of the mill houses the 6 double and 1 regular rotating mechanism of the grain elevator. The upper mechanism of the chain elevator contains a rotating metal pulley in a wooden casing. The pulley holds a belt with buckets for transporting grain and flour. The belt with the buckets can move upwards, as the drive belt turns the metal wheels.

Long screw feeder for transporting the milled material

Grain brusher – for cleaning the grain before milling

The grain brusher cleans the grain with the help of brushes. The grain brusher consists of a horizontal cylinder which holds a thick sieve and horizontally-placed rotating brushes. The refined grain is fed into one end of the brusher cylinder, where the brushes clean the grain of dust and move it along the surface of the cylindric sieve. The dust, removed from the grain, is sucked out with the help of a fan. The brusher cylinder has metal fins that regulate the direction of the grain, which means you can regulate how long the grain must rotate before moving to the other side of the cylinder.



Grain pre-cleaner with a seed screening machine below

The grain pre-cleaner clears the grain from impurities that are larger than the size of the grain – thistles, peas, straw, branches, as well as those smaller than the size of grain – sand, tiny grain, weed seeds etc. The wind is used to clear out lighter impurities like dust and husks etc. The grain is fed onto sloped sieves of various sizes, moved by rotating excentre. As a result of the movement of the sieves, various impurities are removed from the grain. The airflow generated by a fan sucks away lighter impurities and they are removed through a dust collector bunker.

The screening machine separates the grain from weed seeds, vetch, corn cockles, lentils, and half-grains, as well as various impurities that differ from grain in size (smaller) and shape. The grain moves through the slowly rotating screening machine through a sloped cylinder with many semi-circular dimples of the same size on the inside surface. The round and small impurities fall into the dimple as the cylinder rotates, but the clean grain is flowing over. All impurities fall from the dimples into a gutter on the inside of the cylinder and are fed out.

Filtering cabinet

In the milling process, the rollers (during the grinding of the grain) create tiny flour dust. These are suctioned away from the rollers by fans and fed into the filter cabinet. This consists of a wooden cabinet with several cylindrical filters made of fabric. The flow of the flour dust moves through the filters in the cabinet and the clean air passes through the filter fabric, while the heavy flour particles collect at the bottom of the filters, where they are periodically collected into a box at the bottom of the cabinet.

Semolina machine

The semolina machine sorts the ground bits of grain by size – fine semolina and coarse semolina. The ground bits of grain that correspond to the semolina size are fed into the semolina machine from the separator. Sieves are moved by motors, separating the semolina grains into fine and coarse semolina. The fan suctions the fine bran and dust from the semolina machine.

Sieve separator for sieving the milled material

The cylindrical sieves are used to separate the material milled by the millstones. The sieve is covered by a metal or nylon sieve. The size of the sieve must be such that the flour particles could pass through. There are several wooden guides inside the sieve. As the cylinder rotates, the milled material enters the cylinder on one end and is sieved and moved to the other side of the machine by the guides. The milled materials that have not been sieved are fed back to the milling machine until it is all milled. The sieve cylinder may include several sieves of different sizes. The only rule is the sequence of finer sieves followed by coarser sieves, taking into account the movement of the milled material. The flour that has passed through the sieve is moved by a screw feeder to the product discharge.

Sieve separator for sieving fine flour

The separator separates pieces of grain milled by the rolls into four, semolina, coarser grain particles for re-milling, as well as fine and coarse bran. Two rotating sieve packs that are mutually screwed to a metal frame receive in the four upper hatches grain milled by the rollers. To properly separate the material, each pack contains 10 sieves of different sizes. There is a total of 20 sieves. Brushes with guides are installed on tracks between the sieves. As the separator rotates, the brushes move in the same direction to continuously clean the flour from the sieves. The upper brushes are made of softer goat hair to protect the finer sieves, but the lower brushes are made of coarser horse hair to maintain the weight of the brush and to perform the brushing function. The separated flour is collected in bags, the particles not passing through the sieve are returned to the rollers for re-milling, and the bran is collected in bags. The milled parts of the grain that meet the semolina size requirements are transferred to the semolina machine for further processing.

Groats separator machine

The groats separator separates the polished pearl barley into groat and coarse flour. On a sloped, moving platform there are several sieves of various sizes from finer to coarser, where the polished barley and flour particles are poured from the groat splitter. As the platform moves, the split barley particles move downwards and are continuously sieved through the relevant sieve size, acquiring two sizes – groats and coarse flour. The larger groats that do not pass through the sieves are moved by elevator back to the groat splitter for re-splitting. Dust is collected from the upper part of the sieves by fans. Groats are generally processed from polished barley or wheat.

Fabric filters above sheet-metal bunkers

Seed screening machine

The screening machine separates the grain from weed seeds, vetch, corn cockles, lentils, and half-grains, as well as various impurities that differ from grain in size (smaller) and shape. The grain moves through the slowly rotating screening machine through a sloped cylinder with many semi-circular dimples of the same size on the inside surface. The round and small impurities fall into the dimple as the cylinder rotates, but the clean grain is flowing over. All impurities fall from the dimples into a gutter on the inside of the cylinder and are fed out.



Grain pouring location above millstones

Millstones were often used to mill animal feed and it was not cleaned or separated. It was brought directly from the owner’s granary and it contained various impurities, such as weeds and straw. To keep the impurities away from the place of the milling – the quern, the grain bunkers were covered by a mesh.

Pearl barley separator filter box

The process of separating and milling grain results in a large amount of dust, which is moved by fans from the grain processing machines to bunkers – filter boxes. To collect the dust, special dust collection bunkers are used. The bunker consists of a sheet-metal cone bottom, but the upper part is a cone-shaped fabric filter. As the dust moves through the dust bunker, the clean air passes through the filter fabric but the heavier dust and husk particles are collected in the sheet-metal cone.

The finished product collection point for groats and pearl barley

Generally, wooden gutters lead out of various mill machinery to collect the finished product. There are special connections at the end of these wooden gutters to attach bags. This connection contains a damper. To replace the full bag of the finished product with an empty one, you must open or close the damper. These wooden gutters are traditionally called boots.

The finished product collection point for flour, bran and coarse flour

Finished product collection point – the boots – for flour, bran and coarse flour.

Hatches for pouring grain

Hatches for pouring grain into grain and milling product bunkers above rollers No. 1 and No. 2.

Hand-cart used at the mill



Grain splitter

Grain splitter cleans the grain from the outer shells, bran and parts of the germ. The grain splitter consists of a horizontal cylinder covered by stone mass on the interior. Inside the cylinder, there are rotating metal blades placed at an angle. The clean grain is poured into one end of the machine cylinder, where the blades smash and grind them against the stone surface until all shells, germ and fluff are removed from the grain. The removed husks are sucked out of the machine by a fan. The blades are slightly curved to give the grain enough rotation to move to the other side of the cylinder, where the clean, split grain continues the flow.

Roller. Milling grain in a roller mill

The milling process in the rollers of the mill takes place between two pairs of rotating rollers, where one pair has a textured, sharp surface and the other pair has a smooth surface. The milling machine has two pairs of rotating metal rollers. Each pair works independently, but each of the rolls has a different rotation speed. One pair of rollers have sharp, slanting longitudinal grooves. The other pair is smooth. The grain is fed by a special feeding mechanism straight between the grooved rollers – the distance between these rollers is smaller than the size of the grain. The grain is thus crashed into smaller pieces and fed by the elevator further towards the separator. The parts of grains that do not pass through the sieves of the separator are collected by the elevator in a bunker placed above the roller. The miller uses a lever to move one roller closer to the other and the grain particles are re-milled. The grain and the separated but unmilled particles are milled 5 times, while the rollers are gradually moved so closely together that is it possible to remove the last remaining particles of flour from the bran. As the grain is moistened before the milling process, the elastic bran is not crushed and milled and remains intact.

Grain box above the rollers

The grain box above the roller is split into four parts – bunkers. Each of the bunkers has a damper that the miller can manually open or closed to feed grain or separate coarse bits of grain into the roller. Before milling, grain is poured into one of the bunkers. As the milling process happens, the milled bits of grain that are too coarse to be separated as flour are collected in the other bunkers. After the material in one bunker is milled, the rollers are brought closer together and a different part of the bunker is opened to continue the milling of the grain and the coarse particles.

Turbine lever

For the watermill to work, it is necessary to start the water turbine. The turbine blades are opened with a manual lever, water flows through them into the turbine and the force of water is turned into mechanical force. The turbine starts turning the main drive shaft of the mill, through which, with the help of cogwheels or belts, all mechanical parts of the mill are turned. By regulating the amount of water flowing into the turbine, it is possible to increase or decrease the number of revolutions and force applied to the main drive shaft of the mill.

Grain elevator

The elevator moves the grain and the flour vertically to the necessary floor. The grain and flour elevator consist of a metal or wooden case, which contains two rotating pulleys – one on the top floor and one on the bottom floor. A flat, tensioned belt is connected to both pullies with metal buckets. There is an engine connected to one of the pullies that turns the metal pulley and the belt with the buckets containing grain or flour moves vertically upwards. As the belt turns around the metal pulley at the top, the grain or flour is dumped out of the buckets and the empty buckets move back down.

Box for collecting and mixing flour

The flour from different milling sessions is usually poured into the flower box under which a screw feeder is located (in the basement). The screw is used to mix the flour and make them more homogenous. Then the flour is moved upward with the elevator and they are dumped from the upper part of the elevator into a wooden gutter (the boot) from which they fall into a bag on the necessary floor.

De-husking machine

The de-husking machine polishes off the grain husks, leaving the kernels known as pearl barley. The shell of the de-husking machine consists of a cylinder covered with emery mass on the inside and connected to a fan. The de-husking machine has a grain batching mechanism, which periodically feeds a certain amount of grain into the machine. Inside the machine, there is a rotating cylinder with elongated blades that crash the grain against the emery surface, thus polishing the grain. A powerful suction fan removes the dust and the cleaned husks. The duration of polishing by the de-husking machine can be regulated from 5 seconds to 3 minutes, depending on the size of the grain and the specific variety. De-husking is generally done for barley or wheat.

Box for barley or wheat grain above the de-husking machine

To turn barley or wheat into pearl barley or pearl wheat, there is a box placed above the de-husking machine. Clean grain is put into this box. When the de-husking machine is turned on, the miller opens the damper and the grains are poured into the de-husking machine where they are polished. When the box is empty, it is filled up with more grain.

Stone lifting machine for sharpening the stone

When the grain is milled with millstones, the bottom stone is usually stationary, while the top stone is turning, and the grain between the stones are milled. To ensure the quality milling process, there are special slanting grooves made into the stones. As a result of friction, the surface of the stone and the carved grooves wear out. This is when the miller uses a special lifting mechanism to lift the stone to sharpen it. A special chisel is used to carve the grooves again. The stones must be sharpened regularly to ensure quality milling.


There are natural and artificial millstones.

Natural millstones. A long time ago millstones were made only from natural stone. They had to be hard and fairly solid, but at the same time porous enough to be processed with metal chisels. The grey granite meets all these requirements. Later granite was replaced by millstones cut from porous volcanic lava rock (trachita). These were found in Germany, in the region by the Rhine River. Good quality millstones with quartzite were found in France, in the Seine River region and in Marna. Millstones were made by hewing the rock in smooth wedge segments held together by a circular metal hoop. Nowadays natural stones are also used for smaller grain mills to prepare various products.

Artificial millstones. Artificial millstones were first used at the beginning of the 20th century. In the territory of Latvia, the groundwork was done in 1905 by the Riga Polytechnical Institute assistant engineer and chemist Priedītis. To pour artificial millstones caustic magnesium and magnesium chloride was needed, which was imported from Germany. This cement mass was mixed with crushed and separated flint of a certain fraction, adding emery mass, as needed.


Crushed flint 1kg

Magnesite 0.25kg

Magnesium chloride 0.19 kg

Water 0.9 kg

The artificial mass can also be used to renew used and damaged millstones, which the miller can do on location, at the mill. The core mass of the artificial stone was made separately. It was cast from concrete so that the top stone would be heavy and the grain would not be lifting it upwards. The artificial layer for grinding was about 5-10 cm thick and it was renewed every so often.

Milling stone with grain box

 Milling is done with two stones. The stones may be natural – like granite, but they can also be artificial. Artificial stones are made from magnesium and flint. The stones are about 1m to 1,5m in diameter and weigh about 1 to 1.5 tonnes. The bottom stone is usually stationary, while the top stone is turning. The miller can use a lever to regulate the gap between the stones, as this affects how fine or coarse the milling will be. The clean grain for milling is poured on the upper floor – they are fed into the box standing over the stone, while the milled grain is received on the lower floor, under the stone. The stones are generally used to mill coarse flour and animal feed, as they can be used to mill grain that has not been cleaned. The grains for human consumption were sieved through cylindrical separators to obtain finer flour suitable for baking bread.

De-husked grain – groat splitter

Groat splitter splits de-husked grains into groats – smaller bits of grains. De-husked grains are split in the equipment between two disks with sharp projections on the surface. As the polished grains enter between the disks, they are cut into groats. The cut bits are pushed outside the equipment and continue to the groat separator.



The main drive shaft of the mill mechanisms

The main working drive of the mill is powered by a water turbine. There are several drive pulleys and a clutch mechanism on this shaft. The drive pulleys on the main mill shaft drive the smaller shafts of the mill. By removing or installing drive belts, it is possible to disengage or engage certain parts of the mill mechanism. The clutch mechanism on the main drive shaft allows to engage or disengage two millstones used for milling the grain.

The small drive shaft of the mill mechanisms

The small drive shaft of the mill mechanisms is located on the bottom floor of the mill and is turned b the main drive shaft of the mill powered by a water turbine. Generally, the drive shafts of different mill mechanisms are placed on different levels of the mill, parallel to each other. Various wooden or cast iron wheels are attached to the shafts. The wheel diameters depend on the speed of rotation of the specific mechanism. The wheels of mill mechanisms are connected to the wheels of the shaft by belts.

At the beginning of the 20th century, belts were made from leather, later they were manufactured from canvas covered by rubber. To ensure the rotation of the shaft, it was placed on plain bearings, later ball bearings. Plain bearings consisted of a cast iron body and Babbitt inserts. Babbitt was used so that the bearings could be re-cast at the mill, if necessary. Plain bearings had to be oiled regularly. The bearing bodies with shafts were usually screwed to concrete supports or the load-bearing wooden constructions of the mill.

Screw feeder

A screw feeder is used to move grain or other grain products in the necessary directions horizontally or at a slight angle upwards. It is powered by a drive belt.

The bottom part of the grain elevator

The elevator moves the grains and the grain products vertically. On the bottom floor of the mill, there s the bottom rotating metal pulley of the grain elevator, on the pulley, there is a tensioned belt with buckets for transporting grain. As a result of the rotation of the wheel, the belt with the buckets moves to the upper levels of the mill, bringing the grains and the milling products to the required level of the building. The elevator mechanisms are placed into a wooden body, preventing the grain products from spilling out of the buckets. The elevator drive mechanism is on the top floor of the mill building. There are 10 elevators on the bottom floor.

Screw feeder under the flour boxes with on/off clutch

The screw feeder below the flour boxes mixes the flour to ensure uniform quality of the flour milled in different milling sessions. The screw is switched on with a clutch mechanism, without stopping the rotation of the drive shaft.