Drying is a mandatory stage in preparing wood before processing. To prevent logs from becoming deformed, they are dried under certain conditions, which are created in drying chambers. For your home workshop, you can make a wood dryer with your own hands.
The importance of drying
Since ancient times, wood that was cut down several years ago was used to make wood products. Furniture made from damp or improperly dried boards will warp or dry out and crack. When drying, the material shrinks, raw wooden beams will move over time, and cracks the width of a palm will appear in the walls of the log house. Mold grows in damp wood. But overdried boards are also bad - the material begins to absorb moisture and swells.
Drying is carried out with hot air or steam, the process is long and expensive, but it gives the wood additional strength, prevents changes in shape and size, and the lumber is stored longer.
Drying modes
There are several modes of drying lumber. In self-made chambers, the temperature increases in stages, removing moisture from the raw materials. Drying technology is selected taking into account:
- wood species;
- dimensions of lumber;
- final and starting humidity;
- dryer features;
- raw material quality categories.
The drying process can be high temperature or low temperature. In the second case, primary processing is carried out at a temperature not reaching 100 degrees.
Low temperature regimes are divided into categories:
- soft - during the drying process, lumber retains all its properties, strength and color do not change;
- normal - color changes slightly, strength decreases slightly;
- forced - when chipped and split, brittleness is possible, the color darkens.
The change in ambient temperature at low temperature occurs in three stages. The transition to the next stage is possible when the wood reaches the specified moisture content.
High-temperature treatment is carried out in two stages. The second stage occurs when the moisture content of the raw material decreases to 20%. This technology is used when preparing wood for the construction of secondary structures, allowing for color changes and a decrease in strength.
Types of drying chambers
Drying of wood on an industrial scale is carried out in special chambers. Moisture is removed from the lumber by heated air and carried outside. Happens in the device full cycle drying wood. The room can be:
- prefabricated metal;
- constructed from building materials.
The latter are installed directly in carpentry shops or as free-standing buildings. The walls are made of reinforced concrete or brick. At large enterprises, several cameras are installed, combined into a module with common system control and communications. Air circulates in the dryer horizontally or vertically-transversely. Wood can be transported to industrial dryers on rails on carts or laid out using forklifts.
Heat sources in the dryer:
- hot steam;
- radiant heat from special devices;
- heated shelves;
- electric current that passes well through wet logs;
- high frequency electromagnetic field.
The camera is equipped with basic and additional equipment. The main consists of systems:
- supply and exhaust ventilation;
- heat supply;
- hydration.
Additional equipment includes insulation of walls and doors, trolleys for laying material, psychometric equipment, and electric drive.
Industrial dryers are controlled automatically, small homemade dryers are controlled manually. Humidity adjustable supply and exhaust ventilation and humidifiers. To measure the humidity in a room, a moisture meter is installed that collects data simultaneously in several places.
The following energy sources can be used to heat air: electricity, wood processing waste, liquid and solid fuel.
Types of dryers
According to the method of air movement, chambers are divided into:
- with natural;
- with forced air exchange.
Chambers with natural air exchange are low-performing and the process in them cannot be controlled. Therefore, they are used less and less.
According to the principle of action, the following are distinguished:
- convective;
- condensation dryers.
In convection chambers, the wood is blown with streams of hot air, and heat is transferred by convection. They can be deep tunnel or chamber. Logs are loaded into tunnel chambers from one end and unloaded from the other, moving through the chamber, the material is gradually dried. The cycle duration ranges from 4 to 12 hours. Such cameras are installed in large sawmills. Chamber dryers are more compact; a single microclimate is maintained throughout the entire volume. Allows you to prepare any type of wood to the required condition. Therefore, most industrial dryers are chamber type.
Using condensation drying technology, moisture released from the material is deposited on coolers, accumulates in containers and is drained outside. The efficiency of such a device is very high, but the process is long and accompanied by high heat losses. The technology is good for preparing hard lumber in small batches. The price of equipment and the cost of condensation drying are lower than convective drying.
Setting up a homemade dryer
In order to make a dryer with your own hands, you can do without drawings. It is necessary to provide:
- camera room;
- insulation;
- heat source;
- fan.
The area of a dryer built by yourself usually does not exceed 9 square meters. meters. Indoors square shape it is easier to ensure optimal movement warm air. It is advisable that one wall of the chamber be made of concrete slabs, others are made of wood. All walls are insulated from the inside in two layers: polystyrene foam and foil board. An excellent and free insulation material is wood shavings. And the foil can be replaced with penofol, which perfectly reflects heat.
You can build a separate drying room with your own hands from aluminum; such a structure will last a long time. The frame is made of profile, it is sheathed with sheet metal, which is insulated from the outside. The thickness of the insulation is at least 15 cm. The floor is covered with roofing felt, and a thick layer of shavings is poured on top as thermal insulation.
Care must be taken to thoroughly seal the front door!
The heat emitter can be made in the form of pipes or heating radiators. The water temperature should be 65-95 degrees. It is heated by an electric boiler, wood stove, gas boiler. For a small chamber, even a two-burner electric stove is sufficient. If the stove is located directly in the room, you need to line it with bricks. The brick will accumulate heat and gradually radiate it into the dryer. It’s easy to equip a convection chamber with your own hands by installing a fan heater as a heat source.
When setting up a dryer for your home woodworking workshop with your own hands, it is important to follow the precautions fire safety. There should always be a fire extinguisher near the building.
Constant circulation is important warm water, which is provided by the pump. To ensure that heat is evenly distributed throughout the room, a fan is installed. Workroom Equipped with a wet and dry thermometer.
To make it easier to load the board into the chamber, you can use a trolley on rails. And to increase usable area Shelves are lined up on the walls.
The step-by-step instructions are as follows:
- We are building the foundation.
- We are building the frame.
- We cover the frame with sheets of metal.
- Installation of thermal insulation.
- Cover the floor with film and sawdust.
- Installation of supports from bars.
- Installation of heaters and fans.
The design of a homemade chamber for drying lumber in the video:
The quality of the products produced from wood will directly depend on the correctly performed drying process of wood material. of this material. Do-it-yourself vacuum drying of wood can significantly save time spent on drying wood raw materials.
With this method of drying wood, the possibility of various deformations of the dried wood is largely eliminated.
The process of drying wood in a vacuum environment has its positive aspects:
- significant acceleration of drying processes of wood raw materials;
- less money spent on energy expended;
- more uniform methods of drying wood.
This equipment is quite simple in its operation and does not require special training of personnel.
Mini vacuum dryer
The vacuum drying method also has some negative parameters:
- big overall dimensions the equipment itself;
- no control methods for drying different breeds wood;
- typical for large industries.
How to build a vacuum dryer with your own hands?
In most cases, novice businessmen do not have enough money to purchase a factory installation using the vacuum drying method, so we will take a closer look at such an option as do-it-yourself vacuum drying of wood.
To set up homemade vacuum dryers for wood, you must have suitable premises, as well as the presence of any container.
It is necessary to arrange its hermetically sealed closure. Or you can build this dryer using reinforced concrete structures: with this option, one of the walls is made of wood.
Should be made thermal insulation the camera itself - for this you can use various types mineral wool, or use regular foam. You should also cover the insulation with a special film, which will help reflect heat flows into the chamber.
Heating radiators should be used as heating elements - in this case, these radiators should heat the water to seventy degrees. It will be necessary to install a fan of sufficient power: this element promotes a more correct flow of air masses inside the chamber.
Homemade vacuum dryer
To heat the water mass, a boiler is used, from which, using a water pump, water will be supplied to the heating elements. In addition, it will be necessary to install a device to create a vacuum environment. Sensors to monitor humidity conditions will also be needed.
The system that controls this equipment is moved outside the chamber itself - usually some kind of separate vestibule is made. Material can be loaded and unloaded for drying either manually or using a forklift.
Adjustments need to be made temperature regime so that changes in this parameter occur at a smooth pace.
Features of a homemade chamber for the vacuum drying method
When building this equipment on your own, it is necessary to create special technological parameters inside the chamber. When drying in a homemade chamber, the drying time can take more than two weeks.
Materials loaded into the chamber must be treated special solutions, including chalk and drying oil.
When building a homemade vacuum installation, fire safety parameters must be carefully observed, otherwise you may face irreparable consequences.
The wood harvesting process includes a drying operation. It prevents future defects and damage to the material. The procedure takes place in a special chamber. Any logging enterprise cannot do without it. Vacuum drying of wood is most often used. It has a number of advantages over other methods. For example, short time process, uniform processing of all material and ease of installation and dismantling of the installation.
- Wood drying technology
- Vacuum drying
- We build a dryer with our own hands
A tree is a living organism. Like other organic compounds, it contains water. Freshly cut wood has a moisture content of more than 30%. To use it in the future for construction needs or making crafts, excess moisture needs to be removed. The excess water in the material may vary. Its standards depend on where the wood is planned to be used. For making musical instruments, sports equipment and parquet set the humidity at 6-8%. If the raw material will be subjected to further processing, then it is enough to leave 20% moisture in it. For the manufacture of building structures and finishing materials the parameter is controlled at the level of 8-15%.
Wood drying technology
Vacuum drying
The wood drying process consists of several stages. First, it is evaporated from the surface of the material, and then from its interior. Dry first thin places, then moisture moves towards them from thicker layers. If the process is disrupted, the thin layers begin to shift and the material is destroyed. To prevent this from happening, the workpieces are treated with a special mixture. It is made from drying oil and chalk. The end parts of the workpieces are treated with the resulting composition. They usually always have the shape of an equilateral geometric figure.
Accelerated drying mode is distinguishing feature vacuum drying chamber. It is known that water begins to evaporate when it boils. A very low pressure is created in the chamber. Due to this, water boils at more low temperatures than usual. This way the process time is significantly reduced.
Another significant advantage is that vacuum drying significantly saves energy. Heating occurs by contact method. Temperature inside 
chambers and pressure are adjusted automatically. A vacuum is maintained in the chamber at 0.95 MPa. It ensures the heat and mass transfer process. Moisture is released from wood in the form of steam. After drying, raw materials are obtained with a given level of humidity. During the process, it completely retains its structure - it does not collapse.
This drying eliminates the use of fans. Humidification systems are also not needed. Neither dry nor wet bulb thermometers are used in the chambers. Humidity sensors are installed inside. They are controlled from outside. The entire control system is usually located in a separate vestibule.
Vacuum installations are often used for processing expensive types of raw materials: wenge, oak, rosewood, teak, angera. They use heating element convector type. The maximum temperature in the chamber is +65 degrees. However, the process of moisture evaporation begins already at 45.5 degrees. The process completely eliminates the impact high temperatures. Wood is practically not destroyed.
All the structural changes that accompany drying occur inside the tree. First, the moisture evaporates from the surface, then from the inside it approaches the surface again, and so on, up to 250 times over the entire time. Over the entire surface of the raw material, a humidity difference of 0.5-1.5% is allowed. Here are some indicators at which vacuum drying works:
We build a dryer with our own hands
It is not always possible for an entrepreneur to buy expensive equipment and use vacuum technology. For starters there are more simple methods.Do-it-yourself wood drying also occurs in drying chambers. To arrange it you will need the room itself, good insulation and a fan.
The design of the do-it-yourself drying chamber assumes that one wall and ceiling will be made of reinforced concrete. The remaining elements can be made of wood. The walls are insulated with polystyrene foam, lined with clapboard and covered with foil. Penofol can be used as a reflective material. It also reflects heat well and helps keep it inside the camera.
Mobile drying chamber.
Next is mounted heating device. The most commonly used heating radiator. Its power should allow you to heat water to 65-90 degrees. The entire system is mounted separately from others heating circuits. It must work constantly, regardless of the time of year. Electrical and gas appliances. A fan is necessary to distribute air evenly in the chamber. Without this, it is impossible to dry the material evenly with your own hands.
It will also be necessary to build a system for loading lumber into the chamber. They are usually large and heavy. It is convenient to load boards on trolleys moving on rails or with a forklift. Inside the chamber, the material is placed on shelves or simply on the floor. It is also necessary to install control devices over the process, which will be carried out with your own hands. Without this, it is impossible to properly dry the wood so that it later has a marketable appearance and its inherent properties.
When building a drying chamber with your own hands, you need to adhere to the following rules:
When building a dryer with your own hands, the main thing is to ensure that the parameters required by the technology are maintained within it. The materials and equipment that will be used do not matter. Drying the wood in such a chamber, built with your own hands, will take from one to two weeks.
The problem of maintaining optimal moisture content in lumber is relevant both among builders and among those who like to make something in their own carpentry workshop. Drying wood at home allows you to save a lot on its purchase, because dry raw materials are always more expensive than wet ones.
By the way, if you don’t have time for construction work, then you can dry wood at home or in the country even under atmospheric conditions.
Some owners adapt ready-made haylofts, sheds or other suitable buildings for these purposes. This is the way out of the situation that one of our forum members found.
Timakval member FORUMHOUSE
I used the yard attic (former hayloft) size 10*5 m for drying. I laid it out, as it should, through spacers in each row. Total 3.5 cubes of boards of different categories. The advantages of this drying place are always shade, finished roof and is well ventilated. Took it last May different sizes boards, bars and beams - blanks for small construction. The boards were too heavy to lift due to moisture. During the time they were lying in the hayloft (1.5-2 months) they dried to fluff, they did not curl or bend.
Drying under atmospheric conditions is a rather lengthy process, and since we have decided to take a comprehensive approach to this issue, let’s look at the sequence of building a home dryer with our own hands, which allows us to more effectively achieve the required humidity levels. We suggest that you select a building of the required size as a suitable premises, and after that you can begin to work. The room can have dimensions of 2*3 m or 4*3 m (more is possible). It all depends on your needs and the scope of your activity. But when choosing a building, you should remember that there should not be a lot of free space left in the dryer. After all, drafts and chaotic air movement negatively affect the quality of wood.
DIY wood dryer
The room chosen for arranging a homemade dryer must be heated by a stove or a specially installed fireplace. It is good if a heater is pre-installed in the room. If there is none, then be sure to leave room for it.
This is the project for making a home dryer suggested by a member of our forum.
Nikolay Valen member of FORUMHOUSE
There is a large garage with water heating; a potbelly stove using wood and waste is installed as a boiler. There is a pipe with a diameter of 800 mm and a length of 2.2 meters (former ventilation duct With industrial enterprise). The idea is as follows: install sealed covers on both ends of the pipe, leave fittings with a diameter of 150-200 mm for the supply and removal of hot air. The air is heated by a radiator (this can be a car heater). Air supply - table fan. 0.3-0.5 cubic meters of lumber are loaded into the pipe, the stove is heated (the coolant temperature reaches 90 degrees, I think that the supplied air can actually be heated to 50-60 degrees).
If you have chosen a room too large sizes, then the space planned to be used for a homemade dryer should be made insulated and sealed. For these purposes, wooden partitions are made; insulation, brick and other materials can be used to create your own microclimate in the dryer. Do not forget that it is necessary to leave a window in the chamber for ventilation and front door. After all, we shouldn’t end up with a hut without windows and doors.
Fans installed in the drying chamber will help create forced air flow and make the drying process more efficient.
mfcn FORUMHOUSE member,
Moscow.
It is advisable to place fans on the floor on the side of the stack so that the blowing is parallel to the gaskets. Remember that when drying wood, you need to evaporate about several hundred liters of water from each cubic meter of wood.
To place lumber in the dryer, special shelves or flooring should be installed. These products can be made of metal so that the structure can withstand relatively large loads. Wood should be dried to levels corresponding to 8–12% humidity. Its measurements are carried out using a special moisture meter.
Drying wood is necessary following certain rules. Otherwise, the material will be hopelessly damaged and cannot be used in construction. To do this, the wood must be stacked. And between each new layer, spacers made of boards of the same thickness should be placed. Wood of any species, stacked in neat stacks, will never suffer from fungal infections and will retain its integrity and excellent consumer qualities.
Lao Czy member FORUMHOUSE
The spacers need to be made higher for better air ventilation between the boards. They will dry out better. You can place your cut 25*30 or 25*40 cubes on edge. The reason for limiting the height of the stack is to prevent the boards from being driven by a “helicopter blade”, secure the topmost layers of boards in the stack with self-tapping screws. I have been storing my boards using this method for 3 years at my dacha in the Moscow region. They are in excellent condition!
Gaps should also be left between boards located in the same row. This will ensure unhindered air movement inside the stack and improve drying quality.
Wood drying chamber project
Wood can be dried quickly and efficiently in well-equipped and free-standing drying chambers. Construction of such a chamber on the scale of a dacha or suburban area is not always advisable. After all, this type of construction will be very expensive, and its construction will take a lot of time.
The construction of such a premises can well be called the implementation of a full-scale construction project. You cannot avoid labor-intensive operations associated with pouring the foundation, erecting walls and installing complex equipment.
How to make drying for wood can be understood from the diagram.
DIY chamber drying
Such a mini-wood dryer requires the placement of not only basic equipment (heating and ventilation), but also additional systems automatic control.
Operating modes of the drying chamber
A chamber dryer does not require high heat during normal operation. And the full cycle of work associated with drying one batch of wood can be divided into several stages.
The first stage lasts from 15 to 20 hours. During this period, the air in the chamber warms up to 45С. The ventilation does not turn on, and condensation forms on the walls of the room.
The second stage lasts about 48 hours. It involves connecting ventilation and heating the air in the chamber dryer to 50°C.
The third stage lasts until the required final moisture level is reached in the internal structure of the wood (8...12%). At this time, the air temperature rises to 55 C, the exhaust dampers open completely, and the fans operate at full power.
Once the humidity reaches the required levels, the heat supply should be stopped. The fans should remain on for another 24 hours. As a result of this heat treatment, you will receive dry wood, completely ready for use during carpentry or construction work.
You can get acquainted with the practical developments of our forum members regarding the correct construction of a stack in the “” section. Those who want to learn more about the technology of drying lumber can visit the “” section. For those who want to see a master class on wood aging technology, we recommend watching the corresponding video.
The construction industry today is experiencing an active stage of technological development, which is reflected in the tools used, the methodology for performing repair and installation operations, and, of course, the materials. At the same time, due to availability and low cost, traditional materials, including wood, still remain in demand. Another thing is that it cannot be used in its pure form, since even solid rocks no longer meet construction standards in protective properties. This barrier can be overcome by special preparation operations, including drying wood in drying chambers - a technology that improves a whole range of technical and physical characteristics of the material.
Chamber drying technology
The principle of drying in vacuum chambers is based on the laws of evaporation and water circulation. That is, the main objectives of the method come down to ensuring optimally rapid removal of moisture from the wood structure, but without negative consequences for performance. The technology under consideration is aimed at performing this process. In practice, it is carried out using special installations that ensure water circulation through the wood structure in the direction from the core to the outer part. Next, water is removed from the surface through evaporation. But it is important to understand that getting rid of moisture is not the only task that drying wood in drying chambers accomplishes. The technology also allows you to eliminate physical defects, but for this it is used additional equipment like presses. As for the technical implementation of the process, it is usually performed by manually loading the material into the appropriate chamber. Then, due to the heating plates, the unit automatically warms up against the background of intense evaporation.
Features of the vacuum drying method
Compared to traditional drying chambers, new cylindrical vacuum drying technologies allow for a high process speed. This is connected not so much with the principle of influence on the material, but with the mechanics of loading and the location of the workpieces relative to the functional plates. But the thermal effect also has its own characteristics. Since wood material is compressed between the plates under pressure, ensuring a high intensity of impact on the structure - accordingly, a larger amount of moisture is evaporated. In terms of energy consumption, vacuum drying of wood also has its differences. Features of the technology in this parameter are determined by increasing the temperature of the plates and optimizing the physical movement of the material inside the chamber. Therefore, to achieve the same results as alternative drying methods, such chambers consume less energy.
Drying stages
Automated cameras allow you to implement a standard set of technological steps without user intervention, which looks like this:
- Warming up the material. Primary heat treatment, during which the wood structure is prepared for subsequent stages.
- Direct drying. At this stage, a combined moistening-drying operation is performed, which allows the material to be softened as much as possible for further drying.
- Cooling. In essence, this is the stage of crystallization of the structure, thanks to which the wood, which has become pliable due to heat treatment, regains its optimal hardness characteristics.
As noted above, all stages of the drying process are controlled automatically, and the operator monitors the safety indicators. But even before the event starts, the user is required to install optimal mode drying. In particular, it sets pressure and temperature based on the characteristics of the material. For example, for coniferous blanks with a thickness of 2.5 cm, a pressure of 500 kg/m2 is required. As for the temperature regime, it is in in this case can be 80 °C.
Drying chamber device
Modern cameras are made in the form of a parallelepiped or cylinder. The output side of the structure is equipped with a lid, through which material loading/unloading operations are carried out. Moreover, the structure of the cover includes a rubber sheet fixed to metal frame- this solution allows you to create an almost perfect vacuum with increased sealing. Each layer of lumber is lined with heating plates, which are usually made of thermally conductive aluminum alloys. To carry out movements, the plates are equipped with roller mechanisms. Thanks to the movement of the heaters, balanced drying of the wood in the drying chambers is ensured. The chamber manufacturing technology also provides for the connection of circuits with circulating water. Boilers with liquid are located separately and provide their own heating. To maintain a stable vacuum, a special pump is placed inside the chamber.
Application of hydraulic press
It has already been said above that during the drying stages, the structure of the wood softens and becomes pliable. This condition It is within the drying process that it is a by-product and redundant. Actually, to eliminate these consequences it is envisaged final stage cooling. However, the softened structure of the material can be exposed to hydraulic press, which will relieve the workpiece from physical defects - at least ensure its straightening. Such presses are introduced into general complex capacities at which wood is dried in drying chambers. The pressing technology, in turn, eliminates possible defects that were acquired by the material in the chamber. The final workpiece will be “correctly” deformed with the parameters needed for working lumber.
Drying methods
At the moment of technology development, there are three main methods of vacuum drying. The first two methods have already been discussed - direct drying and press-vacuum preparation of the material. But there is also a steam treatment method in vacuum chamber. Its relevance is due to the possibility of eliminating heating plates from the chamber design, since hot steam covers the entire space, without requiring special direction of flows to individual sections of the workpiece. This approach provides many advantages that steam heating methods of wood drying provide. Drying chambers, for example, allow loading not only labor-intensive manually, but also with the help of forklifts.
What effect does drying provide?
Drying itself, as a process of optimizing the hygroscopic properties, gives the wood relatively high strength indicators. This is already enough for the material to correspond basic requirements building regulations. But large woodworking plants use the above-described technologies and methods of drying wood only as preparatory stage for further processing of the material. In particular, for impregnations, which will additionally give the workpieces the qualities of fire resistance, moisture resistance, frost resistance, etc.
Do-it-yourself drying
To make your own dryer available means First of all, you will need a separate room. In size it can correspond to a small utility room or utility room. The structure should preferably be made of brick or concrete, and internal surfaces insulate and insulate with layers of foil-coated foam. The result will be, although not a vacuum, a sealed dryer for boards. How to make thermal elements? To do this, several convectors or radiators should be provided - their number will be determined by the structural capabilities of the room and the requirements for the drying itself. Heating equipment and will provide an evaporation effect. For greater efficiency The thermal function can be supplemented with fans.
Conclusion
During construction and repair operations The question often arises of choosing between different materials. Limited financial resources often exclude metal alloys and high-strength plastics, leaving wood as the only option. But this decision also justifies itself in many cases. technical specifications, if a lumber drying chamber is used. You won’t be able to make such a chamber yourself without spending money on expensive radiators, but long term its use will be worth the investment. As practice shows in the operation of structures based on properly dried wood, the material can serve for years even in harsh conditions without losing its primary properties. Another thing is that a lot will depend on the type of wood that is planned to be used for such purposes.
