Wood is a versatile material used in capital construction, the manufacture of decorative coatings and the production of furniture. There are various forms of wood, differing in structure and method of obtaining. The most durable and aesthetic material, which was used long before the advent of glued and pressed wood masses, are the sawn products of a solid tree trunk.
By longitudinal unraveling of the log into long component parts having at least one flat side (face). Most lumber has two flat edges that are parallel to each other.
Two methods of sawing logs are used - radial and tangential. With a radial approach, the cutting directions are oriented towards the center of the growth rings. The resulting boards or beams have different sizes, and their width is limited by the diameter of the tree to be blossomed.
Tangential sawing is designed to obtain long boards and is directed tangentially to the growth rings. Thus, a large number of fragments with the same size and sectional shape are obtained.
Further processing and giving the appearance depends on. The more work will be carried out to improve the surface and protect it from external influences, the higher the cost of the final product will be.
It is very important to choose high-quality lumber, which you should not buy, you can see on the video:
What are
There are several approaches to the classification of lumber. Allocate directions according to the method of obtaining (preparation), the degree of processing and purpose.
By way of preparation
This approach takes into account the final moisture content of the material. The most common concept is absolute humidity, which is the ratio of the mass of moisture to the mass of dry wood (per unit volume).
According to the magnitude of the absolute water content, there are:
- dry lumber(air-dry or natural humidity) - contain no more than 20% water and are widely used in construction and construction of structures. Obtaining the air-dry state of the tree is preceded by its long stay in the air;
- kiln-dried wood- obtained by drying in a closed box at elevated temperature. The moisture content of the material can be 10-14% or less, depending on the requirements of the consumer. Absolutely dry wood must be treated with protective compounds to prevent moisture absorption.
When stored for a long time in a humid environment, the wood becomes wet (contains 100% or more moisture). Boards made from freshly cut wood have a moisture content of about 50-100%.
By appointment
The following types of lumber are distinguished by size and shape, as well as mechanical properties:
- beam- characterized by a thickness and width of more than 100 mm, is the main load-bearing element of many building structures and is used in the assembly of the base;
- boards– have a thickness of less than 100 mm and their width is more than twice the thickness. Along with beams, boards are the most common lumber and are widely used for industrial, domestic and other purposes. Boards are made by longitudinal sawing of logs and beams;
- bar- It is made of boards, which is the reason for its small size. The thickness of the bar should be no more than 100 mm, and the width should be less than twice the thickness;
- sleepers- short bars used for railway purposes as supports for rails. The sleepers are usually treated with a strong mixture of petroleum or coke-chemical antiseptic, which is highly toxic. The use of impregnated sleepers in everyday life is highly discouraged;
- lagging- is an "unfinished" version of the board, in which only one face is flat. The width of both fields can vary along its length, due to which the longitudinal cut along the sawn plate has a pronounced irregular shape;
- croaker- refers to an intermediate variant between the board and the floor, which has one even surface. The raw surface on the opposite side has a regular cylindrical shape (truncated), therefore, in a longitudinal section, the slab is a rectangle.
Photo of various types of lumber
Beam Boards Bar Sleepers Obapol Slab
According to the degree of processing
The simplest version of lumber has two parallel faces and two raw wane (side faces) of a semicircular shape (external roundness of the tree). Two layers are often not enough to implement a number of construction and design tasks. Wane processing increases the aesthetics of wood and increases its cost.
According to the degree of processing, the following types of lumber are distinguished:
- unedged- have untreated wane, freed from bark and coarse knots;
- edged– wane sawn parallel to each other, giving the transverse profile a rectangular shape;
- planed– the surface of at least one of the faces (plast or wane) is planed to reduce roughness. Such boards or beams are used to create floor and wall surfaces, seats and other outdoor structures.
What trees are lumber made from?
For the production of lumber, coniferous and deciduous wood is used, including their valuable varieties.
The most common species, the trunks of which are used to obtain boards and beams, are:
- larch– resistant to water and practically not damaged by insects and fungi. Even without the additional processing that is required for most other woods, hardwood is resistant to rot and is widely used in wet areas;
- beech- used in the manufacture of furniture, stairs and wooden floors. Due to its high wear resistance, seating for benches in public places is often made from beech lumber;
- pine– differs in the high environmental friendliness supported by the pitches which are its part. Pine wood is less durable than hardwood and is more prone to catching fire and emitting acrid tar smoke. They try not to make benches from pine lumber, so as not to spoil clothes with protruding resins;
- oak- is one of the most popular trees for the construction of houses and structures, has high strength and beautiful texture. Oak products swell slightly with increasing humidity, but are less common due to their high cost;
- ash– has mechanical properties close to oak. The shades of its wood are not always attractive, which is caused by a violation of the integrity of the cellulose fibers as a result of diseases. A high bending tendency and impact resistance are among the main advantages of ash;
- cedar- it is used much less often than other pine species due to its high cost, however, it is distinguished by aesthetics, resistance to decay and the ability to disinfect the air of the room in which it is located. In terms of mechanical properties, cedar is close to pine and has a more pronounced and rich texture;
- deadwood- used to obtain the least quality material from naturally dried wood. Dead wood lumber is usually broken down into small bars and used as ancillary material;
- Linden- has become widespread in the manufacture of quiet and warm floors, as well as walls of warehouse and industrial utility rooms (not damaged by rodents). The relative softness of linden lumber simplifies its processing when assembling composite structures;
- aspen- Most often, aspen lumber is used for the construction of baths and saunas. Low performance reduces the value of solid aspen, a significant part of which is sent to the production of plywood or chipboard;
- Birch- It is used to obtain light and durable lumber. Birch wood is practically resin-free, and its lumber has found the greatest use in furniture production due to its beautiful texture and ease of processing.
The video will tell about the varieties of larch lumber:
Let's evaluate lumber, comparing them with stronger and more durable stone materials for construction:
- price - 5. A wide range of wood allows you to choose lumber for any financial opportunity. In addition to expensive wood species, there are their cheaper counterparts. They are inferior in terms of texture, but not performance;
- practicality - 4. Wood is easier to damage than stone building material, so wooden coatings require care and additional processing;
- appearance - 5. The wood surface is considered the most aesthetic. Even artificial surfaces are often disguised as wood to give the room more flavor;
- ease of manufacture - 3. Although the tree is not very difficult to process, its finishing is quite difficult;
- laboriousness when using - 4. It is better to work with wood in pairs to hold structural elements when marking, trimming or fixing;
- environmental friendliness - 5. Wood is one of the most environmentally friendly materials. To increase the safety and durability of wood, treatment with special antiseptic compounds is used.
Date: 2016-02-24 17:22:17
Wood is a versatile material that is used in various areas of human life. Among the most demanded and popular wood products are lumber - products of cutting solid trunks, which were used long before the appearance of both glued and pressed wood products.
General description of lumber
Lumber is obtained by splitting logs longitudinally into long pieces with at least one flat side. Most products have two flat faces that are parallel to each other.
There are two ways to cut logs:
Radial (the direction of the cut is oriented towards the center of the annual rings, all the resulting bars and boards have different sizes, and their width is limited by the diameter of the tree);
Tangential (direction tangential to annual rings, which makes it possible to obtain a large number of fragments of the same cross-sectional shape and identical sizes).
For the production of lumber, wood of both coniferous and larch species is used. The most common include:
Larch - resistant to the negative effects of mold, fungi, insects and moisture, even without additional processing, is used in almost all areas of construction;
Beech - characterized by high wear resistance, is widely used in the manufacture of floors, stairs and furniture;
Pine - known for its high resin content, which is why it is more prone to fire, not too durable;
Oak - has a beautiful texture and high strength, is one of the most popular wood species in construction;
Ash - has good mechanical properties, as well as good elasticity and impact strength;
Birch is a light but durable wood, characterized by ease of processing and a beautiful texture.
Types of lumber
There are several types of lumber classification: according to the method of preparation, the degree of processing and, in fact, the type.
The first option takes into account the final moisture content of the material, the most common is the concept of absolute moisture: the ratio of moisture to the mass of dry wood. According to the absolute moisture content, there are:
Dry lumber (natural moisture) - dried in the open air and contain no more than 20% water and are most widely used in construction;
Chamber drying - are made by drying indoors at elevated temperatures, humidity is 10-14%, needs additional treatment with protective compounds to prevent moisture absorption.
The second group includes the following varieties:
Unedged (there are untreated wane, freed from coarse knots and bark);
Edged (wane are cut parallel to each other, which allows you to give the transverse profile a rectangular shape);
Planed (the surface of at least one of the faces is planed to reduce the roughness).
The third type of classification, that is, by type (shape, size and mechanical properties), includes:
1. Timber (ordinary, window, glued and imitation timber) - lumber with a width and thickness of more than 100 mm.
2. Boards (floor, deck, terrace) - thickness less than 100 mm, width more than two dimensions of thickness, produced by longitudinal sawing of logs and beams.
3. Bar (regular and planed) - thickness no more than 100 mm, width - less than twice the thickness, made of boards.
4. Obapol - a product with only one flat face, the width can be different along the entire length of the lumber, due to which the longitudinal cut along the sawn plane has an irregular shape.
5. The slab is an intermediate option between the board and the floor, it has only one flat surface, on the opposite side of which there is an untreated surface of a regular cylindrical shape (truncated).
Also, the number of lumber includes: block house, lining calm, straight and beveled planken, logs.
Use in the construction industry
Depending on the types of lumber, the scope of their application also differs. For example, unedged boards are used for the manufacture of flooring, roof sheathing and load-bearing structures. Edged - for the base of floors and roofs, as well as external and internal decoration. A bar with a width of not more than twice the thickness, which does not exceed 100 mm, is used in carpentry, roofing, furniture making and flooring. A beam with a width and thickness of more than 100 mm is used for roofing, ceiling and floor laying. And the slab is used as a crate under the roof, as well as in the construction of temporary and utility rooms.
When purchasing lumber, including from Siberian larch wood, a large selection of which is presented on the Lesinter website, you should immediately purchase special oils for processing them. The use of these substances allows you to protect products from damage and maintain their attractive appearance for many years.
Lumber is produced by sawing wood into separate parts - plates, quarters, bars and beams, boards, slabs. Types of lumber are very diverse.
Classification of lumber by appearance and processing method.
The thickness of boards made under production conditions can be no more than 100 mm, the width has a value greater than the thickness value multiplied by two. For beams, the thickness is not more than 100 mm, the width must be less than twice the thickness.
How lumber is classified according to processing
According to the method chosen for the processing of raw materials, lumber is divided into unedged and edged. The latter are characterized by processing from four sides, on the faces and edges, while the wane values should be allowed only those determined in accordance with the type of product. The wane is the part of the log surface that is preserved on the part after mechanical trimming. It turns out a piece of board that has not been processed along the edges, which can be used in architectural structures or in carpentry finishing of buildings.
Uncut lumber has edges that are partially sawn or not sawn at all. One-sided products have one edge and sawn layers, while the sawn lump is not allowed to have a wane that is larger in magnitude than the parameters allowed for a particular product. This type is used in construction somewhat less frequently. It can be used for sheathing various parts of the structure, laying, and other options are possible.
Types of lumber and cutting logs.
Depending on the processing method, materials can be called unmilled or milled, that is, planed. The latter are a material in which at least one of the cavities is planed. In order to produce planed timber, wood is taken only with a certain diameter, so that the blanks for the timber are formed in compliance with the desired size. The blanks must be dried - this is done using steam chambers or in natural conditions. Products are obtained by processing raw materials on machine tools.
Classification of lumber by size, shape
When processing wood with the use of modern technologies, various types of products are performed. The assortment includes bars and sleepers, boards and slats, quarters, slabs, plates and other products. Types of lumber may vary depending on how the raw materials are processed. You can learn more about them.
Types of lumber
The timber, depending on the number of sides to be processed, will be called two-edged, three-edged, four-edged. The thickness and width of products is usually more than 100 mm. The main scope of their use is the construction of load-bearing structures, cottages or summer cottages, since these products can perfectly withstand significant loads.
The bar is similar to the bar, but has different dimensions. It is carried out with a thickness of up to 100 mm, the width is less than double the thickness. It is used in the furniture and carpentry industry, for finishing buildings, for example, door frames and crossbeams are made from them.
Table of shrinkage coefficients and mechanical strength of lumber.
Boards are made of logs or beams of sufficient thickness. Boards are uncut or cut. The thickness is possible no more than 100 mm, the width is more than double the thickness. Application - wall decoration, flooring, furniture production.
The sleeper is a product with a short length, but wide and thick. This is in some way a kind of timber, in which the size of the cross section differs in size. The most common application is for the execution of railroad tracks.
A croaker is a piece of log, drank off the side. In the process of sawing logs into various boards, waste is obtained, which is called slab. It is convenient to make temporary buildings like sheds from it, they are also suitable for constructing a crate under the roof.
Quarters (obapol) are also obtained from the side parts of the logs. One of the surfaces of the product is propylene, the other is not. It is convenient to use for the manufacture of small joinery.
The plate is half a log, which is obtained by sawing it in the center. The plates have only one straight side. The length depends on the log used as raw material. They are mainly used for the production of the above products - sleepers, beams, sometimes - for the manufacture of massive boards.
How lumber is classified by type of wood
For lumber, the grade will also depend on the tree species - they can belong to a deciduous or coniferous array.
Coniferous arrays include larch, spruce, pine, cedar, fir. Deciduous arrays - oak, birch, beech, aspen, poplar, maple. For the construction of buildings, coniferous trees are more often chosen, since they are little affected by moisture, are more convenient to process, have good hardness and are quite durable. They can be used to create load-bearing structures. But it should be borne in mind that conifers in their composition have a lot of resinous substances, which means that any kind of lumber created from them is faster and easier to ignite.
Spruce wood is especially popular. It also contains the smallest amount of resins, therefore, the susceptibility to fire is reduced. Among hardwoods, oak is widely used - it is very strong and durable. Lumber can be divided into four grades. Thus, the selected grade is used in the manufacture of parts in shipbuilding, in the lathing of car sides, and in other significant areas.
Obtained by cutting logs(blanks). In fact lumber- this is a sawn product of a certain size with two plane-parallel sides ( layers). Sawing can be both radial and tangential. (Fig. 1) are subdivided into plates, bars, boards, bars, croaker.
plates receive at sawing logs along the axis into two equal parts.
bars- This lumber thickness and width of more than 100 mm; there are two-, three- and four-edged.
Boards are no more than 100 mm thick, with a width of more than double the thickness.
bars have a thickness of less than 100 mm, a width of less than twice the thickness.
croaker- the side parts of the log remaining during sawing.
lumber elements
AT lumber highlight the following elements: plasti, edges, ribs, ends.
Plast- longitudinal wide side lumber, as well as any side lumber square section. In the best plasti lumber the smallest number of defects, the best quality of processing. Plast lumber, facing the core, is called internal, and facing the sapwood - external.
Edge- longitudinal narrow side lumber
Edge- line of intersection of two adjacent sides lumber.
Butt- end transverse side lumber.
wane is optional lumber element, this, so to speak, is an element of marriage edged board due to the substandard source material ( logs or blanks).
Planed with giving them curly sectional shapes, they are called planed moldings (architraves, skirting boards, grooved boards for flooring etc.).
Wood sheet materials and various additives plywood, wood fiber (DVP) and chipboard (chipboard).
Lumber production
Manufactured according to GOST 8486-86E:
1) From coniferous wood - pines, ate, larches, firs
2) From hardwood - beech, birches, alder, lindens, aspens and poplars.
Softwood
Coniferous wood usually softer and lighter than wood majority hardwood; however, this is not always the case yew wood heavier and denser than wood some deciduous trees. For processing usually go spruce trees growing in cool or cold climates. Wood they are light yellow, with resin passages and numerous knots. She's cheaper than hardwood and easier to process. spruce wood used for almost all basic carpentry and construction work. Usually on sale lumber as planed or unplaned boards different thicknesses and widths red and canadian spruce. For outdoor use, you will need either a rot-resistant view wood, or spruce wood pre-treated with a special protective compound. It is not enough just to apply this substance to the surface of the wood with a brush - if possible, buy a tree impregnated with an antiseptic under pressure: in this case, the protective composition penetrates deep into wood.
Table 1. conifers
| wood species | Description |
| Thuja western | The wood is reddish brown with a silky surface. Resistant to rot and insect attack. Used for sheathing, building fences and greenhouse frames. disadvantages: the color fades over time, the surface is easily damaged, and the nails in such wood do not hold firmly |
| Larch | The wood is hard and difficult to work with. Advantages: resists decay well, holds nails well. Used for poles and building fences |
| Spruce red | Used for outdoor work. The wood is durable, easy to process, suitable for etching stain and painting. Color varies from light yellow to reddish brown. Rotting quickly, requires antiseptic treatment |
| Canadian spruce | The wood is softer and finer textured than red spruce. Light yellow color does not fade over time. Used for interior decoration. Not impregnated with an antiseptic, therefore unsuitable for outdoor use |
hardwood
Trees such as oak, mahogany, or red, wood and teak. Wood these breeds denser and harder than coniferous wood; it is heavy, resistant to decay, with a denser structure and more decorative than coniferous wood. At the same time, it is more expensive and more difficult to process.
On the transverse cut of the trunk of hardwood deciduous trees grown in Europe or other regions with cool or frosty winters are clearly visible growth rings. Wood these breeds usually light and difficult to process. Coming to market tropical tree wood almost always darker, less textured and easier to work with. Important:
- Allowed
application lumber from hardwood for details of rafters, internal stairs, internal wall and partition linings, filing of ceilings, rolls, pediments, internal architectural details, joinery and fine wood.
- Not allowed
application wood birches, lindens and poplars for rafters; lindens, alder, aspens and poplars for treads of wooden stairs; lindens and poplars for clean floors.
Table 2. hardwood
| wood species | Description |
| Iroko | Grows in West Africa. The cheap wood of this plant is used instead teak for the manufacture of garden furniture. The color is rich brown, the texture is rather rough |
| mahogany (red) wood | Wonderful, but too expensive for outdoor decoration with wood unit. African mahogany has a rich orange-brown color, American has a stronger gloss and is more expensive. |
| Meranti (Shorea) | A cheaper substitute mahogany from Malaysia. The coloration of pronounced red tones is easier to process than Red tree. Used for making garden furniture |
| Oak | The strongest and most durable sessile oak, but it is expensive, difficult to work with, and splits when nails are driven into it. Oak ordinary is slightly softer |
| Teak | Traditional garden furniture material: rot-resistant, water-resistant, flame-retardant. Color light brown with darker stripes |
lumber dimensions
lumber length: conifers no more than 6.5 m, deciduous- no more than 5 m. For special structures can be used lumber length up to 9 m, made by special order. Thickness and width of lumber determined assortment(Table 3, 4, 5, 6).
Table 3 The standard for the output of edged lumber per cubic meter. logs
| Type of wood | Log diameter, mm | Variety | Output from 1 m³ | ||
| lumber, m³ | wood waste, m³ | sawdust, m³ | |||
| conifers | 140-240 | 2 | 0,591 | 0,269 | 0,14 |
| Same | Over 260 | 2 | 0,637 | 0,223 | 0,14 |
| hardwood (including birch) |
140-240 | 2 | 0,533 | 0,307 | 0,14 |
| Same | Over 260 | 2 | 0,565 | 0,295 | 0,14 |
| Aspen | 140-240 | 2 | 0,481 | 0,379 | 0,14 |
| Same | Over 260 | 2 | 0,512 | 0,348 | 0,14 |
Table 4 Thickness and width of sawn softwood in mm.
| Name | Thickness | Width | |
| Least | The largest | ||
| Boards | 16 | 70 | 180 |
| 19 | 70 | 180 | |
| 25 | 70 | 180 | |
| 30 | 100 | 180 | |
| 40 | 50 | 180 | |
| 50 | 50 | 220 | |
| 60 | 60 | 220 | |
| 70 | 80 | 220 | |
| 80 | 100 | 240 | |
| 100 | 100 | 240 | |
| bars | 120 | 120 | --- |
| 150 | 150 | 200 | |
| 180 | 180 | 220 | |
| 200 | 200 | 260 | |
| 220 | 280 | 280 | |
Table 5 Thickness and Width of Hardwood Lumber in mm.
| Name | Thickness | Width | |
| Least | The largest | ||
| Boards | 16 | 50 | 160 |
| 19 | 50 | 200 | |
| 25 | 50 | 220 | |
| 30 | 50 | 220 | |
| 40 | 50 | 200 | |
| 50 | 50 | 260 | |
| 60 | 60 | 220 | |
| 70 | 70 | 220 | |
| 80 | 80 | 260 | |
| 100 | 100 | 260 | |
| bars | 120 | 120 | --- |
| 150 | 150 | 200 | |
| 180 | 180 | 220 | |
| 200 | 200 | 260 | |
| 220 | 220 | 260 | |
Table 6 The volume of one log, cubic meters
| Log diameter, cm | log length, m | |||||
| 4,0 | 4,5 | 5,0 | 5,5 | 6,0 | 6,5 | |
| 12,0 | 0,053 | 0,063 | 0,073 | 0,083 | 0,093 | 0,103 |
| 13,0 | 0,062 | 0,074 | 0,085 | 0,097 | 0,108 | 0,120 |
| 14,0 | 0,073 | 0,084 | 0,097 | 0,110 | 0,123 | 0,135 |
| 15,0 | 0,084 | 0,097 | 0,110 | 0,125 | 0,140 | 0,154 |
| 16,0 | 0,095 | 0,110 | 0,124 | 0,140 | 0,155 | 0,172 |
| 18,0 | 0,120 | 0,138 | 0,156 | 0,175 | 0,194 | 0,210 |
| 20,0 | 0,147 | 0,170 | 0,190 | 0,210 | 0,230 | 0,260 |
| 22,0 | 0,178 | 0,200 | 0,230 | 0,250 | 0,280 | 0,310 |
| 24,0 | 0,210 | 0,240 | 0,270 | 0,300 | 0,330 | 0,360 |
| 26,0 | 0,250 | 0,280 | 0,320 | 0,350 | 0,390 | 0,430 |
| 28,0 | 0,290 | 0,330 | 0,370 | 0,410 | 0,450 | 0,490 |
| 30,0 | 0,330 | 0,380 | 0,420 | 0,470 | 0,520 | 0,560 |
Characteristics of lumber
Lumber ends and draft blanks should be sawdust at right angles to the longitudinal axis. Wane bars(with a partial absence of a cut in the edge) with a section of 120 x 120 mm or more must have a cut width at the thin end of at least one third of the side of the beam.
Maximum allowable lumber moisture for load-bearing structures - 25%, for glued structures - 15%.
The main products of the sawmill industry are sawn timber. Minor - sawdust and wood chips, which are used for the manufacture of particle boards, fuel pallets, etc.
Types of materials produced at the sawmill
If you follow the “letter” of GOST 18288-77, the materials that are produced at the sawmill include:
1) Lumber
lumber- wood blanks with two plane-parallel layers and certain dimensions fixed in the regulations.
- bars- lumber, the width and thickness of which is more than 10 cm, is widely used in the construction of houses, as load-bearing structures, for interior and exterior decoration, for the manufacture of stairs, windows, etc.
- bars- sawn timber, in which the width does not exceed twice the thickness. According to the geometric parameters, square and rectangular bars are distinguished. Depending on the length, these lumber is used as floor joists, bases for wall cladding, in the construction of gazebos, bathhouses and other small architectural forms, in furniture production.
- Boards- lumber in which the width exceeds the double thickness dimension. Depending on the presence of bark on the side edges, they are divided into edged and unedged. Edged boards are more in demand for the manufacture of furniture, windows, doors, for various finishing works - in a word, where not only the strength qualities of wood are important, but also aesthetic parameters. Unedged material it costs an order of magnitude cheaper, therefore it is bought either for self-processing into an edged board to reduce the cost of production, or it is used in construction as an auxiliary material (for roof lathing, for the manufacture of flooring, etc.).
- Sleepers- bars of the established size and shape, which are made as a support for the rails of the railway;
2) Blanks
blanks- edged lumber with wane and edges, which are sawn off perpendicular to the layers in whole or in part. These include plates (half cuts of logs) and quarters;
3) Obapol
Lagging- material with an internal sawn and an outer non-sawn (or only partially sawn) layer. Plank obapol - with a half or more sawn convex part, is used for the production of a picket fence and in the construction of formwork, scaffolding, strengthening mine workings;
4) Slab
croaker- the extreme parts of the log remaining during sawing. The croaker differs from both sexes in that certain ratios of thickness, width and minimum length requirements are not established for it. Most often used as an environmentally friendly fuel or for the production of wood chips.
lumber elements
Plast- wide longitudinal surfaces of the sawn log and any side of the square-section lumber. The internal layers are those closest to the core of the log, the external ones are the surfaces that are farthest from the core.
edges- narrow surfaces, the processing method of which determines the separation of sawn timber into edged, partially edged and unedged;
Edge- the intersection of adjacent two sides at the lumber;
ends– surfaces perpendicular to the edges.
Classification of lumber by sawing method
Depending on the location of the layers to the annual layers, lumber is divided into:
1) Made by radial sawing
A radial cut is a cut in which the cut passes through the core of the log, at right angles to the rings. At the same time, the surface of the layers turns out to be uniform in texture and color, and the distances between the annual rings are minimal.
Boards made by the radial sawing method have excellent quality indicators (swelling coefficient 0.2%, shrinkage - 0.19%). Therefore, radial sawn timber is in demand for the manufacture of parquet, timber, lining, block-house - finished products have practically no gaps, in comparison with similar products of tangential sawing.
Saw-timber made by the method of radial sawing is the most durable and expensive. They are used in construction, in the production of massive shields and window beams. The output of a radial board is usually small (30% is already a good indicator), and depends on the method that will be chosen for cutting the log. The following is considered the optimal sawing scheme for obtaining radial and semi-radial boards.
2) Made by tangential sawing
When sawing a log tangentially, the saw passes tangentially to the annual layers of the trunk, without affecting the core of the tree. Such lumber has a wave-like pattern, which clearly shows the patterns of annual rings and a beautiful woody structure.
For tangential boards, the coefficient of shrinkage and swelling is at least twice that of the radial material, so their cost is more affordable, and the quality of the products is lower. Such boards are not used for the main building elements - the wood can be deformed and the product will “lead”. But, nevertheless, due to high aesthetic qualities and low price, the demand for tangential wood is high - it is used for decorative finishing of furniture, doors, building elements.
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