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Edged board exit. Determination of the yield percentage of sawn timber when sawing wood, in particular, round timber Output of unedged boards from round timber

Lumber is obtained by cutting logs (blanks). In essence, this is sawn timber of a certain size with two plane-parallel sides (layers). Sawing can be either radial or tangential.

On fig. 1 presents various types of lumber - from plate to edged board.

Figure 1. Types of lumber: a - plate; b - double beam; in - not edged board; g- quarter; d - four-edged timber with a wane; e - semi-edged board with wane; g - clean-edged timber; h - croaker; and - edged board; k - planed tongue-and-groove boards; 1- face; 2 - edge; 3 - rib; 4 - butt; 5 - wane

In lumber, the following elements are distinguished: layer, edges, ribs, ends. Plast - the longitudinal wide side of the lumber, as well as any side of the square section lumber. In the best layer of lumber, the least number of defects, best quality processing. The layer of lumber facing the core is called the inner, and the one facing the sapwood is called the outer. Edge - the longitudinal narrow side of the lumber. Rib - the line of intersection of two adjacent sides of lumber. Butt - the end transverse side of the lumber. Wane is not obligatory element lumber, this, so to speak, is an element of defective edged boards due to the non-conformity of the source material (logs or blanks).

Lumber is manufactured according to GOST 8486-86E:

1) from coniferous wood - pine, spruce, larch, cedar and fir;

2) from hardwood - beech, birch, alder, linden, aspen and poplar.

The following are used: boards with a thickness of 100 mm or less with a ratio of width to thickness of 2 or less; bars with a thickness of more than 100 mm (four-edged and two-edged).

The length of lumber: softwood - no more than 6.5 m, hardwood - no more than 5 m. Lumber up to 9 m long, made by special order, can be used for special structures. The thickness and width of lumber are determined by the assortment (Tables 1, 2, 3).

Table 1. Output standard for edged lumber per 1 m 3 logs

Type of wood	Log diameter, mm		Output from 1 m 3
			Lumber, m 5	Wood waste, m 3	Sawdust, m 3
conifers
Hardwood (including birch)

Note:

1) When increasing the grade roundwood up to the 1st standard for the output of sawn timber is increased by 3%.

2) When the grade of roundwood is reduced to the 3rd grade, the lumber output standard is reduced by 2%, to the 4th grade - by 7%.

3) In case of a mixed supply of large and medium logs, the lumber yield rate is taken as the arithmetic average between medium and large logs.

Table 2. Thickness and width of sawn softwood in mm

Name
		Least	The largest

Table 3. Thickness and width of sawn hardwood in mm

Name
		Least	The largest

The ends of lumber and draft blanks must be sawn off at a right angle 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 bar.

The highest permissible moisture content of lumber for load-bearing structures- 25%, for glued structures - 15%.

The use of sawn hardwood is allowed for details of rafters, internal stairs, inner skins walls and partitions, filing ceilings, reels, gables, interior architectural details, joinery and finished floors.

It is not allowed to use birch, linden and poplar wood for rafters; linden, alder, aspen and poplar for treads wooden stairs; linden and poplar for clean floors.

Repair and construction work often involves the use of lumber. But shops, timber trading bases sell them more often not in pieces, but in cubes.

The number of edged boards in 1 cubic meter.

Everything is very simple and fast.

Method for calculating edged lumber

• caliper, tape measure or folding m, with known parameters of the length of wood products, you can limit yourself to a regular ruler;
• calculator is fine mobile phone, a smartphone, if there may be problems with the account “in the mind”;
• a piece of paper and a pencil - to record the results of the calculations, how many boards are in the cube.

1. Volume = Length × Height (product thickness) × Width.

To prevent confusion when converting cubic centimeters to cubic meters, it is more convenient to immediately record the measurement results in meters.

Weight calculation cubic meter wood.

For example, 0.132 cu. m = 6 m × 0.022 m (2.2 cm) × 0.10 m (10 cm).

Now, to determine the number of boards in a cube, you need 1 cube. m divided by 0.132. The result obtained (7, 5757) when purchasing timber must be rounded up to 8 pieces.

This method of calculating cubic capacity is also suitable for timber. So you can determine how many cubes of timber you need to purchase if you know the required number of products, or, conversely, determine right amount cubes.

To determine the required volume of timber, the easiest way is to carry out calculations similar to the above method. Only the final result needs to be multiplied by 1.2 - a correction factor. From unedged boards you can get no more than 70-80% of edged boards.

The width and thickness of each product is measured taking into account its further processing. The technique will help determine the number of cubes wooden products necessary for work, if the final result is planned for their further processing - cropping.

When buying, the widest and thinnest boards are measured to obtain an average width. If the width of the lumber at the butt is wider than at the top, the arithmetic mean of their dimensions is used without taking into account the bast layer or bark, rounded up to 10 mm. In this case, fractions from 5 mm are rounded up to full 10 mm, and fractions up to 5 mm are not taken into account. Lumber length and thickness are measured in the usual way. The volume of timber is determined according to the usual scheme:

Scheme for calculating the cubature of a log.

• the volume of one product is calculated;
• the total cubic capacity of the purchased timber is determined; according to GOST is used correction factors: 0.96 for sawn softwood, 0.95 for sawn hardwood.

In addition to the piece by piece method for determining the volume, there is no edged lumber, the geometric method can be used.

Requirements for a package of unedged timber:

• lumber is laid tightly, without overlaps, in horizontal rows;
• on one side the ends of the boards are aligned;
• all sides of the package are strictly vertical: according to GOST, the displacement of individual products outward, inward should not exceed 0.10 m;
• the entire length of the lumber package must be of the same width.

Then the volume of the package is calculated, the result is multiplied by the coefficient:

• 0.67 - the number of ends in the unaligned side of the package is more than 50% of the total number of boards;
• 0.50 - if the ends are only 50%;
• 0.33 - the number of ends is less than 50% of the total amount of timber.

Piece by piece or geometric methods for determining the cubic capacity will help you navigate when buying unedged timber. If you have problems with the calculations, you can contact the sales assistant, manager, warehouse worker for help.

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When sawing wood, it is important to immediately calculate what the consumption will be, as this will affect the cost of lumber. The output of finished products may be different. It all depends on the quality of the wood used, whether measures are taken to optimize cutting. There are special measures to increase the efficiency of work, make the output better, and the quality of sawing is higher. Before cutting, you must first calculate everything. It is not as difficult as it may seem, but the consumption of roundwood will be optimal, beneficial for obtaining an excellent result.

How to increase cutting efficiency

In order for the lumber yield to be significant, it is necessary to use special measures to increase the efficiency of the process:

1. Calculation should be carried out only when using special programs, manually it will have low performance, the percentage of marriage will turn out to be large.
2. The round timber must first be sorted so that the processing is carried out correctly.
3. Cutting equipment must be used. High Quality. Otherwise, the amount of waste will be large, and the quality of the resulting lumber will become low.
4. It is best to cut wide lumber first, it takes longer to process narrow lumber.
5. Logs are not recommended to take long.
6. Before work, you must configure the equipment.

The output of finished lumber may be different. It must be remembered that at the first stage boards are obtained, then they are sorted. As a result, the percentage decreases even more, for example, for hardwoods it can be only 10-20%.

How to optimize cutting

In order to increase the output of lumber, the sawing process must be optimized. This applies primarily to those blanks that have a significant curvature. To cut a curved roundwood, you need to perform a series of actions:

1. First, only suitable wood is selected for work. If the remaining logs have rot, sprouts, cracks at the ends, then it is necessary to trim some sections.
2. If a rotten core is found during operation, then you can carefully remove it, and then cut the rest. This will avoid large losses, get boards with a length of 1 m with the required quality.
3. It is recommended to use logs with a larger diameter so that the yield percentage is higher. The coefficient can be 1.48-2.1, but it all depends on the diameter, quality of round timber, sorting, and equipment. For frame workshops, this coefficient will be 1.48-1.6, and for lines with milling equipment - 1.6 for large timber. With a round timber diameter of 12 cm or more, the coefficient may exceed 2.1.

Waste volume after sawing

In order for the finished board to come out with a large percentage, it is necessary to prepare everything correctly, work should be carried out only in accordance with the technology. The round wood of coniferous and deciduous breeds gives various output. IN last case the volume is smaller, even if special additional equipment is used. Needles for sawing are considered more convenient, since the trunk is straight, and the log has a larger diameter. Coniferous forest is not so prone to decay, so there is less marriage. For hardwoods, 2 cutting technologies are usually used:

• with help band sawmill on Z75, Z63;
• into collapse, when a half-beam is cut out in the core of the material, passed through a multi-blade machine.

The volume of a band sawmill is 40-50%. When using the technology in the collapse, the yield is different, it can be increased up to 70%, but the costs of such work are higher. If roundwood is sawn, the length of which is 3 m, then you can see that the percentage of rejects is quite large, and the remaining material requires processing. This applies to the bulk with boards 22x105 (110, 115) x3000 mm. There are many options for such a marriage. For example, it may be a wormhole, which is no longer suitable for most jobs.

After sorting, the volume of hardwood material that is grade 0-2 will be only 20-30% of the amount that is obtained after sawing. This means that from the total mass of harvested roundwood, the output of a normal board will be only 10-20%. The rest of the materials are mainly used for firewood. Coniferous round timber will have a different yield, but attention should be paid to what average values ​​of the obtained volume are observed.

lumber output

In order for the lumber yield to be optimal, numerous conditions must be taken into account. For a correct calculation, you can consider the example of the output of round wood. The data was obtained on the real experience of specialists and on the performance of sawmills. This makes it possible to compare percentages and calculate optimal averages.

In conifers, the following output is possible:

1. For unedged board and other unedged materials during sawing, the yield will be 70%. This is the amount of material obtained during processing, the amount of waste will be 30%.
2. For edged material, when using sawmills at 63, 65, 75, there will be a lower yield of lumber, in the region of 45%. For band sawmills, the output is usually up to 55-60% finished material. If you apply the means to improve efficiency, then you can reach 70%, although this requires a lot of experience.
3. 70-75% lumber can be obtained from a sawmill, although with efficiency improvement methods it may well be 80-75%. But experience is required.

According to GOST 8486-86, for grade 0-3, the percentage of yield, excluding sorting, is approximately 70%.

Another 30% can be left for rejection of the finished material. Rejected material is not thrown away, it is used for the manufacture of other types of lumber, which allow the presence of a certain marriage.

Hardwood roundwood has a different yield percentage:

1. For unedged material - 60%.
2. For edged wood - up to 35-40%, since the curvature of the original hardwood forest is usually large.

The output can be increased, for this additional equipment is used. It can be a special multi-saw machine, an edge trimming machine, a slab machine. In this case, it will turn out to increase the yield of lumber by about 20%. The given percentage is given on the basis of data on the production of grade 0-4 boards. When sorting grades 0-1, the percentage of lumber production is 10%. To get a cube of finished hardwood edged material, it is necessary to cut 10 cubes of the original roundwood for sawing.

The output of lumber from roundwood can be different. It all depends on the original wood species used by the sawmill. Special measures to increase efficiency allow you to get a higher percentage than possible, but for this you need to have some work experience.

Edged board is one of the most common lumber in construction. It is used for outdoor work, in construction wooden houses, interior decoration, manufacturing wooden fences. The board is sawn from logs and additionally sawn along the edges. This gives the lumber not only a marketable appearance, but also saves it from various pests. As a rule, the width of the edged board is twice its thickness.
The board made of coniferous wood - spruce and pine, Siberian larch is in the greatest demand in construction. For the production of furniture, more expensive and durable types of wood are used - oak, alder, ash.
The quality and cost of lumber depends on many characteristics: the type of wood, its moisture content, processing and sawing technology. Therefore, it is important to correctly calculate the yield of edged lumber in production.
depends on many factors: on the specification, board grade, sawlog diameter.
For example, from softwood roundwood, the yield of edged sawn timber at band sawmills is usually 55 - 60%. On circular sawmills this percentage increases to 70-75%.
The output of edged boards from hardwood roundwood (aspen, birch, linden) is always very low for all types of sawmills. Approximately 35-40%. This is due to the curvature of hardwood logs. It is possible to raise the percentage yield only by installing additional equipment - a multi-saw, edge trimming and slab machine. The output, in this case, will increase by about 20%.
Generally? Lumber prices fluctuate wildly, and many lumber companies provide edged boards at well below market value. However, before buying lumber from such sellers, you need to think about what pitfalls may lurk here. Often the cost of the board is reduced due to the low quality of lumber. Thus, it is most acceptable to purchase edged boards in those companies for which the sale of wood is not new.

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Actual rates of output of sawn timber during sawing

For example, with rot in the core, then the log is sorted and sawn into lumber, instead of being turned into a bar.

Or vice versa, if the sapwood is rotten, but a beam comes out of the central part, and the log is a log - we sort it for sawing into a beam.

Similarly, you need to think in terms of blueness and curvature.
Approximate output by varieties The situation is quite interesting in terms of varieties.

Attention

It turns out the percentage of output higher grades depends on the following factors:

• The coefficient of obtaining sawn timber from round timber.

The grade does not depend directly, but indirectly.

Guidelines for determining the volume of secondary wood resources

Table 1 - yield of boards when sawing roundwood Diameter, cm Yield of higher grades, % 12 - 16 yield of the first grade 40% 18 - 22 on average 50% 24 - 26 about 50% 28 - 40 about 70% 42 - 60 about 60 - 70% How the percentage of lumber production depends on sawing technology In addition to diameter, grade, defects (curvature) and length, the percentage of board output depends on the technology of sawing wood and the type of equipment.

Stages of sawing round wood

Info

He saws only sorted wood;

• Circular sawing equipment cuts according to individual cuts - this is a big plus for the resulting materials, both in quality and quantity.
Related video And now I will answer why a high yield is not always good, but everything is simple at very high rates, the number of wane boards increases.

Important

It turns out low-grade lumber and its total cost from a log at a certain point becomes lower than the cost of quality materials.

Yes, and the implementation quality material may be more difficult.

Amount of wood waste

In the sawmilling process, various lumpy wastes are obtained, which in some cases are used for energy purposes.

Lump sawmill waste is formed from the peripheral part of the logs and, in the absence of preliminary debarking of the logs, contains such an amount of bark that it can be used for pulping and production wood boards impossible.

Volumes of education various kinds wood waste as a percentage of the volume of sawn raw materials are given in table. 14. Name of logging waste Including 13. Amount of waste generated during logging production Amount of waste per 1000 m1 annual turnover warehouse, m3 The amount of waste from the exported wood, % At the cutting area A.
Solid or lumpy from Hody: Branches, branches, tops 14.00 140 65 75 Roots 11.00 110 .
110 - Stumps 3.00 30 30 - Break-offs 1.75 17 - 17 Roofs 0.75 7 - 7 B.

Sawing round wood: cutting map, necessary tool

In what sequence should the round timber be cut Pay attention! Coniferous woods are considered the best option, due to the fact that they have a straight trunk and a relatively larger diameter.

In addition, such a forest is not so prone to the process of decay, which leads to fewer rejects. When working with hardwoods, 2 processing methods are used:

1. Using a band sawmill at 375 or 363.
2. Into collapse.

   This technology involves cutting a half-beam, which is subsequently passed through a multi-blade device.

In this case, the first method allows you to get about 40-50% of the output.

But the collapse technique differs in a slightly larger volume - up to 70%.
The disadvantage of this technology is that the cost of it is relatively high.

Ways of sawing wood Sector - first, the log is sawn into 4-8 sectors, and then each of them into radial or tangential materials.

Sometimes several unedged boards are sawn in the center. Split-segment - with such a cut, two or more unedged boards are cut in the center of the trunk, and edged one-sided boards are sawn from the segments on the sides. Beam-segment - similar to break-segment, only in the middle of the log a two-edged beam is cut, which is then sawn into edged boards. The yield of lumber is high. Circular - after sawing off one or more unedged boards, the log is rotated 900 and sawn off following boards. This method is used when a large log is affected by heart rot in the center. With its help, healthy wood is separated from low-quality wood.

How much waste is produced when sawing wood

It is easier to do more difficult work with a chainsaw than to buy expensive equipment.

It will only need a special nozzle, a fixative for the trunk and cutting guides.

Bark removal machines. They are quite expensive, but with regular use in an enterprise where large amounts of work are performed, they quickly pay for themselves.

It is not necessary to use them, but it is desirable, because a number of economic advantages and conveniences in the production process can be obtained by doing so.

The fact is that after some kind of golden mean, the more boards we get from a cubic meter, the higher the amount of low-grade wood with wane;

• The larger the diameter, the higher the chance of getting more high quality board;
• The presence of wood defects, such as curvature, rot, blue and others, the smaller they are, the higher the percentage of obtaining a high-quality board;
• The shorter the finished product, the higher the percentage of obtaining a high quality board.

And now let's estimate approximately by diameter the percentage of obtaining first-class lumber from the total volume of boards received.

To do this, I made everything in the form of a small table.
Hello dear readers and subscribers of the blog, Andrey Noak is in touch with you! Today I will tell you about the yield of lumber when sawing round wood.

• 1. Introduction
• 2 Percentage of round timber
• 3 Why does the useful percentage depend on the diameter of the sawn timber?
• 4 Ways to increase the ratio
• 5 Estimated yield by variety
• 6 How does the percentage of lumber production depend on sawing technology
• 7 Related videos

Introduction This parameter is one of the most important parameters in sawmilling.

The efficiency of sawing the forest depends on this indicator.

Many beginners mistakenly believe that the higher this ratio, the better.

In fact, this is not always the case, most experts know about it, but are silent. I repeat once again - high percent lumber output from a cubic meter of wood is not always good.