How much waste is generated when sawing wood? Sawing round timber: cutting map, necessary tools Yield ratio of edged boards from unedged ones

Repair and construction work often involves the use of lumber. But shops and timber trading centers often sell them 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

• a caliper, tape measure or folding m; if the length parameters of wood products are known, you can limit yourself to a regular ruler;
• calculator - suitable mobile phone, smartphone, if problems may arise with mental arithmetic;
• a piece of paper and a pencil - to record the results of calculations, how many boards are in a 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 planks in a cube, you need 1 cubic meter. m divided by 0.132. When purchasing timber, the result obtained (7, 5757) must be rounded to 8 pieces.

This method of calculating cubic capacity is also suitable for timber. This way you can determine how many cubic meters of timber you need to purchase if you know the required number of products, or, conversely, determine required quantity 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 ones.

The width and thickness of each product are 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 - pruning.

When purchasing, 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 to 10 mm. In this case, fractions from 5 mm are rounded to the full 10 mm, and fractions up to 5 mm are not taken into account. The length and thickness of the lumber are measured in the usual way. The volume of timber is determined according to the usual scheme:

Scheme for calculating the cubic capacity of a log.

• the volume of one product is calculated;
• the total cubic capacity of purchased timber is determined; according to GOST, correction factors are used: 0.96 – for lumber from coniferous species, 0.95 – for lumber from hardwood wood

In addition to the piecemeal method of determining volume unedged 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 and inward should not exceed 0.10 m;
• The package of lumber must be the same width along its entire length.

Then the volume of the package is calculated, the resulting 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 there are only 50% ends;
• 0.33 – the number of ends is less than 50% of the total amount of timber.

Piece or geometric methods for determining cubic capacity will help you navigate when purchasing unedged timber. If you have problems with payments, you can seek help from a sales consultant, manager, or warehouse employee.

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Before sawing round timber, it is necessary to calculate how much volume will be left for further use, and how much material will be spent on processing. This is important because it affects the final cost of the product. The amount of untrimmed wood produced will depend entirely on what type of wood is used. At the same time, there are certain measures to increase the yield of lumber after cutting.

What is the yield percentage and its dependence on the diameter of lumber

To understand this, it is necessary to unpack the concept itself. Percentage of lumber yield from round timber- this is all useful tree after cutting. The rest is waste that is sent for further processing to produce materials such as MDF, fiberboard, chipboard. It is worth understanding that the volume that will be obtained as a result of cutting wood is calculated for each individual diameter and selected cutting option.

It is worth understanding the question of why the parameter under consideration depends on the diameter of the forest. Everything here is extremely simple: the fewer cuts there are on the tree, the higher the volume value will be. Of course, a lot will also depend on the cutting technology and on the sequence in which the cutting was carried out. The correct sequence will be shown in Fig. 2. It should be understood that small lumber is obtained from small species of wood, and thick boards and beams are made from large timber. It is also worth considering the average diameters with approximate rates of volumetric flow rate:

• 14 – from 45 to 50%;
• 20 – about 52%;
• 25 – on average up to 57%;
• 34 – this is the diameter of timber timber, which differs in the most high value volume fraction equal to 66%;
• if the forest has a diameter of more than 40 cm, then there is a sharp decrease in the materials obtained.

Volume of waste after sawing

To finished products had a large percentage, everything should be calculated and prepared correctly. And the work process itself must be carried out in full accordance with technology. It should be taken into account that the round forest of coniferous and deciduous trees will give a different yield of lumber from non- edged boards in m3.

Pay attention! Coniferous wood species are considered the best option, due to the fact that they have a straight trunk and a relatively larger diameter. In addition, such wood is not as susceptible to decay, which leads to less waste.

When working with hardwood, 2 processing methods are used:

1. Using a 375 or 363 band sawmill.
2. In ruins. This technology involves cutting out a half-beam, which is subsequently passed through a multi-saw device.

In this case, the first method allows you to get approximately 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 its costs are relatively high. When sawing round lumber 3 m long you can see enough high level marriage. However, the remaining wood will not be immediately useful due to the fact that it requires an additional processing process.

Edged board is one of the most common lumber in construction. It is used for outdoor work, during construction wooden houses, interior decoration, manufacturing wooden fences. The board is sawn from logs and additionally sawed along the edges. This gives the lumber not only a marketable appearance, but also protects it from various pests. As a rule, the width of an edged board is twice its thickness.
The greatest demand in construction is for boards made from coniferous wood - spruce and pine, Siberian larch. 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: the specification, the grade of the board, the diameter of the saw log.
For example, from a coniferous round forest the yield of edged lumber is band sawmills usually 55 - 60%. On circular sawmills this percentage increases to 70-75%.
The yield of edged boards from round deciduous wood (aspen, birch, linden) is always very low for all types of sawmills. Approximately 35-40%. This is due to the curvature of hardwood logs. You can increase the percentage output only by setting additional equipment- multi-rip, edge-edging and slab machines. The yield, in this case, will increase by about 20%.
Generally? prices for lumber fluctuate greatly, and many lumber companies provide edged boards at a price significantly lower than the market price. However, before you buy lumber from such sellers, you need to think about what pitfalls may be hidden here. Often the cost of the board is reduced due to low quality lumber. Thus, it is most appropriate to purchase edged boards from those companies for which selling wood is not new.

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

In Fig. 1 presented various types lumber - from plate to edged board.

Figure 1. Types of lumber: a - plate; b - two-roll beam; c - not edged board; g- quarter; d - four-edged timber with 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 - end; 5 - wane

The following elements are distinguished in lumber: layers, edges, ribs, ends. Face - the longitudinal wide side of the lumber, as well as any side of the lumber square section. The best face of lumber has the least amount of defects, best quality processing. The face of lumber facing the core is called the inner face, and the face facing the sapwood is called the outer face. Edge - the longitudinal narrow side of lumber. Edge - the line of intersection of two adjacent sides of lumber. End - the end transverse side of the lumber. Wane is not mandatory element lumber, this is, so to speak, an element of defective edged boards due to poor quality of the source material (logs or workpieces).

Lumber is produced according to GOST 8486-86E:

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

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

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

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

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

Note:

1) When the roundwood grade increases to 1, the lumber yield standard increases by 3%.

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

3) With a mixed supply of large and medium logs, the lumber yield standard is taken as the arithmetic mean between medium and large logs.

Table 2. Thickness and width of softwood lumber in mm

Table 3. Thickness and width of hardwood lumber in mm

The ends of lumber and rough blanks must be sawn at right angles to the longitudinal axis. Wane beams (with a partial absence of a cut in the edge) with a cross-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.

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

The use of lumber from hardwood is allowed for parts of rafters, internal stairs, internal linings walls and partitions, ceiling lining, eaves, pediments, internal architectural details, carpentry and clean floors.

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