3 grade boards – sawn timber, which has a fairly wide range of applications. To successfully use it, you need to carefully examine the list of possible defects in GOST. And also worth paying attention to the characteristics of the edged and unedged board 3 varieties.
Immediately it is worth indicating that According to GOST board 3 varieties can be divided into edged and unedged type. In the manufacture of a cutting board, the amount of section can be from 1.6×0.8 to 25×10 cm. Special restrictions on varieties of applicable breeds. Important: In the edged lumber cannot be present. So called the outer area covered by the crust, which remained after cutting the logs.
Formally standard Permits a slight presence of obol. However, it is better to take the products without it. In the overwhelming majority of cases, the edged board in length reaches 3, 4 or 6 m (with an accuracy of less than 1 mm). The products of another size are made less frequently and mainly for direct orders. As for the thickness of the board 3 category, in our country it is preferably:
- 15 cm.
If you need to get a product of another thickness, then for this, the timers of the usual size are cut in the longitudinal plane, overs. The category of timber includes a cutting board, in which the aspect ratio of 1: 2 and less. The difference between wood materials is carried out and according to the degree of saturation of water. Products whose specific humidity fall into the crude group, The rest of the sawn timber is recognized as dry, but they can still process with antiseptics.
Can be quite widely found and unedged board 3 varieties. This material is relatively simply processed, which significantly increases its popularity. There is an additional division for intake and carpentry types – the first is less than aesthetic. In most cases, the unedged board is made of spruce and pine.
The main use of -Exnic and auxiliary work. Important: Mechanical quality designs should be assessed when choosing.
The third-rate group includes sawn timber with frankly low quality. They are not allowed to have large bitch united. But the norm is:
- strokes laid by worms;
- passing cracked;
- Tobacco type knots;
- plots and nests of mold;
- Limited bearing capacity (not allowing to apply this material for any responsible deed).
When lumber arrives on the wholesale warehouse, they are stopped checking on flaws. Everything that remains is just trusting regulatory control, accompanying documents and own knowledge. The establishment of a variety occurs on a plot of 1 m long on each side. If there is at least some difference between them, the category is assigned for the worst face. The bitch whose size is less than 50% of the permissible for the varietary group, is not taken into account; If the board is longer than 3 m, then it can be 1 bitch, corresponding to not 3, and 4 varieties.
4 strong bitch is allowed for 3 varieties, including those who have grown, occupying up to ½ the width of the ribs and layers + 1 bitch on criteria 4 varieties. The edge can cover 100% in width – it is not a violation. The fragments of bones and reached tobacco consistency of the bitch can have up to 50% (on ribbed parts, on the edge and on the plastic). The volume of healthy bitch that have grown only partially or is not connected at all, it may normally reach 1/3 in width.
Board 3 grades may contain cracks overlooking the end plane (provided that they along with cracks in other places will reach no more than ½ in length). For plastial through splitting restrictions tougher – no more than 16.67%. Split and crushed slits on the ends, with the exception of drying cracks, are normal up to 50%. Lumber 3 varietal categories may have a widespread slope of wood fibers.
Round is normalized (that is, a one-sided increase in the thickness of the annual rings on the trunk), this defect cannot occupy more than 50% of the surface of the plastic.
On each side there may be 4 resinous pockets, but not more than 30 cm in length. Permitted according to the standard and presence of a double core. But the overgrown ex-wound, having a sloping emptiness of a radius form with the preservation of partially bark and degraded tissues, can be ¼ in width and 1/10 in length with one of the sides. For vegetable cancer, the restriction is established in length 1 m or 1/3, and the restriction always comes to a smaller indicator. About mushroom sound strips and stains indicated only that they are permissible, but nothing about the number. Additionally installed such restrictions:
- worms are no more than 3 units per meter in each plane;
- Sorrow with mushroom coloring, stains and stripes of surface mold – allowed;
- deep damage to mold fungus – no more than ½ in the area;
- Review on the plastics with a distance of no more than 2 cm from the edges and up to 50% of the length of the edges;
- Speed versions of maximum 1/20 from perpendicular part of the end to the plastic and edge;
- wavy and drew plots with a maximum of 3 mm deep;
- Other mechanical defects, extraneous inclusions and processing deformations are not allowed;
- Boxing in diameter up to 2% of the width.
The main part of the third-rate boards is on packaging products. This is mainly about disposable boxes and containers for transportation. You can also make other packaging that does not impose special requirements in appearance. And on the basis of this wood you can make flooring and pallets. Sometimes made of wood 3 varieties of weakly loaded invisible outside structural elements of secondary buildings.
About how to choose a 3 grade board, look in the following video.