Sawing round wood: cutting map, necessary tools. The yield of lumber from roundwood is by grade and depending on the diameter of the logs. Sawing logs into beams What is the yield of lumber from round timber

How to cut a log on a band sawmill was described in a previous article. Well, in this article we want to talk about how logs are cut into beams.

Everyone knows that timber cut from a log during drying begins to deform, but not everyone knows why this happens. The thing is that when sawing the log into beams, it was cut incorrectly. That is, it was cut with an offset, and since its middle is offset, the beam begins to bend in the direction of the offset.

To prevent this from happening, it is necessary to correctly calculate the log before sawing.

Calculation of logs for sawing into beams.

So, let’s get started, first we need to decide what size the beam will be, as well as the dimensions of the material (boards) that we want to get to the beam.

Let's start by taking the required timber, for example, 150 x 150 mm, unedged board 25 mm, 30 mm, 40 mm.

For those who do not know what a non-edged board means, let us explain that this is a board of various widths that does not have specific boundaries due to the presence of bark along the edges, but has a certain thickness size.

Next, take a 25 mm, 50 mm edged board. We think it’s clear here that an edged board is a board that has a certain size, both in width and thickness, and has no bark, or, as they usually say, no wane.

Timber calculation

Let's start the calculation by measuring the diameter of the log, and for us it is, for example, 30 cm. Or, for ease of calculation, we will convert it into millimeters, it will be 300 mm. Since our timber should be 150 mm, we take 300 mm and subtract 150 mm, leaving the remainder with 150 mm, which will be used for boards.

300 - 150 = 150

From the upper and lower edges of the diameter of the log we subtract 5 mm per slab, that is, we will divide the 150 mm remaining into the boards, we get 150 minus 5 and minus 5, and the remainder we get 140 mm.

150 - 5 - 5 = 140

When deducting the slab, it is necessary to take into account the unevenness of the log, since the butt is larger in diameter than the top, that is, it is possible to get a slab of different sizes, and ours will be 25 mm.

Let's return to the log diameter of 300 mm. From the top edge, as described above, we subtract 5 mm, we get 295 mm. And to this numerical value we add a 25 mm under-slab board plus 2 mm for the cut, we get 322 mm. And this is where sawing the logs into beams will begin.

300 - 5 = 295, 295 + 25 + 2 = 322

Calculation of boards

After removing the hump, we are left with a clean residue of 140 mm. Divide it in half and get 70 mm on each side of the log.

140 / 2 = 70

See above where we determined the approximate size required material besides the timber. We have 25 mm, 30 mm and 40 mm boards. And here we begin the calculation.

We take our 70 mm and estimate taking into account the cut, 40 mm plus 2 mm we get 42 mm, 28 mm is missing from 70. Well, here we think it’s clear that the next board will be 25 mm, 25 mm plus 2 mm we get 27 mm. Thus we get 42 mm plus 27 mm, 69 mm.

40 + 2 = 42, 70 - 42 = 28, 25 + 2 = 27, 42 + 27= 69

The question arises, where to put another 1 mm, everything is very simple. We make the first four cuts strictly according to size, and after turning the log over, we take this 1 mm to the slab. In the end, everything turns out according to our calculations.

Based on these calculations, we obtain a carriage sawn in the center of the log.

Calculation of trimming material

To obtain edged material, as well as further sawing of the log into beams, is done by rotating the resulting carriage 90 degrees. The calculation occurs in the same order as described above. But let us immediately note that if we start the calculation, we end up with 20 mm, which we do not need, due to the lack of specified dimensions.

70 - 50 = 20

We will now explain what to do in this case. As described above, we have 5 mm for the slab, we will use this and add 25 mm to the 50 mm of our edged material, plus naturally 2 mm for the cut.

50 + 20 + 5 + 2 = 78

We get a 25 mm underslab board and a 50 mm clean board, exactly what we needed, as well as quality timber 150 x 150.

To obtain a different size of material, it is necessary to use the missing millimeters on the hump, but at the same time distribute them evenly on both sides.

Thus, the logs are calculated and cut into beams on a band sawmill. We wish good luck to all beginning sawmillers in this difficult task, and the main thing is not to make mistakes in the calculations.

Often there is a need to get timber from a log rectangular section. It's not that difficult to do.

If you already know how to cut logs correctly, then cutting out timber will also not be difficult for you. The main thing is to correctly mark the log in order to obtain a beam of the required size.

We have already discussed cutting a log into two edges in the article on preparing logs.

Let's see now how to cut a rectangular or square beam from a log.

Marking logs to obtain a rectangular beam

When marking, you should be careful and take into account that the diameters of the butt and apical parts differ. Therefore, it is best to start marking from the end with a smaller diameter.

Secure the log in any way convenient for you, as described in the article on preparing logs.

Draw a circle, then mark its diameter in the form of a vertical line connecting the top point of the circle to the bottom. For work, use a special carpenter's compass with hardened metal ends.

The resulting diameter must be divided into three equal segments and perpendiculars drawn through their ends so that they intersect with the circle.

After this, connect the intersection points with the circle to form a rectangle.

The most advantageous aspect ratio is 5:7, that is, 10:14, 15:25, 20:28, etc. - these will be profitable sections.

Marking logs to obtain a square beam

In some cases, it is necessary to obtain a square beam. In this case, the circle is divided by two diameters perpendicular to each other, after which the intersection points of the diameters with the circle are connected by straight lines.

All basic operations for marking the ends of logs to obtain rectangular and square beams are shown in the figure below.

Basic operations for cutting timber from a log

First, mark the central axis (diameter).

Then the ends of the log are marked as described above.
After this, chamfering lines are marked along the ends of the log marked with a chalked cord.

To do this, the cord is secured along the edges of the log in pinches made with an ax, so that the cord is taut. After this, the cord is pulled back a little, like a bow string, and released. When the cord hits the log, it leaves a line. The cutting will be done along this line.

First, along the side to be hewn, cuts are made with an ax every 20-40 centimeters, not reaching the hew-off line a few millimeters.

After this, a rough cut is made with an ax, removing the main layer of wood, moving from cut to cut. When the main layer of wood being removed has been removed, the surface to be hewn is cleaned either with careful clearing blows of an ax or with a sherhebel.

Today, beams are rarely hewn from logs with an ax. For this purpose, there are milling-canter lines that produce timber on an industrial scale. However, when building a bathhouse, you may have a situation where you need to hew out a flat surface on one or more sides of the log. Therefore, you need to know the basic techniques for cutting a beam out of a log or cutting a log by 1-2 edges.

In the construction of bathhouses, hand-held electric and gas-powered tools are currently widely used. If you make a plane with a chainsaw, then the sequence of operations will be the same - marking, making cuts along the side to be cut, rough removal of a layer of wood, and only then finishing to the cutting line using an ax or electric plane.

Now you know how to cut a log, how to cut timber from a log. In other articles we will talk about how to correctly make a groove in a beam or log, how to saw wood correctly, how to plan boards and beams.

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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 timber.

This parameter is one of the most important indicators V. The efficiency of sawing wood depends on this indicator. Many beginners mistakenly believe that the higher this ratio, the better.

In fact, this is not always the case; most specialists know about this, but remain silent. I repeat once again - a high percentage of lumber yield per cubic meter of forest is not always good.

I described in detail why this is so in my book “Organization of sawmilling at a modern enterprise,” but for readers I will lift the veil on this question at the end of the article.

This is a truly unique e-book, there are definitely no such books in Russia :-)!!! It provides simply colossal accumulated information personal experience work as a technologist in a large production.

Percentage of round timber

Calculated using the formula:

Kout=Vpil/Vbr

Where TO, % - percentage of lumber yield.

Vpil, m3 - volume of obtained lumber. Calculated:

Vpil = L*H*B*n1+L*H*B*n2 + ...

1. where L is the nominal length of the finished lumber;
2. H - board thickness;
3. B - board width;
4. n is the number of boards of each size.

Vbr, m3 - volume of logs from which lumber is obtained. Determined by the cubature, which is possible.

The useful percentage of lumber in production is calculated for each diameter of the forest and for each sawing technology.

Why does the useful percentage depend on the diameter of the wood being cut?

It's very simple, the fewer cuts to obtain wood, the higher the percentage. Of course, it also depends on the useful use, but once again I will say that it is very important how many saws you have to get a board. As a rule, small boards are cut from small wood, and timber or thick boards are cut from large wood.

The company's performance in the production of timber is especially good; its cubic capacity is good, sawing speed is maximum (there are fewer saws after all) and cutting tool consumption is minimal.

Below are the approximate diameters with consumption rates:

• 12 - 16 cm - yield 45 - 50%;
• 18 - 22 - average 52%
• 24 - 26 - about 57%;
• 28 - 40 - this is timber timber and the best indicators are achieved when obtaining timber - 66%;
• 42 - 60 - in this range there was a decrease in the percentage of boards made of wood. Since this wood is used to produce boards and beams that are not so large, and therefore the number of cuts with a saw becomes many times greater.

These consumption rates are approximate and are valid for the production of such lumber as:

1. 25*150*6,0;
2. 35*150*6,0;
3. 50*150*6,0;
4. 180*180*6,0;
5. 200*200*6,0.

Based on the type of equipment, these standards can be adopted for band sawmills, sawmill frames and circular saw equipment.

Ways to increase the ratio

There are technological tricks that I partially talked about. But as they say, repetition is the mother of learning, here are some of them:

• Use of shorter commercial timber;
• The use of specialized programs is about this. In short, we can say what you need to find using the program optimal cost boards obtained from logs. On the one hand, a high useful yield means a large cubic capacity, and on the other hand, a high indicator means obtaining a larger volume of low-quality wood.
• The use of thinner saw blades due to double-spindle circular saws and the use of stellite tips.
• Use by diameter, species, defects.

And now in more detail about everything. The shorter the wood, the higher the percentage of lumber obtained. In Europe they know this well and therefore the cutting lines there are calculated at 1.5 - 2 meters. Our sawmill frames can only cut 4-meter logs.

With the help of programs, we calculated our supplies for each season in production, increasing the amount of low-quality wood during periods of demand (summer, autumn), and increasing the quantity premium grades during periods of high demand for them (winter, part of spring).

I think everything is clear about using a saw blade with the best characteristics. It is also necessary to monitor the quality of the received cutting tools. On frame and circular saws, you need to constantly monitor the presence of all solder tips, sharpening angles for each season, and rolling on both types of saws.

Sorting allows logs to be separated by diameter, defects and blemishes. For example, with rot in the core, then the log is sorted and sawed into lumber, instead of being turned into timber. Or vice versa, if the sapwood is rotten, but a beam comes out of the central part, and the log is a timber log - we sort it for sawing into timber. You need to think similarly in terms of blueness and curvature.

Approximate yield by variety

The situation regarding varieties is quite interesting. It turns out that the percentage of yield of high-grade products depends on the following factors:

• The coefficient of production of lumber from round timber. Grade depends not directly, but indirectly. The fact is that after some golden mean, the more planks we get per cubic meter, the higher the amount of low-grade wood with wane;
• The larger the diameter, the higher the likelihood of getting more high-quality boards;
• The presence of wood defects, such as curvature, rot, blueness and others; the fewer there are, the higher the percentage of obtaining a high-quality board;
• The shorter the finished product, the higher the percentage of high-quality boards.

Now let’s estimate, approximately based on the diameter, the percentage of first-class lumber obtained from the total volume of boards produced. To do this, I made everything in the form of a small table.

Table 1 - yield of boards when sawing round timber

How does the percentage of lumber production depend on sawing technology?

In addition to diameter, grade, defects (curvature) and length, the percentage of board yield depends on the technology of sawing wood and the type of equipment.

There are two types of sawing technology:

• Individual cutting, the percentage of useful yield approaches 75%;
• Group cutting, depending on other parameters, the useful yield can also reach 70%.

And the equipment for sawing can be the following:

1. Band sawmills produce lumber products with minimal wood consumption rates;
2. Tire sawmills produce lumber with increased consumption when sawing logs, since the thickness of the chain is much greater than the strips.
3. . It is quite inconvenient to process thin wood using this type of equipment. Therefore, sawing is mainly done from a diameter of 20 - 22 cm;
4. Milling canter lines. This type of equipment has both an advantage and a disadvantage over other technologies. He only cuts graded wood;
5. Circular saw equipment cuts according to individual cuttings - this is a big plus for the resulting materials, both in quality and quantity.

Video on the topic

And now I’ll answer why a high yield is not always good, but everything is simple at very high rates, the amount of boards with wane increases.

The result is low-grade lumber and its total cost from a log at a certain point becomes lower than the cost of high-quality materials.

And selling low-quality material can be more difficult.

Good luck and see you again, Andrey Noak was with you.

The basis of a wooden house is a log house, which is a box assembled from prepared logs or timber. The logs, fastened together in the corners with cut-out “locks,” are laid in horizontal rows, each of which is called a “crown.” In order for the logs to support the weight of the structure, the log production technology must be strictly followed. Ensure that the contacting elements fit as tightly as possible - the main task builders when assembling a log house.

Knowledge of the basic nuances and features of various types of log connections will help make right choice. The technology for cutting a log house from timber and logs differs in the way the corners are arranged, otherwise the rules are the same.

The appearance of a wooden house depends on how the log house was cut - with or without a remainder. If the log house has corners with perfectly fitted ends, then it is folded using the “no residue” method; this type of lock is called “in the paw”. If the logs protrude beyond the wall, the method is “with a remainder” (in Russia it is called “in oblo”), the type of lock is “bowl”.

The main tool for cutting log houses is an ax (carpenter's or adze). When working with an axe, the rings of wood that open during the cutting process become jammed, which to some extent protects it from external factors.

When using a chainsaw, the side cut of logs in a log house becomes smooth, the pores of the wood open and become accessible to atmospheric phenomena, which leads to rapid rotting. A log house will last longer if it is sheathed.

Both types of lock - both “bowl” and “paw” - have different options.

Log house "in a bowl"(with remainder)

A simple "bowl" cut down in the lower crown of the log house. The design of such a bowl is a longitudinal groove with a semicircular cross-section.

A “bowl” lock with a ridge cut out at the bottom, which is designed to ensure the strength of the corner connection and seal the frame.

"Kurdyuk" lock has been carved into a log lower crown a tenon that fits into a groove made in the top log. This type of lock is difficult to cut, but is the most reliable.

it is cut down in the log located above, and, as it were, “slams” the lower one - hence the name “slammed”.

The “bowl” lock has several varieties, which are based on the same elements as in the “bowl”: the comb and the fat tail. Depending on the options for their use, locks are called “lock with a comb”, “lock with a tail (spike)” and “lock with a comb and tail (spike)”.

They are used, as a rule, in the construction of commercial buildings, since the connection density is insufficient for a residential building. This is a complex castle, cut in two logs (upper and lower), which is why it is called double. The lock has only two varieties: a simple “ohryap” and “ohryap with a fat tail (thorn)”.

Loghouse locks “in the clutch” (without remainder)

Log houses without residue are those buildings whose ends of the logs are at the level of the walls. In this case, logs or beams are connected with locks of the “paw” type. These connections are not very strong and do not have good thermal insulation. For comfortable living at any time of the year, such a log house should be clad on the outside.

Connection to the paw: 1-straight paw with a cut; 2-oblique paw (dovetail); 3-oblique paw with undercut

The “foot” can be straight, oblique (“dovetail”) and oblique with a notch (groove).

Other types of log house locks

The main types of log houses and castles were described above. In addition to them, there are a large number of other construction methods. wooden houses having different origins and characteristics.

Hook cutting

Hook cutting is a structurally quite complex method of angular connection of logs, characterized by increased strength. This type of fastening has two varieties.

In the first case, the bowl is cut down to ½ the thickness of the log. At the ends of the logs, a kind of hook is obtained with which the logs are connected. This connection guarantees absolute windproofness of the corner.

Hook connection: 1-walls inside are round; 2- the walls inside are smooth.

A distinctive feature of the second option is that, due to the logs hewn on one side, the walls inside the building are smooth. Thanks to this, the usable area of ​​the room is significantly increased.

Finnish log house

Finnish bowl (Finnish groove)

House chopping Finnish technology similar to the Russian "bowl". The difference is in the radius of the inter-crown groove (it should be less than the radius of the bowl) and its configuration. The Finnish groove has two “tenons” at the bottom, and grooves are made at the top. As a result, the crowns fit tightly to each other, and the blowing of the walls is reduced. The intercrown seal is completely located in the groove, and not outside it, and is not affected by moisture, which leads to damage to the wood.

Swedishlock

Swedish cutting is fundamentally different from all others, first of all appearance– aesthetic and very creative. Hexagon - this is the shape of the ends of the logs. The bowl, accordingly, is not round, but in the shape of a trapezoid. Cutting a Swedish log house is very labor-intensive, so it is done when there is a need for beautiful, unusual angles.

Norwegian log cutting is a technology widely used in Scandinavian countries - Finland, Sweden, Norway. Therefore, the names “Norwegian” and “Scandinavian” log cutting are identical.

Lafet (half-beam) is a building material from which a Norwegian log house is made. The carriage is a thick pine trunk hewn on both sides. The corner connection “Norwegian castle” or “house from a gun carriage” is one of the most reliable technologies for constructing wooden houses.

A distinctive feature of the Scandinavian castle is its wedge-shaped section. A wedge-shaped tenon cut into the top log is “settled” into a groove made in the bottom log when assembling the frame. From the outside, the design is similar to a saddle.

Wooden house in Scandinavian style looks monumental and neat. Thick logs reduce the number of crowns, therefore, the log house has significantly fewer “cold bridges”.

Smooth interior walls make the interior of a Scandinavian home very stylish.

Canadian log house cutting is a technology similar to the Scandinavian one: the corner connection is made like a Norwegian castle with a wedge-shaped tenon. Are used round logs, in which a trapezoidal cup is cut out. When laying, the insulation is immediately cut off so that water does not get into it. The result is walls without gaps and cracks, which look like a solid mass.

Simplified version Canadian log house– cutting “into the saddle”. Due to the lack of a tenon and groove for it ( distinguishing feature of this type of felling), the tightness of the corner is significantly reduced, which makes the log house short-lived.

Log house “into the pillar” (“into the fence”)

This ancient wood construction technology is used quite rarely today. Log houses for commercial buildings were cut in this way. The principle of construction of this type of log house is radically different from all traditional ones. Logs with spikes at the ends are laid between vertically dug pillars with grooves cut out. Making a log house “into a pillar” does not require much time or special skill of builders.

So, we looked at the features of making log houses. In addition to logs, another type of lumber is used in wooden house construction - timber. Houses made of timber, like log houses, have a frame as a base, but the corner connections are made somewhat differently.

Cutting log cabins from timber

Type classification corner connections when cutting log cabins, the same as for log cabins. A frame made of timber can be with a remainder (“in a bowl”) or without a remainder (“in a paw”), locks have the same names: “in an okhryap”, “in a fat tail”, “in a half-tree”. The only name that cannot be used is “in the oblo”: the timber has a rectangular shape and it is not possible to make a rounded (oblo) notch in it.

However, there are methods of corner notches that are unique to this type of building material - “on tenons” (root or insert).

The connection of beams in a log house (with or without a remainder) is called joining. Let's look at the main docking methods.

Joining the timber with the remainder

"Half a Tree"

Half-tree connection

This joining method (the simplest) involves cutting a rectangular groove with a depth of half the thickness of the timber - hence the name.

"In the fat tail"

An additional spike ensures a strong and reliable joining of the beams. Carpenters with a high level of skill are required to perform a quality connection of this type.

"To the brink"

A connection in which the main task is to correctly calculate the width of the jumper. When working with timber, due to its standard geometry, cutting can be done using a template (as opposed to working with a log). Error-free sawing significantly speeds up work.

Joining the timber in the corner without leaving a trace

When building houses and bathhouses from timber without residue, the traditional types of locks are “half-wood” (with smooth parallel edges) and “paw” (with edges shaped like a trapezoid). The second type of connection is a little more complicated, but it guarantees greater protection of the corner from drafts.

Beam connection: a - into half a tree, b - into a paw

Spiked joints (in a warm corner)

With this method of cutting timber, a tenon inserted into the groove protects the corner from freezing and blowing due to the formation of an air lock. Connecting the timber “in a warm corner” in itself guarantees the absence of cracks, and an effective addition is punching all joints with jute.

Cutting “in a warm corner” is the most commonly used method of joining beams in Russia.

Straight tenon

Connection in a warm corner - straight tenon

Straight tenon is used in the construction of buildings with a wall, equal to length timber. When cutting a log house, it should be taken into account that the size of the groove is determined by the size of the tenon, that is, balance must be maintained. If the tenon is large, then the groove, accordingly, should also be the same. A groove that is too deep can weaken the beam, which will affect the strength of the connection, so careful calculations must be made before cutting.

A properly designed corner can withstand wind and other loads well.

The uniform shrinkage of the timber frame guarantees the preservation of the weak part of the timber in the corner.

Half swallowtail

Joint in a warm corner - half dovetail

A distinctive feature of this type of lock is a cone-shaped spike up to 5 cm wide. The cone securely holds the beams, which makes the frame more durable. The limit on the size of the tenon is set so that during the shrinkage process the timber in which the groove is made does not crack.

Making a half dovetail tenon is not particularly difficult for a specialist. To speed up work, you can use a template. This connection is used when the length of the wall exceeds the length of the beam.

Corner tenon triangular shape It is used quite rarely, since the knot is less durable, although there are no through gaps in it. The technology for sawing a corner tenon is no different from those mentioned above. A builder who is skilled in working with a chainsaw only needs to turn the bar slightly to obtain this type of connection.

Frame-timber technology

This technology is similar to the cutting method described above log house“to the pillar” (“to the fence”).

Serve as a frame vertical racks with grooves. Bars with ready-made spikes the desired shape at the ends they stack on top of each other. The tenons inserted into the grooves make the corners airtight and reliable. Since the joint itself is not visible, the structure has a very neat appearance.

Using a single template for all tenons provides a significant advantage in the time it takes to make a log house and in the ease of its installation.

Fastening the log house

A very important point in the construction of log houses, both log and timber, is the fastening of the elements to each other. The need for this procedure is explained very simply: the tree dries out over time, as a result of which the logs and beams can change shape or unfold. The crowns of a log house thrown out in different directions are not a pleasant sight. Well, living in such a building (it’s hard to call it a house) is out of the question at all.

What are they collecting for?

Fastening elements can be metal or wood.

It should be noted right away that nails are not used in log house construction! Only non-drying laminated veneer lumber can be secured with metal studs.

In all other cases, the log house is assembled using wooden fasteners - dowels and dowels.

This approach is justified by the fact that drying wood will simply “hang” on metal pins that do not change in size, as a result of which large gaps appear between the crowns.

"Nagel" translated from German means nail. In practice, this is a round, triangular or square long block. Round dowels are used in wooden house construction. Square and triangular dowels are more complex in design and therefore are used less frequently.

Bars with a diameter of 25-30 mm are driven into drilled holes with a diameter 1-2 mm smaller. To make dowels, hardwood is used - spruce, oak or birch. There are certain requirements for this type of fastener - wood moisture content is no more than 12%, the absence of knots or other defects, treatment with antiseptics is mandatory. Compliance with these standards guarantees the strength of the entire structure.

The length of the dowel depends on the cross-section of the timber. The formula for calculating the length is very simple: the height of the three beams (crowns) is multiplied by 0.8.

Assembling the log house wooden dowels is carried out in the following order: first, the lower 2-3 crowns are fastened, then the two rows laid on top are attached to the upper beam or log from the first bundle. This algorithm is maintained until the frame is assembled, that is, until it reaches full height.

The placement of dowels for a log house is done in this way: in the lower bundle, the first dowel is installed in the middle of the log at a distance of 200-600 millimeters from the edge (end), the subsequent ones - after 1.5-2 meters. In the second bunch, the pins are driven in in a checkerboard pattern relative to those already installed. It is very important to maintain a checkerboard order - the dowels should not overlap each other!

The holes for the dowels are drilled to a depth slightly greater than the length of the beam - during drying, the log or beam should “sit” in place and not hang on the fastener.

Experienced craftsmen use small tricks when working with dowels. For example, to make the depth of the holes the same, a tie is made on the drill using masking tape or colored electrical tape, which helps to orientate it. Or they use machine oil (working oil) to smoothly fit the block into the groove - unnecessary blows can lead to cracking of the wood. The forces and strictly vertical direction of impact on the dowel when hammering should be controlled.

Real dowels are expensive. But there are various lumber available for sale from which they can be made. The most budget option is a dry “elite” board without defects, sawn and cut into bars of the required size.

A suitable alternative is ready-made cuttings of suitable diameter (for mops or rakes) - you just need to remove the knots and cut them into pieces of the required length.

Dowels

Dowels are an analogue of dowels. But the sizes of the dowels are such that they can only fasten a couple of logs (crowns). Drilling additional holes in both the bottom and top logs takes time and a certain amount of precision. Installing crowns on dowels is quite hard work. For these reasons, assembling log houses from logs or timber using dowels is a less popular method.

Design features of the log house

Wooden house-building technologies have their own characteristics associated with the specific qualities of the building material – wood. Shrinkage, shrinkage, exposure to the external environment - these indicators are characteristic only of wooden buildings. Therefore, during construction, special techniques are used, without which logs stacked on top of each other will not form a log house (the basis of a house).

Prepared log a - compensation cut, b - lunar groove

Longitudinal grooves

The log house should be cut in such a way that there are no cracks in the walls. This requires cutting out longitudinal grooves.

The width of the groove depends on the climatic conditions in which the residential building is being built. Winter temperature reaching 30° below zero is not dangerous if its width is more than 12 centimeters. If the frost reaches 40 degrees and below, the groove should be 14 cm wide.

A semicircular groove, also called a “lunar” groove, is cut along the entire length at the bottom of the log. Since the log is laid on top, rain and snow water cannot penetrate into the inter-crown space.

The radius of the lunar groove affects the quality of fit of the logs: its smaller size (compared to the log itself) allows you to lay a layer of insulation in the resulting space, the protruding edges of which should be protected from moisture. In the case when the diameter of the groove is equal to the diameter of the log, gaps form between the crowns. The fact is that, as a result of uneven shrinkage of the logs, the crowns cannot sit in the right place to make the joint airtight. Such walls require mandatory insulation.

Compensation cut

This design feature protects the logs in the log house from the formation of cracks that appear under the influence of moisture. Wood – natural material, very much subject to its influence.

The task assigned to the compensation (or unloading) cut is to minimize the number of cracks and give those that appear a single direction.

Only an experienced specialist can perform cutting, one of the most difficult operations. This is almost jewelry work, since the cut must be made to a certain depth (no more than 1/3 of the diameter) and along the entire length of the log, without touching the locks. If the slightest mistake is made, the cut can become a conductor of cold into the house.

Conclusion

Choose suitable way Making a log house from timber or logs is not difficult if you have a clear idea of ​​what kind of house you need - winter or summer, large or small. In any case, if everything is done according to the rules and without errors, it will be an absolutely unique structure, because wood is a true gift of nature!

Wood is one of the most common building materials on earth, dating back centuries. Houses, bathhouses, churches are built from wood, luxury cottages and temporary buildings. The ubiquity and availability of wood provide this material with increased attractiveness in the eyes of developers.

Our portal has already described in detail, and... We continue the series of articles that we started.

So, from our material you will learn:

• How to build warm and comfortable logs.
• How to calculate the required wall thickness.
• What features should you pay attention to when choosing the width of the groove?
• What types of felling are there?
• What nuances do you need to know before starting construction? log house.

Calculation of the thickness of the walls of the log house and the diameter of the log

Will it be warm in a wooden house if the diameter of the logs is 25, 30, 35 or more cm? This is one of the main questions that any developer who plans to build a house from debarked or rounded logs should ask himself. Agree that it is unreasonable if it later turns out that the thickness of the walls is not enough to comfortably survive the harsh winter. Insulating the house from the outside or from the inside is also not an option: all the aesthetics of the log will be lost. All that remains is to intensively heat the log house and increase energy costs or calculate in advance the sufficient thickness of the walls in relation to the region of residence.

In one of our previous articles we already described in detail for a stone house. At first glance, it seems that making a calculation for a log house is simple - you need to find out the required normalized thermal resistance of the walls (R) of your region of residence. To do this, we find this data on the Internet. For example, for simplified calculation(for Moscow and the Moscow region) take R = 3.0 (m²*°C)/W.

Now we need to find out the actual value of the thermal resistance of a wall made of logs of a certain diameter. After which we will be able to find out (based on calculations) whether the heat transfer resistance meets the standards. To do this you need to use the following formula:

R= d/λ, where:

d - material thickness;

λ is the thermal conductivity coefficient of the material W/(m °C).

This is where the first pitfall lies. The thermal conductivity coefficient of wood (λ) is presented in the following table:

As you can see, it contains three values. Which one should you take, and what do “normal” and “wet” conditions mean?

Hermes-sz User FORUMHOUSE

The thermal conductivity coefficient of a material (including insulation) largely depends on its humidity. And the operational humidity of the material depends on the climate zone and the mode of use of the room.

For example, the thermal conductivity of pine and spruce (dry) across the fibers ( thermal energy from a wooden house goes outside across a log ) is 0.09 W/(m °C). Under normal operating conditions (A) and during operation in a humid area (B), the thermal conductivity coefficient of the material increases and amounts to 0.14-0.18 W/(m °C).

If the material is over-moistened, its thermal conductivity coefficient increases and decreases thermal resistance designs. That's why, For approximate calculation, Let's take the following value: wall material - pine, thermal conductivity coefficient of the material (average value under normal operating conditions) - 0.15 W/(m °C).

Most often, the thermal conductivity coefficient of materials and insulation materials is indicated in a dry state, i.e. obtained in laboratory tests other than real conditions operation. You need to remember this when making your own calculations.

So, we figured out the thermal conductivity coefficient of wood. All that remains is to select the thickness of the wall for which you want to make the calculation. And here lies the second pitfall. The logs are stacked on top of each other, i.e. there is a groove. Moreover, depending on the diameter of the log (D), the customer’s requirements, the width of the groove (H) changes, and therefore the actual width of this unit in relation to the thickness of the log. This relationship is shown in the following figure.

It can be seen that with the same log diameter, depending on design features junction of logs, the width of the groove may vary. Therefore, it is impossible to simply substitute the thickness of the selected log into the above formula. Need some common denominator, which can be used for calculations. To solve this problem, we will use the experience of a user of our portal with the nickname zaletchik.

zaletchik User FORUMHOUSE

I want to live in a log house. There is no gas on the site, and there is no prospect of it. Region of residence - Moscow region. This means that the issue of reducing heating costs is urgent. I plan to heat the house with a boiler running on diesel fuel. These input data forced me to study the thermophysical properties of the log house.

At first zaletchik calculated thermal characteristics by calculating the average thickness of the enclosing structure. This approach was not entirely correct, because heat loss was considered directly proportional to the thickness of the wall. As a result of brainstorming and communication with FORUMHOUSE users, zaletchik made a more correct calculation.

To correctly calculate the thermal conductivity of the walls of a log house, I calculated the thickness of a log house made of timber, which has the same thermal insulation properties as a log house made of logs of a certain diameter (D).

Leaving the details of the calculations, which can be found in the topic, outside the scope of the article, we will immediately move on to the obtained coefficients that we need for the calculation.

For different values ​​of ε (H/D ratio of groove thickness to log diameter) the corresponding values ​​of μ (Heff*D ratio of beam thickness to log diameter, having the same heat-conducting properties). The results are summarized in a table.

For clarity, let's consider next example. Let’s say the diameter of the log used in the construction of the log house is 45 cm. The width of the groove is 23 cm. Hence: ε = 23/45 = 0.5. Now we find in the table the value of μ corresponding to the resulting figure. This is 0.83. Next, we find the thickness of a wall made of timber in relation to the diameter of a log that has the same heat-conducting properties: 0.83 * 45 = 37.4 cm. Convert to meters - 0.374 m.

R = d/λ, where:

d - material thickness;

λ is the thermal conductivity coefficient of the material W/(m °C). In our version, pine logs – 0.15 W/(m °C).

R = 0.374/0.15 = 2.49 (m²*°C)/W

Or, you can use this formula:

R = μD/λ, where:

μ - coefficient, taken from the table above;

D is the diameter of the log in m;

λ - thermal conductivity coefficient of wood.

R = 0.83*0.45/0.15 = 2.49 (m²*°C)/W

One of the factors that determines the thermal resistance of walls is the diameter of the log and the type of wood.

Previously, we indicated that for Moscow and the Moscow region R = 3.0 (m²*°C)/W. Based on the result obtained, for walls made of pine logs, R = 2.49 (m²*°C)/W. Those. the wall does not reach the regulated value of thermal resistance. You can increase the diameter of the log or choose another wood - cedar pine. The thermal conductivity coefficient of this material (we leave the diameter of the log and the width of the groove unchanged) is 0.095-0.10 W/(m °C).

We make a calculation.

R = 0.83*0.45/0.10 = 3.74 (m²*°C)/W

That is, the standard for actual heat transfer resistance is exceeded.

You can take a different path and use another formula to find out the required diameter of the log from the ratio: the width of the groove is half the diameter of the log.

D = Rtp*λ/0.83, where:

Rtp – regulated thermal resistance of the wall;

λ - thermal conductivity coefficient of wood;

Let's do the calculation for pine.

D = 3.0*0.15/0.83 = 0.54 m.

Using this technique and “playing” with different values ​​- changing the diameter of the log, the width of the groove, the wood - you can make your own calculation and choose optimal thickness walls of a log house.

My great-grandfather and grandfather were specialists in log building, logging and woodworking. From them I learned about the required groove width of 1/2...2/3 of the log diameter.

Also, the thermal efficiency of a log wall is affected not only by the width of the groove, but also by the profile of the log - its cross-section: round or so-called. half-log, hewn on both sides - carriage. By cutting down the wood, we reduce the thermal resistance of the wall, because... the log in the wall works with its entire section.

Of course the results this simplified calculation approximate. Most of the heat loss in the house occurs through windows, ventilation systems, roofing and foundations. Those. warm wooden house is a balanced system where all nodes work in close cooperation and correspond to each other. There is no point in making walls from logs with a diameter of 0.4-0.5 meters and choosing a wide groove, if the house is blown through cracks, A the corners freeze.

Features of felling a log house

To choose the best option for felling a log house and thereby making it warm, you need to understand what felling options exist and how they differ from each other. First, we need to define such concepts as cutting and crown.

Notching is the connection of various wooden parts of a log house with each other.

With proper cutting, the loads are evenly distributed between the logs. To do this, all contacting parts must fit tightly to each other. Also, moisture should not accumulate in these places, which over time can cause the wood to rot.

Crown- this is a log house consisting of four logs laid in a horizontal plane. At the corners the crown is connected with a notch. During the construction of a house, the crowns are stacked on top of each other - a wall is formed.

It should be remembered that the number of crowns depends on the diameter of the log and the width of the groove, which affects the material consumption, and therefore the final price and thermal properties of the log house. For example, to build a wall 3 meters high from a log with a diameter of 25 cm and 40 cm, a different number of crowns will be required. When building a house from logs of larger diameter, the number of cuts, locks, and inter-crown connections is reduced. Those. places that can subsequently be blown out, which will lead to heat loss.

When choosing a log for a log house, it is necessary to maintain a balance between the diameter of the log, its cost (price for the material) and the price for working with such a log.

Masters working with logs large diameter physically more difficult. You may also need to use special equipment - a crane.

In addition, when choosing debarked logs as a building material, we remember such a parameter as curvature.

Convergence- the difference in the thickness of the log in the ratio of the diameter of the butt and the top. A debarked log that has not undergone machine processing, unlike a rounded log, cannot be completely flat. His Bottom part(especially with a long log) is always thicker than the top. To make the wall even, when building a log house, craftsmen alternate logs of different thicknesses when laying the crowns.

The cutting itself is usually divided into two types:

1. Without a trace (in the paw).
2. With the remainder (into the bowl).

Chopping without residue, or into a clean corner, involves maximum use of the entire length of the material.

This type of cutting produces a right angle, which increases the usable area of ​​the house and reduces the consumption of logs. But based on practical experience, we can say that this type of corner is susceptible to freezing. To avoid this, back in the old days, the corners of a house cut down “in the paw” were sheathed with overhead boards, or, as an option, the house was subsequently lined with bricks. This prevented freezing and blowing through the corners.

Chop with remainder- a more expensive, but also more thermally efficient option. Because the ends of the logs protrude at the corners of the house; this unit is more protected from blowing, rain and freezing.

Leaving all the diversity beyond the scope of this article various types felling, we will focus on the key features of the three main types of log felling. This:

• Russian cutting;
• Canadian felling;
• Norwegian cutting.

In our country, wooden houses are traditionally built from round logs. A semicircular groove is made along the log. The corner lock is made by cutting into the “oblo” into the bowl. The name comes from the word “obly”, i.e. round. The bowl can be positioned down or up.

If the bowl is located downward (cutting the bowl “in the middle”), then such a connection is considered more moisture resistant, and the log is better preserved.

When choosing this type of felling, you need to take into account one nuance.

The main disadvantage of Russian felling is that the logs dry out differently along and across the grain. As a result, after shrinking, the logs do not sit tightly enough in the log house.

As the diameter of the log decreases, the shape of the connecting bowls changes. The bowls open up and turn from semicircular to oval. Gaps appear. As a result, the log house has to be caulked again. In addition, open insulation is exposed to adverse atmospheric phenomena. It becomes saturated with water, and the logs can begin to rot.

A log house made in Finnish does not have this drawback. The principle is the same as in Russian cutting, except that in this version the inter-crown groove is made of a smaller radius (oval). Thus, the upper log rests on the lower one only with its edges (undercut).

As a result, when the logs shrink, the edges of the inter-crown groove do not open, the logs sit tightly, there are no cracks, and the insulation is not exposed to wind and rain.

Unedged boards……………………………………………. 13 Business croaker………………………………………….. 16 Sawdust and cuttings………………………………………………………………. 13 Shrinkage………………………………………………………………. 8 When carrying out practical calculations, these figures should be clarified based on a study of local conditions. Wood debarking waste. The amount of bark found on wood depends mainly on the species, as well as on the age of the trees, their growing conditions, trunk diameter, etc. The total amount of bark obtained from debarking wood at enterprises, taking into account the loss of bark during logging, varies ranging from 10 to 14.5% of the volume of marketable wood. When transporting wood by raft, part of the bark falls off and the actual yield of bark is on average 8...

Current norms for lumber yield when sawing

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

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

You need to think similarly in terms of blueness and curvature.
Approximate yield by variety The situation by variety is quite interesting.

Attention

It turns out that the percentage of yield of high-grade products depends on the following factors:

• The coefficient of production of lumber from round timber.

Grade depends not directly, but indirectly.

Guidelines for determining the volume of secondary wood resources

Table 1 - yield of boards when sawing round timber Diameter, cm Yield of the highest grades, % 12 - 16 yield of the first grade 40% 18 - 22 on average 50% 24 - 26 about 50% 28 - 40 timber timber, in the production of timber you can get indicators about 70% 42 - 60 about 60 - 70% How does the percentage of lumber production depend 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 timber

Info

He only cuts graded wood;

• Circular saw equipment cuts according to individual cuttings - this is a big plus for the resulting materials, both in quality and quantity.
Video on the topic And now I’ll answer why high yield is not always good, but everything is simple at very high rates, the amount of boards with wane increases.

Important

The result is low-grade lumber and its total cost from a log at a certain point becomes lower than the cost of high-quality materials.

And selling low-quality material can be more difficult.

Amount of wood waste

During the sawmilling process, various pieces of waste 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 is impossible to use it for pulping and the production of wood-based panels.

The volumes of formation of various types of 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 of annual warehouse turnover, m3 Amount of waste from exported wood, % At the cutting site A.
Solid or lumpy from Hody: Branches, twigs, tops 14.00 140 65 75 Roots 11.00 110 .
110 - Stumps 3.00 30 30 - Points 1.75 17 - 17 Canopies 0.75 7 - 7 B.

Sawing round wood: cutting map, necessary tools

In what sequence should the round timber be cut? Please note! 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.

Methods of cutting 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 cut in the center. Break-up-segment - with this type of cutting, two or more unedged boards are cut in the center of the trunk, and edged one-sided boards are cut from segments on the sides. Beam-segment - similar to split-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 the next boards are sawed off. 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 generated when sawing wood?

It's easier to do more difficult jobs with a chainsaw than to buy expensive equipment.

All you need for it is a special attachment, a barrel fastener and cutting guides.

Machines for removing bark. They are quite expensive, but with regular use in an enterprise where large volumes of work are performed, they quickly pay for themselves.

They are not required to be used, but are desirable because they can provide a number of economic advantages and conveniences in the production process.

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

• The larger the diameter, the higher the likelihood of getting more high-quality boards;
• The presence of wood defects, such as curvature, rot, blueness and others; the fewer there are, the higher the percentage of obtaining a high-quality board;
• The shorter the finished product, the higher the percentage of high-quality boards.

Now let’s estimate, approximately based on the diameter, the percentage of first-class lumber obtained from the total volume of boards produced.

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 Percent from round timber
• 3 Why does the useful percentage depend on the diameter of the wood being cut?
• 4 Ways to increase your ratio
• 5 Approximate yield by variety
• 6 How does the percentage of lumber production depend on sawing technology?
• 7 Videos on the topic

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

The efficiency of sawing wood depends on this indicator.

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

In fact, this is not always the case; most specialists know about this, but remain silent. I repeat once again - a high percentage of lumber yield per cubic meter of forest is not always good.

Woodworking today it is one of the leading domestic industries in terms of liquidity. It’s no wonder that more and more entrepreneurs and, above all, beginners, are striving to find their niche in this business.

In the sawmill, when the struggle is for ideal lumber geometry, the combination of quality, performance and price in equipment is the key commercial success. It is very important to select operating technology and equipment that optimally meets all these indicators.

Choosing the type of sawmill

Now on Russian market presented tape, disk, and frame sawmills. In order to compare the efficiency of their work, we will use the following parameter: percentage of finished lumber yield. The maximum indicator in this comparison is band saws oram, which give 82-88%. For comparison: for a frame sawmill - only 61%.

The second very important point: with what forest types This or that sawmill works best. U band sawmills these are thin and medium-sized wood; disc sawmills cut large wood well, but they encounter big problems when sawing thin gauge, and a frame sawmill will not be able to cut a log larger than 480 mm in diameter.

Selection of sawmill technology

Gate technology (sawmill frames)

Morally outdated technology. The equipment requires the installation of a multi-ton foundation. It is also necessary to sort the lumber into at least 12 standard sizes to optimize the yield of the suitable material coefficient. Needs constant reconfiguration drank. It has poor board geometry and high surface roughness. Cut thickness 5-6 mm. Most common sawmills have difficulty coping with the common saw log (saw log diameter more than 70 cm). The yield coefficient of suitable edged lumber is about 50-55%.

However, it has excellent cutting stability, good performance, unpretentious in maintenance, does not require highly qualified sawyer. It still enjoys well-deserved popularity, producing products mainly for the unpretentious domestic market, where the cheaper the better. It cannot cut radial cut boards mainly due to poor accuracy.

Recommended apply if you have your own logging and large quantity cheap raw materials of medium thickness. The undisputed leader among all technologies for the production of unedged lumber of medium quality.

Band saw technology

Relatively young technology. A steel strip welded into a ring has teeth cut on one or both sides. It is put on two rotating drums with a diameter of 0.5 to 1 m. The main thing is that the tape must be flexible enough to rotate for a long time and at the same time hard enough to cut for a long time and not become dull. Sometimes the teeth are hardened, or teeth from another metal are welded. It is necessary to distinguish between machines operating with narrow tape width 20-60 mm and with wide ribbon 100-300 mm. The teeth on a narrow belt are set apart. The wide belt has flattened or stellited teeth.

Many band saws can cut logs with a diameter of more than 1 m. They do not require foundation equipment. Cut thickness 2-3 mm. Easily handles hard wood. They require lubrication: in summer - water, in winter - diesel fuel. As a rule, they have an individual cut and do not require subsorting of logs. Have the highest among all technologies output ratio suitable for edged lumber - up to 75%.

Machine tools farm class on a narrow belt with a productivity of about 5 cubic meters per shift and are quite cheap. Middle-class machines on a 100-130 mm wide belt saw up to 10-15 cubic meters per shift and cost several times more.

Machines with narrow belts they cut badly dirty and frozen wood. They give you a corrugated board, and the saw becomes dull after just one cut on a dirty log. The cost of a decent saw is more than 25 dollars, and it can cut about 10 cubic meters of logs and becomes unusable. Technology has the most high unit cost tools per cubic meter of output and average cutting stability.

After two hours of sawing, the band saw should be removed and hung up to rest for a day to maintain fatigue strength. In reality, it turns out that to ensure two-shift operation of a machine on a narrow belt, it takes about 100 saws in year! Required high qualification the sharpener and the sawyer's caution; the slightest mistake can lead to the tape breaking. To repair it, they use quite expensive imported welding machines. Their use makes it possible to weld tape from literally meter-long pieces, which prolongs its life, significantly reducing tool costs.

Band saws on a narrow belt, due to their low cost, most of the smallest sawmills and farmers have them. The main disadvantage of a narrow tape is the wavy cut, which greatly limits production possibilities. Therefore, this technology is only suitable for small business production, and without the possibility of growth.

It is more preferable to use horizontal band saws with a tape 80-100 mm wide. Such belts have stellited teeth and are not afraid of dirty and frozen forests. These saws cost $200 and up. During their life, they can cut up to 300 cubic meters of lumber. However, such saws require a whole complex of equipment to maintain them in working condition, comparable in cost to the machine itself.

Horizontal sawmills with a belt width of 80-100, it is recommended to use them as first-row machines in the presence of fairly thick and expensive raw materials, when the cost-effectiveness of its processing comes to the fore. For these purposes, of course, you should use machines with a belt width of 100 mm and above.

It is advisable to use band saw technology on narrow belts e as machines of the second row. These are four-head and five-head multi-saws of the Avangard brand. This class of machines perfectly complements the currently widespread circular log sawing machines such as “Kara”, “Magistral”, and TsDS. It is quite difficult to make and perfect a wide band saw. High level Pilotech has achieved mastery in the production and preparation for work of wide band saws.

Circular, circular saw technology

Machines using this technology are divided into three types.

1. Vertical circular saws

With the beginning of market reforms, circular log sawing machines with big saw such as “Kara”, “Limet”, “Slidetek”, allowing the production of lumber export quality with an accuracy of 1-2 mm. Prototypes began to be produced in Russia: “Magistral SPR-1100”, TsDS-1100, etc.

All of them, as a rule, use saws with a diameter of 900-1100 mm. Price one saw, depending on the degree of its preparation, ranges from $300 to $700. One saw can cut up to 3,000 cubic meters of edged lumber; it is sharpened directly on the machine. But once a week the saw requires balancing and shaping of the teeth. To do this, you will need a sharpening machine for circular saws or a semi-automatic sharpening machine, for example, TchPA-7 from the Kirov Machine Tool Plant. Steel saws get dull quite quickly. In winter they require sharpening 2 times per shift, and in summer up to 4-5 times per shift.

Can be used carbide And stellited drank. Moreover, it is better to use carbide saws in the summer, and stellited saws in the winter. Maintaining the tool in working condition and producing boards with export geometry require a qualified sawmill. Most sawmills do not have these and produce boards that can only be sold on the Russian, unpretentious market.

The cutting width of a saw with a thickness of 4 mm is 6-10 mm. The cut is individual and does not require any sorting of diameters. The yield coefficient for edged lumber is actually 52-56%. If you saw through a slab onto a picket fence - 56-58%.

Circular technology has the highest cutting speed: a six-meter log is cut in 8-14 seconds, a board is cut in 4 seconds. Productivity is quite high (up to 15 cubic meters per eight-hour shift). Allows you to work at temperatures down to -30 C o.

Accordingly has low tool costs: 3-4 saws can be used for two years. Cutting stability is high when the log is not very dirty. The machine performs the functions of a product transporter around the workshop, which is not unimportant. The Russian machine has not very reliable, but easily accessible and inexpensive hydraulic elements: hydraulic motors, pumps, distributors. And most importantly, it is 3-4 times cheaper than its imported analogues, while, of course, it is inferior to them in reliability.

Recommended for creating production of small and medium capacity as the basic elements of the first row. Suitable for both the production of finished edged lumber and for breaking logs into large pieces for further processing on highly economical band saw machines.

2. Angle saws

There is a whole class of circular log sawing machines called "anglers". This can be two or three saws installed at an angle of 90 degrees to each other. For example, machines “Grizzly”, “Bobr-2000”, DP-1200, “Vyatka 600”, “Alpha”. As well as machines with a single rotary saw blade, for example the Slovak UH500 and UP700. The Bars machine has two independent saws installed at an angle of 90 degrees, and unlike imported prototypes, it performs the functions of transporting lumber around the workshop.

Machines of this class have a number undeniable advantages: can cut logs with a diameter of more than a meter, having a yield yield of up to 70%; they use saws with carbide tips D = 500-800 mm of relatively low cost; cope well with dirty logs because they have carbide tips; require sharpening once a day or less; have unsurpassed cutting accuracy of 1 mm.

Recommended use for processing thick gauge and primarily for the production of radial sawn timber. In particular, Slovak machines and Russian “Bars” are very good for radial sawing of larch into blanks for lamellas.

On the Russian market there are also inexpensive angle sawing machines with a rotary disk, which completely replace a band sawmill for a small business, but do not have problems with the geometry of the lumber - “Sever 550”, PDU1.

3. Horizontal circular saws

There is another type of circular saw, which confirms that the possibilities of circular technology are far from being exhausted. These are machines with horizontal arrangement of two saws in one plane. Representatives here are the Slovak machine KP58 and the Russian “Bars DG”, “Toima 600”.

Advantages: the machines are quite powerful and can process logs with a diameter of up to 500 mm; there is no need to change saws frequently, they work for at least 24 hours without sharpening; productivity when using a log loader and tilter can reach 6-12 or more cubic meters per 8-hour shift; provide good surface quality and geometry of lumber.

As you may have guessed, there is no universal woodworking technology. The sawmill should be selected according to the raw materials that you are going to cut and the products that you are going to produce.

Vladislav Permin, especially for the site

EXPERT OPINIONS

Dmitry Bychkov, director of Kamsky Bereg LLC (www.kbstanok.ru):

The main selection criterion is operating costs per 1 cubic meter of lumber. Accordingly (other things being equal), the higher the productivity, the lower the cost.

Find professionals, study the experience of other industries, study the lumber market - demand is subject to seasonal fluctuations, profitability is, on average, low, and it is very difficult to work with purchased raw materials. Profitability also depends on the depth of wood processing. And remember: the sharpener is the most important worker, since the woodworker's profit is at the tip of the saw tooth.

I would also mention such a class of equipment as lumber disk machines the first row and multi-saw disc machines of the second row, pass-through type. In the Russian Federation, heavy timber beams (log diameter up to 500 mm) are now made by only two companies - Ecodrev-Machinery (Arctant) and we, Kamsky Bereg-Stankostroy (Vityaz 640M). If you need to process 100 cubic meters or more per shift, there are no other domestic production options. If the sawlog is up to 300 mm (fine gauge), you can use disc cutters for fine gauge (“Vepr 700”).

Multi-disc saws are a reliable and widespread solution for serious business. Their use requires a high degree of mechanization of the site, but the cost of a mechanized integrated circular sawing line is quickly justified due to the high flow rate, low operating costs and high reliability of the equipment.

Arthur Zainutdinov, CEO LLC TF ExpoForm (www.expoform.ru):

Nowadays, a wide range of woodworking equipment prevails on the Russian market, both from well-known and not so well-known manufacturers. When selecting it, first of all you need to look at the service support of the purchased equipment. Equipment is often purchased with very favorable price or complete set, and then problems begin with the supply of spare parts and service support. You should always choose as a supplier a company well-known on the market that supplies reliable equipment from a trusted manufacturer.

The second point that is worth paying attention to is the build quality, materials and components used in the manufacture of specific equipment. Budget equipment has an advantage at the stage when production is just opening and funds are needed for promotion, but you want to equip the production with all the necessary equipment as much as possible. But you must always remember that after some time the question of repairing or replacing equipment will arise.

It is no secret that most often we encounter poor quality when purchasing equipment from Southeast Asia, especially from China. There are also complaints about European manufacturers whose production or assembly sites are located in the above regions.

It is important to remember that equipment on the secondary market good quality is also appreciated and is always easier and faster to sell. Therefore, sometimes it is better to buy the desired machine from a well-known manufacturer on the secondary market than to purchase new machine, painted bright colors, with shiny handles and a lot of bells and whistles of dubious quality.

When sawing wood, it is important to immediately calculate what the consumption will be, as this will affect the cost of lumber. Exit finished products may be different. It all depends on the quality of the wood used and whether measures are taken to optimize cutting. There are special measures to increase work efficiency, make the output better, and the quality of sawing higher. Before sawing, you need to pre-calculate everything. This is not as difficult as it might seem, but the consumption of round timber will be optimal and profitable to obtain an excellent result.

How to increase cutting efficiency

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

1. The calculation should only be carried out when using special programs, manually it will have low efficiency, the percentage of defects will be high.
2. The round timber must first be sorted so that processing is carried out correctly.
3. For cutting it is necessary to use high quality equipment. Otherwise, the amount of waste will be large, and the quality of the resulting lumber will be low.
4. It is best to cut wide lumber first; narrow lumber takes longer to process.
5. It is not recommended to take long logs.
6. Before work, you should set up the equipment.

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

How to optimize cutting

To increase the yield of lumber, the cutting process must be optimized. This applies primarily to those workpieces that have significant curvature. To cut a crooked round timber, you need to perform a number of steps:

1. First, only suitable wood is selected for work. If the remaining logs have rot, sprouts, or cracks at the ends, then it is necessary to trim off some areas.
2. If a rotten core is discovered during work, you can carefully remove it, and then saw the remaining part. This will allow you to avoid large losses and obtain boards with a length of 1 m or more 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 the round timber, sorting, and equipment. For frame shops this coefficient will be 1.48-1.6, and for lines with milling equipment - 1.6 for large timber. With a round log diameter of 12 cm or more, the coefficient can exceed 2.1.

Volume of waste after sawing

In order for the finished board to come out with a high percentage, everything must be prepared correctly, the work must be carried out only in accordance with the technology. Roundwood of coniferous and deciduous species produces different yields. In the latter case, the volume is smaller, even if you use a special optional equipment. Needles are considered more convenient for sawing, since their trunk is straight and the log has a larger diameter. Coniferous forest is not so susceptible to rotting, so there is less waste. For hardwood, 2 cutting technologies are usually used:

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

The volume of a band sawmill is 40-50%. When using technology for collapse, the yield is different, it can be increased up to 70%, but the costs of such work are higher. If you cut round timber, the length of which is 3 m, you can see that the percentage of scrap 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 could be a wormhole, which is no longer suitable for most jobs.

After sorting, the volume of hardwood material, which belongs to grade 0-2, will be only 20-30% of the amount obtained after sawing. This means that of the total mass of harvested round timber, the yield of normal boards will be only 10-20%. The remaining materials are mainly used for firewood. For coniferous round timber, the yield will be different, but attention must be paid to what average values ​​of the resulting volume are observed.

Lumber output

In order for the yield of lumber to be optimal, numerous conditions must be taken into account. To calculate correctly, you can consider the example of round timber yield. The data was obtained from the real experience of specialists and from the performance of sawmills. This makes it possible to compare percentage, calculate optimal average numbers.

For conifers, the following solution is possible:

1. For unedged boards 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 equal to 30%.
2. For edged material, when using sawmills of 63, 65, 75, there will be a lower yield of lumber, only around 45%. For band sawmills, the yield is usually up to 55-60% of the finished material. If you use means to increase efficiency, you can reach 70%, although this requires extensive experience.
3. From a circular sawmill you can get lumber in quantities of 70-75%, although using methods to increase efficiency it may well be 80-75%. But work experience is required.

According to GOST 8486-86, for grade 0-3, the yield percentage, not taking into account sorting, is approximately 70%.

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

For deciduous roundwood, a different yield percentage is observed:

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

The output can be increased; additional equipment is used for this. This can be a special multi-sawing machine, an edge trimming machine, or a slab machine. In this case, the yield of lumber will increase by about 20%. The given percentage is given based on data on obtaining boards of grade 0-4. When sorting grades 0-1, the percentage of lumber obtained is 10%. To get a cube of finished edged hardwood material, you need to cut 10 cubes of the original round wood.

The yield of lumber from roundwood may vary. It all depends on the original type of wood used by the sawmill. Special measures to increase efficiency allow you to get a larger percentage than is possible, but for this you must have some experience.

Sawn timber yield rates from roundwood

In the report of the UN European Commission/FAO Timber Committee ECE/TIM/DP/49 on timber conversion factors different types forest products, in particular, the yield coefficients of sawn timber from round timber are given. These data, based on the experience of 16 countries, may well serve as guidelines for woodworking enterprises as world standards.

Lumber covers a significant portion of solid wood lumber products. They include a wide range of products from unedged, fresh sawn to edged, dry, sized and planed lumber. The type of products produced has a significant impact on the yield of final sawn products from round timber. So from one cubic meter round wood, you can get 0.8 m3 of unedged lumber and only 0.4 m3 of dry edged, sorted and planed lumber. Therefore, various countries were asked to provide their yield ratios for various categories of lumber products to understand why national lumber yield ratios differ so widely.

For example, in Germany, 1.67 m3 of roundwood is required to produce 1 m3 of softwood lumber, while in the USA it is 2.04 m3. At first glance, it may seem that sawmilling in the United States is less efficient compared to Germany (the given coefficient indicates that the production of the same volume of lumber in the United States requires 22% more roundwood). But when taking a closer look at the production of the same types of lumber, such as rough lumber and dry lumber, it turns out that lumber yield rates in these countries are similar. This means that the differences in lumber yield rates are due to the production of different types of finished products. Obviously, Germany produces more rough-cut lumber, while the USA produces more dry and planed lumber.

Some countries note that lumber production in their countries is recorded in the fresh sawn form to avoid double measurement of volumes for dry and planed lumber. This is in contrast to other countries, especially the Scandinavian region and North America, where the volume of lumber is most often given taking into account its final processing. This, for example, could result in a rough green lumber yield ratio of 1.57 (64%) or 1.75 (57%) for dry lumber or 2.27 (44%) for planed and finished lumber, as shown in the diagram below.

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