How to cut sizes on a band sawmill. Sawing frozen wood on a band saw

For a small woodworking industry specializing in sawing wood into boards and beams, the optimal equipment to use is. It has good productivity, allows you to dissolve large-sized trunks into lumber. But in order for the equipment to work with full efficiency during the work, you need to know how to cut on band sawmill. Taking into account certain recommendations and features of the operation of such a unit will allow you to avoid problems and get high-quality business material at the output.

The process of sawing timber with this sawmill comes down to the fact that the log is placed and fixed on a special frame, which also acts as a guide. A frame with a cutting tool mounted on it, driven by an electric motor or internal combustion engine, moves along the barrel along the rails.

Preparatory stage

One of the main conditions for the normal operation of the equipment is the preparatory work before sawing on a band sawmill. And they include:

cleaning the sawn log from dirt and sand;
evaluation of the tree (breed, humidity);
selection of a saw (shape, profile, sharpening angles of teeth) depending on the material being cut;
correct performance of adjustment work (tensioning of the cutting element, drive belts).

Proper preparatory work will allow you to quickly saw the wood with proper quality.

An important factor for normal sawing is the correct sharpening and setting of the saw. These works should be carried out only on special machines. A well-sharpened saw with a properly selected tooth profile will provide high speed work and a clean cut.

Attention should be paid to the adjustment of the cutting blade. Correctly tensioned tape will ensure an even cut. Any violation of the tension will lead to a "waviness" of the surface of the boards, or to a rush of the cutting tool.

The more sand and dirt on the wood, the faster the saw will become dull, which will greatly affect the performance of the equipment. Therefore, it is better to prepare the material before sawing, as well as to sharpen and set the cutting tool in a timely manner.

sawing process

In the process of sawing, it is important to ensure a uniform speed of movement of the bed along the log. This will eliminate the possibility of idle tape movement and ensure maximum productivity.

Before sawing wood with a high resin content on a band sawmill, care should be taken to ensure that water or cleaning solution is supplied to the cutting area. This will prevent sticking of the teeth and ensure a good cutting speed.

After each pass, you should evaluate the quality of the cut and make sure that there is no “waviness”, and only then continue to cut the log. This will allow you to immediately identify problems with the configuration of the equipment and eliminate them in a timely manner.

Periodically, it is necessary to clean the moving elements of the sawmill from sawdust. This will eliminate unnecessary vibrations during the operation of the unit, which may affect the quality of sawing, and will also extend the life of the units.

In general, sawing on a band sawmill is not difficult, the main thing is to fully adhere to the manufacturer's recommendations regarding operation. should not be neglected and preparatory work, because the performance of the unit directly depends on them.

The band sawmill is a compact unit, the main component of which is band-saw. Sawing logs on a band sawmill, as a rule, is used in woodworking or repair and construction industries.

Advantages and disadvantages

Horizontal band sawmills today are one of the most promising woodworking devices for sawing. roundwood. Their advantages are as follows:

economy in operation;
minimum energy consumption;
excellent maneuverability;
a good yield of material (about 70%);
the possibility of private cutting of each log.

Among the shortcomings, one can identify such points as the low accuracy of the radial cut, low throughput, as well as the appearance of a "wave" due to increased resinousness and the release of a significant amount of moisture from a freshly sawn coniferous tree. To get rid of resin sticking to the cutting edges of the electric saw and to the moving components of the sawmill, intensive lubrication with special solutions and regular change of cleaners helps.

However, despite all these shortcomings, the use of band sawmills in small and medium-sized businesses in terms of woodworking is very popular. Their acceptability for the price and receiving from a band sawmill on average 20-25% more commercial wood, in contrast to traditional sawing honey, make such sawmills very competitive and extremely profitable when sawing logs in a private, small business.

Types of sawing logs

How to cut a log correctly to get an optimized lumber yield? You need to choose the right cutting pattern. This action is due to various factors: the type of wood, the volume of logs, the aggregate system and the grade of lumber that will need to be produced. In addition, it should be taken into account how the lumber will be trimmed in the future.

In practice, the following 3 schemes for the classic sawing of a log at a sawmill are known:

Sawing a log in a circle. This sawing configuration is beneficial for medium to high quality logs. First, a cut is made, then the log is turned over to a new edge, then sawn again, and turned over again, and so on until at best 5 turns occur.
Elementary sawing of a log (or ordinary sawing through). It is rational to use a similar scheme for low-grade wood. The resulting lumber will be more prone to warping during drying, unlike the first scheme, and will also come out heavier and drier with a larger amount of residue, since each element will then still need to be sawn on the sides. In this model of sawing, the log is sawn until the central part of it opens. Then it turns 180º and is finished to the end.
Sawing timber. This sawing combination is generally used when working with medium to large wood. In this case, the log can be of medium or low quality and is sawn in the same way as when sawing in a circle. However, the core part of a log with dimensions of 18x23 cm or 25x25 cm is not sawn. Such a bar is either sold as is, or processed on other units in the technological direction.

When using one or another model for sawing logs, the productivity of the sawmill is increased and time and effort are saved on the production of products of various qualities. (Fig. 1 Sawing logs at the sawmill)

Sawing logs on a band sawmill can be productive and easy, depending on how you approach this process.

By planning in advance efforts and time, it will be possible to cut logs with greater productivity. You can make this process as efficient as possible by following these guidelines:

When sawing logs, it is recommended to use only sharp saws. An indicator that the saw has become dull will be its frequent pulling up during the cut, because the dull blade heats up and expands, i.e. loses tension. Thus, the saw starts to walk, get stuck in the log, and create problems in pulling it back. A replacement saw in time will help to avoid such situations.
Avoid breaks. Daily inspection and lubrication of the sawmill takes not so much time compared to the costs that will go into replacing the bearings on the flywheels, as well as the cost of spare parts itself.
Prepare logs for cutting in advance. Before you start sawing trees, they need to be washed from dirt, using a metal detector, remove possible nails driven into them that could remain in the logs after the signs were removed from them. Before sawing logs, the procedure for trimming knots and protruding nodes on it with a chainsaw will help save time, and you will also need to cut the end of the sawn tree in advance so that it fits as closely as possible to the diameter of the log.
During the cutting of the timber, it is necessary to immediately produce its edging. It is necessary to cut off the edges immediately after sawing the log into beams directly on the band sawmill: first on one side, and then on the other, and so on until the last board, until the entire process of sawing and processing the sawn log is completed.

Sawing a log on a band sawmill is not so fast, because it is primarily electromechanical equipment, and it tends to overheat, and working it on the edge will not lead to anything good. It is necessary to give a break to the equipment and not to rush - let everything go as it should. As a result, unnecessary experiences will be reduced, and productivity will only increase from this.

Birch lumber sorting

Birch lumber is sorted for two main markets: America and Europe

Grade 0 -Select - America orA3 - Europe

One face of boards of this grade should be free of knots and other wood defects.

On the other side, knots are allowed every 1 m.

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Grade 1 -Common 1 (1 Common) - America orAB - Europe

On both sides of the boards there may be knots every 1 m. in length.

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Grade 2 - BB - Europe

Any number of knots is allowed on both sides of the boards. false core is not allowed.

Grade 3 - BC - Europe

In grade 3, the number of knots is not limited on both sides.

False core on one side without restriction.

If the false core is on 2 sides, then no more than 50% of the board width

Marriage

false core (red core) on both sides more than 50% of the width

center board with core tube

The path to prosperity for your sawmill business

Wood is a versatile material. While wood is plentiful in Russia, we still need to make sure we don't waste this valuable natural resource when we turn it into lumber and when we turn lumber into furniture, houses and other useful things.

Remember: only a tree of good size should be cut. Your plan should be to cut as much high quality lumber from this tree as possible. You strive to do this with as little waste as possible, while at the same time wanting to achieve high value and utility in the product you produce. How to do it?

Raw material quality

The efficiency of sawing depends on knowledge about the quality of logs. It is very difficult to get good lumber from crooked, knotty logs of small diameter. Therefore, the first step, even before starting sawing, is to evaluate and sort the logs according to their quality.

Sorting is carried out depending on the appearance of the logs. The main criteria are the diameter, curvature, the presence of knots and the amount of false core. It is believed that the log has four faces, each face consists of 1/4 of the circle and occupies the full length of the log. These four faces do not overlap. A clean edge is free from knots, bark scars, cracks, chips, rot, insect damage, etc. The cleaner the edge, the higher its value, and the higher quality lumber produced from this log can be.

We have data on sawing thousands of cubic meters of wood. Based on these data, it is possible to estimate the volume (total and by grade) and the cost of lumber produced from logs. different sizes and varieties.

Curved logs of small diameter produce less valuable lumber than straight and large diameter logs. Therefore, when choosing raw materials, you should buy logs with a diameter of at least 26 cm in the upper part, optimal length and with the least distortion.

Logs used for sawing must be properly stored. In warm weather, they can spoil after a few weeks. It is best to start working on a tree as soon as it is cut down. The ends of the logs will immediately begin to dry out, and, as a result, the wood here will first change color, and then cracks will appear. For several months of storage, cracks can penetrate into the log by 15-20 cm, and the crack spreads up to 1 m. from the ends to the depth. In addition, dry ends are difficult to cut. In such material, the saw gives a wave and boards of variable thickness are obtained.

Sawing

Getting started with sawing is the key to getting the most profit and the most good quality lumber from each log. The sawmiller must keep in mind the full range of potentially useful products in order to manipulate the log to achieve maximum yield. This requires a sixth sense or even "X-ray" vision to "see" what is inside the log before sawing.

For a sawmiller to be efficient, he must receive logs that have been felled and stored properly. Logs should not have large bulges, bends, dirt and cracked, burst ends. The ends of the logs should not be dry. In short, the sawmill is not a magician: the way trees are cut, length-selected, and sorted before sawing affects the potential volume of lumber.

To optimize production volume, the sawmiller must consider how the lumber will be trimmed. If the sawmiller is not engaged in trimming, then the trimmer and sawmiller should closely communicate with each other, exchange experiences. They must work as a team. At a minimum, these people should match the required plank dimensions with the current volume of wood.

Clean, without knots, the most valuable wood is in the outer part of the log. The quality decreases as you start sawing closer to the center of the log. The most valuable are wide, long, clean boards.

Wood sawing methods

Which sawing operation to use (the sawing operation includes decisions about board thickness, log flipping and log taper compensation) depends on many factors: the type of wood, the quality of the log, its dimensions, the design of the machine and the grade of lumber to be obtained. There are 3 standard schemes cut.

Sawing in a circle
A cut is made and the log is flipped to a new edge, sawn and flipped 90 or 180 degrees again, until the center of the log is gone. From a financial point of view, this the best way for medium to high quality logs, although some sawmills will find it difficult to turn the log and daily productivity will be low. Of course, a machine with hydraulics solves this problem.

Simple sawing (or loose sawing)
The log is sawn into unedged boards without overturning to the end. While this may be the fastest and easiest method of sawing, each board must be cut at the sides. In addition, lumber sawn in this way is of lower quality, has a lot of waste and is extremely susceptible to cracking at the center boards. In short, loose sawing is justified only in the case of very low quality logs, when all the above disadvantages are no longer particularly important.

Sawing timber
In this case, the log is first sawn as when sawing in a circle, but the central part of the log can have any dimensions, or it is transferred for processing to another machine along the production line. Sawing cant maximizes sawmill productivity. Mostly logs of medium and low quality are sawn in this way, when it is impossible to obtain valuable lumber from a log. Thus, time and effort are saved in the production of a product of not very high quality and therefore not very high price.

First cut

Of all the problems a sawmiller faces, deciding on which side of the log to start sawing (and therefore which side of the cut to open first) is the most important. (As already mentioned, we divide the log into 4 faces, each of which extends along the entire length of the log and occupies 1/4 of its circumference). The choice of the first face is determined by the position of all others. Before sawing begins, a log can be sawn in a million ways, but only a hundred of them will actually bring benefits! Having decided on the first cut, the sawmiller has only a few thousand other decisions to make.

In the case of sawing in a circle and sawing a bar, two basic rules apply.

Rule 1 The worst side of the log is sawn first, regardless of the taper of the log. (Accounting for log run means raising or tilting the log so that the saw runs parallel to the bark.) Since this is the worst part of the log, it will make short boards and a lot of slabs. Since we do not take into account the taper of the log, this gives us the opportunity to saw from the opposite, better side of the log parallel to the bark, without lifting or tilting the log. This means that more boards of high quality will come out of this best part of the log, moreover, the same length as the length of the log.

Rule 2 First cut the best edge of the tree, taking into account the taper of the log. This means that the log must be raised or tilted so that the first cut is made parallel to the bark.

The end result of both methods will be about the same, but the second method has one advantage: in this case, it is easier for the sawyer to position the log (i.e., rotate it), because the open edge is the cleanest, there are no defects on it. In the case of rule 1, the best part of the tree is opposite the open face. It is not visible, and it is impossible to accurately position the log. Usually, if the wood is of good quality, rules 1 and 2 work pretty much the same. However, if you encounter a worse log, adopt rule 2.

Large high-quality logs (these are logs from the bottom, butt of the tree) provide the most valuable lumber.

Remember: you won't make money just sawing boards - the boards still need to be sold. For this reason, the critical factor for you is not the sawing process itself, but the product - its grade, value and usefulness.

If the log is good, produce lumber big size and railroad ties are unreasonable to say the least. Because the price of a bar is always less than the price of a board.

For logs of high grades, sawing in a circle is recommended. In fact, sawing with the taper of the log (i.e. slanting the log so that the cut is parallel to the bark) is recommended for all "good" edges. The result will be clean wood throughout the length, more valuable pieces of lumber. When you get to the low grade part of the log, go to the shape of the cant and minimize the operation of cutting the cant on the sides.

From logs of small diameter, from which it is impossible to obtain a wide and knotless material, the profit is very small, or none at all. So they need to be cut as quickly as possible. Any method of sawing is suitable here. Most often they are sawn into a beam (this is good from a financial point of view), or they are simply sawn “in collapse”. Remember that every minute of sawing costs money, so you need to find a compromise between production costs and the prices of the final product. In this case, it is generally better to reduce log flips to zero.

Logs with small diameters from 16 to 22 cm give such an insignificant profit that it is better not to deal with them at all. Invest money in good wood instead of going for the cheap stuff is my top tip.

Logs of large diameters - this is a real challenge for the sawmill. I say this because such logs can produce a significant amount of good lumber, and here a lot depends on the sawyer, on how he will turn the log over. Here the decision to rotate the log is critical to profit.

To begin with, the sawyer, guided by rule 1, selects the worst part of the log and cuts it without taking into account the run-off. But don't saw too much on this side. For small logs, you generally need to cut one board, and then turn the log over to the opposite side.

Another way is that the sawyer, guided by rule 2, chooses the best side of the log and starts cutting taking into account the taper of the log. After that, this particular part is sawn for a long time before the log is turned over.

log flip

Lumber is sawn from one side until the sawmill expects the next board on that side of the log to be at least as good as the boards that can be obtained from the other side. (Exception: if you started sawing from the worst side of the log, then cut until you have a perfectly smooth cut surface to flip the log onto). In other words, the good side of the log needs to be sawn deep, and the slab or slab and one board are simply removed from the bad side.

Usually, when sawing, the log turns over 180 degrees. Because many sawmills do not have a log turner, the benefits of turning the log need to be discussed in detail.

When sawing with a 180 degree turn, we get several unedged boards, which need to be additionally cut on the sides, and the half-beam is sawn into finished edged boards. When flipped by 90 degrees (always turning to the adjacent edge), we will get unedged boards and additionally several semi-edged boards that need to be cut on one side. This circumstance alone can already be a significant argument in favor of turning a log 180 degrees, especially for small enterprises. In addition, this way of sawing produces more wide boards, and they are usually more valuable. However, if the edging machine has only one blade, the 90 degree flip sawing method may be more convenient.

In addition, turning over to the adjacent edge at a sawmill with manual tilting of the log can be more difficult due to the need to accurately "catch" the angle of 90 degrees, and from an economic point of view and from the point of view of sawing speed, it is more profitable to rotate the log by 180 degrees.

After sawing two opposite sides of the log, you need to move on to the third and fourth. Usually the worst of these edges is sawn first, regardless of the taper of the log. However, a good quality edge should always be sawn parallel to the bark to increase the yield of good lumber from the log.

With any turn of the log, the internal stress of the wood is removed, which, as a result, avoids bending of the log, cracks and cracks.

Lumber size decision

The width of the first board when sawing from all four sides of the log is critical.

Edge of good quality
If the sawmill believes that the first sawn board can be classified as good grade, then the minimum width of sawn lumber should be 11 + 1 cm. Why? Because the board of natural humidity must have a width of at least 11 cm. To take into account further processing boards (trimming on the sides) are recommended exactly 11 + 1 cm, not 11 cm, but still it is not recommended to specially produce a lot of this size, because the number of narrow boards in a batch is limited.

Variety definition

Since our company is focused on the export of lumber to the United States, there are five main types of hardwood in their market:

FAS, Select, 1 Common, 2 Common and 3 Common. Briefly describe these varieties:

FAS means lumber that is at least 85% clean on 4 sides. Clean - it means without knots, rot, loose core, cracks, wane, stains and other defects. The clean surface should be extensive in both length and width of the lumber. The size of the lumber in this case is not less than 165 mm. x 2.45 m.

Select- this is actually the same as FAS, but one face of such lumber can be like Grade 1 Common. The size of the lumber in this case is at least 11 cm x 2.15 m.

1Common- at least 70% clean from the worst edge. (no more than 1 knot per 1 meter of length). The size of the lumber in this case is at least 11 cm x 1.85 m.

2 common- only 50% clean on the worst side (no more than 2 knots per 1 meter of length)

3Common- this is lumber, which, on the worst side, is only 33% clean.

Of course, this is only a general description of sorting. In fact, there are rules issued by the American Hardwood Association (NHLA rules) that explain individual cases in detail.

Currently, US buyers are limited to only two varieties -

it's a variety Select&btr. - mixture of FAS and Select grades

and grade 1Common

The rest of the material, lower grades, is in demand among European buyers.

conclusions

Log sawing can be a profitable business if done wisely and safely.
Storage of logs in a warehouse should be minimal in time.
Logs must be protected from the ends from drying out.
Logs should be sawn from the worst edge without compensating the log taper or from the best side, but taking into account the log taper.
Logs need to be turned over on the bed every time the other side of the log promises to give boards best quality than the one you are sawing now.

Sawing frozen wood sawmill equipment is associated with a number of problems that need to be addressed. Under conditions of negative temperatures, the physical and chemical properties of wood undergo changes.

Let's consider this problem in the context of working on band saws, because. the specificity and type of the cutting tool contribute to the greatest difficulties when sawing frozen wood due to the fact that the structural parts freeze through unevenly, forming areas of different density.

Why is sawing harder in winter?

Sawing as such is possible when the wood chopped during operation is completely removed from the cutting zone. In other words, for high-quality sawing, it is necessary that the volume of the cavity between the teeth accommodate the cut chips, and they are immediately released when they exit the cut.

The degree of chip compaction directly depends on the density of the wood and its hydrothermal characteristics - the higher the moisture content of the wood, the higher the value of the chip compaction coefficient.

When the ambient temperature drops to -25 C°, the moisture present in the wood structures crystallizes, thus creating additional resistance to the load produced by the saw teeth during sawing.

What to pay attention to first of all?

The key to solving this problem lies in comprehensive measures to prepare the machine, the saw and the processed wood itself for sawing.

1. Prepare the log for sawing!

Soaking and debarking of logs to equalize the contrast of density values in the structural parts of wood is a mandatory procedure included in the technological cycle of material preparation during primary woodworking. In Russia, it is lowered as "unnecessary".

Such saws are designed with a reduced radius of curvature at the base of the tooth by 2-3 mm and a stepped shape of the teeth themselves, which prevents the sawn surface from sticking to wood dust and facilitates easy removal of chips from the cut.

3. Optimum saw tooth setting is the key to high-quality sawing

The effective type of tooth set is “complex”: one tooth is to the right, the second is not set, the third is to the left. This scheme ensures the stability of the saw in the cut and the high-quality removal of sawdust.

4. Rolling and forging saws are especially relevant in winter.

The processes of rolling and forging not only help eliminate defects in the saw body, but also reduce the value of fatigue wear - this is a good help, because. the load on the cutting tool in conditions of negative ambient temperatures is especially high.

Do not forget that the profile of the pulleys must match the parameters of the saw blade.

Fundamental Principle

Summing up, we want to remind you that the operation of any woodworking equipment is influenced by a combination of many factors. If you are working with frozen wood for the first time, we recommend that you contact specialists who can give specific recommendations “on the spot”.

For processing logs on a band sawmill, it is necessary to adhere to the accepted technology. In this way, you can get the maximum quality materials- boards and beams. But first you should familiarize yourself with the basic rules of cutting.

Types of sawing wood

At the first stage, a carriage is formed from a log. To do this, cuts are made on its two sides. In some cases, processing is performed on four sides. Pre-mapped band sawing blank, which indicate the dimensions of the components.

The determining parameter when choosing a scheme is the direction of processing the log. In particular, the movement of the cutting edge relative to annual rings. According to this, lumber of various qualities is formed, which has a unique appearance. Not only their aesthetic qualities depend on this, but also the price.

There are the following types of cuts:

tangential. The cut is made tangentially relative to the annual rings. As a result, oblong patterns in the form of arches, rings are formed on the surface;
radial. For its implementation, perpendicular processing along the annual rings is necessary. A feature is a uniform pattern;
transverse. Processing occurs across the fibers, the cut pattern is an even cut of annual rings;
rustic. It can be done at any angle, contains a certain amount of knots, sapwood or other similar defects.

Often in the woodworking industry, waste from band sawing of logs is used - slab. On the one hand, a flat plane, and the other remains unfinished.

For the most accurate cutting, it is recommended to use special programs. They take into account not only the dimensions source material but also the type of wood.

Sawing on a sawmill with a log rotation of 180 °

To form the maximum number of boards, it is recommended to use a technology in which some of the tape processing processes are rotated by 180°. This allows you to achieve the maximum amount of lumber with various types cuts.

The principle of processing is to make initial cuts along the edges of the log, which are at an angle of 90 ° relative to each other. They will serve as the basis for further tape cutting. Works are carried out on equipment with a vertical arrangement of cutting elements. The diameter of the trunk must be at least 26 centimeters.

Step by step workflow.

Processing of the side with the cut edge part. The result is two boards.
Turning the workpiece by 90°. The cut is made from the opposite side. The number of products varies from 3 to 4.
Repeated 90° turn. The main part of the source material is being processed. Depending on the planned ones, 7-8 blanks can be obtained.

Despite all its positive qualities, this method has one significant drawback - the low production speed. It is recommended to use it on equipment that has a block for automatically changing the position of the log relative to the cutting part of the machine.

A detailed scheme is most often used for the manufacture of rustic boards, which are subject to reduced quality requirements.

Sawing on a sawmill with a log rotation of 90 °

For the manufacture of tangential and radial boards, it is recommended to use a different technique. It consists in systematic band processing of logs with simultaneous analysis of defects. Thus, products of the required quality can be obtained.

After delimbing, the workpiece is placed on the feed frame of the sawing machine. Then you need to do the following.

Removal of the primary slab. It is carried out until the width of the base is 110-115 mm.
Removing unedged boards with a thickness of about 28 mm.
If the number of defects on the surface exceeds the required level, the material is rotated by 90°. If the quality of the board is high enough, the next one is cut off.
Repetition of the operation.

A similar technique is applicable for processing installations that have one cutting surface or have the function of temporarily dismantling the rest.

With a sufficiently large number of defects, it is possible not to postpone the workpiece, but to perform its processing using the 180° turn method.

The above tape processing technique can be applied to create any configuration of wood products. Often, the core area is used to form a beam, and the remaining parts are used to make boards. But there may be exceptions - it all depends on the required shape of the blanks.

The quality of work is affected by the current state of the sawmill, the level of saw sharpening and processing speed. These factors must be taken into account before starting the production process. If necessary, preventive maintenance or repair of equipment is carried out.

The video shows the method of sawing logs on a homemade band sawmill: