home Auditorium 7 Sharpening band saws for wood. Proper sharpening of band saws. Sharpening machine for band saws and methods for sharpening them

Sharpening band saws for wood. Proper sharpening of band saws. Sharpening machine for band saws and methods for sharpening them

Sharpening band saws with a narrow abrasive wheel.

Currently, this method is becoming a thing of the past. Machines for sharpening band saws with a bakelite or ceramic wheel have many different adjustments and it is quite difficult for a novice master to take into account all the nuances, as well as avoid mistakes. These include burns, rough surfaces (burrs), lack of bosom grooves, and the formation of irregular angles of band saw teeth. As mentioned above, all this leads to the inevitable failure of the cutting tool.

Perhaps the only advantage that can be highlighted is the relative low cost of machines and equipment.

Factors influencing the correct sharpening of band saws when using narrow abrasive wheels:

technical factor (correct adjustment of the machine along all axes, entry and exit angles, groove height, metal removal depth)
instrumental factor ( correct selection grinding disc, forming the angle of attack of the disc, grain size, etc.)
the human factor (often laziness and lack of proper attention on the part of the master plays an evil role and leads to sad consequences)

Sharpening band saws with a borazon (CBN) disc.

Preparing cutting tools for use on machines using diamond tools is a modern and reliable way to avoid problems when sawing sawlogs and obtaining the correct geometric dimensions of lumber.

Unlike narrow circles, CBN exactly repeats the tooth profile band saw. Constantly rotating on an axis, the circle makes up and down movements, grinding through the sinus, corners, relieving tension in one pass. The process occurs automatically, the band saw is pushed by a special drive pusher.

The accuracy of sharpening depends on the correct selection of the grinding wheel profile. The most commonly used band saw profiles are:

The 4°/32° profile is a rarely used profile, designed for extra-hard wood, dry wood and for use in the cold season.
Profile 9°/29° profile is designed for hardwood in the cold season.
The 10°/30° profile is a universal profile, most often used in the southern and middle zones with mild climates.
13°/29° profile is more suitable for soft wood, increases cutting speed

The service life of CBN discs depends on the following factors:

1) correct selection of “saw profile - sharpening disk profile” (if this point is violated, the sharpening disk will “go bald” in places where there is a discrepancy)

2) quality and layer of borazon coating

3) reliable supplier (we supply only high-quality CBN grinding wheels, proven by experience and time, from manufacturers such as Wood-Mizer and Astron)

4) the presence of a cooling system and right choice coolant

5) correct adjustments

6) condition of sharpening equipment.

All photos from the article

Band saws designed for cutting various materials, including wood various levels hardness Their working part is a closed steel belt with teeth.

The cost of sharpening band saws in special workshops is relatively low. But often the speed and quality of order execution are not very satisfying. Based on this, the work can be done on your own.

Design features of band saws

Belt devices are made from alloyed tool steel, which has a hardness of 40 to 46 HRC.

The width of the cut (kerf) of band tools is much smaller than that of disk analogues. When cutting cheap wood this moment not so noticeable, but when cutting valuables it is critically important.
The machine can cut workpieces of any size. At the same time, the band tool works quickly and creates a high-quality cut.
There is very little waste (shavings, sawdust) when using this type of saw..

Note!
In order for the machine to always work stably and efficiently, its maintenance should be approached with the utmost responsibility.
Sharpening and setting of band saws for wood must be carried out in a timely and competent manner.

Profile, teeth and sharpening angle

Tape devices have different tooth geometries, which depend on the type and characteristics of the materials being cut. Wood tools can be carpentry or dividing. There is a third type, designed for sawing timber and logs. All these subspecies have their own parameters and shape of the teeth.

The sharpening angle of wood band saws is selected by the manufacturing company based on several points. The main one is that the harder the material, the smaller the rake angle should be. Below is a table with the main parameters of the saws.

Characteristics	Carpentry tools (1 profile)	Dividing analogues			For cutting logs and beams (4 profile)
Characteristics	Carpentry tools (1 profile)	2 profile		3 profile	For cutting logs and beams (4 profile)
Thickness of the canvas, mm	0.6-0.9	0.9-1.2	0.9-1.2		1.4-2.2
Width of the canvas, mm	10-60	50-175	50-175		230-350
Teeth pitch, mm	6-12	30-50	30-50		50-80
Height of teeth, mm	2-6.5	9-13	7.5-15		16-24
Rounding radius at the cavity, in mm	1.5-2.5	3-4	3-4		5-8
Rear angle, in degrees.	35	20	15		12
Sharpening angle, in degrees.	50	45	45		53
Front angle, in degrees.	5	25	30		25

Preparing the device for work

With constant use of the tool, a decrease in the quality of the cutting edge is inevitable. It becomes dull, and the width of the teeth is reduced. Based on this, sharpening a wood saw and setting it up are necessary components of the maintenance of a band saw machine.

It should be noted that the setting of the teeth should be carried out before sharpening them, and not vice versa.

Tool layout

Setting is the process of bending the teeth to the sides. This operation is necessary to ensure that the saw blade does not clamp in the workpiece, and also to reduce friction during operation.

There are 3 main types of breeding.

At classical method the teeth bend left and right in strict order.
With the stripping method, every third of the teeth remains in its original position. It is optimal for devices designed for cutting particularly hard wood.
With a wavy setting, each tooth is given its own separate bend value. In this case, the profile of the canvas takes on the appearance of a wave. This method most difficult.

Note!
When setting, you should not bend the entire clove, but only a third or two-thirds of it from the top.
Manufacturing companies advise performing the operation so that the bending range is within 0.3-0.7 millimeters.
The work is carried out using a specialized spreading tool.

Sharpening band saws for wood, instructions and safety rules when carrying out this operation - these are the basic questions that everyone should know House master, who has saws of a similar design on his farm. The fact is that they are used not only in production, but also in everyday life. For example, many residents rural areas They are used to make boards or saw logs into beams.

However, like any saw, the band tool must be periodically repaired. At the same time, this Maintenance consists of carrying out such technological operations as sharpening and setting. They are quite complex technically, and if you do not have experience in carrying them out, it makes sense to contact a specialized service center for maintenance of sawing and cutting tools.

If you have experience in servicing woodworking tools, you can sharpen and sharpen your saw yourself. The point of carrying out such work yourself is to save Money, because sharpening saws is quite an expensive pleasure.

Types of band saws

Despite the fact that all band saws contain an element such as a tape, and therefore differ little from each other in appearance, there are fundamental hidden differences between them that are understandable only to an experienced craftsman. They consist in the form of teeth and the way they are set. Different teeth are designed to perform different types works

So, based on this indicator and the type of material being cut, all band saws can be divided into:

carpentry;
divisional;
sawing machines

Based on this information, it is worth choosing one or another type of saw for sawing work.

In addition, when choosing the saw you need, you should carefully examine its teeth, namely, study their geometry. There is an immutable rule: the harder and denser the material you are going to saw, the smaller the pitch of the teeth of the product and their rake angle should be.

If you are going to saw wood with a thin-walled surface, then for this you will need a tool with a small or standard tooth pitch, since they are specifically adapted for such work. If you start sawing the product using a saw with large teeth, the risk of its breakage will increase significantly. It is best to use it for its intended purpose: for processing thick-walled metal and wooden products.

Rules for sharpening saws

If you decide to sharpen your band saw yourself, follow some fairly simple rules regarding process technology, as well as safety precautions when carrying out such work.

Firstly, when carrying out operations for sharpening band saws, use only special-purpose wheels. They are selected depending on the level of hardness of the teeth of your saw. In addition, the shape of such a circle is also important, chosen depending on the technical features your saw. Thus, profile grinding wheels are known, flat and in the form of a plate or cup.

Secondly, before you start sharpening the saw, be sure to check how evenly the saw teeth can cut the surface being processed. During the sharpening process, avoid sudden movements and jerks. This will help you maintain the height of the teeth and their original appearance.

Thirdly, monitor the coolant level in the grinding wheel mechanism. This will help you avoid overheating and ensure greater accuracy in sharpening the saw.

Fourthly, after completing the sharpening procedure, be sure to check that there are no burrs or burrs on the blade. If any are found, they should be removed using a grinder or a grinding wheel.

As for safety precautions, all work on sharpening saws should be carried out exclusively in safety glasses and using a respirator. IN as a last resort You can wear a protective mask.

Methods for sharpening band saws

There are 2 main types of sharpening of band saws: full-profile and with sharpening of tooth edges. When sharpening the first method, professional sharpening machines are used. If the second method is used, the edges of the teeth themselves are sharpened.

The first option is considered the most accurate, since all operations are performed by an automatic sharpening machine. The worker only has to choose the right grinding wheel and set the operating mode of the machine. However, such sharpening is very expensive, since the machine itself and the consumables for it have a high price.

If you decide to sharpen your saws using the second method, you can safely do so using hand tool. You can also use special professional devices. In this case, you will need to have the skills of an engraver, since your movements must be very precise so as not to damage the metal of the teeth.

If you are going to sharpen a saw by hand for the first time, you should try rehearsing this procedure on a simple sheet of metal. It is best if the front and rear edges are sharpened, but usually only the rear edges are sharpened, since it is more convenient and simpler.

If you absolutely need to sharpen the front edges, you will have to do it on a machine. In this case, you will have to select the exact shape and size of the grinding wheel (as in the case of full-profile sharpening).

Saw setting methods

The second mandatory operation for preparing saws for work after sharpening is setting them. From a technical point of view, it consists of bending the teeth to the sides to the required angle. The point of this procedure is to reduce the friction force between the teeth. This allows for free movement of the tool blade along the sawn surface.

The most common saw layout is standard. At this method The saw link wiring is bent in different directions at a distance of no more than 0.4 mm. It is quite possible to carry out such a layout at home, but it will be necessary to check that the angle of deflection of the teeth is the same.

Another type of wiring is protective. It is usually not used at home, because it requires bending 2 teeth in different directions, leaving the third one in place. The wavy layout is similar in complexity to it. Here the links of the canvas are bent in one direction, creating a kind of “wave” on the canvas. These types of wiring can only be performed by an experienced craftsman, so they are practically never encountered in everyday life.

When doing this work, you must remember that different types saws require an individual approach.

In this regard, it is necessary to carefully study the operating instructions for a particular type of saw. In particular, in this document the density of the metal blade is indicated, as well as the recommended angle of deflection of the teeth. Typically it is 30-60%, although for some products it can be increased.

Selecting a saw sharpener

Since a band saw designed for cutting a large volume of wooden products is almost impossible to cut and sharpen on your own, the question arises of selecting a specialist who will carry out such work. It will be better if he performs this work on a professional machine. Therefore, be sure to clarify this point when placing your order.

In addition, the master must be able to perform all types of sharpening and setting, and not just the simplest ones. This will allow you to save your tool from premature wear and get a quality cut. If a master tells you that there is only one type of sharpening, immediately refuse his services, because he is not a professional.

A true professional must have the appropriate certificate. You will need to focus on its presence or absence when selecting a specialist for sharpening band saws.

Saw material

Band saws are made from different materials- depending on what material they are intended for cutting.

Wood saws are made from alloy tool steel with a hardness of 40-45 HRC. Domestic manufacturers use steels 9ХФ, В2Ф (for metal band saws), etc., foreign manufacturers use their own steels (C75, Uddeholm UHB 15, etc.). When the teeth of such saws are hardened by high-frequency currents, they can acquire a hardness of up to 64 HRC and higher.

Saws for cutting carbon steels and non-ferrous metals of small thickness are also made from tool steel with mandatory hardening of the teeth with high-frequency currents. However, more often, bimetallic saws are used for cutting metal, in which the blade is made of spring steel, and the strip on which the teeth are cut is made of high-speed steel with a high content of tungsten and cobalt. After hardening, it acquires a hardness of up to 65-69 HRC. High-speed steel is welded to the base of the saw using an electron beam.

Bimetallic saws are capable of cutting thick metal from tool, stainless, heat-resistant and other steels, titanium alloys and other metals.

Teeth with greater wear resistance are obtained by surfacing them with stellite (an alloy based on chromium and cobalt with additions of tungsten and/or molybdenum) or by soldering plates of hard alloys to them. Such saws are superior in cutting capabilities to bimetallic ones. They are used for cutting fiberglass, tires, cables, reinforced plastics, heat-resistant alloys, graphite, aerated concrete, bricks and other materials that are difficult to cut.

Geometry of band saw teeth

Depending on the type and properties of the material being cut, band saws have different tooth geometries.

Three main types of teeth are used for sawing wood: for carpentry, for dividing saws, for sawing beams and logs.

Specific sharpening angles for band saws are determined by manufacturers based on many factors. In general, we can distinguish the following dependence - the harder the wood, the smaller the rake angle (γ).

Also used for metal saws different shape teeth depending on what metal they are intended for cutting. Constant pitch saws come in two basic forms.

Standard, designed for cutting thin-walled metal with short chips with a rake angle (γ) of 0°.

A tooth with a positive rake angle (γ) used in saws for cutting thick-walled metal with long chips.

For thin-walled material, saws with a relatively small pitch are used (the number of teeth per inch is from 4 to 18). Saws for cutting thick-walled material do not need a large number of teeth, their number is 1.25-6 teeth per inch.

To eliminate the resonance effect, which leads to blade vibrations, some saws are made with variable pitch, in which the distance between the teeth varies within separate group. The step size is indicated by the largest and smallest values.

Setting up band saws

Setback is the operation of bending the saw teeth in one direction or the other in order to reduce the friction of the saw blade on the walls of the cut and prevent it from pinching. In order for the blade to move freely in the cut, the width of the cut must be 30-60% greater than the thickness of the blade.

There are several types of wiring, the names of which may differ depending on the different manufacturers. The main types are as follows.

Standard, in which the teeth alternately bend in opposite directions.

Cleaning, in which, after bending two teeth, the third does not move apart, remaining in place.

It is mainly used for saws intended for cutting particularly hard alloys and materials. Every third tooth has a trapezoidal shape, it remains in the center of the saw and serves to guide the entire saw blade.

Wavy, the most complex, in which the teeth bend with a variable value of the bend, forming a kind of wave.

When setting, not the entire tooth is bent, but only part of it at a distance of 1/3-2/3 from the top. Saw manufacturers have their own recommendations on the setting parameters of their saws, however, in general, the values they recommend fall within the range of 0.3-0.7 mm.

The general rule is that softwood band saws should have a wider offset than hardwood saws. But the teeth should never be so bent that there remains an uncut wedge in the center.

When setting, it must be ensured that it is identical for all teeth. The deviation should not exceed 0.1 mm. If the setting is uneven, the saw may move towards a stronger setting.

Divorce Devices

Divorce is carried out with special divorce devices. Despite the relative simplicity of the operation, there are quite a few a large number of designs of devices for divorce, differing in the level of functionality.

A simple lever adjustable device (model RU-05) is shown in the figure below.

The saw is installed in the groove of the device with its tooth opposite the probe of the dial indicator, which serves to measure the amount of the spread. Using a moving scale, the indicator needle is set to zero.

When you press the adjustable lever, the bolt (1) presses on the tooth, bending it and thereby adjusting it. The indicator arrow shows the wiring amount. By screwing the bolt in or out, its required value is set, after which the bolt is locked with a lock nut (2).

The setting is carried out through one tooth, after which the blade unfolds and the operation is repeated for the remaining teeth.

There are more simple devices for setting, intended for setting hacksaw saws. Although they cannot provide high accuracy and require some physical effort, as a last resort, you can use them too.

Band saw sharpening

It is believed that about 90% of cases of band saw rupture occur due to poor sharpening, or more precisely, due to the concentration of stresses in the tooth profile that arise when sharpening is performed poorly. The need for sharpening is determined visually, by the condition of the teeth or the appearance of the cut walls. In the latter case, a sign of a dull wood saw is an increase in the roughness of the cut surface.

Depending on the hardness of the teeth, different wheels are used for sharpening band saws - electrocorundum, diamond or CBN (aka borazone). To sharpen saws made of tool steel, corundum wheels on a bakelite base are used. Sharpening bimetallic hole saws or other saws with hard teeth requires a CBN or diamond wheel.

The shape of the wheel used is determined by the parameters of the saw and the method of sharpening - i.e. what tooth profile the saw has and what edge is sharpened. The circle can be profiled (have a shape identical to the profile of the tooth), flat, cup-shaped, or disc-shaped. To select the abrasive grain size, in accordance with the stage of sharpening, you can use the table in the article about sharpening stones. The peripheral speed should not exceed 20-25 m/s.

To increase the durability of sharpening, it is important to refine it (processing the front and rear edges with fine-grained whetstone), carried out after sharpening.

If there are jagged marks on the surface of the tooth, the protrusions will chip away when the saw is used, and it will become dull very quickly. You should strive to keep the surface of the tooth very smooth.

Most instructions for sharpening band saws recommend sharpening along the front surface of the tooth or simultaneously along the front and back surfaces. In practice, sharpening is often carried out one at a time. back surface tooth - because of the special convenience of this operation.

In general, band saws are unpretentious in terms of sharpening. They can be sharpened with wheels of different composition and shape, along the tooth profile or front and/or back surfaces, with special machines and manually.

When sharpening, you need to maintain the radius at the base of the tooth. This requirement is very important; a sharp transition in shape at the base of the tooth contributes to the appearance of cracks in the material, which lead to rupture of the blade.

There are two main methods for sharpening band saws - full-profile sharpening with a borazone profile wheel and sharpening the tooth edges separately.

Full-profile band saw sharpening is the highest quality. With it, a CBN wheel, having a shape that exactly matches the shape of the tooth profile, sharpens the entire interdental cavity with the back and front surfaces of adjacent teeth in one movement. At the same time, all parameters of the tooth profile are absolutely preserved and angular shapes at the base of the tooth, which weaken the saw, are eliminated.

Machines and devices for sharpening

Machines for full-profile sharpening of band saws operate in automatic mode. The movement of the motor with the wheel, installed at the desired angle, is synchronized with the movement of the pusher, which moves the tape one step after sharpening one intertooth groove.

The disadvantage of full-profile sharpening is the need to have your own sharpening wheel for each saw of a certain profile.

There are a large number of machines for sharpening saws on the front, back or front and back surfaces of the tooth. Flat wheels with a suitable abrasive - electrocorundum, CBN or diamond coating - are used as grinding wheels.

The principle of their operation is similar to the operation of machines for full-profile sharpening. The movement of the wheel with the engine is synchronized with the movement of the pusher, which moves the saw step by step.

Special sharpening machines with automatic mode It is advisable to use sharpening blades for large volumes of sharpening work. When occasionally sharpening a band saw at home, it makes more sense to sharpen the saw manually on a regular sharpening machine or using an engraver. You can sharpen both the front and back edges.

This is what sharpening a band saw on the front surface of a tooth looks like on a sharpening machine with a corundum wheel with beveled edge.

Sharpening a band saw on the back surface:

You must remember to periodically adjust the grinding wheel.

And this is what sharpening on the back surface of a tooth looks like with an engraver with a small flat circle.

Despite the high rotation speed (10,000 rpm, at minimum rotation speed), due to the small diameter of the circle (20-30 mm), a normal peripheral speed of 11-16 m/s is ensured. When working, be sure to wear protective glasses or a mask, because due to the thinning of the circle, there is a high probability of its partial or complete destruction.

Well, if you don’t have a machine and an engraver, you can sharpen the saw the “old-fashioned” way - using a needle file. Sharpening is carried out in several movements (3-4) along the back and/or front edge of the tooth. In fact, this operation is quite simple and the skill of high-quality sharpening, with some effort, is acquired quite quickly.

Video:

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When starting to sharpen band saws, you should know that doing it correctly this process depends on how high quality your lumber will be - boards, beams, slats, etc. Sharpening band saws is a responsible process, but not very complicated. By following the recommendations below, you will quickly learn this simple, but very useful process in sawmilling.

First of all It is necessary to inspect the tape for visible cracks and broken teeth. To do this, take the tape in your hands with the teeth facing away from you and, moving your hands, slightly wringing the tape, begin viewing. If defects are found, the tape must be sent for repair or simply thrown away.

Secondly The tape must be cleaned of dirt and tree resin adhering to it. After all these procedures, the tape is ready for sharpening.

Carefully take the tape to avoid injury, since the teeth are sharp and can damage your hands, and insert it onto the sharpening machine. The tape must be installed on all holders on the machine and secured with a special clamp.

We lower the pusher rod into the groove between the teeth; with the help of this rod, the feed of the belt is regulated. A sharpening stone is lowered onto the belt from above and is fixed with a rod that regulates the depth of sharpening.

Before starting the sharpening machine, set the sharpening angle; for a summer forest this angle is 55-60 degrees, and for a winter forest it is 70-80. The angle is set by rotating the frame on which the stone is fixed, according to the divisions on the machine body.

Please note that the sharpening stone has a chamfer at an angle of 45 degrees and during preparation for the sharpening process you must correct the stone if the chamfer does not correspond to the above angle. Editing is done with a diamond tool or a simple large stone.

Let us immediately note that the edit a simple stone more complicated and requires some skills, and also does not comply with safety regulations.

Starting the sharpening machine

You have prepared the machine and saw to begin sharpening, now let's begin the process of sharpening the band saw itself.

First of all, turn on the feed at the lowest speed, for this there are toggle switches for turning on the engine and a feed speed regulator, it reduces or increases the engine speed.

Using the screw on the feed bar, we move the saw tooth forward or backward and make sure that the stone with its flat side (without a chamfer) begins to touch the straight side of the tooth.

Then we turn on the second toggle switch, which sets the engine with the stone in motion. Little by little, without sudden movements, you begin to lower the stone using the screw rod that fixes it, until the stone completely passes the pocket from one tooth to another.

Under no circumstances should the tape turn blue, so try not to lower the stone too much, and also push the feed rod back or forward, otherwise the stone will simply “eat” your tooth. Sharpening of band saws should proceed smoothly according to the factory tooth profile.

By manipulating the feed screws and the stone lowering rod, it is necessary to achieve complete absence burrs on the tip of the teeth. The work of the machine can be considered completed after the band saw has passed at least two circles.

Sharpening band saws in winter

Winter sharpening is practically no different from summer sharpening with the only difference: the angle of inclination of the teeth is more straight and reaches 90 degrees, depending on the freezing of the wood. The more the wood freezes, the greater the sharpening angle, but keep in mind that in the summer with such an angle the load on the saw increases and it is possible quick exit it is out of order.