Angle of resharpening of band saws table. Recommendations
Sharpening band saws on wood, instructions and safety rules for this operation. these are the main issues that every home handyman, who has in his household saws of this design, should know. The fact is that they are used not only in production, but also in everyday life. For example, many people in rural areas use them for making boards or sawing logs into logs.
Like any saw, however, the band saw must be serviced from time to time. In this case, this maintenance consists of carrying out such technological operations as sharpening and deburring. They are quite complicated technically, and if you are not experienced in them, it makes sense to contact a specialized service center for the maintenance of sawing and sharpening tools.
If you are experienced in servicing woodworking tools, you may be able to deburr and sharpen your saw yourself. The point of doing such work yourself is to save money, i.e. к. Sharpening saws is quite expensive.
Design features of band saws
- The cutting width (kerf) of band tools is much smaller than that of their disc counterparts. When cutting cheap wood it is not so noticeable, but when cutting valuable and exotic types of wood it is critically important.
- The machine can saw blanks of any size. A band saw works fast and produces a high-quality cut.
- Very little waste (chips, sawdust) is generated when using this type of saw.
Please note! To ensure that the machine always works consistently and accurately, its maintenance should be treated with the utmost responsibility. Wood band saws must be sharpened and set in good time and competently.
Profile, teeth and sharpening angle
International Classification of Tooth Profiles.
Belt devices have different geometry of teeth, which depends on the type and characteristics of the materials to be cut. The woodworking tool can be either a joinery tool or a cutting tool. There is a third type, designed for sawing beams, logs. All of these subspecies have different parameters and tooth shapes.
Angle of resharpening of band saw blades for wood is chosen by manufacturer on the basis of several points. The main one. the harder the material, the smaller the rake angle. Below is table with basic parameters of band saws.
|saw blade characteristics||Joinery fixtures (1 profile)||dividing counterparts||For sawing logs and beams (4 sections)|
|2 section||3 profile|
|Thickness at the blade, in mm||0.6-0.9||0.9-1.2||0.9-1.2||1.4-2.2|
|Width at blade, in mm||10-60||50-175||50-175||230-350|
|Tooth pitch, in mm||6-12||30-50||30-50||50-80|
|Tooth height, in mm||2-6.5||9-13||7.5-15||16-24|
|Rounding radius at the trough, in mm||1.5-2.5||3-4||3-4||5-8|
|Rear angle, deg.||35||20||15||12|
|Angle of sharpening, in degrees.||50||45||45||53|
|Angle forward, deg.||5||25||30||25|
There are three characteristic features of band saws. they are made only from special kinds of tool steel to ensure high strength and durability of the teeth. Russian manufacturers usually use steels of 9HF and B2F categories, foreign companies prefer C75 series. In any case the hardness of material should be no lower than 45 HRS.
Cutting width of band saw blade is much narrower than that of circular saws. As mentioned above, this is a fundamental factor in the processing of valuable wood and business wood.
Saws can handle workpieces of any length and diameter without any problem. Properly sharpened band saws offer a high production output.
It’s necessary to mention that the reliability of band saws can be explained by the heterogeneity of material used for the band saw blade.
In particular, the body of the saw tool is usually made of spring steel, which has incredible resistance to tensile and dynamic loads. Steel grades with high m of tungsten and cobalt are used for cutting edge production. Individual blade segments are welded together with high-frequency currents. Tools made by this technology can be used for sawing metal.
Materials and their characteristics
Before you begin, you should know what bandsaw (band saw) is used for, what materials are used and what parameters should be observed when working on sharpening the bandsaw.
Band saws are specialized tools for cutting wood in special machines. The blade of such a tool is a closed band, which may have teeth or a flat sharp cutting edge (serrated). Such woodworking tools make very accurate and very thin cuts, which allows using them for finishing work, working with valuable wood, as well as for making both longitudinal and transverse cuts, as well as cuts at any angle and in any plane of the material. Their advantages include high material processing speed, high service life of the cutting edge and the accuracy of the cutting line. To keep the saw always ready for use and to get a quality cut, it is necessary to constantly sharpen the cutting edge, and if it is worn out, to sharpen it completely.
What you need to know about cutting angles
The tooth geometry of band saws can vary depending on the characteristics of the material being cut. This is expressed in the shape of the tooth and the distance between the individual elements of the cutting edge.
The profile of the band saw blade is determined by the marking applied by the manufacturer. It looks like this:
- WM is a universal version designed for sawing soft and hard wood;
- AV. used for longitudinal cutting and sawing of hard materials, such as frozen wood;
- NV. has a narrow width of the blade, so it is ideal for shape cutting;
- NU. wide tooth pitch cutting edge that provides high performance when cutting soft wood;
- PV. almost full analogue of previous blade, but has flattened shape of teeth;
- KV. the profile is used for wide band saws designed for soft wood;
- PU. wide saw for cutting hardwood.
Tooth pitch is selected individually depending on the material. For sawing hard wood and metal, for example, only the fine-toothed blades are used to avoid damage to the cutting edge. Soft materials and thick-wall materials are processed with large tooth pitch to accelerate the production process.
The correct process for sharpening the tool
It has been proven in practice that over 80 percent of tool breaks are caused by improperly sharpened band saw teeth. The need for sharpening is measured by eye. by the condition of the walls of the kerf
Sharpening wheels for band saws are selected according to the hardness of the tooth. To sharpen tools made of tool steel, use a corundum wheel. Bimetal saws should be sharpened with diamond or Borazon abrasive. tool wheel shape should be determined based on the parameters of the saws. It can be cup-shaped, profiled, cup-shaped, disc-shaped, or flat.
Before putting the saw to work it is necessary to keep it in a suspended turned-out state for about eleven hours.
- it is necessary to remove metal evenly along the profile of the tooth;
- avoid excessive pressure on the wheel (this can cause damage to the tooth);
- Always use coolant;
- Ensure the preservation of the tooth geometry;
- deburring should be avoided.
Standard instructions state that tool sharpening should be along either the leading edge of the tooth, or both the trailing edge and the trailing edge. In practice, many craftsmen and professionals sharpen only on the back side, so, in their opinion, it is more convenient to.
This tool is rather unpretentious in terms of sharpening
, in spite of a lot of requirements and rules. Sharpening can be carried out both manually and with the help of a special sharpening machine; use for processing circles different in material and shape, etc.д.
Before sharpening a tool, you should learn the basic ways of sharpening. There are also videos available on the internet.
Types of sharpening
If you have neither an engraver nor a machine, you can sharpen the tool with the old-fashioned conventional method, using a file
With diligent and regular performance of the operation very quickly become skilled in manual quality sharpening.
- When sharpening the tool on a machine, before you start sharpening you need to make sure that the sharpening blade is in the right position relative to the saw.
- It is necessary to remove such a layer of metal from the cavities to ensure that all microcracks are eliminated.
- If saw is used without quality maintenance longer than the one provided by the manufacturer, it is necessary to increase metal layer, which is removed per one sharpening operation.
- Always use a new tool as a reference to check the sharpening results.
- The shape of the saw’s cutting part is a parameter that has been fine-tuned and developed over the years. That’s why it is not worth it to deduce your parameters and hope for a good quality of work.
- If you follow the rules of operation and the requirements of the band saw manufacturer, the band saw will last until its width is reduced to 65 percent of its original size. The width is reduced by resharpening the teeth.
- It is imperative to remove burrs when sharpening the tool, otherwise it will lead to micro-cracks in the sawing process.
- Immediately clean sawdust and resin from the tool when work is complete and inspect the saw carefully before sharpening. Otherwise shavings will clog the sharpening blade, resulting in an improper sharpening of the band saw.
Setting up the band saw
In order for the work on the sawmill to be effective, it is necessary to regularly check and adjust all the important mechanisms of the equipment.
During operation it is necessary to control the following points:
- blade tension. It is recommended that the bandsaw be used for no more than 2 hours continuously. If the saw blade becomes too hot remove it and let it rest for 24 hours.
- Saw tempering. For a good cut it is necessary to check this parameter continuously. The optimum setting is when the sawblade sawdust to air ratio is 3:1.
- Speed of the sawmill. Sawing logs at high speed gives a better cut, but it reduces the life of the band saw. It is best not to exceed 1/2 of the permissible value.
- To increase service life of band saw mechanisms it is necessary to use band saw lubricant. Optimal mixture includes lubricating oil for chain saws and diesel fuel in proportion of 1:1. The mortar is applied in small quantities to both sides of the blade.
After checking and adjustment of band saw mechanisms the wood is prepared for sawing.
Signs of a properly set saw
The correctness of the saw cut can be judged by the content of the saw cut, 2/3 of which is sawdust and 1/3. air. In practice, this manifests itself in the fact that a saw with proper deburring evacuates more than 4/5 of the volume of wood fines from the cut.
Too much set-up increases the air volume in the saw, and the waste removal is impaired. If the tip spread is too narrow, the board is covered with a layer of hot, densely compacted sawdust.
If the tip is set too far apart, the sawing will be jerky; if the tip is too narrow, it will become undulating. it is worth reminding that only the upper part of the tooth is set, so that the sawing is carried out with only sharp corner at the tip of the tooth. Before sharpening the saw the minimum of metal removal, literally limited to deburring.
Types of band saw deburring
Like any other tool, band saws are subject to wear after every cutting cycle. It is a natural and unavoidable process. That’s why every band saw blade needs regular and expert service. adjusting and sharpening. Such maintenance not only keeps the cutting blade in good working order but also significantly increases its service life.
To increase blade life and significantly improve blade operation, proper setting-up is the key to extending blade life. The sawing operation is based on the following principle: the cutting teeth are bent in different directions in order to reduce the friction that occurs during the cutting process and to minimize the risk of the blade being trapped by the workpiece. The band saw blade can be set up in three ways, the choice of which depends on the type of material to be cut.
- In the so-called deburring type, the teeth are bent so that every third tooth is untouched. This arrangement is used if the blade is to be used to cut very hard metals and alloys.
- The classical type of setting implies that each cutter tooth is bent in turns.
- When set to corrugated each cutter tooth is bent to a specific angle. It is clear that this type of setting is the most complicated of all the others.
To bend band saw teeth special equipment is used to perform such technological operation quickly and as accurately as possible. According to common standards the maximum degree of teeth setting should not exceed 0,7 mm, but usually it is in the range of 0,3-0,6 mm. It is important not only to choose the type of setting, looking at the material to be sawn, but also to set it correctly, bending teeth only 1/3 or 2/3 of their height.
After deburring, you can send the cutting blade to the band saw sharpening machine. Statistics show that band saws most often lose their function because they have not been sharpened properly or in time. An indication that the band saw blade needs resharpening and resharpening on the machine is an increased roughness of the cutting surface. The need for such a procedure can also be determined by the appearance of the cutting teeth.
The basic elements of any sharpening machines are wheels, the choice of which depends, first of all, on the hardness of the material used for the cutting teeth. In order to sharpen hard materials, it is necessary to use appropriate grinding wheels. So, for sharpening bimetallic type blades choose sharpening tools consisting of borazon or diamond elements, and for putting in order saws made of tool steel, corundum wheels are quite suitable.
Tools for band saw blade sharpening are chosen both by composition and design. The following types of grinding wheels can be used in the machines for different designs and sizes:
Wood-Mizer band saw blade sharpening and setter kit
According to the instructions, the following points must be observed when sharpening band saw blades on the machine.
- No burr may be left on the tooth surface when sharpening.
- The sharpening wheel must remove a uniform layer of metal across the entire tooth profile.
- Always use coolant to avoid overheating the teeth when sharpening them on the machine.
- The profile and height of the teeth to be sharpened must not be altered.
- Always pay attention to the pressure exerted by the sharpening machine’s wheel on the tooth to be sharpened. If this requirement is neglected, the pressure may be too high, which could lead to burnt-out teeth.
To facilitate the process of grinding, the band saw blade previously turned out and hung in this state for 10-12 hours.
Band saw sharpening with your own hands has some features. In such cases, as a rule, the back surface of the teeth is sharpened, although, if to use the manufacturer’s instructions or watch a thematic video, it is possible to sharpen their front surface as well.
Methods of sharpening and equipment for it
It is up to the individual to decide which method of sharpening to choose, but there are two basic schemes for carrying out this process.
To perform such sharpening, automated machines are used, on which the elbor type wheels are installed. It is very difficult to grind with your own hands. Technology of processing according to this scheme implies selection of the sharpening wheel for each type of band saw blade. The size and shape of the teeth are taken into account. The sharpening itself has the following features: it is performed in one movement of the wheel, and it simultaneously processes the surfaces of two teeth, located next to each other. This method of sharpening makes it possible to obtain a smooth transition at the bottom of the teeth. The biggest disadvantage of the sharpening process is the necessity to use separate grinding wheels for saws with different cutting teeth.
It is possible to sharpen the tool on your sawmill by hand or on a machine in this way. Saw tooth flanks can be sharpened manually with a conventional engraver or file. However, grinding using this method is made possible by special machines of higher quality and faster. In this case it is also necessary to select band saw blades of different sizes and tooth configurations.
Device for band saw blade sharpening AZU-02/6.
The design of a standard sharpening machine includes the following elements:
- Drives for feeding the saw blade, rotating and swinging the sharpening wheel;
- the device for clamping the tool to be sharpened.
All movements of the grinding wheel and the saw blade are controlled by a special electronic control.
When sharpening saw teeth by hand (especially if the person who does it, does not have the appropriate experience), the following problems can occur: the appearance of irregularly shaped grooves between the teeth and non-compliance with the angle of their inclination. The causes of such defects are, in general, the following: wrong profile wheel is used for turning, wrong angle of inclination, the eccentric of the sharpening machine is displaced.
Mistakes when sharpening and setting band saw blades
We would like to tell you about typical mistakes that occur in the process of sharpening and unsharpening the tape.
Such cracks are caused by improperly installed guide rollers. As a result, the back side of the saw keeps rubbing against the rim of the roller during operation.
In this case the band dulls quickly. The reason for this error is that the grinding wheel was pressed too hard during the sharpening process.
3 and 3a. Visually, it can be seen that the sharpening wheel does not complete the tooth profile when sharpening. Incorrect setting of the angle of the sharpening head or the profile of the sharpening stone if a non-Borazon CBN disc is used.
Alternatively, the cause could be due to a break in the eccentric shaft of the sharpening machine. Cracks have appeared in a place that has not been ground.
4 and 4a. Zero angle of attack. the band rattles strongly during operation, causing the saw head to vibrate. In this case the body of the saw is cracked in the area indicated by the circle.
Cause: the head of the sharpening machine is not set correctly. With a very small (4a) tooth height, the belt begins to “wobble” because the slot is not large enough to eject the sawdust, which in this case is very fine (dust).
Tooth not sharpened all the way. Caused by off-axis setting of the sharpening machine head in relation to the clamping plate. The band will quickly become blunt.
Too much tooth pitch. The cutting edge of the tooth (tip) is not equidistant from the band groove, which dulls very quickly. Significant jerking of the head during sawing.
The mouth of the divider tool is set too low, which causes a noticeable deflection of the band below the tooth cavity. Such a band makes a “wave” in the kerf, despite the correct readings of the riving tool.
Daryush Kuiava Customer service manager Wood-Mizer, Poland
Design features of band saws
- Width of cut (kerf) of band tools is much less than that of their disk counterparts. Not very noticeable when cutting cheap wood, but critically important when cutting valuable and exotic types of wood.
- The machine can cut blanks of any size. The band saw works quickly and produces a high-quality cut.
- There is very little waste (chips, sawdust) when using this type of saws.
Please note! To ensure that the machine always works consistently and accurately, its maintenance should be treated with the utmost responsibility. Sharpening and setting of band wood saw blades must be done in time and competently.
Profile, teeth and sharpening angle
International classification of tooth profiles.
Bandsaw accessories have different geometry of teeth, which depends on the type and characteristics of the material to be cut. Woodworking tools can be carpenter’s tools and dividing tools. There is a third type, designed for sawing beams, logs. All these subtypes have their own parameters and tooth shapes.
The sharpening angle for wood band saws is selected by the manufacturer based on several points. The main rule is that the harder the material, the less the rake angle should be. Below is a table with the main parameters of the saws.
|Saw characteristics||Joinery attachments (1 profile)||Dividing analogues||For sawing logs and squared beams (4 section)|
|2 profile||3 profile|
|Thickness at the blade, in mm||0.6-0.9||0.9-1.2||0.9-1.2||1.4-2.2|
|Width at blade, in mm||10-60||50-175||50-175||230-350|
|Teeth pitch, in mm||6-12||30-50||30-50||50-80|
|Tooth height, in mm||2-6.5||9-13||7.5-15||16-24|
|Radius of rounding at the recess, in mm||1.5-2.5||3-4||3-4||5-8|
|Rear angle, deg.||35||20||15||12|
|Sharpening angle, deg.||50||45||45||53|
|Angle of advance, in degrees.||5||25||30||25|
Teeth and their sharpening angles
Band saws have different tooth geometries: This is influenced by the properties and type of material being sawn. So, to work with wood, a carpenter saw is used, for cutting logs, a dividing saw. Each type has its own tooth geometry.
For band saw blades designed to work with wood, the sharpening angle is defined by the manufacturer, but the following is typical. the harder the material, the smaller the front angle should be.
Two tooth shapes are characteristic of constant pitch saws when working with metal
Saws with small tooth pitch are used for thin wall thicknesses (pipes, sheets). otherwise there is a risk of breaking or damaging the tooth. thick-walled workpieces are best handled with tools that have fewer teeth per inch.
To eliminate oscillation effects, a series of saws is produced with a variable tooth pitch.
setting and sharpening
Setting and sharpening of band saw blades are not done separately. They should be set one after the other, first setting and then sharpening the blade. The blade is set in order to reduce its friction against the material to be processed and to prevent the band from jamming. Depending on the tasks of the machine, different alignments are made. The most common is alternating, when the teeth are bent from the plane of the blade in different directions one by one. Less common is deburring. Its difference from the previous one is that out of 3 teeth one is not bent, t.е. The first tooth bends to the right, the second to the left, the third stays straight.
The most complex and rare is the wavy setting, in which each tooth is bent at an “individual” angle. Sharpening can be done with standard pliers, but be careful to observe the tooth deflection angles and hold the blade firmly in place. The main nuance is that during setting, only 2/3 or ½ of the tooth length is deflected, not the entire tooth (from the base).
To sharpen the band saw, you should buy sharpening wheels and a sharpening machine. Material of the wheels is determined by the material of the saw. Particular attention should be paid to the shape of the sharpening wheel, which depends on the cutting surface of the saw. The shape of the grinding wheel determines the grinding angles. At the start of the sharpening machine the wheel is positioned and clamped as standard, then the band is inserted into a special clamping device and also clamped. The sharpening process proceeds as follows: The rotating sharpener is lowered to the bar, one tooth is sharpened, then lifted and proceeds to the next. When all the teeth are sharpened within the limits of the sharpening machine movement, the machine is turned off, the blade is unclamped and shifted to sharpen the following teeth. In doing so, the initial teeth are marked with a marker.
The secrets of the sharpening
To prevent cracks from forming on the back of the blade during sharpening, it must be mounted so that there is no friction between the blade and the machine (so that there is a gap between the blade and the surface of the machine).
It is impossible to press the wheel hard, neglecting it will allow the sharpener to remove a large layer of metal from the cutting edge and will lead to rapid wear and unserviceability of the saw.
Too much deflection of the teeth when setting leads to a rapid loss of sharpness and can cause tooth breakage.
Small kerf width means relatively low energy requirements for material removal. Finally, a band saw can cut almost any thickness of workpiece, while the geometry of a circular saw has limitations on the thickness of the material it cuts. But to take advantage of these benefits, band saws must be properly prepared for cutting. The main preparatory steps are sharpening and setting up the band saws.
Saws for wood are made of tool steel of 40-45 HRC hardness. Domestic producers use steels 9KhF, V2F (for metal band saws) and others for metal band saws., Foreign producers use their own steels (C75, Uddeholm UHB 15, etc.).). When the teeth of such saws are hardened by means of high-frequency currents, they can acquire hardness of up to 64 HRC and higher.
Saws for cutting of carbon steel and nonferrous metals with small thicknesses are also made of tool steel with teeth hardened by high-frequency currents. However, more often bimetal saws are used for cutting metal, where the blade is made of spring steel and the band on which the teeth are cut is made of high-speed steel with high m of tungsten and cobalt. After quenching it gets hardness up to 65-69 HRC. The high-speed steel is electron-beam welded to the base of the saw.
Bimetal saws can cut thick metal of tool, stainless, heat-resistant and other steels, titanium alloys and other metals.
Teeth with higher wear resistance are made by cladding them with stellite (chromium-cobalt alloy with additions of tungsten and/or molybdenum) or by soldering hard alloy plates to them. Such saws are superior to bimetal saws in their cutting ability. They are used for cutting fiberglass, automotive tires, cables, reinforced plastics, heat resistant alloys, graphite, aerated concrete, bricks and other difficult-to-cut materials.
Teeth geometry for band saws
Three basic types of teeth are used for cutting wood: joinery saws, thinning saws, and sawing logs and timbers.
Specific values of band saw blade cutting angles are determined by the manufacturers based on a variety of factors. But in general the following relationship can be seen. the harder the wood, the smaller the rake angle (γ).
Metal saws also have different tooth shapes depending on what metal they are designed to cut. There are two basic ways to cut a fixed pitch band saw blade.
The standard one, designed for cutting thin-walled metal with short chips with a front angle (γ) of 0°.
Tooth with positive rake angle (γ) used in saws for cutting thick-walled metal with long chips.
Saw blades with relatively small pitch (4 to 18 teeth per inch) are used for thin-wall materials. Saws for cutting thick walled material do not need a large number of teeth, ranging from 1.25 to 6 teeth per inch.
To eliminate the effect of resonance that causes the blade to vibrate, some saws are made with a variable pitch in which the distance between the teeth varies within a single group. Pitch size is indicated by the largest and smallest values.
There are several kinds of tapering, the names of which may differ from manufacturer to manufacturer. The main types are.
Standard, in which the teeth are alternately bent in opposite directions.
Stripping, in which, after bending two teeth, the third one does not unfold, remaining in place.
Primarily used in saws designed for cutting extremely hard alloys and materials. Every third tooth has a trapezoidal shape, it remains in the center of the saw and guides the whole band.
Corrugated, the most complicated, when the teeth are set in a wavy pattern by varying the bend value.
When bending, do not bend the whole tooth, but only a part of it at a distance of 1/3-2/3 from the apex. Saws producers have their own recommendations on setting parameters of their saws, but in general the values they recommend fall within the range of 0,3-0,7 mm.
As a general rule, the tooth setting of band saws for cutting soft wood must be greater than that of hard wood. But the teeth should never be bent so much that there is an uncut wedge in the center.
At the setting it has to be equal for all teeth. The deviation should not exceed 0.1 mm. Uneven setting can cause the saw to be set closer to the edge.
Fixtures for the divider
A simple lever-type sharpener (model RU-05) is shown in the picture below.
Insert the saw into the slot with the tooth against the feeler gauge for the setting measurement. Use the sliding scale to set the indicator pointer to zero.
When the setting lever is pressed, the bolt (1) presses the tooth to bend it, thus setting it in place. The indicator hand shows the amount of setting. Screw in or unscrew the dial to the required value, then secure it with the lock nut (2).
Set to one tooth, then turn the blade around and repeat with the remaining teeth.
There are also easier setters for setting hacksaw blades. Although they cannot be very accurate and require some physical effort, in extreme cases. You can use these as well.
Band Saw Grinding
Depending on the hardness of the teeth, different grinding wheels are used for band saws. electro-corundum, diamond or CBN (aka Borazon). For sharpening tool steel saw blades, bakelite-based corundum wheels are used. Sharpening of bimetal flying saws or other saws with teeth of high hardness requires an elbor or diamond wheel.