How to properly sharpen band saws. Materials and specifications

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Band saw refers to the category of cutting tools and is an integral part of specialized woodworking equipment. It is a closed strip, on the outer edge of which there are teeth.

Special grades of steel are used for manufacturing. 9XF, B2F or C75. During production, the teeth are subjected to high-frequency currents. This increases their hardness. It is this fact that affects the cutting edge separation and repairability. Often more than one type of steel is used in manufacturing. The main strip is made of spring steel, and the cutting part is made of steel with a large amount of tungsten or cobalt.

Features of band saws for wood:

• wood requirements. The harder it is, the faster the blade will blunt;
• installation conditions. It is imperative that the tension value is observed. If it is less than required. sagging will occur. If the tension is high, the probability of blade breakage will increase;
• occasional sharpening. A special machine is needed for this.

Fulfillment of the last point will increase the service life of the band structure. However, it is problematic to do the sharpening yourself. it is necessary to select the correct setting, to observe the angle of processing the blades.

When buying used saws one should pay attention to welds on the blade. They indicate frequent breakdowns of the tool.

Saw sharpening and setting

The basic cutting element of any hand saw. a row of teeth cut on the blade to form a wedge-shaped cutter. Wood is sawn lengthwise, crosswise and diagonally to the grain and in each case a distinction is made between crosswise, lengthwise and diagonally to the grain and in each case a different kind of saw is used which has the shape of its teeth.

а. cross sawing; b. longitudinal sawing; 1. wood; 2. kerf; 3. saw trimmer line marking for sawing; Θ. angle of marking to wood fibers in mixed sawing.

crosscut saws are used in crosscut sawing, the teeth cutting edges of which, while moving in the wood, cut through its fibers like a knife and form saw kerf. Slogging is different from crosscutting in that the saw’s cutting direction is parallel to the wood fibers. Tooth flanks of slitting saws plan wood like the knives of a planer, deepening to create a kerf. When wood is cut at an angle Θ to its fibres, universal (mixed) saws are used with teeth that are an intermediate form of transversal and longitudinal saws teeth.

Saw sharpening

as the saw teeth dull, the cutting leading and trailing edges become rounded, the motion of the saw becomes heavy, and the saw has to be pressed hard. Experienced sawmakers can easily tell the sharpness of a saw by the shine of the cutting edges and tips of the teeth and by the sound of the saw. To restore cutting ability of teeth, they are sharpened by files or files giving them sharpness and saving their parameters: sizes of angles, steps and heights.

Sharpening saw teeth. is an art in its own way, and requires good hands, good judgement and attention. It is not difficult to learn this business, it is necessary to have a desire and clearly adhere to the following rules:

• It is necessary to fasten the saw-blade rigidly in a special adaptation made of wood, which is also stable to set on a well-lighted working table. Sharpening saw teeth on stools or on your knees does not give a satisfactory result.
• A personal file should be used, followed by deburring the sharpened tooth edges with a velvet (fine-cut) or nail file. It is desirable that the file be new, sharp and with a set handle. If you do not have one at the right time, you can use a second-hand one, but it must be cleaned with a steel brush and rubbed with charcoal, so that the file does not get clogged and blunted. When sharpening a tooth, the file should engage in its metal and remove its layer, depending on the strength of pressure. If it slides on the tooth without removing metal, it means the saw teeth are overhardened or the file is worn out. If this is the case a new file must be sharpened again. If in this case it slides on the tooth too, you are left with another saw.
• Use your right hand to clamp the file grip and your left hand to hold the end of the file and guide the file to the saw teeth. Here’s how to work the file depending on the type of saw.
• It is important that the file is pushed smoothly and evenly on the file teeth, and only from one side to the other. When the file is returned to its original position it must not touch the teeth.
• It is necessary to try to grind metal of minimum identical thickness from tooth flanks, driving file always with the same amount of times with the same pressure which allows to save size of angles, pitch and height of teeth after sharpening.
• Tooth flanks on the file exit side get burrs that reduce tooth sharpness, and if they are not removed, they become pitted and the teeth become significantly duller as the saw goes on. To deburr, the tooth flanks are sharpened with a file with a velvet file and the flanks are deburred with a wet burr.
• Once the teeth have been sharpened, their sharpness must be checked. Look at the point of a needle and the edge of a razor blade: when sharpened, they do not glint in the light. And if they are blunted, then rounded surfaces appear on the tip of the needle and on the edge of the blade, which reflect the light and shine well. This principle is the basis for checking the quality of sharpening saw teeth. To do this, place the saw in front of your eyes and look at its teeth along the blade. If their cutting edges and tips don’t shine, then the teeth of the saw are sharpened satisfactorily, and if some of them are shiny (it often happens so), then they must be sharpened with file with velvet nib, take off burrs and check again the light reflection by their tips and edges.

Crosscut saws. Crosscut saw teeth are sharpened using a fine-toothed file with an apex angle of 60°.

To sharpen the teeth the saw is clamped in a special device that allows to set its blade at an angle of 45-50° to the plane of the working table. Base file is parallel to the working table at an angle of 60-75° to the saw blade and thus in the first tooth the left edge A1A2B2B1 is sharpened.

Grinding the crosscut saw:1. saw blade; 2. sharpened tooth; 4. sharpening fixture; 5. working table for sharpening saws; 6, 8. direction of file 7 with respect to the working table and teeth of the saw to be sharpened; 9. the saw blade for the tooth trimmer bends as it reaches out

saw teeth are sharpened in several steps. At first a file passes on the left faces of odd teeth, located in the far row, adjusting hands on the same movement. Then pass a file over the right edges of the same odd teeth, completing the sharpening of the main cutting edges with very sharp tips. After sharpening the odd-numbered teeth, turn the saw blade over in the sharpener and sharpen the even-numbered teeth on the far side. When sharpening the cross band saw teeth it is necessary to observe carefully that in each tooth the main cutting edges are sharp with dihedral angle φ = 60-75°, short cutting edge and sharp tip.

Band saw sharpening

Band saw blades, which are blades with serrated edges that are connected at their ends to form a continuous band, have their own inherent advantages. The kerf they leave behind is narrower than that of circular saws. When sawing common wood this feature may not be too important, but when cutting valuable wood and expensive metal it is essential.

Resharpening of band saws

Small cutting kerf requires relatively low energy to cut through the material. Finally, a band saw can cut almost any thickness of workpiece, while the geometry of a circular saw imposes limitations on the thickness of the material it cuts. But to take advantage of all these advantages, band saws must be properly prepared for work. Sharpening and setting up band saws are the main preparatory steps.

Saws material

Bandsaws are made of different materials. depending on what material they are to be used for cutting.

Saws for wood are made of tool alloyed steel of 40-45 HRC hardness. Domestic manufacturers use steels 9KhF, V2F (for band saws on metal) and others for cutting., foreign. their steel (C75, Uddeholm UHB 15, etc.).). When teeth of such saws are hardened by means of high-frequency currents, they can acquire hardness up to 64 HRC and higher.

Hardened band saw teeth

Saws for cutting of carbon steel and nonferrous metals of low thickness are also made of tool steel with obligatory hardening of teeth by high-frequency currents. However, more often bimetal saws are used for metal cutting, 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. It becomes hard up to 65-69 HRC after hardening. High-speed steel is electron-beam welded to the saw bed.

Bimetal band saw production

Bimetal band saws can cut thick metal of tool, stainless, heat resistant and other steels, titanium alloys and other metals.

Bimetal band saw

Teeth with greater wear resistance are made by cladding them with stellite (a chromium-cobalt alloy with additions of tungsten and/or molybdenum) or by soldering hard alloy plates to them. These saws outperform bimetal saws in cutting ability. They are used for cutting fiberglass, car tires, cables, reinforced plastics, heat-resistant alloys, graphite, aerated concrete, bricks, and other difficult-to-cut materials.

Bandsaw with carbide tipped teeth

Tooth geometry of band saws

Depending on the type and properties of the material to be sawn, band saws have different tooth geometries.

Three main saw blade types are used for cutting wood: joinery saws, delimbing saws, and for cutting logs and timbers.

Tooth profile for band saws

Tooth characteristics of band saws

Specific values for band saw tooth angles are determined by manufacturers based on a variety of factors. In general, we can distinguish the following dependence. The harder the wood, the smaller the rake angle (γ).

Metal band saws also have different tooth shapes depending on what kind of metal they are used to cut. In constant pitch saws there are two basic forms.

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

Tooth with positive rake angle (γ) used in saws for cutting thick walled metal with long chips.

For thin-walled material, use saws with a relatively small pitch (number of tines per inch. 4 to 18). Saws for cutting thick walled material do not need many teeth; the number of teeth is 1.25 to 6 per inch.

Tooth pitch

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 separate group. The pitch size is indicated by the largest and smallest values.

Bandsaw set

The pitch is the operation of bending the teeth of the saw to one side and the other to reduce the friction of the saw blade against the walls of the kerf and to prevent its jamming. In order for the blade to move freely in the kerf the width of the kerf should be 30-60% greater than the thickness of the blade.

There are several kinds of set-up, the names of which may differ from manufacturer to manufacturer. Basic types are as follows.

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

Standard setting

Stripping, in which after bending back two of the teeth, the third one does not bend and stays in place.

Stripping set

Primarily used in saws designed for cutting extremely hard alloys and materials. Every third tooth is trapezoidal in shape and stays in the center of the saw to guide the entire saw blade.

Expert recommendations

The result of improper operation is burned tool teeth.

• Tooth shape is a feature that has been developed and verified by experts. If you change it, you won’t be able to process the workpieces efficiently. Based on this, sharpening should be carried out so that the shape of the teeth and the profile of the blade remain the same as they were originally sharpened at the factory.
• If you follow all the rules of operation and maintenance, a band saw blade will serve you reliably until its width has worn down to 65 percent of its original value.

Please note! There is a common opinion among do-it-yourselfers that there is no particular need to remove burrs that occur during the machining process. This is fundamentally wrong, as microscopic cracks can develop in the blade.

Clean wood sap, sawdust, resin immediately after completing work. Inspect the tool carefully before you start maintenance or you will block the wheel. This will cause a significant drop in sharpening efficiency.

Common errors

• Baked saw tooth cavities. This is caused by excessive force applied to the sharpening disc. This defect causes the teeth to sharpen very quickly.
• Sub-optimal tooth pitch and incorrectly angled tooth flanks.

This sharpening result is possible due to several errors:

• Drift of the eccentric of the sharpening machine;
• Incorrect angle of inclination of the machine head.
• Incorrectly selected sharpening blade profile.

Sharpening and sharpening

Deburring and sharpening of band saws are not made separately from each other. They should be done one after the other, first to separate and then to sharpen the blade. Set the blade to reduce friction against the material being worked and to avoid jamming the strip. Depending on machine application, different setting patterns are possible. The most common is alternating, where the teeth are bent from the plane of the blade in different directions in turn. Less common head setting for deburring. It differs from the previous one in that one of the 3 teeth is not bent, t.е. the first bends to the right, the second to the left, the third remains flat.

The most complex and rare is the corrugated setting, in which each tooth is bent at an “individual” angle. Can be set with standard pliers, but take care to maintain deflection angles of the teeth and hold the blade firmly in place. The main nuance is that during the sharpening process only 2/3 or ½ of the tooth length is deflected, and not the whole tooth (from the base).

To sharpen band saws you need sharpening wheels and a sharpening machine. The material of the wheels is determined by the material of the saw. Particular attention must be paid to the shape of the sharpening wheel, which depends on the cutting surface of the saw. The shape of the band saw blade determines the cutting angles. As standard when starting work, the wheel is placed in the sharpening machine and fastened, then the band of the blade is inserted in a special clamp and also fastened. The sharpening process is as follows: The rotating sharpener is lowered to the blade, one tooth is sharpened, then lifted and proceeded to the next. When all teeth are sharpened within the range of the sharpener’s travel, the machine is shut down, unclamped, and the blade is moved to sharpen the next teeth. Use a marker to mark the initial teeth.

Basic information on band saws

Band saw is a cutting tool made in the form of a toothed band, which has a closed contour. It requires a special sharpening machine for band saws. In addition, band saws have a number of other significant differences from traditional circular saws. The most important of these differences is the minimum kerf width that can be obtained with the band saw. It should be noted that this is especially true when it is necessary to perform the sawing of precious wood and blanks made of expensive metal.

Machines equipped with a band saw can be successfully used for machining parts made of different materials and configurations. Such machining is characterized by minimal waste of the machined material, exceptional cut quality and high speed of the process. These machining parameters, however, can only be achieved if band saws are sharpened correctly and regularly on the machine. When servicing band saw blades (especially if you do it yourself) you must strictly follow the recommendations of qualified specialists.

Band saws, depending on the characteristics of the material to be cut, can be made of different materials, different geometry of cutting teeth. If we talk about the division of blanks made of metal, here the two grades of steel used for sawing are the most common: 9KhF and B2F. Wood sawing equipment is equipped with saw blades made of. hardness of which according to HRC scale is not less than 45 units.

Bandsaw tools for sawing wood are further subdivided into three types: joinery tools, dividing tools, for processing logs. Tools belonging to different types, of course, have different parameters (blade size, shape and sharpening angle). Sharpen harder types of wood with tools with a smaller sharpening angle.

Today, bimetal band saws are increasingly used, which are necessary to separate blanks made of hard steel. These saw blades are called bimetal because they are made of two different metals: the cutting teeth are made of steel with a high proportion of tungsten and molybdenum, while the blade itself is made of spring steel. Of course such blades are considerably more expensive than standard models because they require special equipment where two dissimilar metals are joined under the effect of an electron beam.

Types of setting of band saws

Just like any other tool, band saws are subject to wear and tear after every cutting cycle. This is a natural and unavoidable process. That’s why every band saw needs regular and expert service. adjusting and sharpening. Such maintenance allows not only to keep the cutting blade in working condition, but also significantly increases its service life.

Correct setting-up increases the service life of the saw blade and significantly improves the blade’s function. This operation means that cutting teeth are bent in different directions to reduce friction during cutting, and to minimize the risk of jamming the blade with the workpiece. The band saw setting can be done 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 deburred in such a way that every third tooth remains untouched. This arrangement is used if the saw blade is to be used to cut very hard metals and alloys.
• The classic type of setting means that each cutting tooth is bent in turn.
• In the wavy set-up each cutting tooth is bent at a defined angle. Clearly, this type of setting is the most complex of all.

To bend the teeth of band saws special equipment is used to perform such technological operation quickly and as accurately as possible. As a rule, the maximum degree of setting should not exceed 0,7 mm, but usually it is between 0,3-0,6 mm. It is important not only to choose the type of setting based on the material to be sawn, but also to set it correctly, bending the teeth only 1/3 or 2/3 of their height.

After setting, the cutting blade can be sent to a band saw sharpening machine. Statistics show that band saws most often lose their functionality because they have not been sharpened properly or in time. An indication that the band saw blade needs setting and sharpening on the band saw machine is an increased roughness on the cutting surface. The need for such a procedure can also be determined by the appearance of the cutting teeth.

The main elements of any sharpening machines are grinding wheels, the choice of which depends primarily on the hardness of the material used to make 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 circles are quite suitable.

Tools for sharpening band saws are chosen both by their composition and by their design. The following types of wheels can be used in the machines for different blade designs and sizes:

Wood-Mizer band saw blade sharpening and setting kit

According to the instructions, the following should be observed when sharpening band saws on the machine.

• There must not be any burrs on the tooth surface during sharpening.
• The sharpening wheel must remove a uniform layer of metal across the entire tooth profile.
• Always use coolant to prevent overheating of the tooth while sharpening it on the machine.
• The profile and height of the teeth to be sharpened must not be altered during sharpening.
• Always pay attention to the pressure exerted by the sharpening machine’s wheel on the tooth to be sharpened. Failure to observe this precaution could result in excessive pressure, which could lead to burnt-out teeth.

To facilitate the sharpening process, the band saw blade must be unscrewed and suspended for 10-12 hours.

Band saw sharpening with your own hands has some peculiarities. In such cases, as a rule, the back surface of the teeth is sharpened, although, if you use the manufacturer’s instructions or watch a thematic video, you can also sharpen their front surface.

Maintenance of saws

Sharpening the teeth is not enough for maintenance, the teeth must also be set. These two procedures are performed in order of succession: beginning with the setting of the teeth, and finishing with their sharpening. The following chronology of work must be strictly observed. Setting is carried out to reduce the saw’s friction while cutting a material (wood, metal, plastic, etc.). There are several ways of setting, depending on what elements are to be obtained afterwards and the strength of the original workpiece.

Recommendations from the experts

The result of improper work is burned tool teeth.

• The shape of the teeth is a characteristic that has been developed and verified by specialists. If you change it, you won’t be able to work effectively. Based on this, sharpening must be carried out in such a way that the shape of the teeth and the profile of the blade remain the original factory settings.
• If you follow all the rules of operation and maintenance, the band tool will serve you faithfully until its width is worn down to 65 percent of its original value.

Please note! There is a widespread opinion among amateur craftsmen that there is no special need to remove burrs that arise during machining. This is fundamentally wrong, because microscopic cracks can occur in the blade.

After completing work, the band tool must immediately be cleaned of wood sap, sawdust, resin. Inspect the tool carefully before you start maintenance, otherwise you will clog the wheel. This will significantly reduce sharpening efficiency.

Common Mistakes

• Baked saw tooth flanks. This is caused by excessive force applied to the sharpening disc. This fault causes the teeth to blunt very quickly.
• Sub-optimal tooth angle and irregular, angular groove shape.

Such a sharpening result is possible due to several errors:

• drift of the eccentric of the sharpening machine;
• Incorrect angle of inclination of the machine head.
• the wrong profile of the sharpening blade.