A circular saw (the modern name is a circular saw) is a much more effective tool in comparison with reciprocating, longitudinal and chain saws. The quality of the cut and the convenience of work are beyond doubt. With the help of a circular saw, you can perfectly evenly cut a workpiece of a large area, make cuts at different angles and work with a variety of materials.
The circular saw allows you to cut the material both along and across the fibers with the same accuracy and quality. Of course, you can get a clean cut only with properly sharpened teeth. Circular saws fall into three categories:
- All-metal
- All-metal with spraying of hard materials in the working area
- Carbide-tipped saw blades
The presence of technological grooves on saw blades is very important
- A lot of force is required to advance the workpiece during sawing.
- Chips, cracks appear on the cut
- The drive motor becomes very hot during operation
- There is a smell of burnt material
- Dark traces of overheating are visible on the edge of the cut
In addition, the sharpness of the teeth can be checked tactilely and with a magnifying glass. The radius of rounding of the cutting edge should be within 0.1-0.2 mm. When sawing workpieces of large thickness, not only the main working edge is subjected to wear, but also the side ones.
IMPORTANT! When working, always use the right disc for the material. Otherwise, you will mistakenly send a working disk for sharpening.
General rules for sharpening a circular saw
The discs are sharpened a limited number of times. With each procedure, the size of the tooth is reduced. Sooner or later, the tooth grinds down to a critical value, after which the use of the disc will become impossible.
IMPORTANT! It is unacceptable to work on a blunt disk. In addition to deteriorating cut quality, sharpening excessively dull teeth will require more metal to be removed.
In order to extend the resource, sharpening is carried out along two working surfaces of the cutting edge. In this case, the thickness of the surface to be removed is halved.
Schematic representation of the correct sharpening of teeth
If you do not violate the processing rules, sharpening can be done up to 25 times. Before sharpening, the disc must be cleaned of dirt. Mechanical processing is undesirable, it is better to use washing liquids containing solvents in their composition. The standard amount of removal of the tooth surface is 0.05-0.15 mm.
Sharpening angles are individual for each disc, and are indicated in the passport or directly on the sidewall.
Saw blade marking with sharpening angles
For sharpening discs, there are special ones that mechanically control the selected angles for each tooth. Depending on the intensity of use, the grinder can have an automatic or manual drive. At home, as a rule, inexpensive models are used in which the rotation of the disk to the next tooth and the control of the thickness of the metal being ground is carried out manually.
In such devices, the disk is fixed perpendicular to the grindstone, the angle and pitch of the tooth are set. The master runs the sharpened surface on the grindstone a fixed number of times and moves on to the next tooth.
Grinding discs are made of CBN, silicon carbide or use diamond coating. It makes no sense to talk about the fundamental advantage of one material over another. There are only application features. For example, diamond whetstones are capable of cutting harder teeth but are sensitive to overheating.
You can sharpen manually, using a high-quality file. It is better to leave the disc in the machine. The first tooth is marked with a marker, the disc is fixed with wooden bars, clamps or a vice. A fixed number of file passes must be made on each tooth surface. Then rotate the disc by one tooth and repeat the procedure.
How to sharpen a circular saw with your own hands video
Sharpening carbide-tipped discs
Many home craftsmen are faced with the problem of sharpening discs with victorious soldering. If you sharpen with standard abrasives, you have to carry out the procedure longer, and the material can “release” from overheating. Diamond grinding wheels do a much better job, but they are too expensive. Sometimes it is more profitable to buy a new victorious disk.
The choice is up to the owner of the saw, but the general advice is as follows:
When sharpening discs with victorious soldering, in any case, you will have to use the machine, regardless of its technical level. If you have such a machine, purchase a diamond abrasive and sharpening disks of any hardness will not be a problem. If there is no machine, it is better to contact a specialized workshop to sharpen discs with victorious soldering.
You can spend money on the purchase of equipment of any complexity, the main thing is that it does not stand idle, and is in demand. For large volumes of work, it is more profitable to have your own grinding machine for circular saws. If you only perform periodic repairs, it is cheaper to contact the workshop.
How to sharpen a circular saw? A circular saw is an indispensable tool in the construction of a summer house. It surpasses other types of saws in its accuracy and cut quality. The duration of operation of the structure depends on the quality of its sharpening.
The service life of a circular saw also depends on the quality of its sharpening.
An unsharpened disc increases the load on the mechanism. As a result, it may break.
Periodic sharpening of circular saws is necessary.
Signs that indicate that the saw needs to be sharpened:
- when cutting, you need to apply a large load;
- the edges of the cut burn;
- the engine overheats;
- smoke appears during operation.
Sharpening circular saws
Materials and tools:
- saw blade;
- file;
- diamond file;
- marker;
- thin wooden blocks;
- vise;
- wiring;
- wrench.
How to sharpen a circular saw blade? A circular saw must be sharpened from the back when working with the blade facing the wood. The front surface, which is on the material when cutting, remains in the same position.
You can turn the disk in the machine. You can pull the canvas out of it. If turning is carried out in the device, the plug must be unplugged from the electrical outlet to prevent accidental turning on of the device. It is necessary to wedge the product by placing thin sticks under it on both sides and press them against the teeth.
It is necessary to mark with a marker the element from which turning is started. When turning, care must be taken and maximum attention must be paid. Turning is done with a file or a diamond file.
It is necessary to remember the number of movements and the applied efforts when turning the first tooth. The same effort must be applied when turning the remaining parts. If the blade is removed from the machine, you need to clamp it in a vice, then sharpen each tooth in the same way. Then the canvas is installed back into the device.
Perform a cut check on the sample. If noise occurs during operation or the material feed is uneven, check the height of the teeth. To do this, bring a marker to the cutting edge. Then you need to slowly turn the canvas by hand 1 turn in the direction opposite to the direction of rotation. In this case, a mark will appear on each tooth. On examination, you can find out which elements are higher than the rest. If the difference turned out to be significant, you need to carefully reduce the height of the elements.
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How to set the disc teeth
If it is necessary that the movement of the disk be more free, then the teeth are set.
It is necessary to bend all the teeth in turn in different directions at the same distance. The work is done with the help of wiring. Routing is a tool for performing the routing of elements. To perform the wiring, you can use an adjustable wrench. When working with soft woods, they are bred more. When working with hard rocks - less.
To choose the right wiring, you need to test the device when cutting durable wood. The best wiring will be approximately 0.3 - 0.5 mm in one direction. The main requirement is the wiring of elements no more than the thickness of the canvas on both sides. The wiring is done before sharpening.
In the case when it is necessary to turn a blade of higher quality, a machine for mechanized turning is used.
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Mechanized disc sharpening
Materials and tools:
- saw blade;
- disk sharpening machine;
- pendulum goniometer;
- marker.
How to sharpen a circular saw in a mechanized way? There are a large number of different machines. Some mechanisms have software systems to provide a fully automated turning mode. In a home workshop, when turning discs is episodic, a simpler device can be used.
Sharpening angles of teeth of a circular saw: front angle (γ), back (α) and bevel angles of the front and rear planes (ε1 and ε2).
How to sharpen a disc? In such a machine, after it is installed and fixed in a position that provides the required sharpening angle, all other operations - turning the blade around its axis, controlling the thickness of the metal removed from the tooth - are performed manually.
Sharpening of a straight tooth along the front plane is performed in the following sequence. Install the canvas on the frame of the machine. Clamp with a centering sleeve. Then, using the mechanism, it is installed in a strictly horizontal position. Thus, the bevel angle of the front plane is equal to zero. If the machine does not have a built-in angular scale, the horizontalness of the disk is checked using a pendulum goniometer.
Then the screw of the mechanism is rotated, which ensures the horizontal movement of the frame with the circle. Set the required front angle of sharpening. The blade moves in a position in which the front plane of each element fits snugly against the working surface of the circle.
A marker makes a mark on the first tooth, from which sharpening begins. Then the engine is turned on and the front plane is sharpened. The machine brings the tooth into contact with the wheel and performs several movements of the blade back and forth while pressing the element against the wheel.
After sharpening one element, the blade is removed from contact with the abrasive wheel, rotated by one element. Then the operation is repeated in the same way. So the machine works until the element marked with a marker completes a full circle, showing that all elements are sharpened.
Sharpening a beveled tooth differs from turning a straight one in that the saw is placed with an inclination equal to the angle of the bevel of the front plane. To sharpen the element along the back plane, it is necessary that the machine allows you to install the blade so that the back plane of the element is in the same plane as the surface of the circle.
To sharpen a circular saw on a machine, you do not need to have special skills. Any person can cope with this work if they follow all the instructions and rules for working with machines for sharpening discs.
Circular saws with hard-alloy teeth consist of a blade (disk) made of steel 9HF, 65G, 50HFA, etc., and hard-alloy plates that act as cutters.In domestic saws, sintered tungsten-cobalt alloys of VK grades (VK6, VK15, etc., the figure means the percentage of cobalt) are used as the material for cutting plates. BK6 has a hardness of 88.5 HRA, BK15 has a hardness of 86 HRA. Foreign manufacturers use their alloys. Hard alloys VK consist mainly of tungsten carbide cemented with cobalt. The characteristics of the alloy depend not only on its chemical composition, but also on the grain size of the carbide phase. The smaller the grain, the higher the hardness and strength of the alloy.
Fasten hard-alloy plates to a disk by high-temperature soldering. As a material for soldering, at best, silver solders (PSr-40, PSr-45) are used, in the worst case, copper-zinc solders (L-63, MNMTs-68-4-2).
Carbide tooth geometry
Carbide tooth has four working planes - front (A), back (B), and two auxiliary side (C). Intersecting with each other, these planes form cutting edges - the main one (1) and two auxiliary ones (2 and 3). The given definition of faces and edges of the tooth is given in accordance with GOST 9769-79.
The following types of teeth are distinguished by shape.
Typically used in fast rip saws where quality is not a concern.
Oblique (beveled) tooth with the left and right angle of inclination of the rear plane. Teeth with different angles of inclination alternate with each other, which is why they are called alternately beveled. This is the most common form of the tooth. Depending on the size of the sharpening angles, saws with alternately beveled teeth are used for sawing a wide variety of materials (wood, chipboard, plastics) - both in the longitudinal and transverse directions. Saws with a large angle of inclination of the rear plane are used as scoring saws when cutting boards with double-sided lamination. Their use avoids chipping of the coating at the edges of the cut. Increasing the bevel angle reduces the cutting force and reduces the risk of chipping, but at the same time reduces the tool life and strength of the tooth.
The teeth can have an inclination not only of the rear, but also of the front plane.
A feature of these teeth is the relatively slow rate of blunting of the cutting edges compared to alternately beveled teeth. They are usually used in combination with a straight tooth.
Alternating with the latter and slightly rising above it, the trapezoidal tooth performs rough sawing, and the straight one following it - finishing. Saws with alternating straight and trapezoidal teeth are used for cutting boards with double-sided lamination (chipboard, MDF, etc.), as well as for sawing plastics.
Cone tooth saws are auxiliary and are used to cut the bottom layer of the laminate, preventing it from chipping when the main saw passes.
In the vast majority of cases, the front face of the teeth is flat, but there are saws with a concave front face. They are used for fine cross cutting.
Tooth sharpening angles
There are four main sharpening angles of a circular saw, which, along with the shape of the tooth, determine its characteristics. These are the front angle (γ), rear (α) and bevel angles of the front and rear planes (ε 1 and ε 2). The taper angle (β) has an auxiliary value, since it is set by the front and back angles (β=90°-γ-α).
The values of the sharpening angles are determined by the purpose of the saw - i.e. for cutting what material and in what direction it is intended. Rip saws have a relatively large rake angle (15°-25°). For crosscut saws, the angle γ usually ranges from 5-10°. General purpose saws designed for crosscutting and rip sawing have an average rake angle - typically 15°.
The sharpening angles are determined not only by the direction of the cut, but also by the hardness of the material being cut. The higher the hardness, the smaller the front and back angles should be (less sharpening of the tooth).
The front angle can be not only positive, but also negative. Saws with this angle are used for cutting non-ferrous metals and plastics.
Basic sharpening principles
The main wear of a carbide tooth occurs along its main (upper) cutting edge. In the process of work, the latter is rounded to 0.1-0.3 mm. Of the faces, the front wears out the fastest.When sawing massive workpieces, the side edges are also subject to rapid wear.
The saw must not be overblown. The cutting edge rounding radius should not exceed 0.1-0.2 mm. In addition to the fact that when working with a very blunt saw, productivity drops sharply, it takes several times more time to sharpen it than to sharpen a saw with normal bluntness. The degree of dullness can be determined both by the teeth themselves and by the type of cut they leave.
Proper sharpening of circular saws is to simultaneously ensure the proper sharpness of the cutting edge, to ensure the maximum number of sharpenings, which in the optimal case can reach 25-30 times. For this purpose, it is recommended to sharpen the carbide tooth along the front and back planes. In fact, the teeth can be sharpened along one front plane, but the number of possible sharpenings is almost two times less than when sharpening along two planes. The figure below clearly demonstrates why this happens.
The last pass when sharpening saw blades is recommended to be done along the back plane of the tooth. The standard amount of metal removal is 0.05-0.15 mm.
Before sharpening, it is necessary to clean the saw of impurities, such as resin, and check the sharpening angles. On some saws they are written on the disk.
Equipment and materials for sharpening saw blades
Depending on the material from which the teeth are made, circular saw blades can be sharpened with CBN, green silicon carbide, or diamond (PCD) wheels. So, CBN wheels are capable of sharpening high-performance high-speed steel wheels, diamond wheels and green silicon carbide wheels - hard alloy cutters.When using abrasive wheels (especially diamond wheels), it is desirable to cool them with coolant.
One of the significant disadvantages of diamond is the relatively low temperature stability - at a temperature of about 900°C, the diamond burns out.
With increasing temperature, the microhardness of abrasive materials decreases. Increasing the temperature to 1000°C reduces the microhardness by almost 2-2.5 times compared to the microhardness at room temperature. An increase in temperature to 1300°C causes a decrease in the hardness of abrasive materials by almost 4-6 times.
The use of water for cooling can lead to rust on machine parts and assemblies. To eliminate corrosion, soap and certain electrolytes (sodium carbonate, soda ash, trisodium phosphate, sodium nitrite, sodium silicate, etc.) are added to water, which form protective films. In normal grinding, soap and soda solutions are most often used, and in fine grinding, low-concentration emulsions are used.
However, when sharpening saw blades at home with a low intensity of grinding work, they do not resort to cooling the circle so often - they do not want to spend time on this.
To increase the productivity of sharpening with abrasive wheels and reduce specific wear, you should choose the largest grit that provides the required surface cleanliness of the tooth being sharpened.
To select the grit size of the abrasive, in accordance with the stage of sharpening, you can use the table in the article about sharpening bars. For example, in the case of using diamond wheels, wheels with a grain size of 160/125 or 125/100 can be used for rough sharpening, and 63/50 or 50/40 for finishing. Wheels with a grit size of 40/28 to 14/10 are used for chipping.
It is necessary to strive to ensure that the surface of the tooth is very smooth. If there are notches on the surface of the tooth, then the protrusions will crumble when the saw is used, and it will become dull very quickly.
The circumferential speed of the circle when sharpening carbide teeth should be about 10-18 m / s. This means that when using a wheel with a diameter of 125 mm, the engine speed should be about 1500-2700 rpm. Sharpening of more brittle alloys is carried out at a lower speed from this range. When sharpening carbide tools, the use of hard modes leads to the formation of increased stresses and cracks, and sometimes to chipping of the cutting edges, while wheel wear increases.
When using machines for sharpening circular saws, changing the relative position of the saw and the grinding wheel can be implemented in different ways - by moving one saw (the motor with the circle is stationary), by simultaneously moving the saw and the engine, by moving only the motor with the circle (the saw blade is stationary).
A large number of grinding machines of various functionality are produced. The most complex and expensive programmable complexes are capable of providing a fully automatic sharpening mode, in which all operations are performed without the participation of a worker.
In the simplest and cheapest models, after installing and fixing the saw in a position that provides the required sharpening angle, all further operations are turning the saw around its axis (turning on the tooth), filing for grinding (introducing into contact with the wheel) and controlling the thickness of the tooth removed from the tooth. metal - are made by the worker manually. It is advisable to use such simple models at home, when sharpening circular saws is episodic.
An example of the simplest machine for sharpening circular saws is the system, a photograph of which is shown in the photo below. It consists of two main units - an engine with a circle (1) and a caliper (2), on which a sharpened saw is installed. The turning mechanism (3) is used to change the angle of inclination of the blade (when sharpening teeth with a beveled front plane). With the help of the screw (4) the saw is displaced along the axis of the abrasive wheel. This ensures that the required value of the front angle of sharpening is set. The screw (5) is used to set the limiter in the desired position, preventing excessive entry of the wheel into the interdental cavity.
Saw blade sharpening process
Sharpening a straight tooth along the front plane. Sharpening of a straight tooth of carbide saw blades is carried out in the following sequence.The saw is mounted on a mandrel, clamped with a conical (centering) sleeve and a nut, then set in a strictly horizontal position by means of the mechanism (3). This provides a bevel angle of the front plane (ε 1) equal to 0°. On machines for sharpening disks that do not have a built-in angular scale in the tilt mechanism, this is done using a conventional pendulum goniometer. In this case, the levelness of the machine should be checked.
By turning the screw (4) of the mechanism that provides horizontal movement of the mandrel with a circle, the required front angle of sharpening is set. In other words, the saw moves to a position in which the front plane of the tooth fits snugly against the working surface of the circle.
The marker makes a mark of the tooth from which sharpening begins.
The engine is turned on and the front plane is sharpened - by putting the tooth in contact with the circle and several movements of the saw back and forth while simultaneously pressing the tooth against the circle. The thickness of the removed metal is regulated by the number of sharpening movements and the force of pressing the tooth against the abrasive wheel. After sharpening one tooth, the saw is removed from contact with the wheel, rotated by one tooth, and the sharpening operation is repeated. And so on until the marker mark makes a full circle, indicating that all the teeth are sharpened.
Sharpening a tooth beveled along the front plane. The difference between sharpening a beveled tooth and sharpening a straight one is that the saw must be installed not horizontally, but with an inclination - with an angle corresponding to the angle of the bevel of the front plane.
The angle of inclination of the saw is set using the same pendulum goniometer. First, a positive angle is set (in this case +8°).
After that, every second tooth is sharpened.
After sharpening half of the teeth, the saw blade angle changes from +8° to -8°.
And again, every second tooth is sharpened.
Sharpening on the back plane. To sharpen a tooth along the back plane, it is necessary that the saw blade sharpening machine allows you to install the saw in such a way that the back plane of the tooth will be in the same plane as the working surface of the abrasive wheel.
If there is no machine for sharpening saw blades
Sharpening circular saws on functional and convenient specialized machines does not require special professional skills. A little practice - and sharpening will go without any problems. But most people use carbide saw blades occasionally, as needed. Spending a significant amount on a special sharpening machine, which is used for several hours a month, does not seem reasonable to everyone.Accurately maintaining the required sharpening angles, holding the saw in your hands on weight, is an impossible task even for a person with a unique eye and an enviable hardness of hands. The most reasonable thing in this case is to make the simplest sharpening device, which makes it possible to fix the saw in a certain position in relation to the circle.
The simplest of these devices for sharpening circular saws is a stand, the surface of which is flush with the axis of the grinding wheel. By placing a saw blade on it, it is possible to ensure the perpendicularity of the front and back planes of the tooth with respect to the saw blade. And if the upper surface of the stand is made movable - fixing one side hingedly, and the other - resting on a pair of bolts that can be screwed in and out - then it can be installed at any angle, making it possible to sharpen an oblique tooth along the front and rear planes.
True, in this case one of the main problems remains unresolved - maintaining the same front and rear sharpening angles. This problem can be solved by fixing the center of the saw relative to the abrasive wheel in the desired position. One way to implement this is to make a groove on the surface of the stand for the mandrel on which the saw is mounted. By moving the mandrel with a circle along the groove, it will be possible to maintain the required front angle of sharpening the tooth. But for sharpening circular saws with different diameters or sharpening angles, it should be possible to either move the engine or the stand and the groove with it. Another way to ensure the required sharpening angle is simpler, and is to install stops on the table that fix the disk in the desired position. At the end of the article there is a video demonstrating such a device.
Sharpening quality control
The sharpened teeth must be free of cracks, chips, visible risks from the grinding wheel. The radius of rounding of the cutting edge should be no more than 0.015 mm. Visually, this can be defined as the absence of glare on the cutting edge.GOST 9769-79 establishes certain tolerance values for sharpening parameters. The end runout of the tops of the teeth should not exceed 0.2 mm (for saws with a diameter of up to 400 mm), the radial runout should not exceed 0.15 mm. The runout is checked using a conventional dial gauge.
Deviations of sharpening angles should not exceed:
- for front angle - ±1°30";
- for the rear corner and bevel angles of the front and rear planes - ± 2 °;
Video:
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A circular is a device on which work is carried out with building material. As a rule, a tree is processed. A toothed disk is used as a cutting tool. Over time, he dulls. Sharpening a circular saw blade is carried out both on a special machine and with your own hands at home.
Sharpening circular saw blades is required when work becomes impossible. This can be understood by three signals:
- Protective cover heating. Smoke appears from under it, exits the cutting zone.
- The need for additional effort when feeding the workpiece at the time of cutting.
- When wood comes into contact with cutting metal, burning and smell appear.
Types of teeth
The main cutting element of the disc are the teeth. They are made from hard metal. The tooth consists of four sides: anterior, posterior and two lateral. Also from the main cutting edge and two additional ones.
Teeth requiring sharpening are divided into:
- Direct. Are applied to longitudinal sawing of a cloth.
- Beveled. They have an angle cut on the back plane of the tooth. They can cut not only wood, but also plastics or chipboard.
- Trapezoidal. In cross section, the cutting plane has the shape of a trapezoid. Thanks to this, they can be sharpened less often.
- Conical. They have the shape of a cone.
Sharpening angles
A circular saw has four corners which, after blunting, must be sharpened. These are the front and back corners. Also the cutting angles formed by the front and back surfaces.
Depending on the direction of sawing, they are needed. In longitudinal cutting, the value of the front angle is in the range of 15−25 degrees. In the case of cross cutting, the grinding angle is reduced to 5-10 degrees. If universal cuts are required, then the tooth is sharpened at an angle of 15 degrees.
An important influence on the value of the angle is the density of the material. The lower it is, the sharper the tooth is required. If the material being processed is plastic, then the angle can be negative.
Sharpening circular saws with pobedite soldering
The sharpening angles of carbide-tipped saw blades are not easy to maintain because the tooth is applied to win. This alloy is attached by soldering. The geometry of the cutting part is complex, and the sharpening parameters require precise exposure.
The work is carried out when the cutting edge is smoothed to a radius of 0.3 mm. A larger value should not be allowed.
- Sharpening is carried out on the front and back planes of the tooth. If the work is carried out correctly, then the total number of sharpenings until the blade is completely worn out will be 30 times.
- Start work from the front plane.
- The part of the tooth that is soldered should fit snugly against.
- Turning time is 3 to 5 seconds. It can't be longer. This leads to excessive heating of the metal. It is reheated and tempered with a decrease in hardness.
- The thickness of the material to be ground is around 0.15 m.
Machine Application
The simplest machine for working at home is is an abrasive motor. Wheels can be diamond, elbor or silicon carbide.
It is difficult to keep the canvas in a certain position relative to the abrasive. You need to use the tools. This may be a horizontal stand or a fixing device, where the upper plane must coincide with the axis of the abrasive.
The tooth to be sharpened is positioned on a plane so as to be perpendicular to the blade. After turning on the engine, the canvas is brought to the circle and pressed against it with a tooth. The layer of the removed metal is regulated by pressing force. Having finished work with one tooth, the next one is brought up in the same way. And so on in a circle to the end.
For the purpose of universalization, the stand is modernized. The front part is made movable, and a pair of bolts is screwed into the back. With their help, you can adjust the inclination of the canvas. It becomes possible to sharpen the front and back plane of the oblique tooth.
There remains the problem of maintaining the same angles of front and rear sharpening. To do this, it is necessary to fix the canvas relative to the center of the abrasive wheel. To do this, the disk is inserted into a special mandrel, and a groove is made under it in the stand. The necessary is maintained by moving the mandrel along the groove. If the diameter of the discs is different, then it must be possible to move the engine or stand with a groove.
Another way is to install stops that will fix the desired position of the disk.
Sharpening by hand
In the absence of a machine, sharpening can be done with a file. To do this, it is important to clearly fix the disk. This is done with a vice. If the canvas is not removed from the circular, then you can do without them. Bars are inserted between the teeth, and the tool rests against a vertical plane.
A mark is made at any point of the circle with a marker. This will make it clear when the work is completed. Processing is carried out with a flat file, which fits well between the teeth. The upper edge of the tooth and its front face are subjected to the greatest wear.
First, work is carried out with the back surfaces of the teeth around the entire circle. At the second stage, they begin to sharpen the front edges. It is important to remember that the applied force must be the same, then all the teeth will be evenly sharpened.
It is really possible to sharpen a circular disc at home. To do this, it is better to purchase a simple machine. In his absence, you can use a vice or homemade stops. At the end of the work, check the tool. In the process of cutting, his work should be smooth and quiet.
Sharpening circular saws with your own hands is not difficult for a person who has the skills to work with metalwork equipment. The popularity of circular saws is due to the advantages provided by the operation of this equipment. The main advantages of this tool are cutting accuracy, high quality and cleanliness of its surface. Circular saws are a very popular tool that is very actively used, which leads to rapid wear of the working surfaces. Recovery is carried out by sharpening the working element of the tool.
Signs of need for sharpening and tools used
In order to sharpen the saw, you need to prepare the following tools:
- file;
- assembly vise;
- a block of wood;
- colored marker.
Sharpening of the circular saw is carried out as needed. The need for sharpening saws on wood is determined depending on the intensity of use of the tool.
There are several signs of this:
- Saw sharpening is required if, during the operation of the device, a strong heating is observed on the safety cover in the area of the electric drive. In some cases, an increase in temperature causes smoke to form from under the saw guard.
- It is necessary to sharpen the saw when, in order to obtain a high-quality result, a stronger impact must be exerted on the saw blade.
- During the operation of the unit, dark marks appear at the place where the cut was formed, which are traces of soot. The formation of such marks may be accompanied by the appearance of a characteristic smell of burnt wood. If these signs occur, stop using the tool and sharpen the working edges on the cutting elements of the saw blade of the electric saw.
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Varieties of working elements of the saw blade of a circular electric saw
In order to know how to correctly sharpen elements on circular saw blades, it is necessary to study the structural features of that part of the circular tool with which wood is sawn. The main element of this part of the disc are the teeth. The production of teeth is carried out using carbide metals. In each of the teeth, four working planes are distinguished:
- front;
- back;
- right and left side.
The planes provide a supporting role. In the geometry of the tooth, one main and two additional cutting edges are distinguished. The edges for cutting the material are formed on the line of intersection of the work planes. Depending on the configuration, all the cutting parts of the working element of the unit can be divided into several varieties:
- straight;
- bevelled;
- trapezoidal;
- conical.
Straight teeth are used for fast ripping. This type of cutting elements is not used when obtaining an ideal cut quality.
Beveled working elements are characterized by the presence of a flat surface on the back of the tooth on the left or right side. Some models of circular saws have working elements with different sides of the bevel, which alternate with each other. Such discs are called alternately bevelled. This type of disc is used when it is necessary to cut, in addition to wood, chipboard and various plastics. The presence of a large bevel ensures high-quality sawing without the formation of chips on the edges. The working elements in cross section have the shape of a trapezoid. Due to the presence of such a tooth configuration, the working elements of the disk are able to work for a long time without a visible deterioration in the quality of the cutting edges.
Conical working elements on the cross section have a conical shape. Most often, discs with such working teeth are used as auxiliary ones when pre-cutting the laminate. Discs with such teeth help to avoid the occurrence of chips when cutting the laminate.
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Principles and angles of sharpening the working elements of a circular saw
The working surfaces of the elements are sharpened at the four corners of sharpening. The sharpening angles and the shape of the cutting element are the main parameters of the disc, on which the quality of the work performed depends. The circular tooth has two main angles (back and front), in addition, the characteristics of the working element include the cutting angles of the front and rear surfaces. The characteristics of the sharpening angles depend on the purpose of the device for sawing, the material being processed and the direction of processing.
A saw for a circular saw intended for longitudinal cutting of material is sharpened at a large rake angle, for sawing in the transverse direction, a sharpening angle of 5-10 ° is used. A universal sharpening option is considered to be an angle of 15 °. The level of hardness of the material being processed affects the angle of sharpening of the working elements. The harder the material being cut, the smaller the sharpening angle the saw tooth should have.
During the operation of the tool, the upper cutting edge wears out to the maximum. As a result of the use of the tool for its intended purpose, the cutting edge is rounded. The rounding factor can reach 0.3 mm or more. Among the planes, the front one is subjected to maximum wear.
Proper sharpening should ensure the appearance of the edges, in which their rounding does not exceed 0.2 mm.
For this purpose, simultaneous grinding of the rear and front planes of the work items is used. This sharpening method is optimal. It is possible to sharpen only the front plane, but in this case, the sharpening process takes more time, and the tooth wears out faster due to the fact that it is necessary to grind the metal. With standard sharpening, it is necessary to remove metal with a thickness of 0.05 to 0.15 mm.
