How To Change A Blade On A Saw Blade
DIY circular saw repair
When starting to repair the unit with your own hands, it is not necessary to disassemble it completely to find out the reasons for the breakdown. Some malfunctions are characterized by specific symptoms, by which you can determine the problem and purposefully disassemble one or another part of the device.
Reducer housing gets very hot
Rapid heating of the gearbox occurs if the shaft bearing has become unusable, on which the gear is fixed and the equipment is attached. In this case, in addition to heating, you can replace the appearance of extraneous noise in this unit of the device. It is necessary to disassemble the gearbox and change the bearing. Also, the gearbox will warm up if there is not enough lubricant in it or it is completely absent.
Shaft jammed during operation
This malfunction can occur when, for any reason, the stopper is pressed while the tool is running. It is designed to secure the shaft when changing tooling and should be used after the motor has come to a complete stop. Otherwise, the stopper stem breaks and debris falls into the engine, causing seizure. There are often cases when this leads to deformation of the armature shaft. Also, the consequence of pressing the stopper can be a split in the gearbox housing, the fragments of which can damage the gears and cause them to jam. To solve the problem, you will need to replace the armature, stopper, drive (large) gear of the gearbox and its housing.
In some cases, the gearbox can jam when the bearing is completely destroyed.
The saw does not start
If, when you press the start button, the engine of the unit is “silent”, then the first thing to focus on is the mains cable, provided that there is electricity in the outlet (to check, connect the device to another outlet).
To check the electrical cable, you need to disconnect the handle. This will help you get to the pins where the power cord wires are soldered. Next, using a tester, ring each wire by pressing one probe to the soldered contact, and the second to the pin of the plug.
If the network cable is intact, then in search of a malfunction, do the following.
- Test the entire circuit with a tester, starting from the cable entry into the unit to the start button. You should also check the contacts of the button at its input and output when the key is pressed. In the normal state, an open circuit should be closed. Ring all the wires after the button, going to the motor brushes.
- If everything is in order with the conductors, check how worn out the brush electrodes. After the electrode is worn out by 2/3 of its original size, it should be replaced. Brushes, no matter how worn out each of them, change in pairs.
- If the brushes are in good condition, then, most likely, the engine is out of order. An open or interturn short circuit could occur in its windings. In this case, it is better to entrust the engine repair to specialists who will rewind the stator or armature coils.
The device and principle of operation of a circular saw
A hand-held circular saw differs from a miter saw in the absence of a bed with a rotary table, as well as in the placement of the handle. But in general, both models are similar in internal structure, principle of operation and do not differ in the complexity of the design. The following figure shows the device of a hand-held circular saw.
The unit includes the following main elements.
- Upper protective casing with an opening for ejection of sawdust.
- The body, which houses the electric motor and the start button. Some saw models can operate on rechargeable batteries. In this case, the battery pack is also placed on the case.
- Lower (movable) protective cover that automatically closes the cutting element after it leaves the workpiece.
- Saw blade. Fastened to the gearbox shaft with a nut or bolt.
- Parallel stop. Allows you to make an even cut without the use of additional devices.
- Base plate (base) of the unit. Thanks to it, the tool is installed on the workpiece or rail at different angles.
- Depth adjuster. It can be used to adjust the overhang of the saw blade relative to the base plate.
- Sole angle adjuster. Allows you to tilt the unit for cutting at an angle.
This tool works according to the following principle. Mains or battery power is supplied to the start button, which breaks the circuit. When you press the start button, the current begins to flow to the electric motor. Below is the wiring diagram of the unit.
The electric motor starts and transfers the rotary motion through the gearbox to the saw blade. The unit is installed using a soleplate on a workpiece or a guide rail, after which the process of both longitudinal and transverse sawing is performed.
The saw stops during operation
In most cases, the engine stops due to worn-out electric brushes. When the contact between the brush electrode and the collector lamellae is broken, the unit turns off.
Often, when buying brushes for this device, you come across products with a short conductor connecting the electrode to the plate. This conductor is located inside the spring and does not allow it to fully unclench. When the electrode wears out to a certain length, then pressing it to the collector stops, since this is prevented by a short conductor. If, while inspecting the brush, you find that it is not yet worn out and the spring does not expand, then the part should be replaced.
Main malfunctions and their symptoms
Typical malfunctions of hand-held circulars include the following situations.
- The saw does not start. The mains cable, power plug, start button, or electric brushes may be defective.
- The engine of the instrument is very hot. Such symptoms may be the result of a turn-to-turn short circuit (breakage) in the armature or stator coils, as well as an excessively intensive mode of operation of the unit.
- The gearbox of the device is overheating. Overheating of this unit may occur due to bearing failure or lack of lubrication on the gears.
- The brushes sparkle. This is usually due to excessive wear and tear.
- A burning ring is visible around the engine manifold. If, during operation of the unit, a circular spark is observed around the engine manifold, then its appearance can cause a malfunction of the armature winding or clogging of the space between the collector lamellas with graphite dust.
- The unit does not develop the required power. The drop in power may be due to a voltage drop in the network, malfunction of the motor windings, wear of the electric brushes, malfunction of the start button.
- During the operation of the unit, grinding and other extraneous sounds are heard. These symptoms can be caused by broken gear teeth or bearing malfunction.
- The engine is humming but the unit is not running. A jam may have occurred in the gearbox.
The saw stops during operation
Stopping the engine in most cases is caused by a cavity of worn out electric brushes. When the contact between the brush electrode and the collector lamellae is broken, the unit turns off.
Often, when buying brushes for this device, you come across products with a short conductor connecting the electrode to the plate. This conductor is located inside the spring and does not allow it to fully unclench. When the electrode wears out to a certain length, then pressing it to the collector stops, since this is prevented by a short conductor. If, while inspecting the brush, you find that it is not yet worn out and the spring does not expand, then the part should be replaced.
Tool disassembly
Almost all malfunctions of electric circular saws cannot be eliminated without disassembling the device partially or completely. Complete disassembly of an electric hand saw using the example of the Interskol unit is performed in the following order.
- Unscrew the angle and depth adjusting screws attached to the sole of the machine.
- Press the gearbox shaft stop button and use the hex wrench to unscrew the bolt holding the saw blade.
- Pulling the lower guard to the side, remove the circular disc.
- To remove the support sole, first unscrew the fasteners on its underside.
- Next, using two screwdrivers, remove the Sieger ring, which locks the rod on which the sole turns, to change the angle.
Insert a screwdriver into the gap between the body of the shield and the sole, then push it aside and remove.
Next, disconnect the unit’s gearbox by unscrewing 2 screws.
Removing one half of the handle, you will see the soft start module and the start button.
This concludes the complete disassembly of the circular saw.
How to sharpen?
Like any other tool, the saw needs timely maintenance. The most important point is the sharpening of circular saw blades. Experts note that the carbide tooth wears out on the main top, except that if the massive workpieces are sawn, the flanks wear out quickly. Excessive blunting of the saw should not be allowed, as it will be less productive, and not so that it will be possible to sharpen the discs.
Correct sharpening requires at the same time ensuring the correct sharpness of the cutting edge. If you sharpen them on the same front plane, the amount of sharpness will be less. Many owners of these tools are interested in how to sharpen a circular saw blade. And it depends on the material of the teeth. Sharpening is most often performed on a circle of CBN or green carbide or on the basis of diamond wheels. Elborovye rings are suitable for sharpening HSS saws and diamond cutters for carbide cutters. For sharp grinding quickly, but less impact on the degree of wear, it is worth choosing diamond wheels with the greatest detail.
For shredding, you can also use machines that have different functionality. The most complex and expensive models. these are ways to provide automated grinding. When sharpening, it is necessary to part the teeth: if this is not done correctly, the smell of burning, external noise will appear during cutting, and the material itself will move with jerks, which is not very convenient.
In general, the condition of the disks must be constantly monitored, since their wear will affect the increased load on the mechanisms and, sooner or later, will lead to its complete failure. Regular sharpening can extend equipment life, increase productivity and shorten the cutting process itself. If after sharpening the cut remains inaccurate and the material moves unevenly, then you should pay more attention to the position of the teeth.
Count your teeth
How will you see it?
The saw blade for a circular saw should be selected according to the type of cut. it can be transverse or longitudinal. In addition, the content you plan to see plays an important role. wood, plastic, chipboard, non-ferrous metals, pipes Note one thing: each series of discs is designed specifically for certain types of work ,
The quality of the disc blade directly affects the cutting efficiency. A good blade is created by laser cutting, with balancing done on a computer. Each disc is ground separately. A good quality fabric in the light will reflect marks from the sander. If the canvas is rough and looks rough, this circular saw blade will not work efficiently and will dull faster.
Brushes are burning
Strong sparking from under the brushes is caused by excessive wear when the spring can no longer press the electrodes against the collector with the required force. To replace the brushes, you need to disconnect the motor cover or remove them through the special holes in the motor housing (depending on the saw model).
Technical data?
The device and principle of operation of a circular saw
A hand-held circular saw differs from a miter saw in the absence of a bed with a rotary table, as well as in the placement of the handle. But in general, both models are similar in internal structure, principle of operation and do not differ in the complexity of the design. The following figure shows the device of a hand-held circular saw.
The unit includes the following main elements.
- Upper protective casing with an opening for ejection of sawdust.
- The body, which houses the electric motor and the start button. Some saw models can operate on rechargeable batteries. In this case, the battery pack is also placed on the case.
- Lower (movable) protective cover that automatically closes the cutting element after it leaves the workpiece.
- Saw blade. Fastened to the gearbox shaft with a nut or bolt.
- Parallel stop. Allows you to make an even cut without the use of additional devices.
- Base plate (base) of the unit. Thanks to it, the tool is installed on the workpiece or rail at different angles.
- Depth adjuster. It can be used to adjust the overhang of the saw blade relative to the base plate.
- Sole angle adjuster. Allows you to tilt the unit for cutting at an angle.
This tool works according to the following principle. Mains or battery power is supplied to the start button, which breaks the circuit. When you press the start button, the current begins to flow to the electric motor. Below is the wiring diagram of the unit.
The electric motor starts and transfers the rotary motion through the gearbox to the saw blade. The unit is installed using a soleplate on a workpiece or a guide rail, after which the process of both longitudinal and transverse sawing is performed.
Soldering circular saws
A carbide tooth saw blade includes a steel blade (disc) and carbide inserts that protrude as cutters.
Tungsten-cobalt alloys of the following grades are used in Russian products: VK (VK 6, VK 15, etc.). Foreign manufacturers have a different alloy composition. The properties of the alloy depend on the grain size of the carbide cutter. Smaller grains are characterized by high hardness and strength of alloys. Plates are fixed to the disc using high-temperature soldering. For soldering, silver solders are used (PSR-40.45), the worst option would be copper-zinc solders (L-63, MNMTs-68-4-2).
The tooth has four working planes. These are the front and back, and, accordingly, the side ones. According to the shape, the teeth are divided into straight, oblique, trapezoidal, conical.
The cutting edge and the leading edge of the cutters are subject to the main deformation. Correct sharpening implies the achievement of the required edge sharpness, for this the maximum number of sharpenings can reach about thirty. The tooth is sharpened along the front and back planes. Before sharpening, the saw must be free of all types of dirt.
Repair and soldering of discs for circular saws
There are many saw blade models on the market today. The blade is a working tool for cutting a variety of materials. It is used both in a stationary machine and in a portable tool.
Cutting teeth on a circular saw
The teeth are cut with a file in case of breakage. Before cutting the old teeth, grind it down to the defect mowing line, then plan it. If it is necessary to cut small teeth up to 5 mm high, they are planed to half the height of the tooth, then the tooth is cut in half with a file. This is a rather laborious process that requires significant expenditure of man-hours. In addition, a set of files is consumed for the process of cutting one blade. To speed up cutting, a device is used that resembles wire cutters in shape. They chip the metal before the teeth form.
Saw blade for wood with carbide taps
The discs are designed for sawing wood products from the most common wood species. Included with circular saws. The maximum permissible speed is about ten thousand revolutions per minute. They are made of molybdenum high-carbon steel with additions of chromium, nickel, pobedit, which serve to extend the service life. Protects against thermal deformation. Carbide tipped teeth contain cobalt and tungsten compounds. This improves their wear resistance, sharpens cutting edges and increases resistance to shock loads.
Repair of saw blades for wood
If the disc becomes dull and stops doing its job, then there is no need to contact a repair shop. You can do the sharpening process yourself.
Due to the large dimensions of the disc, it will be impossible to hold it during operation. For this it is worth making a holding device. A board can play its role. Its level should be aligned with the axis level on the disc. The location of the wheel on the stand should be such that the working surface of the teeth is perpendicular to the surface of the disc. To work with deformed incisors on the front and back surfaces, it is necessary to use movable hinges.
Since it is difficult to control the rake and rake angle, it is necessary to strictly fix the center of the saw in relation to the grinding wheel. This must be corrected using the dressing groove.
With the help of this article, you will not be confused if you suddenly need to fix your instrument. Hope this article helped you.
How to remove a blade from a circular saw?
To properly remove the canvas, you need to adhere to the following sequence:
- For your own safety, be sure to disconnect the power cord from the mains or remove the battery
- For more convenient replacement, you need to place the tool on a flat, hard surface
- To start unscrewing the bolt, you must press the locking spindle, which blocks the rotation of the disc when unscrewing
- Unscrew the bolt using the special wrench included in the kit
- Pull out the bolt and remove the washer holding the saw blade
- Move the lower guide arm to raise the guard
- Remove the saw circle
Removing and replacing the circular saw blade
Due to the competition in the market, the choice of electrical tools is constantly increasing, and are becoming more affordable. Now women are happy to give them to men on February 23rd, or relatives and friends for their birthday. Almost every second household man has his own circular circular saw.
Over time, the circles fail (dull or break), they must be replaced depending on the material with which you need to work. For example, you cannot cut wood with a metal cutting blade. Therefore, the ability to correctly and quickly remove the disc, put a new one is necessary for everyone.
How to change a circular saw blade?
The new canvas must be installed in the following sequence:
- Clean the pulley and protection from accumulated dirt, sawdust.
- Check the correct direction of the saw teeth in accordance with the arrow on the guard.
- Put the blade on the pulley and lower the lower protective shield.
- Install the retaining washer and screw in the bolt. Tighten it again with the recessed locking spindle.
Washer for circular saw?
A flange or washer holds the disc securely in place. On various saw models, both a flange separate from the bolt and soldered to it is used.
Change a reciprocating saw blade
The main function of the hold-down washer is to evenly press the saw blade against the pulley. A correctly installed washer should sit symmetrically on the circle.
The main and main rule when replacing a blade on a circular saw is to completely disconnect the tool from the power supply. To avoid accidentally injuring yourself with the saw teeth, it is best to wear gloves.