Do-it-yourself circular saw repair. Repair of circular saws. How long will the repair take

First, we remove the saw and the safety cover; to remove the lock washer, you will have to use a special tool or contrive,

I, to remove the counterwasher, used a drill, a rivet and bent round pliers.

Next, remove the collector cover and the handle, thus freeing access to the worm gear

Remove the gearbox, unscrew the bolts securing the main bearing flange

we bend the insulating gasket of the handle from the body, remove the brushes

and pull out the flange of the main bearing - a burnt anchor, here it is, in all its glory

further - we alternately knock the bearings off the armature shaft from the side of the collector and the worm, for these purposes it is better to use a puller, but if it is not at hand, you can take, for example, a powerful key, clamp it in a vise and tap on the end of the armature shaft, put it on him, bearing. In the same way, but, already with an emphasis on the protrusions of the main bearing flange, the main bearing is knocked down.

after removing the bearings from the burnt armature, they can also be put on a new anchor by lightly tapping on the end of the bearing, gradually pulling the bearing onto the armature shaft, the same is done with the second bearing. The assembly of the saw, but, already with a new anchor, occurs in the reverse order. We wish you success, do not rush during assembly, so as not to touch the armature with something sharp and hard and not damage the windings and the collector of the new armature.

The merits of any home tool can only be fully appreciated after it fails. This axiom is known to every home master. The presence in the arsenal of a large number of devices has led to the fact that most people simply cannot imagine how to do this or that operation without them.

A circular saw is used for smooth cutting of various materials.

In the case of a circular saw, this is especially true. The fact is that it is indispensable for longitudinal sawing of wood; it does not have a worthy analogue among hand tools. You can't do this with a regular hand saw. Therefore, when the circular for some reason refuses to work, all work stops. Something urgently needs to be done. However, do not rush to carry it to the workshop, it is quite possible to repair the circular saw yourself.

Fault localization

The first step is trying to determine what is broken. This refers not to a specific node, but to the nature of the damage. It can be mechanical or occur in the electrical part of the saw. In other words, if smoke came out of it, this is one thing, and when extraneous noise or whistle appears, this is quite another. It is these two criteria that are the main ones in the localization of a malfunction. There is, however, a third, when the saw does not make any sounds at all. Let's start with him.

Oddly enough, the fact that the saw is silent can be a good sign. Here it would be useful to mention those malfunctions that are usually printed on the last page of the instruction manual. At first glance, they seem ridiculous, but show them a little respect. Check if there is voltage in the socket and if the power cord is working. If everything is fine, then there is only one chance to avoid a complete disassembly - check the brushes.

On the vast majority of circulars, in order to get to the brushes, you need to unscrew two bolts. This assembly consists of two carbon elements that abut against the manifold. Since it constantly rotates, the brushes are subject to wear and over time “freeze”, i.e. don't get to him. It is necessary to pay attention to it first of all. In addition, the carbon brushes are connected to the stator terminals. In this place, contact is sometimes lost. Check it. If everything is fine, disassembly can not be avoided.

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Disassembly and its features

The operation itself is quite complicated, some workshops take money for it, regardless of the result of the repair. Each saw has its own device, and exact advice cannot be given. You can deal with this on your own. But what to disassemble in the first place, we will consider in more detail.

A very common damage, regardless of brand, is a switch button failure.

For all models, it is located in the handle, which, when untwisted, diverges into two parts.

You can’t halve it to the end, it will hold on to other parts, but you can already get to the button, but it will be a little inconvenient. Despite this, it is necessary to check the operability of the switch with the probes of the tester.

If it turns out to be faulty, the repair is complete. However, in order to put a new one in place, the saw will have to be completely disassembled. But if the button is working, you will also have to do this.

Take off the disc. There was an opportunity to remove the protection, which you do. Under it are 4 long bolts, unscrew them. The sequence and number of parts may be slightly different, but in the end, the engine with a gearbox, a handle and an electric cord should remain in the hands. Disconnect the gearbox, and then it's time to remember how the malfunction manifested itself.

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Mechanical failures

Symptoms of such malfunctions can manifest themselves in different ways, but almost always work is accompanied by extraneous noise. It can be whistling, grinding or clicking. Now, while the motor and gearbox are still assembled, it is necessary to establish which of them is faulty. Try turning the motor by the shaft. It should rotate quite hard, but evenly, i.e. should not wedge.

If the motor shaft does not rotate or rotates jerkily, the motor is faulty. Take it apart and look at the bearings. The first is in the engine housing, the other on its rotor. With full confidence, we can assume that one of them is to blame. It would be nice to have the first one, it is quite easy to change it.

If the bearing at the anchor of the engine is to blame, you can safely carry it in for repair. It is almost impossible to remove it yourself without a special tool. In addition, any attempt to do so may result in damage to the anchor. Not the whole saw will have to be carried to the workshop, but only the rotor. It's easier and cheaper.

The main malfunction of the gearbox is the wear of the gear teeth. In this case, it must be replaced. You should also pay attention to the slots of the anchor. They shouldn't be damaged either.

A circular hand saw is a fairly practical tool with which you can quickly saw a wooden blank of any length and width along or across, cut any wood-based sheet material. In addition, after changing the equipment with a circular saw, you can cut plastic, metal corrugated board and corrugated board. Despite the simplicity of design and high reliability of this unit, it is prone to breakdowns, like any power tool. But in most cases, the repair of a circular saw can be done independently at home.

A hand-held circular saw differs from a miter saw in that it does not have a turntable bed, as well as the placement of the handle. But in general, both models are similar in internal structure, the 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 consists of the following main elements.

1. The top protective casing having an opening for ejection of sawdust.
2. The housing in which the electric motor and the start button are located. Some models of electric saws can run on batteries. In this case, the battery pack is also placed on the case.
3. The lower (movable) protective cover, which automatically closes the cutting element after it leaves the workpiece.
4. Saw disc. Mounted on the gearbox shaft with a nut or bolt.
5. Parallel stop. Allows you to make a smooth cut without the use of additional devices.
6. Base plate (sole) of the unit. Thanks to it, the tool is installed on the workpiece or tire at different angles.
7. Depth adjuster. With it, you can adjust the reach of the saw blade relative to the base plate.
8. Sole angle adjuster. Allows you to tilt the sawing unit at an angle.

This tool works according to the following principle. Power from the mains or battery is supplied to the start button, which breaks the circuit. When the start button is pressed, current begins to flow to the electric motor. Below is unit wiring diagram.

The electric motor starts and transmits rotational motion through the gearbox to saw blade. The unit is installed with the help of a sole on a workpiece or a guide rail, after which the process of both longitudinal and transverse sawing is carried out.

Main malfunctions and their symptoms

Typical malfunctions of manual circulars include the following situations.

1. The saw does not turn on. The mains cable, electric plug, start button or electric brushes may be faulty.
2. The motor of the tool gets very hot. Such symptoms may be the result of an interturn circuit (open circuit) in the armature or stator coils, as well as too intensive operation of the unit.
3. Gear box overheats. Overheating of this assembly may occur due to bearing failure or lack of lubrication on the gears.
4. Brushes sparkle. This is usually due to their excessive wear.
5. Burning ring visible around the engine manifold. If during the operation of the unit there is a circular spark around the engine collector, then its appearance can cause a malfunction of the armature winding or clogging of the space between the collector lamellas with graphite dust.
6. The unit does not develop the required power. A drop in power may be due to a voltage drop in the network, a malfunction of the motor windings, wear of the electric brushes, and a malfunction of the start button.
7. A rattle is heard during operation of the unit and other extraneous sounds. These symptoms may be caused by broken gear teeth or bearing failure.
8. The engine hums, but the unit does not work. Perhaps there was a jam in the gearbox.

Tool disassembly

Almost all malfunctions of electric circular saws cannot be eliminated without disassembling the device partially or completely. Complete disassembly of a manual electric saw using the example of the Interskol unit is performed in the following order.

1. Unscrew the angle and depth adjustment screws fixed on the base of the machine.
   
   
2. Press the gearbox shaft stop button and use the hex wrench to unscrew the bolt holding the saw blade.
   
   
3. Slide the lower protective cover aside and remove the circular disc.
   
   
4. To remove base plate, first unscrew the fasteners on its underside.
   
   
5. Next, use two screwdrivers to remove the Sieger ring that locks the stem on which the sole rotates to change the angle.
   
   

   

6. Insert a screwdriver into the gap between the body of the shield and the sole, then move it away and remove it.
   
   

   

7. In the next step, unscrew all the fixing screws located on the upper casing of the unit.
   
   
8. Also unscrew the screws holding the movable saw cover.
   
   
9. Disconnect both protective covers from the saw.
   
   

   

   

10. Using an open-end wrench, unscrew the bolt holding the riving knife and remove it.
    
    
11. Unscrew the rod holding the movable mechanism of the casing, and disconnect all its elements.
    
    

    

12. Next, you should disconnect the gearbox of the unit by unscrewing 2 screws.
    
    

    

13. When the mechanical part of the device is disassembled, you can proceed to electrical disassembly devices. Loosen the fasteners holding the engine cover and remove it.
    
    
14. After removing the cover, you will see two electric brushes. If they need to be completely disconnected from the engine, it is recommended to mark one of them with a marker, as well as the place where it was removed from.
    
    
15. Next, you should unscrew the screws with which the motor housing is attached to the gearbox housing.
    
    
16. After unscrewing the fasteners, disconnect both nodes.
    
    
17. In the detached part of the engine housing you will see stator coil.
    
    
18. Next, you should unscrew all fasteners from the handle of the unit. But before disconnecting it, you need to remove the rubber pad by prying it with a screwdriver.
    
    

    

19. After removing one half of the handle, you will see motor soft start module and start button.
    
    

    

This completes the disassembly of the saw blade.

Do-it-yourself circular saw repair

When starting to repair the unit with your own hands, it is not necessary to completely disassemble it to find out the causes of the breakdown. Some malfunctions are characterized by specific symptoms, by which you can identify the problem and already purposefully disassemble one or another part of the device.

The saw does not turn on

If, when you press the start button, the engine of the unit is “silent”, then the first thing to focus on is network cable, provided that there is electricity in the socket (plug the device into another socket to check).

Advice! Before checking the cable, you need to disassemble the electrical plug and make sure that the cord conductors are connected to its pins.

To check the electrical cable, you need to disconnect the handle. This will help you get to the pins to which 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 plug pin.

If the network cable is intact, then in search of a malfunction, do the following.

1. Ring the entire circuit with the 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. Normally, an open circuit should close. Call all wires after button going to the motor brushes.
2. If everything is in order with the conductors, check how worn brush electrodes. After the electrode has worn 2/3 of its original size, it should be replaced. The brushes, no matter how worn out each of them, are changed in pairs.
3. If the brushes are in good condition, then most likely engine failed. In its windings, an open circuit or an interturn circuit could occur. In this case, it is better to entrust the repair of the engine to specialists who will rewind the stator or armature coils.

The engine is warm

The unit may become excessively hot, for example when intensive use, as well as when sawing hardwoods or using a saw blade with a large number of teeth, when the load on the engine increases significantly. Also cause overheating of the motor malfunctions associated with the stator and armature windings, which are eliminated only in the service center.

Burning brushes

Strong sparking from under the brushes is caused excessive wear and tear 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 special holes in the motor housing (depending on the saw model).

Stuck shaft during operation

This problem may occur when, for any reason, the stopper is pressed while the tool is running. It is designed to fix the shaft when changing equipment and should be used after the engine has completely stopped. Otherwise, the stopper rod breaks, and its fragments fall into the engine, causing jamming. It is not uncommon for this to lead to armature shaft deformation. Also, the result of pressing the stopper may be a split in the gearbox housing, the fragments of which can damage the gears and cause them to jam. To solve the problem, it will be necessary to replace the anchor, stopper, drive (large) gear of the gearbox and its housing.

In some cases, the gearbox may jam when the bearing is completely destroyed.

The saw stops during operation

Stopping the engine in most cases is caused by a cavity worn out electric brushes. When the contact between the brush electrode and the collector lamellas is broken, the unit is turned off.

Often, when buying brushes for this device, you come across products with short conductor, connecting the electrode to the plate. This conductor is located inside the spring and does not allow it to fully open. 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 you, inspecting the brush, find that it is not yet worn out and the spring is not unclenched, then the part should be replaced.

The gearbox housing gets very hot

Rapid heating of the gearbox occurs if shaft bearing failed, 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 heat up if it contains not enough lubrication or it is completely absent.

Advice! Periodically, the gearbox should be disassembled and checked for lubrication. If necessary, generously lubricate the interior of the assembly. For these purposes, you can use a special lubricant for grinder gearboxes.

The saw does not gain power

If during the use of the unit you notice a drop in its power, it is first recommended check the voltage level in the network. Sometimes even a slight drop can adversely affect the power of the power tool.

Also, power loss can be observed when wear of armature bearings or gearbox bearings. In this case, extraneous noises that were not previously characteristic of this unit will be heard. By their localization, you can determine where the problematic bearing is located - in the gearbox or engine. To replace the bearings, you will need to disassemble the saw blade. How to do this was described above.

If no extraneous noise is heard during the operation of the unit, and the engine still develops poor speed and power, then pay attention to its manifold. Usually you can see a circular spark (ring of fire) on it. This may be due to an interturn circuit of the armature coil or the accumulation of dirt between the collector lamellas.

Open the motor housing and carefully inspect the collector (the place over which the brush electrodes slide). It consists of parallel strips (lamellae). There is a small gap between them. When this gap gets clogged conductive graphite dust formed during wear of the brushes, then a short circuit occurs between the lamellas, and a burning ring appears around them.

The problem will be solved by replacing worn brushes and cleaning the gaps between the lamellas with a toothbrush, cotton wool and alcohol, followed by polishing the plates with fine sandpaper.

In some cases, a power drop can be caused by a faulty start button. If the check by the tester confirmed its malfunction, then the part should be replaced with a new one, since it cannot be repaired.

Extraneous sounds appeared during operation

Grinding and other extraneous sounds can be caused by faulty bearings or gears of the gearbox and shaft with worn or broken teeth. In the following figure, the arrow shows where the armature gear is located.

The gear located on the motor shaft can be licked when the saw jams in hard or loose wood. Usually the gearbox gear does not suffer. To eliminate this breakdown, you will have to completely change the anchor of the engine. In the event of bearing failures, it is easy to remove them with a puller and replace them with new ones.

Due to the active use of equipment often needs repair. However, repair of circular saws may be required even under moderate workload. In the process of using and maintaining circular saws, popularly called circular saws, one should take into account some of the nuances of their functioning, be able to diagnose and, if possible, troubleshoot.

If the saw lost power, began to jam and stop, these are clear symptoms of its failure. Additional signs indicating a malfunction of the device include engine overheating, difficulty starting, smoke or burning smell, sparks inside. In all these cases, the tool must be taken out of service immediately and sent for diagnosis. For the purpose of repairing a circular saw, they usually turn to the services of craftsmen, but there are ways to deal with the breakdown yourself.

Main problems and their causes

A circular saw is a very convenient and practical tool that allows you to implement a lot of ways to process wood. With its help, you can cut boards along and across, without restrictions on size and distance, make slats, remove excess material in parts. Such a device is indispensable when working at height, in cramped and hard-to-reach places where large-sized and stationary analogues are powerless.

Like any electrical appliances, these saws vary in quality and allowable working intensity. Experts distinguish two main classes: industrial and household. An industrial circular saw is designed for use in conditions of prolonged intensive use, while a household saw is considered a low-quality tool for which failure is a common thing.

It is with the latter type of devices that you most often have to deal with when working at home. Household saws are designed for periodic short-term use, but even this does not save them from frequent breakdowns. These power tools usually do not have power controls, safety devices, or fuses. There is only a power button.

Such a tool is especially vulnerable to various malfunctions and can break at any time. The main reasons why this can happen are:

• short circuit;
• careless handling;
• strong pressure;
• working with a dull saw blade;
• use of the instrument for purposes other than intended.

Diagnosis and elimination of simple defects

First of all, when repairing circular saws, it is recommended to use LATR (adjustable laboratory autotransformer), designed for a load of at least 9 A and equipped with a built-in linear ammeter and voltmeter. For safety reasons, LATR should be connected to the mains through an isolation transformer with a transmission ratio of 1:1. These measures will help to eliminate possible damage to the wiring and interference in the network due to short circuits and errors in handling the unit.

Repair of a circular saw begins with determining the nature of the malfunction. This may be mechanical damage or failure of an electrical component. Localization of failure is carried out on the basis of certain signs. For example, smoke with a sharp burnt smell comes out from inside the instrument, unusual sounds, noise and whistle are heard during operation.

However, sometimes the saw does not work at all. No sounds, no smell - does not turn on. Paradoxically, this case is the most optimistic, since the reason for this inoperability may be a banal violation of the integrity of the power cord or a break in its contacts. Therefore, the first step is to check the supply wires for a break.

If everything is in order with the cord, you should not rush to disassemble the device. Before this, it is better to check the contact brushes. These are elements of the so-called sliding contact, which are designed to supply current to moving rotating elements of electrical appliances. They are several small blocks of a special conductive material (coal or graphite) resting directly on the collector (the rotor part of the electric motor).

Due to the constant rotation of the commutator, the brushes wear out a lot, rubbing against moving surfaces. After some time of operation, they grind down to the point that they can simply “hang” over the pads, not reaching them. In addition, sometimes there is a violation of contact at the junction of the brushes with the stator terminals. All this should be regularly checked and corrected, for which most tools have a special casing or cover with easily unscrewed bolts.

Inspection of internal parts

Disassembling a circular saw is a rather complicated process; it is individual for each individual device. Nevertheless, if everything is in order with the cord and brushes, and the device still does not work, disassembly of the case is inevitable.

The body of most of these electrical appliances consists of two fastened halves with a longitudinal seam between them. Having removed the disk and unscrewed the bolts and other fasteners, carefully open the shell, trying not to damage the internal elements and not lead to even more serious damage.

Regardless of the brand and build quality, one of the most vulnerable spots of such units is the power button. Its malfunction is a very common cause of functioning problems.

For most models, this button is usually located in the handle of the device. Unscrewing and disconnecting the case, you can get direct access to it. We check the health of the switch using a tester. If there is no contact closure when pressed, the button is replaced.

Repair of engine elements

At this stage, it is worth remembering how the circular saw showed itself in the event of a breakdown, what signs it was accompanied by. Damage of a mechanical nature is almost always accompanied by the occurrence of extraneous noise: whistling, crackling, grinding, etc. In this case, the first thing we try to turn the motor shaft: it should rotate evenly and not too tight, without wedging and vibrations.

If violations are observed, we disassemble the engine and carefully inspect the bearings in the housing and on the rotor: in all likelihood, one of them is to blame. Another possible defect is the wear of the gear teeth of the gearbox. Broken parts must be replaced. It should be borne in mind that some operations, for example, removing the bearing from the motor armature, should not be done on your own, but it is better to contact the master with special equipment.

Rotor and stator failure is a common problem. Its main signs are strong sparks and smoke in the brush compartment, accompanied by a characteristic smell. If, when disassembling the tool, strongly noticeable traces of burning are detected, it is necessary to replace all burnt parts with new ones. In the same case, when the armature looks intact, and there is a layer of soot on the stator, you should not rush to change the stator, as the problem may lie in the rotor (not even in the rotor itself, but in its windings, where a wire break could occur).

It is not difficult to check the armature for a break: to do this, disconnect the stator contacts from the graphite brushes and fix the tester probes in such a way that they come into contact with the motor windings through the brushes. The tester should show little resistance. Then we begin to slowly turn the motor shaft, without stopping to monitor the readings of the device. At some point, the resistance may increase dramatically: this will mean that the anchor is broken and needs to be replaced.

Conclusion on the topic

A circular saw is a reliable assistant when processing and cutting wood materials. We examined all the practically implemented at home ways to fix it.

However, many breakdowns can be avoided if you follow the elementary operating rules specified in the instructions for each device.

The use of the saw is usually allowed no more than a few hours a day with obligatory breaks. You should also work only with well-sharpened sharp discs.

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About the repair and operation of circular saws

Repair of household appliances, unfortunately, is an integral part of the problems closely related to the intensity of operation of this equipment. However, it is not always only intensive operation that contributes to the accelerated defect or breakdown of a modern power tool.

About some specific problems that arise during the operation and circular saw repair and will be discussed in this post.

For cutting boards, two years ago, my relative purchased an inexpensive hand-held circular (circular) electric saw DWT HKS-160 (photo 1). As the distributors assured, they were made in Germany. In the people, electric saws of this type are called "circulars".

It should be noted that a circular saw this type is very easy to use. It is a pleasure to work with such a "circular": it is easy, simple and quick not only to cut the boards across, but also along, without limiting yourself to any distances. Until the hands get tired, then everything can be cut ...

Of particular value is manifested in the manufacture of rails, when it is extremely difficult to do this manually. The circular saw also allows you to carefully and evenly remove part of the material across the width.

And if you need to work at height, for example, when fixing the roof, then the circular is invaluable, since no stationary tool will help out here, because. it is not possible to lower the wooden parts to the ground.

The considered circular is not intended for intensive and long-term work, but for occasional use. There is a difference between the most common consumer goods and power tools designed for so-called industrial use, i.e. permanent or intensive use.

However, even with the non-intensive use of the circular in question, it broke down clearly ahead of time, quite unexpectedly and untimely, in the midst of carpentry work ... The engine power began, as it were, to sharply decrease. Moreover, an excessive amount of electricity was consumed, along with a simultaneous decrease in power on the motor shaft. Soon there was a noticeable sparking in the contact area of ​​the graphite brushes and the motor collector. And then the circular “became”.

There are no power controls on this power tool. There are also no protective devices (fuses). There is only a push button switch.

After a breakdown, not having any knowledge in the field of electrical engineering, the owner of the circular carried the failed circular to his friend on the market. But:

Firstly, the owner was asked for a very decent amount of money for repairing his circular saw.

Secondly, the malfunction indicated by the repairman-electrician did not correspond to reality. The electrician-repairman argued that it was necessary to replace the rotor part of the collector motor (“collector”) and requested for his services an amount equal to more than a third of the price of a new circular ...

To repair a circular saw a 9-ampere LATR was used, which is equipped with a three-limit (to improve the accuracy of readings) pointer ammeter with a linear scale (0 ... 200 mA, 0 ... 2 A and 0.-10 A) and a pointer voltmeter, which also has a linear scale. To ensure safety, a powerful isolating transformer with a transformation ratio of 1: 1 was used, through which LATR is connected to a 220 V / 50 Hz network ..

The current consumption of the faulty circular was not at all. Instead of taking a closer look at the product, as it is strongly recommended to professional repairers, namely: always start repairs with a thorough inspection; it was decided to quickly move on to decisive action and dismantle the "circular" in order to get to the collector. The latter must be removed. To do this, you must first remove the protective plastic cover and gain access to the collector bearing (photo 2). And here the fun begins.

The whole secret, which lies in the method of removing the armature from the circular body, lies in the safe, for the armature bearing, disconnection of the motor armature shaft from this bearing.

The subtlety of the situation lies in the fact that, by inadvertently applying excessive force for other purposes (and nothing will work here without the proper application of force!), It is easy to bring the bearing into complete disrepair.

Therefore, it is necessary to use a pointed tool, such as a regular core. And only then, with its help, use the force of the percussion instrument [hammer]. In the center of the motor shaft, on its end side, a special recess is provided by the manufacturer. It is hardly noticeable, but the tip of the core is fixed in this recess and they begin to produce blows with a hammer. If the core is not installed in the recess, then it can break the bearing. The direction of application of the impact force must strictly coincide with the axis of the motor shaft. If the blows are made at a certain angle to the axis of the motor shaft, then the force will have to be considerably increased, which leads to deformation of the moving parts (bearing). The core in this case can leave its original position and bring a lot of trouble. Replacing the mentioned bearing is a much more troublesome occupation than the procedure for removing the anchor.

Therefore, from the very beginning, several hammer blows were applied to the core, carefully observing each movement (down) of the motor shaft. The most important thing is to move the shaft from its place, from the "dead center". And do it with minimal effort.

The armature has 24 outputs from the collector coils. It turned out that all these bends are in such a deplorable state that they required mandatory cleaning of their surface from oxides and deposits. The color of the plaque was almost black.

The anchor can be removed, cleaned of soot and replaced independently, without resorting to the services of repair companies. This, in turn, means that the repair with the replacement of the anchor will be much cheaper and you will have to spend money only on the purchase of a collector.

After the armature was sorted out and the contacts of the collector windings were cleaned, it was decided to install the armature again in its original place, because. Quite unexpectedly, about 8000, defects were found in completely different places in the design of the "circular".

Before installing in their original place, all collector windings were checked with an ohmmeter, and then the test was continued with an inductance meter.
The fact is that an ohmmeter cannot detect many defects in the coil windings. In practice, a current often occurs called a neighboring turn defect, when short-circuited turns are located nearby and their shorting does not allow detection of such defects even with precision ohmmeters. If the winding has at least one or, moreover, several short-circuited turns, then the inductance decreases several times.

Checking the collector coils with an inductance meter, as well as an ohmmeter, did not reveal a noticeable difference in the parameters of the windings. But it was found that one of the brushes moves very tightly in its fastener-holder (photo 3).

Increased friction between the brush holder and the brush itself caused intermittent brush sticking. As a result, the graphite brush “jammed” in the fastener and the power supply to the anchor was stopped.

Since the design of most graphite brushes in various commutator motors is largely similar, it is appropriate to assume that the considered defects are also widespread. Therefore, the method of eliminating defects will be similar.

The brush fastener is a metal structure in the form of a parallelepiped (box) located inside the insulator housing, which is made of heat-resistant insulating material. The metal (brass) walls of the box body should ideally not only have smooth inner surfaces, but their shape should form a parallelepiped. We, however, encountered a manufacturing defect - a “hidden” defect was already embedded in a brand new power tool: the brushes stuck in the brush holder due to its irregular shape,
Initially, it was thought that the excessive friction with which the brushes moved inside the brass fasteners was due to thermal effects and overheating with fireworks of sparks, but it turned out that the reason was different,
The very design of these brushes is very delicate. It is not difficult to damage the contact in the brush itself, as well as its flexible conductors (connected with graphite), which are easily torn off.

The method of connecting the brushes themselves with the contacts inside the brass guides (“parallelepiped”) is not very reliable and is carried out by pressing [that is, contact) of two contact metal (brass) strips-platforms.

One of them is inside the "parallelepiped", the second is connected to the spring of the brush itself. All this contact "economy" oxidizes rather quickly, which contributes to poor contact. Given the magnitude of the currents passing through these contacts, it is strange that such a powerful power tool (its engine) is able to function for a long time.

For normal operation, the opposite sides of the brass case-case must be strictly parallel. But it was not the current. It is for this reason that the old brushes wore out rapidly, which led to increased sparking. But the removal of brass fasteners from its plastic case is associated with a real risk in terms of irreversible deformation of the shape of the case and its complete destruction.

If it is difficult to change the irregular shape of the brass fasteners, then it is necessary to change the shape of the graphite brushes themselves.
But even this seemingly “simple” task turned out to be rather complicated. To give the brushes the desired shape, they are processed with an emery wheel. Here you are required to be extra careful and attentive so as not to overdo it. The graphite brush is placed on the surface of the emery wheel, pressed and the “extra” graphite is removed. The operation was carried out in several steps, each rose making an appropriate fitting.
As a result, the brushes should enter the brass holder without excessive friction and effort and move freely in it. No jamming should be observed. Unfortunately, even many new electric motors have the defects described earlier.

It seems that in Germany a production defect of this nature is hardly possible. Those. the assembly of the entire product, most likely, was carried out outside of Germany, apparently in the CIS.

Therefore, before buying an expensive power tool, you should carefully examine the outside and look inside the case. An external inspection of the interior, allowing you to notice bad contacts (in new electric drills) when the connections were "loose" due to poorly tightened screws. And the first time the tool will work properly.

One rule helps: it is advisable to pay extra and purchase a more solid tool designed for constant and intensive use.
Of course, such a tool turns out to be much more expensive (on average, 1.5-2 times), but the probability of its failure under periodic loads is much lower. For example, circulars with a capacity of 2 kW of a domestic manufacturer (Sevastopol) are intended for production purposes ), and they actually turn out to be more reliable than the considered "German" 1.2 kW DWTs.

Note that a circular with a power of 1.2 kW is enough if there is no long-term work with timber (boards) with a thickness of more than 30 mm (“thirty”). With thicker layers of wood (“magpie”, for example), the considered circular begins to “suffer” and exhaust the nerves of the one who operates it. A significant slowdown in the process of cutting timber begins to appear. The cutting speed is strongly influenced by the type of wood, the presence of knots, and the condition of the material being processed (drier or wetter wood).

Here it should be noted that the 1.2 kW "circular" does not allow for any "maneuvers", except for simple rectilinear movements of the saw. Moreover, it is already quite difficult for her to cut the “thirty” board. If the saw is even slightly pressed in some direction, and even more so, there is a forced change in the cut line from a straight line, then the “circular” can no longer work normally. A powerful saw already has other nuances that simply do not exist with a saw with less power. However, the risk of injury when working with a powerful saw also increases. Such a saw will no longer stop with some pressure or when the tool is skewed (with a sudden change in the position of the saw plane). She will "tear" and "kick" in her hands. Hence, there is an increased danger when working with such a tool.

It should be noted that a dangerous factor in the operation of such tools is insufficient experience in practical use.
There are known cases of not only injuries, but also serious injuries, because the circular saw does not care what to cut! For seconds, a person leaves the power cord of his “circular” out of sight, as he saw it right there and cuts it! When working with this tool, one must be not only extremely collected, but also very attentive to the material being processed. There are various heterogeneities in the wood, and when working with a tool, sometimes you have to hold it with only one hand.

Thus, "circulars" intended for industrial use are preferred in all cases without exception. They are inferior to less powerful circulars only in mass and dimensions, but not so much as to acquire not very reliable consumer goods.
If you have to build a house, that is, the tool is supposed to be used very often and for a long time, then there is no point in buying cheap hardware. The “circular” at peak loads can fail, and taking into account the costs of repairing it or purchasing a second copy of the saw, it will turn out that it would be cheaper to buy a normal and more reliable tool from the very beginning.

This power tool has, perhaps, only two drawbacks:

Firstly, the "circular" is much heavier than a hand saw.

But, despite this, physically healthy workers almost always work with the "circular" with only one hand, which is associated with the release of the second hand for other operations. This has to be done, first of all, when there is no one to help in working with timber.

The second disadvantage is closely related to safety. The sad thing is that the widespread use of circulars and grinders has increased the number of injuries and injuries during the operation of these tools. Such work requires not only sober hands and head, but also increased attention.

And the last thing, which, unfortunately, cannot be overlooked in any way, is the deplorable state of our power transmission lines, which has already become a kind of disaster.

Therefore, without exception, all household appliances must be protected from the abnormal value of the mains voltage. For powerful electrical appliances, as a minimum, protection is required at least against exceeding the mains voltage.

Powerful electric motors can often be fully protected even with fuses. They are selected taking into account the maximum current, which has the greatest value during the inclusion of the motor in the network (starting current).