In our country, one of the most popular hammer drills is the Makita 2450. And this is no coincidence. After all, the Makita 2450 has good characteristics, and its assembly diagram allows you to do it yourself. Makita is known as a quality Japanese manufacturer, but the HR 2450 is made in China. To draw conclusions about the quality of the equipment presented, you should consider user reviews of the Makita 2450 left in different sources. Having deepened the knowledge about the presented tool, it will be easy to draw a conclusion about the advisability of its purchase.
General characteristics
"Makita 2450" is known among builders and repairmen as a fairly functional professional tool. It is simple and reliable in operation, lightweight and well balanced. Thanks to this, the Makita 2450 will last for quite a long time. It has a good dust protection system, which makes the equipment durable.
Its popularity is explained by the possibility of repairing the Makita 2450 rotary hammer at home. You won't need to spend a lot of money on its maintenance. However, before assembling the 2450" you should familiarize yourself with the technology for disassembling and repairing it.
Specifications
The Makita 2450 hammer drill has a certain set of qualities. The characteristics presented by the manufacturer in the instructions are as follows.
The weight of the tool is only 2.4 kg. The drills are secured by the SDS+ system. The hammer drill is designed for crushing, drilling and impact drilling. It has three operating modes. Number of revolutions idle speed is 1100 per minute, and the maximum number of beats is 4500 per minute. The maximum translational force is 2.7 J. Maximum drilling diameter:
- for wood - 32 mm;
- for metal - 13 mm;
- for concrete - 24 mm;
- for a hollow crown - 54 mm.
There are also additional features at the Makita 2450 rotary hammer. Characteristics include the presence of a safety clutch, reverse, locking the power button, as well as electronic speed control.
The power supply network is 780 W. The cable length is 4 m.
Signs of a fake
Due to the great popularity of the equipment presented, cases of counterfeiting are not uncommon. There are characteristic features, which identify the fake HR 2450 rotary hammer. These include a short cord (about 0.5 m). The letters on the black clasps of the suitcase are matte on the fake, but shiny on the original.
In the photo of the hammer drill in the instructions for this product, the background is light gray, almost white. The copy will have a dark, dull color in the background of the image.
If the HR 2450 case shows Japan as the manufacturer, it is not a genuine instrument. The original says: “Made in P.R.C.”, i.e. “made in China.”
Includes a rubberized handle with serial number. All parts of the suitcase must also each contain its own designation. The fake handle is made not of rubber, but of plastic. This should also be a signal about the need to refuse to purchase such an instrument.
Disassembly diagram
In the process of repairing the presented equipment, the user must be able to disassemble the tool. The assembly diagram of the Makita 2450 rotary hammer has many components and elements. To carry out repairs, you do not need to know all of them. Here are the most basic elements that the diagram represents (Makita 2450 is a very complex device).
The first is the retaining ring. It is involved in the process of dismantling the cartridge cover. Next comes the ring locking device. It holds the ball to secure the drill. It is guided by a washer and a conical spring.
The gearbox is connected to the motor by 4 screws. The circuit contains many rubber parts, which when worn out become common cause breakdowns.
This knowledge is enough to carry out repairs at home. Next, you should familiarize yourself with the technique of its implementation.
The feasibility of self-repair
Repairing the Makita 2450 hammer drill yourself is worth doing for several reasons.
Service center representatives troubleshoot problems using a specific algorithm. This leads to quite high costs for
There is also a high probability that the employees of the company’s representative office will simply conduct a routine inspection, the need for which is questionable. And you still have to pay for it.
If a unit or several of them still require replacement, the service staff will supply only licensed Makita 2450 parts. Repair in this case may be comparable in cost to purchasing a new tool. All these facts speak in favor independent conduct adjustments or replacement of equipment parts.
Repair
"Makita 2450" can be repaired with your own hands if you have certain knowledge and skills. The technology for inspecting and replacing parts of the HR 2450 model is quite simple. It involves disassembling the tool, after which all old grease, dust, and dirt are removed. Damaged nodes are replaced with new ones. Then all the parts of the hammer drill are assembled together. It is necessary to familiarize yourself with each point of such work. They can be produced in the area of the chuck, mode switch, or hammer housing.
To carry out repairs, first remove the cartridge, then the speed switch. After this, repairs are carried out inside the housing. Lubricant and worn rubber elements are replaced.
Cartridge
Using a flat-head screwdriver, the cartridge is disassembled. Repairing a Makita 2450 rotary hammer with your own hands begins with this element. Squeeze the cartridge cover and remove the rubber boot. The retaining ring is removed. Then the cartridge cover and metal ring are removed. It locks the drill fixation ball in the barrel. It is removed, and the metal washer and conical spring are removed without effort.
The cause of the breakdown may be wear and tear of parts. It is detected if the drill does not lock automatically without releasing the lid. After checking all the details, the cause of the breakdown is identified. Old elements are cleaned of dirt and old grease. The ball is thickly treated with new oil. The conical spring is installed with the narrow side facing the resistor.
The guide washer should press it so that it is below the hole in the barrel. Repairing the Makita 2450 rotary hammer from the chuck area requires fixing the ball in the hole. All parts are assembled in reverse order.
Mode switch
To carry out disassembly, remove the T-shaped latch on the switch handle. Use a 2mm screwdriver for this. You need to very carefully tighten the tabs of the latch. She is pulled out. The red latch must be held so that it does not fly out under the action of the spring.
After performing these steps, the switch handle should be turned to the extreme left position. So its protrusions will coincide with the grooves of the editor body. The switch is easy to remove. The retainer is removed along with the spring. The rubber ring on the switch handle should be pryed off with a thin screwdriver and removed. It prevents lubricant from leaking out of the housing.
The assembly diagram of the Makita 2450 rotary hammer in the switch area assumes a certain sequence. All parts and the seat are cleaned of old dirt. Thickly lubricate two metal pins and a rubber ring. It is put on the switch. A spring is inserted into the handle, then a latch. It should not pop out when the latch is installed into the housing.
The switch is then inserted into the gearbox. In this case, the handle is directed to the sector between the designation of the combined mode and the impact. It will not insert all the way. The switch should be turned to the drilling mode and a little further. In this case, you must remember to press the lock button so that it does not interfere with movement.
Then turn the switch clockwise and press the latch all the way.
Switch faults
In the process of familiarizing yourself with the question of how to assemble a Makita 2450, you should find out frequent switch malfunctions. They may be caused by worn metal pins. In this case, any of the modes will not be activated. The switch will need to be replaced. This should also be done if the landing lugs are broken.
If the rubber ring is worn out, a slight leakage of lubricant will occur. We'll have to replace it.
It happens that the clamp breaks the beak with which it is attached to the cavities of the gearbox. The clamp tabs may be damaged. To avoid all of the above damage, you need to handle the tool carefully.
Gear housing
To remove the housing from the gearbox, you need to lift the tool barrel up. The hammer drill should be pressed against the workbench while simultaneously pulling the shell upward. In this position, all parts remain in place.
After their inspection, testing and replacement, the gearbox housing is installed in place. All its elements must be located in their original form. Required Items needs to be lubricated.
During the assembly process, the gearbox housing must be cleaned with kerosene or gasoline. Next, the shell is put on the original place. The mode switch should not be in it.
Malfunctions in the gearbox housing
The body of the HR 2450 model is characterized by high strength; failures in this unit are quite rare. But it happens that certain troubles occur here too. If the case was received together with it, then its seat is badly worn. When this part becomes extremely loose, the housing should be replaced.
Sometimes the seat of the intermediate shaft is broken. The repair is expected to be similar to the first case.
The gear housing pin has If it is damaged construction dust(happens extremely rarely) or careless actions of the repairman, it is replaced along with the body.
The same procedure is performed in case of failure of the mode switch holes. The listed types of breakdowns are typical for counterfeit copies.
Most tools used on the farm are not insured against breakage. Grinders, which almost every craftsman has, fail over time. Various models angle grinders may have similar types of faults. But each brand has its own characteristics in design and components. The famous Makita brand is valued for high quality– strength. However, devices of this brand also tend to break.
Repairs can be done at home. Spare parts for the machine can be easily purchased. Before repairing the device, you must familiarize yourself with the attached diagram.
Types of Makita brand angle grinders and their features
Based on the diameter of the working wheel, brand grinding devices are divided into classes:
- Lightweight - have a circle with a diameter of 115–125 mm. They are easy to control.
- Medium - the diameter of the circle is 150–180 mm. There are professional models and household ones, differing in motor power.
- Heavy – disc diameter 230 mm. This class is represented by models for professional purposes when working with concrete, brick, etc. Characterized by the latest protective systems.
Homemade devices vary in power and price. Professional equipment is designed for long-term heavy loads and has an increased power reserve. Models with power above 1000 W are equipped with a comfortable rear handle, which is covered with special pads that protect against vibration.
As for the design of grinders of this brand, it is characterized by the presence of the following additions:
- a labyrinth device used to protect against dirt and dust;
- armored coating of motor windings;
- special system for soft start and overload protection (Super-Joint-System).
Types of damage
Malfunctions when working with Makita angle grinders can be divided into two types:
- electrical (failure of the rotor, stator or defects in the control circuit);
- mechanical (bearing failure on the gearbox).
First you need to inspect the device. The mechanism of operation of the grinder is to supply torque from the rotor through a gear to the spindle of the working tool (circle, cutting stone).
Sources of breakdown can be increased loads, untimely replacement of brushes and lubricants. Thanks to the presence of a quick-release protective cover, Makita models can be repaired in a short period of time.
Troubleshooting the Control Circuit
The control circuit contains components whose malfunction can be repaired independently. Weak point are brushes. Therefore, checking them is necessary first of all. You should also check the integrity of the power circuits from the plug to the switch terminals.
If the fault is a broken switch, then it needs to be replaced. If the supply wire is damaged and broken, the damaged parts are removed or the entire wire is replaced.
Stator repair
Appearance unpleasant odor, constant overheating and spontaneous acceleration indicate stator failure. The stator winding may break or a short circuit may occur. Using a tester or IR-2 device, you can find a short circuit. In the event of a malfunction, a new wire must be wound.
Rotor repair
The reason for the breakdown of the angle machine may be the failure of the stator. This can be understood by the large number of sparks in the collector area and the presence of a burning smell. The rotor is connected to the gearbox. Therefore, when removing it, it is necessary to disconnect it from the gearbox. Rotor repair consists of complex technology. It would be more practical to replace it with a new part.
The new rotor is placed in the housing with bearings already installed. The drive gear is also put on. Then you should check the press fit of the bearing and tighten the nut.
Then the rotor and gearbox are placed in the stator. In this case, the bearing should be covered with a boot and rotate easily.
Gearbox repair
If the gearbox is damaged, play in the spindle shaft appears. The gearbox begins to jam and the gear slips. Repairing a gearbox usually involves damaged gear teeth. For each Makita model, the driven gears are either attached to the shaft or pressed onto the spindle. In addition to the driven gear, the gearbox consists of a housing and a drive gear. To execute angle grinder repair, the gears need to be replaced, and the replacement should be done in pairs. You will need a puller to remove the driven gear. You can also use a press. It is not recommended to use a hammer due to the fragility of the housing shell.
Features of assembly after repair
After troubleshooting the Makita angle grinder, components are purchased and repairs are made. The following recommendations should be followed:
- assembly must begin by checking the parts for integrity and cleanliness;
- assembly begins with putting the bearing on the spindle;
- The driven gear is installed after the bearing;
- the spindle is placed in the gear housing, using a rubber ring;
- When assembling the gearbox, the bolts are lubricated with sealant;
- when placing lubricant in the gearbox housing, the volume of its space is taken into account (the volume of lubricant is equal to 1/3 of the volume of the space);
- at the end of the assembly, the torsion of the gearbox is checked and the fastening bolts are screwed in;
- Carbon brushes are replaced after 7 thousand hours of operation or wear up to 8 mm in length.
Makita grinders very often undergo repair procedures due to the high number of counterfeit devices. A common problem is the breakdown of the gearbox, namely its gears.
Repair of other brands of angle grinders
In addition to the popular Makita brand, other grinding devices are known from the Bosch, Sparky, and Stern brands. All of them are reliable and easy to use. But cases of breakdowns cannot be ruled out.
Bosch grinders often require replacement of bearings. The mechanism of the machine is based on the torsion of the spindle shaft, which is pressed into the driven gear. It also rests on a needle bearing. If the bearing is destroyed, then its race is very difficult to get. Moreover, the drive gear is attached to the rotor shaft with a left-hand thread. As a result, the fixation occurs with a nut. The gear, which is the driven gear, is pressed onto the spindle shaft.
Gearboxes of Sparky angle grinders are characterized by a gear pair placed in a housing. The driven gear is fixed with a press or keyed connection. The key is a ball of small diameter. The drive gear is also secured to the rotor shaft with a key or a right-hand threaded nut. Grinders of this model are also distinguished by easy removal of brushes without removing the handle.
When disassembling Stern angle grinders, the gearbox does not need to be removed from the body. During repairs, keep an eye on the small gear key, which does not hold well. Lubricant must be changed promptly.
You can and should try to repair any instrument. Bulgarians do not differ much in mechanism. The diagram is always included when purchasing the device. Therefore, any craftsman who has necessary tool and devices.
Since the early seventies of the last century, electric cutting tools from Bulgaria have been supplied to the territory of the USSR and other countries. He was different good quality and was popular, for which it received the short name “Bulgarian”.
Since then, it has been much clearer to Russian people than the technical term - angle grinder or angle grinder for short. Thanks to simple device and useful features, an angle grinder is necessary home handyman for renovating an apartment with your own hands.
We explain in this article how to choose it for your tasks, taking into account specific work.
Purpose
The grinder was originally created for grinding surfaces. But due to significant design upgrades, it quickly began to perform such useful functions as cutting and processing any building materials, including cement, concrete, brick, tiles, slate and all types of metals.
According to the methods of performing work, angle grinders, like all power tools, are designed for operation in one of two modes:
- constant work in construction conditions with overcoming maximum loads during a full work shift - professional models;
- for single use with the organization of breaks at rated loads - a household tool.
This is one of the important differences to consider when purchasing. It affects the cost of the grinder.
Professional models
To ensure that the tool works for a long time in extreme conditions and is at the same time convenient, manufacturers use all sorts of technical tricks. For example, an insulated copper wire not familiar to us round section, but in the shape of a square.
Even the plastic composition for the body is selected in such a way that when heated to 140 ° C it does not transfer high temperature to the operator’s hands and at the same time does not lose its strength.
Expensive models of grinders have:
- vibration-proof inserts on the handles that prevent the development of occupational diseases;
- quick-release nuts SDS, allowing you to install working parts without using a special wrench;
- rotating rear handle;
- gear rotation function or the ability to move the front handle to one of three positions;
- special bearing design that ensures balancing of the working body;
- long power cord with a protective layer of durable insulation;
- the ability to regulate the speed of the working circle and a number of other useful functions.
Household tool
Grinders of this class are inferior in their characteristics to professional tools. However, they are produced according to strict technical standards, meet safety standards, and allow work to be carried out while observing breaks.
Design and principle of operation
After connecting the power cord to the mains voltage and turning on the start button, the electric motor rotor begins to rotate. A gear transmission at its end transmits torque to the working circle.
When rotating under load, the disk material is subjected to significant loads and if the rules for handling it were violated during storage, it can break into pieces.
Automatic wheel balancing
Wear work surface does not always happen evenly. WITH outside Due to impacts and uneven loads, small potholes are formed, creating beating. This is most typical on large-diameter cutting wheels.
This function makes the operator’s work easier and allows him to do it better. The presence of auto-balancing indicates the prestige of the grinder model.
Protection against accidental activation
When the mains voltage is lost for various reasons and power is re-supplied to the angle grinder, an unplanned engine start occurs, which causes injury or equipment breakdown. Manufacturers prevented the occurrence of such an unpleasant situation by creating an appropriate block.
Motor protection against electrical overloads
To implement it, control is used by:
- current flowing in the motor circuit;
- winding temperature;
- or both of these options.
Such protection can only signal to the operator that the load has been exceeded by the light coming on or reduce the performance of the angle grinder by reducing the speed or completely stopping the engine.
Among workers who strive to quickly complete work under increased loads at any cost, this function causes irritation. But in general, it allows you to save the life of the tool and consumable wheels.
Motor overload protection in case of accidental jamming of the wheel
During a sharp stop of the wheel while the engine is running, a strong mechanical shock is transmitted to the latter, which is also felt as a sharp jerk from the operator’s hands. Different manufacturers use their own technical solutions for shock smoothing. Three variants are common technical solution, working on the basis of mechanics:
- safety slip clutch;
- centrifugal clutch;
- SJS spring design.
Slip clutch
The design includes several disks that engage the driven gear with the spindle. They provide adjustable torque transmission. When the nominal value is exceeded, the rotor continues to rotate and the working element stops.
The engine in this situation experiences a load, but it is less than during a jam.
Centrifugal clutch
The work is based on the transmission of torque due to petals, which provide traction from the action of centrifugal forces. Torque is transmitted to the working body when the rotor rotates and is removed when it stops.
SJS function
A coupling made using this original technology is used in Makita angle grinders. It prevents impact due to the spring pressing the small bevel gear. This smoothes out the shock, and at the same time reduces vibration, ensuring smooth operation of the working element.
In some expensive models of angle grinders, engine protection during overloads is carried out by relieving the voltage using a built-in electronic circuit.
Fixing the switch
This useful feature designed for using the tool with its stationary fastening in the holding mechanism and supplying the surface to be processed to the working element. But we don’t recommend using it to remove your finger from the button and cut it conveniently.
If the disc gets stuck in the material being processed, it may fly apart and the grinder may jump out of your hands. The engine will run when the switch is locked. Try to stop him in this situation.
Dust protection
When cutting or grinding, a cloud of tiny particles of the material being processed forms around the wheel. It penetrates through the cracks of the housing, settles on the bearings, brushes, commutator motor, and changes the electrical resistance of the current-carrying circuits until a turn circuit is created. To combat dust install:
- fine mesh or filters on ventilation openings;
- armored stator windings and rotor cord bandage;
- closed type bearings;
- windings filled with epoxy resins;
- increased tightness housing.
Automatic brush shut-off
The function works on expensive models, it allows you to control the compression of the contact surfaces of the brushes to the rotor commutator plates, and preserve the service life of the engine.
To implement this, a spring-loaded dielectric pin is introduced into the brush design. It controls the degree of wear of the carbon electrode and, when the length is critically reduced by more than 2/3, presses the brush contact away from the commutator.
The self-switching mechanism of the brushes also works when an increased potential is supplied to the angle grinder in the event of a zero break, protecting the engine by breaking the current circuit.
Removing dust
Try cutting a concrete slab indoors and you will immediately appreciate the cloud of dust that is generated during the work. A professional tool has a flange to which it is connected construction vacuum cleaner, which picks up debris directly from under the working element and takes it to the dust collector through a hose.
The function is very useful. But for performing single tasks around the house, such an angle grinder is quite expensive. However, you can purchase a special casing for these purposes.
The inner diameter has a built-in metal ring. It is the base for installation on the bushing and its surface ensures precise alignment relative to the axis of rotation due to four protruding teeth.
The side surface of the ring serves to hold it on the surface of the circle. It is not a basic surface that ensures pressing of the disk inside the flange, if only for the reason that the cutting wheel can have a thickness of 1 mm, and the recess in the flange and nut is about three.
The circle is pressed against the annular protrusion of the flange with its end surface due to the force of screwing the nut, and is held by the plane that creates the greatest moment of resistance - at the periphery.
On the side of the circle there is a picture with technical characteristics. The inner ring, like the picture, can be applied on both sides or on one. This marking is specified by the manufacturer not for installing the disk, but for other purposes. However, some workers mistakenly believe that it is a guide to the direction of rotation.
Where to direct the sparks
According to the laws of inertia, fragments fly from the rotating circle. Their high temperature can burn through clothing material and cause skin burns. If the circle gets stuck in the part being cut, it may fall apart into pieces that will fly in the same way. To protect the operator of the grinder, a metal casing is installed.
When working, the tool should always be positioned so that at any time an unusual situation arises protective cover ensured its function as much as possible - it protected the human body from sparks and fragments falling on it.
Checking the condition of the brushes
Service life
The service life of carbon electrodes as reliable current conductors is approximately 80÷120 hours of operation. After this period, wear occurs and they need to be replaced.
Signs of defect formation on contacts are:
- the appearance of sparks forming a circular beam on the collector;
- noticeable reduction in engine power;
- obvious depletion of the length of the carbon rods or the formation of chips on the surface of their contact.
Clamping force
Factory adjustment ensures optimal contact force between the brush and the commutator plates. If the brush assembly is worn out or incorrectly replaced, it may be damaged in the direction of increasing or decreasing contact.
Increased pressure
Excessive pressure from the hard brush is created on soft material collector plate, leading to excessive heating of engine parts.
Reduced pressure
Additional electrical resistance appears at the contacts, which does not ensure reliable current flow when switching the windings located on the rotor. A spark discharge appears that can develop into an arc that damages the brush assembly, commutator, and motor.
Therefore, when replacing brushes, it is necessary to control their force and use original spare parts from the manufacturer.
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Angle grinder Mastermax MCP – 2800
Angle grinder device
The angle grinder in our household use is necessary power tools. Depending on the installation of one or another attachment on the grinder, you can perform a varied amount of work.
In my own way appearance and designs similar to grinders are so-called grinders, consisting of such parts as:
- protective casing;
- ventilation hole;
- push-button switch;
- side handle;
- spindle lock.
The photograph shows the engagement mechanism, or in other words, the coupling of the mechanical part of the gearbox with the electric motor.
Grinder gearbox and electric motor
For the mechanical part, the following are subject to wear:
- bearings;
- reducer gears.
I would believe that giving a complete explanation of the mechanical part of the gearbox simply does not make sense.
Attachments for angle grinders have a different range, depending also on the work being carried out.
Electrical diagram - angle grinder
Let us concentrate our attention \Fig. 2\ on the following schematic representation - the principle of operation of the electric motor.
The red arrow in the figure shows the direction of the current, as is commonly believed in the section on electrical engineering: » Current in electrical circuit flows from a source \clamp\ with a positive potential to a source with a negative potential. Moreover, the positive potential changes its sign to the opposite - from the resistance that has a connection in the electrical circuit.
The electrical circuit here is closed on the collector, or more precisely on the contact connections “winding - collector” \for the electric motor rotor\.
That is, the rotor commutator through the graphite brushes in the circuit has electrical connection.
The two stator windings of the electric motor are connected in series in the electrical circuit.
In my practice, a similar electrical connection \Fig. 2\ for all elements of a commutator electric motor - I have not seen a wire with one potential have a direct electrical connection to the commutator through a graphite brush, and a second wire with a different potential have a series connection through two stator windings with a second graphite brush.
The simplest and most complete explanation for these electrical connections is given directly by the electrical circuit of the commutator motor itself \Fig. 3\. It is this connection of all elements that is typical for grinder engines, where the electrical circuit is closed on two rotor windings - in this way.
Connection of electric motor windings
Here we can notice that the two windings of the electric motor rotor for this section are connected to each other in series and have a contact electrical connection “commutator - brush”.
The connection of the two rotor windings relative to an external alternating voltage source is parallel.
Among the causes of malfunctions of the electric motor of a grinder, one can cite such a malfunction as wear of the graphite brushes that are in contact friction with the commutator of the electric motor.
This part, like other other parts for power tools, can be purchased at specialized technical departments shops.
Electric motor diagnostics — grinders
Diagnostics of the electric motor of the grinder \Fig. 3\ should be carried out for individual areas electrical circuit of this circuit.
To do this, you will need either an ohmmeter or a multimeter. The Multimeter device is preliminarily for measuring resistance - it is set in the appropriate position.
To measure the resistance of two separate stator windings, one probe of the device is connected to the brush contact, the other probe of the device is connected to the corresponding pin electrical plug.
If this section breaks, the device will accordingly indicate the absence of resistance.
If it is working properly, the device will indicate the presence of resistance in one or another measured section of the electrical circuit.
By connecting the two probes of the device to the two pins of the electrical plug of the grinder, the display of the device will show the total resistance for:
- two stator windings;
- two rotor windings,
- that is, it will indicate the total resistance value.
Changing the rotation speed of the electric motor rotor \Fig. 4\ is carried out through the following electrical circuit.
Electrical diagram consists of:
- resistor R1 \0.5 W\;
- resistor R2;
- resistor R3 \5 W\;
- diode VD1;
- triode thyristor VS1.
Resistor R2 acts as a potentiometer, due to which the current in the load changes. The load in this explanation is the electric motor.
Triode thyristor - creates current blocking for the reverse direction. Control is carried out via the cathode.
Well, we figured out simple electrical circuits. All that remains is to make your decision in cases of malfunction - to send the electric motor for repair or to repair it yourself.
Let's go to a repair shop household appliances, - you can already state the reason for the malfunction of your power tool.
That seems to be all.
Everyone who has been using an angle grinder for more than one year has had it break. At first, every master tried to repair grinder sparkling on its own, hoping that it will work after replacing the brushes. Usually, after such an attempt, the broken instrument remains lying on the shelf with burnt windings. And to replace it, a new grinder is bought.
Drills, screwdrivers, hammer drills, and milling cutters are necessarily equipped with a speed control. Some so-called calibration grinders are also equipped with a regulator, while ordinary grinders only have a power button.
Manufacturers do not complicate low-power grinders additional schemes deliberately, because such a power tool should be cheap. It is clear, of course, that the service life of an inexpensive tool is always shorter than that of a more expensive professional one.
The simplest angle grinder can be upgraded so that its gearbox and armature winding wires will no longer be damaged. These troubles mainly occur during a sharp, in other words, shock start of the angle grinder.
All modernization is just a matter of assembly electronic circuit and securing it in the box. In a separate box, because there is very little space in the handle of the sander.
Verified, working diagram posted below. It was originally intended to regulate the intensity of lamps, that is, to operate on an active load. Her main advantage? simplicity.
- The highlight of the soft starter, the circuit diagram of which you see, is the K1182PM1R microcircuit. This microcircuit is highly specialized, domestically produced.
- The acceleration time can be increased by choosing a larger capacitor C3. While this capacitor is charging, the electric motor accelerates to maximum speed.
- There is no need to replace resistor R1 with a variable resistance. A 68 kOhm resistor is optimally selected for this circuit. With this setting, you can smoothly start the angle grinder with a power of 600 to 1500 W.
- If you are going to assemble a power regulator, then you need to replace resistor R1 with a variable resistance. A resistance of 100 kOhm or more does not reduce the output voltage. By short-circuiting the pins of the microcircuit, you can completely turn off the connected grinder.
- By inserting a VS1 semistor of type TC-122-25 into the power circuit, that is, at 25A, you can smoothly start up almost any commercially available grinder with a power from 600 to 2700 W. And there remains a large reserve of power in case the grinder jams. To connect angle grinders with a power of up to 1500 W, imported semi-sectors BT139, BT140 are sufficient. These are less powerful electronic keys cheaper.
The semisistor in the above circuit does not open completely; it cuts off about 15V of the mains voltage. This voltage drop does not affect the operation of the grinder in any way. But when the semistor heats up, the speed of the connected instrument decreases greatly. This problem can be solved by installing a radiator.
This simple circuit has one more drawback - it is incompatible with the speed controller installed in the tool.
The assembled circuit must be hidden in a plastic box. A housing made of insulating material is important because you need to protect yourself from mains voltage. You can buy a junction box at an electrical supply store.
A socket is screwed to the box and a cable with a plug is connected, which makes this design look like an extension cord.
If experience allows and there is a desire, you can assemble a more complex soft start circuit. Below circuit diagram is standard for the XS–12 module. This module is installed in the power tool during factory production.
If you need to change the speed of the connected electric motor, then the circuit becomes more complicated: a 100 kOhm trimmer and a 50 kOhm adjustment resistor are installed. Or you can simply and crudely introduce a 470 kOhm variable between the 47 kOhm resistor and the diode.
It is advisable to connect a 1 MΩ resistor in parallel with capacitor C2 (it is not shown in the diagram below).
The supply voltage of the LM358 microcircuit ranges from 5 to 35V. The voltage in the power circuit does not exceed 25V. Therefore, you can do without an additional zener diode DZ.
Whatever soft start circuit you assemble, never turn on the tool connected to it under load. Any soft start can be burned if you rush. Wait until the grinder unwinds, and then work.
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