In detail: do-it-yourself grinder repair gear replacement from a real master for the site my.housecope.com.
Do-it-yourself grinder repair is a completely solvable task. The main thing is not to rush, to understand the structure, to remember all the circumstances under which it broke down, to determine what could have worn out during operation, to make diagnostics and start repairing it.
Angle grinder (angle grinder) is called a grinder. The name of the instrument is due to the fact that it was produced by the Eltos-Bolgarka plant in Plovdiv. It is designed to perform work on grinding or trimming hard material:
Performs well sharpening of the tool.
Nowadays, a grinder is a very necessary tool, so almost everyone has it.
There are grinding machines of different power: from 500 W to 2500, depending on the thickness of the wheel - from 115 mm to 230 mm. The most popular in the work are angle grinders with a power of 1.2 W, and the most used disc is 125 mm thick.
Every year the choice for this construction power tool is becoming wider, but the operating rules hardly change. And even if you always adhere to them, sooner or later there are malfunctions in the mechanism that you can try to fix with your own hands, collecting everything you need to repair the grinder.
Any grinder consists of the following parts:
rotor - a part of an electric motor that rotates during operation and is speed-controlled, also called an anchor;
collector - the place on the rotor where the control winding wires are located;
brushes - parts that serve as conductors of current from the cable to the collector winding;
reducer - a mechanism that acts as a drive from a rotating rotor to a rotating disk, consists of a spindle, a bearing, two gears (large and a shaft gear);
stator - the part of the electric motor in which the rotor works;
grinder cooling impeller;
start button;
network cable with electric drive;
protection casing;
grinder body;
additional handle.
Video (click to play).
All these details can be divided into two parts:
How to disassemble a grinder? Not so difficult process. This does not require special knowledge, but everything must be done carefully and carefully. Each owner needs to know how to disassemble any working tool, because from time to time it needs to be cleaned internally from dirt and trapped dust, and its durability depends on it.
At the present time on the market, you can choose for yourself a different type of grinder, which differ in performance, size, quality. Manufacturers are also different. Whichever model of grinder you buy, everyone has the same assembly model.
Dismantling the grinder will require few tools, you just need a regular screwdriver or a reversible screwdriver with a ratchet mechanism.
Having prepared a screwdriver, you can start disassembling:
We unscrew the screws from the body and remove one side of the product.
Remove the nut that holds the disc, unscrew the bolts securing the protective casing.
We remove the brushes.
Disconnect the wires from the engine.
We unscrew the bolts that secure the gearbox inside, and very carefully remove it, and the rotor is also removed with it.
We unscrew the bolts that hold the stator and remove it.
We put the grinder back, put everything in place in the reverse order and fasten it.
When disassembling the grinder, it is important to remember the order in which the parts are removed in order to assemble them correctly.
VIDEO In the event of a malfunction, first of all, it is necessary to exclude elementary breakdowns:
The grinder does not turn on.The angle grinder suddenly became faulty - it stopped turning on. In this case, you need to check the serviceability of the outlet, then the plug and the power cord, perhaps the drive simply does not work due to the fact that no current flows into the product.
The cable and plug are intact, but the drive does not work. You need to check the start button. It is easier to repair the grinder switch by purchasing a new button and replacing it. Since it rarely needs to be repaired - basically, the plastic rod of the switch breaks inside. If you want to experiment, you can disassemble it by numbering the contacts, and put everything back together in place so that after assembly does not happen a short circuit.
The above parts are intact and the angle grinder doesn't want to work - so it's time to check the brushes. Perhaps it's time to change them in the grinder. The brushes are constantly heated from work, so they wear out quickly and more often than other parts need to be replaced, and in pairs.
Having excluded all minor breakdowns, it is necessary to understand why the tool does not want to turn on, and how to repair it. Most likely, the malfunctions are serious and require additional knowledge. This happens if:
the body is deformed;
one of the bearings is seized;
the armature or stator does not work;
the teeth of the gear wheel of the reducer are broken or worn out;
the collector is out of order;
the sensor of the control electronics does not show signs of life.
If it is determined that a malfunction has occurred in the mechanical part of the grinder, then you need to pay attention to the condition of the large gear located on the shaft, and to the bushings. If the teeth are partially worn out or the shafts are wobbling, they must be replaced immediately.
Grinder malfunctions happen quite often. Everyone who works with this tool knows about this. What goes wrong most often?
Just one awkward pressing of the spindle lock button while the disc is rotating will break it. It can sometimes be broken if used to remove a jammed disc. To prevent this from happening, you need to use an open-end wrench inserted into the special holes near the place where the disc is attached.
It mainly occurs when a jam occurs. If a rumble is heard in the gearbox, this is a symptom of just such a malfunction. When more than one tooth is broken at the gear, the grinder will not be able to cut the required material.
In order for the tool to continue working, it is necessary to change the gears, and everything, and even the bevel wheel. Before going to the store for spare parts, remember the manufacturer's firm, the model and the power of the product.
This type of breakdown happens with angle grinders, which work in places where there is a lot of dust, and when they are given rest, they are left on the ground. Dust that gets inside will damage the winding. Large loads, especially for a small power grinder, turn into a motor breakdown.
If the grinder is used for cutting materials that create a lot of dust, then it is recommended to cover the ventilation holes with something.
The weakest link, and not only among the grinders, are the bearings. A high speed will quickly wear out the mechanism. The good news is that changing the bearing is easy. Replacing a sprinkled bearing at a grinder must be done in time so that a breakdown does not happen that cannot be fixed.
This breakdown is easy to determine when the angle grinder has turned on, but the disc revolutions are too intense and differ from normal operation, which means that there is a turn circuit in the stator on the winding. Stator breakdown is considered the most serious, and special skills are required to eliminate it. When you have doubts about yourself, it is better to turn to professionals so that you do not have to buy a new instrument later.
If the decision to fix it yourself is made, it begins with cutting off the frontal parts of the winding, all the remnants are removed. The next step is to make a new winding according to the template.It should be identical in the number of turns, with the same density, and made of wire of the same thickness as the previous one.
LBM, the power of which is less than 1100 W, are usually equipped with spur gears. They are located on the stator. Bulgarians with more power have helical gears. Each of the options has a conical shape, the rod of the grinder's gearbox crosses with the stator shaft at an angle.
Repair of the grinder gearbox mainly consists of replacing the gears. If the disc gear breaks, it is difficult to replace it because it is very firmly fixed. It is easy to disassemble the gearbox:
you need to unscrew the nut from its side;
gently take the rotor body in a vice and knock out the gearbox housing with light blows;
change the position of the clamped rotor and knock out the bearing through a wooden board;
unscrew the gear from the shaft.
The speed regulator is not present on all models of grinders. When the angle grinder is used for cutting, it is, in principle, not needed, but if grinding is carried out, it is simply necessary. If suddenly it stopped working, then, most likely, the board burned out, which must be removed and bought the same in a power tool store for further replacement.
Self-repair of the grinder is not always feasible. If suddenly something does not work out or everything is not clear, it is better to contact the service center.
Before it completely breaks down, the angle grinder signals the beginning of a malfunction.
Pay attention to the work of your assistant: you should be alerted if:
the brushes began to spark too much;
the grinder is heated during work;
the motor hums inside the case when the tool is turned on;
the vibration of the body has become much greater during work;
the grinder's gearbox is bursting inside;
you hear the sound of a creak of bearings during spin-up or periodic wedging when the rotor shaft rotates;
The angle grinder has smoked, or an uncharacteristic burning smell emanates from it.
In order not to buy a new grinder, you need to be careful about the operation of the tool. In case of any deviations from the usual work, start troubleshooting, determine the cause and repair the power tool.
The service life of the grinder directly depends on the owner's care for it. Each instrument needs good care, then it will work properly for a long time.
Any grinder will warm up during operation, but in order to postpone the repair of angle grinders for a long time, you must adhere to some rules in the work:
Do not overload the tool to avoid overheating and smoke.
Do not put pressure on it while working.
Timely clean and lubricate the necessary parts inside the case.
If malfunctions are noticeable, discontinue operation and inspect for malfunctions.
Replace wearing parts in a timely manner.
If the grinder smokes, immediately stop working and do not turn it on again.
Do not use the tool when processing wood-type material.
Hold the grinder firmly during work so as not to drop or damage.
Adhering to the listed simple recommendations and rules in working with a tool called a grinder, you can extend its life longer than provided for by the warranty period.
VIDEO
Angle grinders during the Soviet era were made in Bulgaria. Therefore, the angle grinder began to be called a grinder. Currently, there are many companies for the production of angle grinders of various models. But the basic elements are the same. Having familiarized yourself with the device, probable breakdowns and diagnostics of the tool, you can repair the grinder of any modification with your own hands.
The grinder is designed for grinding and cutting various materials.
The main elements of the grinder
The grinder consists of the following elements:
The flat aluminum alloy gear housing provides better heat dissipation.
Carbon brushes.
Fastening the handle.
Electronic soft start system.Prevents start-up jerk and reduces starting loads on the engine.
Quick-detachable protective cover.
Ball bearings.
Electric motor.
Grinder switch.
A large selection of bearing products is offered by the Termopolis company -
Main breakdowns and reasons:
For troubleshooting, the grinder must be disassembled.
Remove the nut that holds the scraper disc.
Unscrew the bolts securing the protective cover.
Unscrew the bolts of the grinder body and those with which the body is attached to the gearbox.
Remove the upper part of the back case. Unscrew the bolts securing the cord. Remove the wires and the button from their grooves. In some models, for example, in DWT, the rear case is not disassembled into parts, but removed entirely.
Disconnect the motor wires.
Remove the brushes.
Disconnect the gear case from the grinder body. Together with it, the engine anchor is removed.
Unscrew the gearbox bolts located around the casing mount.
To disconnect the armature from the aluminum housing, unscrew the nut located in the gearbox housing.
Assemble the tool in reverse order.
During operation, the disc can be tightened so tightly with the nut that it begins to crumble. It is impossible to unscrew the nut with a wrench. And you don't need to do this, since you can break the grinder. First, break the disc down to the nut. Then find a metal plate slightly thinner than the scratch disk. With its help, grind off the remnants of the disc under the nut. It can be easily unscrewed with a key or by hand. To avoid bringing the tool to this problem, place a washer under the nut.
VIDEO
For some grinders, for example, Bosh, the casing is not bolted, but snapped into place. To remove it, you need to turn the cutout of the casing perpendicular to the grinder. To dress, turn until it clicks.
The stator is checked with a multimeter.
Turn-to-turn closure. Set the resistance mode to 200 ohms. Connect the test leads of the device to the ends of one winding. One means open, and zero means short circuit between turns. If it shows a resistance of more than 1.5 ohms, then check the second winding. Both windings should have approximately the same resistance.
Breakdown to ground or short circuit of the winding with the metal stator housing. Set the multimeter to the maximum resistance mode. Connect one probe to the end of the winding, the other probe to the metal stator housing. The unit indicates the absence of breakdown.
First, visually inspect the manifold and winding. There may be visible damage: black marks, bent windings, raised, worn or burnt collector plates. After inspection, proceed with the tester check.
Put a resistance of 200 ohms. Connect the test leads to the two adjacent manifold plates. If the resistance is the same between all adjacent plates, then the winding is in good order. If the resistance is less than 1 ohm and very close to zero, there is a short circuit between the turns. If the resistance is two or more times higher than average, then there is a break in the winding turns.
The determination of the breakdown to ground is done in the absence of a winding break. Set the maximum resistance on the scale of the device. Depending on the tester, it can be from 2 MΩ to 200 MΩ. Connect one probe to the shaft, and the other to each plate in turn. In the absence of faults, the resistance should be zero. Do the same with the rotor. Connect one probe to the iron body of the rotor, and move the other along the plates.
Put the tester in the dialing mode.
Insert one probe into the outlet of the button and the other into the opposite inlet.
Click the button. A sound signal indicates the health of this part of the button.
Do the same with the other input and output buttons.
VIDEO
Connect one probe to the contact of the plug, the other to the inputs of the button. There must be an audible signal in one of the two positions. Do the same with the other contact of the plug.
If the power button and power cord operate but the engine will not turn on, check the soft start control board. Remove the screw that secures the control board. Remove it carefully. Call all the elements. If the grinder has a speed controller, then it can be connected in series with the power button and have one board with a soft start. But it may have a separate fee. It is checked in the same way as for soft start.
Read the instructions. Check out the description and assembly diagram of the grinder.
Unplug the instrument from the mains.
Prepare your work area on a table with good lighting.
Record on paper or a photo the procedure for disassembling the tool in order to properly assemble it after repair.
If you are unsure of your abilities, then it is better to take the tool to the workshop.
The damaged cord and button must be replaced. On the button, unscrew the bolts securing the incoming and outgoing wires. Disconnect it from the chain and replace with a new one.
If only the triac is out of order in the control board, then a new one must be installed in its place. Pre-lubricate the metal part of the element with thermal grease. If other elements of the board are burnt out, replace it completely.
The brushes should be checked periodically. When one is worn by 40%, change both. And also clean the brush holders.
To remove the brushes, you must either remove the rear housing, or remove the plugs in the housing.
Clean brush holders from dust and carbon deposits. Wrap a cloth around a screwdriver and moisten with alcohol. The carbon deposits are cleaned off with a file. The brush should walk easily in the brush holder, then it will be well pressed by the spring.
Insert new brushes.
VIDEO
For high-quality winding of coils, you will need enamel wire and electrical cardboard.
Remove the winding and old insulation from the housing. Examine the grooves carefully. When the coils are burning, the insulation is burned through and a short circuit to the case occurs. There are deposits on it, which must be removed with a file or a diamond bur. Deposits will interfere with the new winding. It can tear.
The winding is impregnated with varnish. To disconnect the wires and count them, you need to blow off the insulation. Preheat the winding with an industrial hair dryer or any burner.
Use a fire to burn matches or lighters on any wire so that the enamel is completely burnt out. Take a micrometer and measure the thickness. Record the wire diameter and the number of turns.
Take any wire and make a loop out of it so that it fits in the grooves of the stator. Choose a cylinder for winding turns for the diameter of this loop. For example, an aerosol can. If its diameter is not enough, then wrap the can with paper.
Wind both windings from the enamel wire. Fasten the frontal parts with glass tape or thick thread. The thread should not break or melt. Place a shrink sleeve on the riser ends.
Make sleeves from electrical cardboard and insert into the grooves. Place the windings in them.
Check the resistance in the windings with a tester. If everything is ok, continue.
So that during operation the wires do not vibrate or rub against each other, they must be impregnated with any oil-based varnish. Put the starter preheated in the oven upright and squeeze the varnish onto the winding with a syringe. When the varnish begins to run out from below, turn the stator over and saturate it on the other side.
When the varnish is dry, start connecting the windings. Connect the two ends of different windings to each other and connect to the nearest brush. Connect the other two connected ends to the start button. Also connect the wire from the second brush to the button.
VIDEO
If the balance is out of balance, the armature must be replaced. The winding and the collector are subject to repair. Small short circuits are eliminated. If a significant part of the winding is damaged, it can be rewound.
A not very depleted collector is corrected by a groove. But if the plates are worn down to the plastic base or partially burned out, then the restoration is carried out by soldering or galvanic build-up.
Severely damaged manifold
If the collector has been completely worn out, then after soldering it will last no more than a month of active use. And not completely damaged plates after such a repair withstand several brush replacements and are not soldered out. You will need to cut the copper plates to size and solder them in with plenty of solder. Grind off excess with a file and grind.
Reduced copper is very hard when electroplated. The service life of the collector is the same as that of a new one.
Completely rebuilt manifold
Galvanic build-up can be used to restore both a completely worn-out collector and partially damaged plates. The restored manifold must be grooved and the plates must be cut with a drill or a hacksaw blade.
In order to rewind the anchor correctly, you need to disassemble it correctly and remove the parameters for the template:
Winding direction.
How many grooves and slats.
The number of conductors in the groove.
Winding step, that is, how many grooves between the grooves of one section. For example, if the conductors leave the first slot and enter the sixth, then step = 5.
How many conductors go into one groove, there are so many coils in one section.
Wire thickness.
For example, 80 conductors in a groove, 12 slats and 24 grooves. 12 sections of 2 coils. The winding takes place in two circles, so we divide the 80 conductors in the groove by 2, and another 2, since there are 2 coils. We get 20 turns of one coil.
We solder the beginning of the wire to lamella 1 and pass it through the first and sixth grooves. We make 20 turns. The first coil of the first section is ready.
We solder the wire to the lamellas 2 and repeat the winding through the same grooves. The second coil of the first section is ready.
We solder the wire to the lamellas 3. Pass the coil through the second and seventh grooves. We wind the first coil of the second section and seal the wire on the lamellas 4.
We fix the second coil of the second section on the lamella 5.
How to remove the old one and wind the new winding:
Use a metal saw or wire cutters to remove the winding ends.
Carefully, without damaging the slot insulators, knock out the rods of the remaining parts of the winding using a hammer and a metal chisel.
Use a file to remove the remaining impregnation. Count the conductors in the groove and measure the wire diameter. Draw a diagram. Cut the insulation sleeves out of cardboard and insert them into the grooves.
After winding, weld the leads of the sections with the collector plates. Check the winding with a tester.
Saturate the winding with epoxy.
Bearings will crumble or seize over time. They need to be changed.
Disassemble the grinder, remove the armature from the stator.
The armature is inserted into the gearbox housing with a bearing. If the housing cannot be removed, secure the rotor in a vise and tap with a wooden block on the gear housing.
The gearbox has to be disassembled not only for repair, but also for preventive cleaning and lubrication.
Unscrew the bolts and disassemble the gear housing. You will see dirty grease that needs to be removed.
old grease will pour out of it. Clean the parts with a rag or toilet paper. Rinse the body and parts with kerosene.
Apply new grease recommended by the manufacturer in the instructions for the tool.
If the button has departed, then it is impossible to work with such a grinder.
Since the spindle can spontaneously lower itself onto the gear and lock it during operation.
The fixing unit consists of a spindle with a rubber ring, a spring and a plastic button.
Disassemble the gearbox to replace the button.
Remove the spindle from the body.
Slide the spring onto the button from the inside.
Insert the spindle into the gear housing from the inside and the button from the outside. Press until you hear a click.
Assemble the reducer.
VIDEO
To make the grinder work for a long time, follow the rules:
Watch the integrity of the insulation of the wire, plug. Do not remove protection. Lubricate and clean the entire tool.
After turning off the grinder, wait until the circle stops rotating, then put it on the ground. When the engine stops, the tool sucks in particles of earth and other hard particles through the air vents, which hit the winding of the motor. The result is an open or short circuit.
Try not to use the grinder outdoors in winter. The engine heats up while you are running. The air is icy. As a result, condensation forms. Moisture is harmful to the engine.
Always use the discs recommended by the tool manufacturer. If the grinder is 180 mm, do not put more than 200 mm there. The larger the circle, the lower the rpm should be. You will have to remove the protection, and the turnover will be exceeded. Oscillation and vibration will increase. As a result, the circle will fly apart. This is fraught with not only serious injuries. The bearing of the reducer is broken, the gears are erased.
If you actively use a grinder, then you are a good craftsman. It will not be difficult for you to understand the structure of the tool and fix it with your own hands. First, find the problem and determine which parts to check. Repair the grinder carefully, without haste, so that a minor breakdown does not turn into a major one.
The grinder's anchor is most exposed to thermal, mechanical and electromagnetic loads. Therefore, it is a common cause of tool failure, and as a result, it often needs repair. How to check the anchor for performance and fix the element with your own hands - in our article.
The grinder's motor armature is a conductive winding and a magnetic circuit, into which the rotation shaft is pressed. It has a drive gear at one end and a manifold with lamellas at the other. The magnetic circuit consists of grooves and soft plates coated with varnish to isolate from each other.
In the grooves, according to a special scheme, two conductors of the armature winding are laid. Each conductor is half a turn, the ends of which are connected in pairs on lamellas. The beginning of the first turn and the end of the last one are in the same groove, so they are closed on one lamella.
Types of armature malfunctions:
An insulation breakdown to ground is a short circuit of the winding to the metal rotor body. It occurs due to the destruction of the insulation.
Unsoldering of collector leads.
Uneven manifold wear.
If the armature is faulty, the motor overheats, the winding insulation melts, the turns are short-circuited. The contacts connecting the armature winding with the collector plates are unsoldered. The power supply is cut off and the motor stops running.
visually;
multimeter;
light bulb;
special devices.
Before taking the device for diagnostics, inspect the anchor. It may be damaged. If the wiring melts, the burnt-on insulating varnish will leave black marks or a peculiar smell. Bent and crumpled turns or conductive particles such as solder residue can be seen. These particles cause short circuits between the turns. The lamellas have folded edges, called cockerels, to connect to the winding.
Due to the violation of these contacts, the lamellas burn out.
Other damage to the manifold: Raised, worn, or burnt fins. Graphite from the brushes can accumulate between the lamellas, which also indicates a short circuit.
Put a resistance of 200 ohms. Connect the test leads of the device to two adjacent lamellas. If the resistance is the same between all adjacent plates, then the winding is in good order. If the resistance is less than 1 ohm and very close to zero, there is a short circuit between the turns. If the resistance is two or more times higher than average, then there is a break in the winding turns. Sometimes, when there is a break, the resistance is so great that the device goes off scale. On an analog multimeter, the arrow will go all the way to the right. And on digital it will not show anything.
VIDEO
If you don't have a tester, use a 12 volt light bulb up to 40 watts.
Take two wires and connect them to the lamp.
Make a break on the negative wire.
Apply voltage to the wires. Attach the ends of the gap to the collector plates and twist it. If the light is on without changing the brightness, then there is no short circuit.
Conduct a short to iron test. Connect one wire to the lamellas and the other to the rotor iron. Then with the shaft. If the light is on, then there is a breakdown to ground. The winding closes to the rotor housing or shaft.
This procedure is similar to diagnostics with a multimeter.
There are anchors that have no visible wires connected to the collector due to filling with an opaque compound or due to a bandage. Therefore, it is difficult to determine commutation on the collector relative to the slots. The indicator of short-circuited turns will help in this.
This device is small in size and easy to operate.
First check the anchor for breaks. Otherwise, the indicator will not be able to detect a short circuit. To do this, measure the resistance between two adjacent lamellas with a tester. If the resistance is at least twice the average, then there is a break. If there is no break, proceed to the next step.
The resistance regulator allows you to select the sensitivity of the device. It has two bulbs: red and green. Adjust the regulator so that the red light starts to light up. On the indicator body there are two sensors in the form of white dots, located at a distance of 3 centimeters from each other. Attach the indicator with the sensors to the winding. Rotate the anchor slowly. If the red light comes on, then there is a short circuit.
VIDEO
The armature checking device determines the presence of a turn-to-turn closure of the winding. An inductor is a transformer that has only a primary winding and a magnetic gap cut out in the core.
When we put the rotor in this gap, its winding starts to work as a secondary winding of the transformer. Turn on the appliance and place a metal plate such as a metal ruler or hacksaw blade on the anchor. If there is a turn-to-turn short circuit, the plate will vibrate or magnetize to the armature body from local oversaturation of iron. Rotate the anchor around the axis, moving the plate so that it lies on different turns. If there is no closure, then the plate will move freely along the rotor.
VIDEO
Due to the anchor, a third of the breakdowns of the screwdriver occurs. With daily intensive operation, malfunctions may occur already in the first six months, for example, if the brushes are not replaced on time. With sparing use, the screwdriver will last a year or more.
The anchor can be salvaged if the balance is not disturbed. If during the operation of the device an intermittent hum is heard and there is a strong vibration, then this is a violation of the balance. This anchor must be replaced. And you can repair the winding and the collector. Small short circuits are eliminated. If a significant part of the winding is damaged, it can be rewound. Grind worn out and heavily damaged lamellas, build up or solder. In addition, you should not undertake an anchor repair if you are unsure of your capabilities. Better to replace it or take it to the workshop.
Over time, the brush develops on the collector. To get rid of it, you must:
Grind the manifold using longitudinal cutters, that is, through cutters.
Do not forget to clean the swarf from the rotor to prevent a short circuit.
VIDEO
Before disassembling the armature, write down or sketch the direction of the winding. It can be left or right. To determine it correctly, look at the end of the armature from the collector side. Put on gloves, use sharp cutters or a metal hacksaw. Remove the winding ends. The manifold needs to be cleaned, but it is not necessary to remove it.Carefully, without damaging the slot insulators, knock out the rods of the remaining parts of the winding using a hammer and a metal chisel.
VIDEO
Using a file, without damaging the insulator film, remove the impregnation residues. Count the conductors in the slot. Calculate the number of turns in the section and measure the wire diameter. Draw a diagram. Cut the insulation sleeves out of cardboard and insert them into the grooves.
VIDEO
After winding, weld the leads of the sections with the collector cockerels. Now check the winding with a tester and short circuit indicator. Proceed with impregnation.
After making sure that there are no problems, send the anchor to the electric oven to warm up for better epoxy flow.
After warming up, place the anchor on the table at an angle for better flow through the wires. Place a drop of resin on the forehead and slowly twist the anchor. Drip until glue appears on the opposite frontal area.
At the end of the process, lightly grind the manifold. Balance the anchor with dynamic balancing and grinder. Now grind finally on the bearing. It is necessary to clean the grooves between the lamellas and polish the collector. Do a final check for open and short circuits.
The peculiarity of the winding for grinders with a variable speed is that the rotor is wound with a power reserve. The current density affects the speed. The wire cross-section is overestimated, and the number of turns is underestimated.
If the insulation breakdown was small and you found it, you need to clean this place from carbon deposits and check the resistance. If the value is normal, insulate the wires with asbestos. Place a drop on top with Supermoment-type quick-drying glue. It will seep through the asbestos and insulate the wire well.
If you still have not found the place of insulation breakdown, then try to carefully saturate the winding with impregnating electrical insulating varnish. Punched and non-punched insulation will be impregnated with this varnish and will become stronger. Dry the anchor in a gas oven at about 150 degrees. If this does not help, try rewinding the winding or changing the armature.
The lamellas are installed on a plastic base. They can be erased to the very core. Only the edges remain, which the brushes cannot reach.
Such a collector can be restored by soldering.
Cut the required number of lamellas from the copper pipe or plate to size.
After stripping the armature from copper residues, solder it with ordinary tin with soldering acid.
When all the lamellas are soldered, sand and polish. If you don't have a lathe, use a drill or screwdriver. Insert the armature shaft into the chuck. Sand with a file first. Then polish with zero sandpaper. Remember to clean the grooves between the lamellas and measure the resistance.
There are not completely damaged lamellas. To restore them, it is necessary to carry out more thorough preparation. Slightly whip through the manifold to clean the plates.
As you know, nothing is eternal and even the tools of brand manufacturers break, not to mention the so-called “consumer goods”. And the grinder (angle grinder) is no exception. By the way, they began to call angle grinders "grinders" at the time of the Union, because then this instrument was produced in Bulgaria and the first models were supplied from there. The grinder, as a tool, has become very widespread due to its versatility and ease of use. There are also many varieties and models of grinders, but the principle of operation and device is not fundamentally different. Therefore, having considered the device of the tool, possible malfunctions and repair methods, they can be applied to any model of the grinder.
Grinder device relatively simple. The basis of the tool is its body, inside which there is an electric motor, a starting device and a gear transmission to the spindle, on which various attachments are attached.
The body is made of strong impact-resistant plastic.Depending on the power, there are different dimensions and shapes of the tool. Some models have an angular speed regulator, which is designed to optimally select the speed for various types of work.
A button for replacing the working disk, when pressed, which locks the disk in a certain position, preventing it from scrolling when removed.
The overload clutch acts as a limiter in the event of a sudden reactive torque. Otherwise, when the disc is jammed in the material, the grinder itself begins to rotate abruptly, which can lead to injury to the worker. This clutch does not allow such rotation.
The electric motor consists of a stator and a rotor as standard. The stator is located in the guide lugs of the plastic housing of the grinder. On the back of the stator there is a special device called a brush mechanism. It contains copper-graphite brushes. Brushes are required to transfer voltage to the rotor through the manifold assembly.
The rotor is located inside the stator and is fixed in the housing in bearing assemblies, which are inserted directly into the tool housing. The front bearing assembly is usually made in a metal plate, or this plate can be made of an aluminum alloy.
The grinder's gear housing is almost always made of aluminum alloy and has several threaded holes for attaching an additional handle. By screwing the handle into various holes, you can change the planes of location during operation.
The reducer consists of two gears, with the help of which the direction of the output shaft changes by 90 degrees and the rotation speed is reduced. The ratio of the number of teeth on the primary gear to the number of teeth on the secondary gear is called the gear ratio.
The grinder suddenly stopped working .disconnect physically from the network and manually rotate the disc. If the disc does not spin or is spinning very tightly, immediately disassemble the instrument for visual inspection. If it turns easily, then the most likely thing is that electricity does not reach the brushes of the electric motor. That is, the problem lies either in the power plug, or in the wire itself, or in the mechanism of the “Start” button. It is enough to disassemble the case and “ring out” the cable with an ordinary tester, or in some other way, for the presence of a break. After eliminating the break or replacing the wire, the grinder will work.
The wire and plug are guaranteed to be intact, but the tool still does not work.
The start button and the power wire are in working order, the grinder does not work. Check brushes and brush holders. There may be a breakage or complete wear of the brushes. The resource of these devices is usually limited to several years, of course, it all depends on the intensity of use. Eliminate open or replace brushes.
Then there are more serious malfunctions, respectively, and repair requires certain knowledge and skills.
- breakage or licking of the gear teeth of the gearbox;
When determining the mechanical defects of the grinder, more attention should be paid to the condition of the plonitarka (large gear), shank (gear on the shaft) and bushings. Uneven wear of the teeth or wobbling of the shafts indicates immediate replacement of the worn parts.
Breaking out the spindle lock button.
Chipped gear teeth.
Failure of the electric motor.
Bearings.
Stator If, when turned on, the disk starts to gain speed and accelerates too much, there is definitely a turn circuit on the stator winding. Stator repair is one of the most serious breakdowns and requires appropriate skills. If you are not confident in your abilities, then it is more expedient to entrust it to professionals or use the services of a repair shop.
We start repairing the grinder's stator by cutting off the frontal parts of the winding, the remnants of which we take out. Next, we make a new winding using a template sandwiched between two large plates on an axis, which can be inserted into an electric drill. The main thing is to achieve an identical number of turns, made with the proper density and withstand the thickness of the wire. We insert two coils into the stator case, we make conclusions from the same winding wire, insulating with flexible tubes of the appropriate diameter.
Reducer In models with a power of up to 1100 W, spur gears are usually used, mounted on an anchor, but grinders with a higher power, for example, 1500 W, require helical gear wheels. Both options are tapered, since the axis of the gear stem intersects with the armature shaft, and transmission is possible only by angular engagement of the teeth.
Speed regulator Almost all modern models of drills, jigsaws, screwdrivers have a speed controller.But not all grinders (grinders) are equipped with such a mechanism. In principle, a regulator is not needed for cutting metal with a cut-off stone, but for grinding it simply cannot be replaced. The proposed scheme of a home-made regulator is very simple and reliable. There are not many parts and they are not expensive. If you already have a grinder without a standard speed governor, then you can easily improve it.
Can be assembled separately in a box with a power outlet and used as a carrier with a power regulator. Or you can immediately assemble the regulator in the grinder body and remove the resistor handle.
The power tool must not be allowed to operate under load for a long time at significantly reduced speeds (this can be determined by ear) in comparison with idle speed, and even more so, clamping (blocking) of the tool must not be allowed, otherwise it will burn out within a few seconds.
Do not turn off the power tool immediately after operating at reduced speed. To prevent local overheating, it needs to run for some time (more than 1 minute).
It is important to strictly observe the intervals for changing (adding) the lubricant and its quantity specified in the operating instructions.
Video (click to play).
Prevention consists in complete or partial disassembly of the tool, cleaning, lubrication and replacement (if necessary) of some parts.
The most common breakdowns
