How to Wear a Metal Brush on an Angle Grinder

How to exchange brushes for an angle grinder (grinder), where are they located at all?

An angle grinder in the arsenal of a home foreman should be required. After all, with its help it is possible to perform such work that tools familiar to us, such as a hacksaw for metal, chisels, hand tools for grinding, etc. cannot do it. For example, making a neat longitudinal cut-groove to a certain depth will not work with chisels, neither a hacksaw for metal, nor a gas welding torch. But the angle grinder can do this job easily.

how to put a brush for metal on an angle grinder

To perform curly cutting of ceramic tiles will not work with a tile cutter, and an angle grinder will do this job perfectly.

But you never know there are such household chores where this versatile tool can come in handy! And how can one not be upset if during operation the angle grinder suddenly refuses to work.

If this suddenly happened, first unplug the plug and conduct an initial test.

Try turning the disc with your fingers. There may be two options:

1). the disk rotates with difficulty or does not spin at all;

2). the disk rotates freely.

In the first case, it can be assumed that most likely the problem lies in the mechanical part and serious repairs cannot be avoided here.

The second option means that voltage has disappeared on the way from the outlet to the electric motor and one of the reasons may be brushes that transmit voltage from the wires to the motor armature.

Getting to the brushes is not difficult. It is necessary to remove the back cover of the case and under it there will be two brush holder closed by protective caps. By pulling out or unscrewing the protective caps (depending on the design), you will get access to the brushes directly.

After removing them from the nests, inspect. Malfunctions will open even to an inexperienced eye, since there are only two of them:

severe wear when the brushes do not touch the anchor (most likely);

breakage of the conductor (extremely rare).

The fault is eliminated by simply replacing the brushes. The breakage of the conductor can be eliminated by soldering, if, of course, it did not occur at the place of attachment directly to the brush, but it is still better to replace this entire assembly.

Important: you must change both brushes immediately, even if everything is okay with the second one.

Warning: do not try to install the brushes by making them yourself from brushes similar to yours, for example, from the Zhiguli generator. As a temporary option, a similar solution to the problem is acceptable, but change them to "native" as soon as possible. The fact is that manufacturers calculate and manufacture these parts in accordance with the characteristics of the tool and the working conditions as a whole, and you must agree that the conditions of the VAZ generator and the angle grinder are completely different.

And one more addition: before installing new brushes in place, clean the motor anchor with a regular school eraser. Do not use sandpaper, even the finest, for these purposes. After cleaning, blow the anchor well with compressed air.

To help with the upcoming brush replacement work, angle grinder watch this video.

Replacing brushes with an angle grinder

One of the most popular home power tools is rightly considered an angle grinder. At one point, the brushes begin to grind and need to be replaced. A sure sign of brush wear is a violation of the sound of the electric motor, an angle grinder. Also, if you look closely, a sheaf of sparks is visible through the ventilation grilles and an unpleasant smell is felt. When the first signs of wear of the brushes appear, they must be urgently replaced. Delaying the moment of replacement, you risk ditching the collector, which is equivalent to buying a new anchor for an angle grinder.

So, first of all, you need to decide on the technical feasibility of replacing the brushes.

Here we have two options:

1. On some models on the sides of the angle grinder there are two small covers that hold on two screws. You just need to unscrew them and replace the burned brushes.

2. In most models, in order to replace the brushes, the angle grinder must be disassembled. Below we look at explanatory photos of disassembling a small angle grinder and read the instructions for replacing brushes.

We look carefully at the handle of the power tool and look for fixing screws. In our case, the handle of the angle grinder consists of two parts, but there are models where the handle simply extends towards the power cord. Having disassembled the handle, we look for the location of the brushes that are in the special brush holders.

The design of the brush holders may be different, but in any of them the brush must be disconnected from the general electrical circuit of an angle grinder. To do this, remove the tips and study the design of the brush holder. In some cases, the brush is simply pulled out. In the angle grinder we are considering, the brush holder leans back, and after this procedure we insert the brush.

Not every one of us has the opportunity to find suitable brushes in size, but the gimmick of invention is cunning. If you did not find your own brushes, then take something similar to them, the main thing is that they would be a little larger. Using a file, we bring them to the right size, the main thing is not to rush, so as not to waste too much. If the brushes have different tips, then cut off the leash from the old brush and screw it onto a new one.

After all these manipulations, we assemble the angle grinder in the reverse sequence.

Note: If you have already disassembled your angle grinder, blow it with a compressor against dust, also look at the condition of the collector of the anchor. When working with heavily worn brushes, scratches may occur on the collector, which can be removed with zero sandpaper.

How to replace the brushes with an angle grinder

Very often, a manufacturer of angle grinders completes their products with a spare pair of brushes (graphite contacts that allow electric current to be transmitted to a rotating rotor).

Is this part so worn out so intensively that it is only intended to add it? If you use the tool from time to time, then the brushes will survive the owner. But if you operate the angle grinder daily, then, indeed, their wear will be significant. And the day will come when a few-centimeter graphite rod will be erased to a thin plate. Extreme wear of the brushes must not be allowed so as not to damage the rotor contacts. It is necessary to check the condition of the rods periodically, after operating hours of dozens of hours.

Brush replacement

This is where a sensible question arises for manufacturers of grinders, why not make a window of transparent plastic in the case in order to visually assess the condition of graphite contacts without analyzing the power tool (in some models of grinders it is not necessary to unscrew the case)?

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Attention! When starting to replace the brushes, as with any penetration into the body of the power tool, it is necessary to turn off the power supply by removing the plug from the outlet.

In view of the structural diversity of angle grinders, the replacement of graphite contacts for each model of tool may have its own characteristics.

The most elementary way, without disassembling the case

Some manufacturers have come to the possibility of replacing the brushes very rationally. There are screw plugs in the machine body. And the whole process of checking or “repairing” takes two minutes (for both graphite contacts):

  1. Unscrew screw plug.
  2. Pry off the pressure cap with a thin screwdriver and remove the brush.
  3. If the brush has lost 70. 80% of the length compared to the new one, then it should be replaced. Otherwise, the old graphite contact must be placed on the same side as it was before extraction, in order to exclude the grinding process. After all, the brushes wear out unevenly due to the fact that they are in contact with a rotating cylindrical surface.
  4. Screw the plug all the way. Attention! The cork can be screwed upside down. Therefore, it is necessary to ensure that the groove for the screwdriver is on top. Otherwise, the next unscrewing will cause difficulties.
  5. Repeat all steps with the brush located on the back side of the case, an angle grinder.

This is the easiest way to replace the brushes on an angle grinder, without disassembling the case. Therefore, when buying a new instrument, this nuance can be taken into account.

angle grinder without rear handle

For grinders that do not have a rear handle, the brushes are replaced in the following sequence:

  1. Unscrew the angle grinder from the end face.
  2. Pull off protective cylinder cover.
  3. Pull cover off contact block.
  4. Pry off the brush pressure cap with a thin screwdriver and pull out the graphite rod.
  5. Insert a new brush, close the contact block with a cover.
  6. Repeat all operations with another brush.
  7. Put on the casing on the angle grinder and fix it with a self-tapping screw.

Often there is another way to attach the brushes. In this case, the sequence of actions will be as follows:

  1. Remove the casing by first unscrewing the self-tapping screw.
  2. Release the brush from the clamping belt spring by tucking the last with a screwdriver.
  3. Remove the brush from the guide block by tinkering it with a screwdriver.
  4. Remove the brush contact from the connector. Also with a screwdriver.
  5. Connect the contact of the new graphite rod to the connector, insert the brush into the guide block and press down with the spring.
  6. Repeat all operations with the second brush, close the housing with a casing and screw it with a self-tapping screw.

These are the two most common ways to replace graphite contacts. Although other grinder design options are not ruled out.

angle grinder with rear handle

An angle grinder with a rear handle allows you to get to the brushes in a slightly different, simpler way:

  1. Near the handle, you need to find a small repair window, covered with a plastic plate, which is fixed with a self-tapping screw.
  2. It is necessary to unscrew the screw, pry a plastic plate into the groove with a screwdriver, remove it from the housing, opening the repair window.
  3. The following steps to replace the brushes are the same as for low-power grinders: release the tape spring (1), release the plug (2), remove the brush from the guide block by the wire.
  4. Then insert a new brush, connect the plugs, fix the graphite rod with a tape spring, close the repair window with a plastic plate and screw on the self-tapping screw.
  5. Repeat all actions with the second brush located on the opposite side of the case.

It is possible that there may be other ways to replace graphite brushes, due to the design features of grinders.

Conclusion

Structurally, the angle grinder is different from each other, so the brush replacement method may differ slightly from the basic methods described above. But the general features are still visible:

  1. The brushes are located next to the rear handle or to the part of the body that is designed to hold the tool.
  2. The most common designs of graphite brushes: with and without a spring.

The first type of design involves a simplified method of replacement, because it has a wire, a contact plate, and a compression spring.

Video: How to Wear a Metal Brush on an Angle Grinder


Springless brushes require a slightly more time-consuming replacement process, because the fixing spring is attached to the body and it is more rigid, and the wire is attached in a separate place with a plug.

How to replace brushes with an angle grinder Link to main publication

DIY angle grinder repair: how to disassemble angle grinders, check brushes, replace the stator, etc. video

Angle grinders in Soviet times were made in Bulgaria. Therefore, angle grinder began to be called an angle grinder. Currently there are many companies producing angle grinders of various models. But the basic elements are the same. Having familiarized yourself with the device, possible breakdowns and tool diagnostics, you can repair the angle grinder of any modification with your own hands.

The device and purpose of the angle grinder

angle grinder is designed for grinding and cutting various materials.

The main elements of the angle grinder

The main elements of the angle grinder

The angle grinder consists of the following elements:

  1. The aluminum alloy flat gear housing dissipates heat better.
  2. Carbon brushes.
  3. Grip mount
  4. Electronic soft start system. Prevents jerking when turned on and reduces starting loads on the engine.
  5. Quick detachable guard.
  6. Ball bearings.
  7. Electric motor
  8. Switch angle grinder.

Main malfunctions, their causes and diagnostics

The main breakdowns and causes:

  1. Burns, sparks and twitches. Reasons: violation of the insulation of the armature winding, wear of the brushes, collector, clogging of the brush holders. Even after replacing the brushes, the angle grinder sparkles and twitches if the brush holders are clogged.
  2. Clapping sound. Brushes or interturn circuit of any of the windings.
  3. Crispy sound. The reason is in the bearings.
  4. Mechanical rumble and heavy tapping. Gearbox malfunction.
  5. angle grinder has stopped working, does not turn on. If the disk is manually spinning tightly or not spinning, the cause is the gearbox. If it turns easily, check the electrical circuits. If chains work, check motor and brushes.
  6. The spindle lock button has broken. The reason is clicking on it during rotation of the disc or jamming of the disc.
  7. The angle grinder works in fits and starts. Check engine for interturn short circuit.
  8. Vibrates. The reason for mechanics. Check bearings, rotor shaft and gearbox.
  9. Heats up. If it heats up in the engine area, the cause is worn out brushes or a short circuit in the turns of the windings. If the gear case is warming, then the grease has dried or the gears have worn out.
  10. It does not gain momentum or power drops. The reason is in the electronics or engine. Check soft starter control board and speed controller, brushes and collector.
  11. Smokes. The reason is overheating of the tool. Check motor windings for insulation melting.
  12. Humming and not spinning. Check motor bearings and gearbox.

How to disassemble and reassemble the angle grinder

To troubleshoot the angle grinder must be disassembled.

    Remove the nut that holds the working disk. Mounting a working disk

Turn off bolts of fastening of a protective casing.

Remove the housing bolts from the angle grinder and those that secure the housing to the gearbox.

Remove the top of the rear housing. Turn off bolts of fastening of a cord. Remove the wires and button from your grooves. In some models, for example, in DWT, the rear case is not disassembled into parts, but is removed entirely.

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Remove the gearbox bolts located around the casing mount.

Gear housing

To disconnect the anchor from the aluminum housing, unscrew the nut located in the gear housing.

Unscrew the nut

Reassemble the tool in the reverse order.

The clamping nut is not untwisted

During operation, the disk can tighten so tightly with a nut that it begins to crumble. It is not possible to unscrew the nut with a wrench. And you do not need to do this, since you can break the angle grinder. First, break the disc all the way to the nut. Then find the metal plate a little thinner than the working disk. Use it to drain off the rest of the disc under the nut. It can be easily unscrewed with a key or hands. In order not to bring the tool to this problem, put the washer under the nut.

How to remove a tightened nut

The casing cannot be removed

In some grinders, for example, Bosh, the casing is not bolted, but latched. To remove it, you need to turn the cutout of the casing perpendicular to the angle grinder. To dress, turn until it clicks.

Stator check

The stator is checked with a multimeter.

  1. Inter-turn closure. Set the resistance mode to 200 ohms. Connect the test leads to the ends of one winding. A unity means an open, and zero means a short circuit between the 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.
  2. Breakdown on the mass or shorting of the winding with the metal housing of the stator. In the multimeter, set the maximum resistance mode. Connect one probe to the end of the winding, the other probe to the metal housing of the stator. The unit indicates the absence of breakdown.

Anchor Check

First visually inspect the collector and winding. There may be visible damage: black marks, bent turns of the winding, raised, worn or burnt collector plates. After inspection, proceed with the tester.

    Set the resistance to 200 ohms. Connect the test leads to two adjacent collector plates. If the resistance is the same between all adjacent plates, then the winding is working. 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 above the average two or more times, then there is a break in the turns of the winding. Diagnostics of the inter-turn short circuit of the armature

The determination of the breakdown to mass is done in the absence of a winding break. Put 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.

Determination of breakdown to the mass at the anchor

Checking the power button

Put the tester in dialing mode.

Insert one probe into the output of the button and the other into the opposite input.

Click the button. A sound signal indicates the health of this part of the button.

Do the same with the other input and output of the button.

How to ring the start button

Power cord check

Connect one probe to the plug pin, the other to the button inputs. In one of two positions there should be a sound signal. Do the same with the other pin of the plug.

Check soft start and speed control

If the power button and power cord are working but the engine does not turn on, check the softstart control board. Remove the screw that secures the control board. Remove it carefully. Call all items. If there is a speed regulator in the angle grinder, then it can be connected in series with the power button and have one board with soft start. But may have a separate fee. It is checked similarly to soft start.

Precautions before starting repairs

  1. Read the instructions. Read the description and assembly diagram of the angle grinder.
  2. Unplug the tool.
  3. Prepare a workplace on a table with good lighting.
  4. Recorded on paper or on the photo order of disassembly tool to assemble it correctly after repairs.

DIY troubleshooting

If you are unsure of your abilities, it is better to take the tool to the workshop.

Power cord and power button

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 install a new one.

Soft start and speed control

If only the triac is out of order in the control board, then a new one must be put in its place. Pre-grease the metal part of the element with thermal grease. If other elements of the board burn out, replace it completely.

brush

Brushes must 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 of dust and carbon deposits. Wrap a cloth around the screwdriver and moisten with alcohol. Nagar is 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.
Brush holder cleaning

Stator Rewind

For high-quality winding coils, you will need an enamel wire and an electric cardboard.

Remove the winding and old insulation from the housing. Look carefully at the slots. When the coils burn, insulation is burned and a short to the case occurs. Deposits remain on it, which must be removed with a file or a diamond bur. Deposits will interfere with the new winding. She may tear.

The winding is saturated with varnish. To disconnect the wires and count them, you need to strip out the insulation. Preheat the winding with an industrial hairdryer or any burner.

Burn matches or lighters with any fire to make the enamel completely burnt out. Take a micrometer and measure the thickness. Record wire diameter and number of turns.

Take any wire and make a loop out of it so that it fits in the grooves of the stator. Under the diameter of this loop, select a cylinder for winding coils. For example, spray can. If its diameter is not enough, then wrap the can with paper.

Wrap both windings from the enamel wire. Fasten the frontal parts with glass tape or thick thread. The thread should not break and melt. At the loose ends, put on shrink cambric.

Make sleeves from the electric cardboard and insert them into the grooves. Place the windings in them.

Rewound stator

Check the resistance in the windings of the tester. If everything is fine, continue.

So that during operation the wires do not vibrate and do not rub against each other, they must be impregnated with any oil-based varnish. Put the starter preheated in the oven vertically and squeeze the varnish onto the winding with a syringe. When the varnish starts to leak from below, turn the stator over and soak on the other side.

When the varnish is dry, proceed to connect the windings. Connect the two ends of the different windings to each other and connect to the nearest brush. Connect the other two connected ends to the start button. Connect the wire from the second brush to the button.

Rewind stator on video

Anchor Repair

If the balance is disturbed, the anchor must be replaced. The winding and collector are subject to repair. Small short circuits are eliminated. If a significant part of the winding is damaged, it can be rewound.

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A not very developed collector is corrected by a groove. But if the plates are erased to a plastic base or partially burnt out, then the restoration is carried out by soldering or galvanic building.

Badly damaged collector

Badly damaged collector

If the collector was completely worn out, then after soldering it will be enough for no more than a month of active use. And not completely damaged plates after such a repair can withstand several brush changes and do not evaporate. You will need to cut the copper plates in size and solder them with a lot of solder. Strain excessively with a file and polish.

With galvanic build-up, reduced copper is very solid. The life of the collector is like new.

Completely restored collector

Completely restored collector

By galvanic build-up, it is possible to restore both a completely wiped collector and partially damaged plates. The restored collector must be grooved and the plates divided with a drill or hacksaw blade.

In order to rewind the anchor correctly, you need to correctly disassemble it and remove the parameters for the template:

  1. Winding direction.
  2. How many grooves and slats.
  3. The number of conductors in the groove.
  4. The winding pitch, i.e. how many grooves between the grooves of one section. For example, if the conductors exit the first groove and enter the sixth, then step = 5.
  5. How many conductors are in one groove, so many coils in one section.
  6. Wire thickness.

For example, 80 conductors in a groove, 12 lamellas and 24 grooves. 12 sections of 2 coils. The winding passes in two circles, so we divide 80 conductors in the groove by 2, and another 2, since there are 2 coils. We get 20 turns of one coil.

Anchor winding pattern

Winding anchor

  1. We solder the beginning of the wire to the lamella 1 and pass it through the first and sixth groove. We make 20 turns. The first coil of the first section is ready.
  2. We solder the wire on the lamellas 2 and repeat the winding through the same grooves. The second coil of the first section is ready.
  3. We solder the wire on the lamellas 3. Pass the coil through the second and seventh groove. We wind the first coil of the second section and solder the wire to the lamellas 4.
  4. The second coil of the second section is fixed on the slats 5. Two-round winding scheme
  5. We continue this until the end of the wire reaches the lamella 1 Finished Winding Scheme

How to remove the old and rewind a new winding:

Use a hacksaw or wire cutter to remove the frontal parts of the winding.

Carefully, without damaging the slot insulators, knock out the rods of the remaining parts of the winding with a hammer and a metal chisel.

Use a file to remove any remaining impregnation. Count the conductors in the groove and measure the diameter of the wire. Draw a diagram. Cut the insulation sleeves from the cardboard and insert them into the grooves.

After winding, weld the conclusions of the sections with the collector plates. Check the winding with a tester.

Winding sections

Soak the winding with epoxy.

Anchor Bearings

Bearings crumble or jam over time. They need to be changed.

  • Disassemble the angle grinder, remove the anchor from the stator.
  • An anchor is inserted into the gear housing by a bearing. If the housing cannot be removed, fasten the rotor in a vice and tap the gear case with a wooden block. Removing the anchor from the gear housing
  • Remove the gear from the armature shaft.
  • There are two bearings on the armature shaft. The one next to the collector is easy to remove. Remove the second bearing with a puller. If it is not there, hang the anchor by the bearing and tap on the shaft with a piece of wood. The hammer must not be used. How to remove the bearing
  • Slide the new bearing on the manifold side onto the shaft. Place the second bearing into the gear housing on the rotor side. Insert the gear inside the housing and loosen the nut so that it fits into the grooves of the gear. Insert the anchor into the gear housing. Tighten the nut.

Gearbox disassembly and repair

The gearbox must be disassembled not only for repair, but also for preventive cleaning and lubrication.

  • Remove the bolts and disassemble the gear housing. You will see dirty grease that needs to be removed. Dirty grease in gear housing
  • Swing the gearbox shaft to check the bearings. He should not hang out.
  • Remove the snap ring from the shaft, nut and gear.
  • Hang the shaft by the housing and gently tap the shaft on the shaft to remove it.
  • Remove the snap ring from the housing that holds the bearing.
  • Using a tip, such as an end head, knock the bearing out of the housing. Disassembled gearbox
  • Replace the bearing and gear if necessary.
  • To insert the bearing into the housing, select the extension according to the size and tap it gently. Bearing in gear housing
  • To clean the gearbox, heat the housing with a hairdryer and Clean gearbox

old grease will spill out of it. Clean parts with a rag or toilet paper. Flush the housing and parts with kerosene.

  • Apply new grease recommended by the manufacturer in the tool manual. Gearbox after cleaning and lubrication
  • Spindle lock button

    If the button has flown out, then such an angle grinder cannot be operated.

    Spindle lock button

    Spindle lock button

    Since the spindle can spontaneously lower to the gear and block it during operation.

    Spindle Lock

    Disassembled spindle lock

    The locking unit consists of a spindle with a rubber ring, a spring and a plastic button.

    1. To replace the button, disassemble the gearbox.
    2. Remove the spindle from the housing.
    3. Put the spring on the button on the inside.
    4. Insert the spindle into the gear case from the inside, and the button from the outside. Press until it clicks.
    5. Assemble the gearbox.
    Spindle lock button replacement and gearbox repair

    Care and proper operation of the angle grinder

    For the angle grinder to work for a long time, follow the rules:

      Watch integrity of isolation of a wire, plug. Do not remove protection.

    Lubricate and clean the entire tool.

    After turning off the angle grinder, wait until the rotation of the circle stops, then lay it on the ground. When the engine stops, the tool through the ventilation holes sucks together with the air stream particles of earth and other hard fractions that hit the motor windings. As a result, an open or short circuit occurs.

  • Try not to use the angle grinder in the winter on the street. While you are running, the engine heats up. The air is icy. As a result, condensation forms. Moisture for the engine is fatal.
  • Always place the circles recommended by the tool manufacturer. If the angle grinder is 180 mm, do not put more than 200 mm there. The larger the circle, the less speed should be. You will have to remove the protection, and the speed will be exceeded. Oscillations and vibrations will increase. As a result, the circle will fly apart. This is not only fraught with serious injuries. The bearing of the gearbox is broken, the gears are erased.
  • If you are actively using an angle grinder, then you are a good master. It’s not difficult for you to understand the device’s device and repair it with your own hands. First, find the fault and determine which nodes should be checked. Repair the angle grinder carefully, without haste, so that a minor breakdown does not turn into a major one.

    • Posted by: Natalya Pankova
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