How to correctly install the brushes on the angle grinder

Why do the brushes on the motor collector spark? Causes of arcing under the brushes of the manifold. Methods of eliminating arcing.

It is difficult to imagine an arsenal of home without such a popular power tool as angle grinder angle grinder or angle grinder (popular name). The angle grinder has gained its popularity due to its versatility, as this tool can be used for cutting, grinding, sawing, polishing, deburring, grinding and other works. over, you can handle absolutely any material. There are all kinds of tool failures during use, and one of the most common is brush arcing on an angle grinder. Not many people know why the brushes on the angle grinder spark, so let’s look into this issue, as well as find out why they burn out and how they are replaced.

Before you figure out the causes of sparking brushes on the angle grinder, you need to understand their purpose. Collector brushes are used not only in the construction of angle grinders, but also in the construction of all modern power tools. drills, torches, jigsaws, etc. In the construction of angle grinder and other power tools there are 2 brushes, which have a simple design. This design is based on the following elements:

correctly, install, brushes, angle, grinder
  • The main part is rectangular in shape and made of carbon or graphite
  • The contact is a wire strand of appropriate diameter through which electric current flows. The contact connects the wire to the graphite part
  • The spring is the mechanism that holds the main part against the collector. There may be no spring on the element, and this suggests that such a brush is designed for installation in power tools, where brush holders have a built-in clamping mechanism in the form of a curved plate

The devices are designed to transmit electrical current to the rotor of the power tool. The voltage drawn from the stator is applied to the rotor, which is reproduced by the carbon brushes and the collector. Feeding current to the collector enables the collector to rotate. As the rotor rotates, the devices make contact with the collector (copper lamellas. armature winding leads), thus ensuring the continuous flow of electric current.

During use, the devices are subject to abrasion, so they are classified as consumables. the service life of the brushes depends not only on the service life of the power tool, but also on the materials of which they are made. Brush wear is affected not only mechanically by friction, but also thermally. Electric current flowing through a conductor causes it to heat up. the higher the amount of current, the higher the heating temperature. When graphite brushes are subjected to current, they become hot. The higher the load on the power tool, the higher the current, and therefore the temperature increases, which negatively affects the integrity of the consumables.

This is interesting!There is no difference between the brushes for the respective power tool (apart from the way they are mounted), because they are chosen solely according to such parameter as the dimensions of the main part.

What it is?

These components are made by mixing soot substance with graphite and other binding components. hardeners. Such a mixture is a good conductor of electric current.

Rectangular brushes are commonly used. They may vary in length and width, depending on the specific electrical appliance in which they are installed.

In the “body” of each brush is mounted copper wire without a winding, to the free edge of which is soldered a plate with an individual configuration. The wire is located inside a spring that rests with one edge on the brush and the other edge on this plate. The spring exerts a free-flowing pressure, and the brush rests firmly on the collector as it rotates.

In the process of work, the brushes wear down because of the constant friction. This makes it necessary to replace them routinely. For this purpose, the manufacturer supplies the power tool with a spare set of brushes.

In other situations, you may observe sparks in the area where the brushes are located. This is accompanied by a characteristic sparking sound and smell of burnt graphite. If the brushes spark on the angle grinder. it is a sign of malfunction of its components. In this case, you need to diagnose the appliance.

Brushes replacement on angle grinder

One of the most popular power tools at home, is rightly considered an angle grinder. At one point the brushes begin to wear down and need to be replaced. A sure sign of brushes wear is a violation of motor noise of the angle grinder. Also, if you look closely, you can see a sheaf of sparks through the ventilation grills, and you can feel an unpleasant smell. At the first signs of wear the brushes are replaced as soon as possible. Procrastinating the moment of replacement, you run the risk to ruin the collector, which is tantamount to buying a new anchor for the angle grinder.

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

Some models of angle grinder have two small covers on the sides of the grinder, which are held on two screws. You just need to unscrew them and replace the burned brushes.

In most models, that would replace the brushes, you need to disassemble the angle grinder. Below we look at the explanatory photos of the disassembly of the small angle grinder and read the instructions for replacing the brushes.

Look closely at the handle of the power tool and look for the fixing screws. In our case the handle of angle grinder consists of two parts, but there are models where the handle is simply pulled to the side of the power cord. Having disassembled the handle, we are looking for location of brushes, which are located in special brush holders.

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

Not all of us can find brushes to match the size, but this is a clever trick. If you can not find native brushes then take approximate similar to them, most importantly that they would be slightly larger. Using the file bring them to the right size, the main thing is not in a hurry, so as not to cut off unnecessary. If the brushes have different tips, then cut the leash from the old brush and screw it to the new one.

See also  How to Change Gears to Angle Grinders

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

On a note: If you have already disassembled your angle grinder then blow it with a compressor from dust, also look in what condition the collector armature. When working with heavily worn brushes, scratches may occur on the manifold, which can be repaired with zero-grit sandpaper.

What is made of

Brushes for angle grinder and other power tools are made from different materials, but the main ones are. carbon and graphite. It is this material that has a low coefficient of friction, and also has a high resistance to abrasion. To improve the contact, different impurities are added to the graphite or carbon in the composition of brushes. Depending on the impurities used, distinguish the following types of brushes:

The composition of the core not only affects durability or wear, but also the characteristics of the arcing. The extent of arcing depends on the composition of the brushes. When buying them you need to pay attention to their composition, and not to buy equipment of unknown origin and dubious quality.

This is interesting!The brushes are designed with a ceramic tip, which perform one of the important tasks. When the graphite layer is worn to the limit, the tip starts to contact the copper lamellae on the collector. Ceramics do not conduct electricity, so the angle grinder will operate intermittently or not at all until the devices are replaced.


To fasten the current-carrying wire to the bolt of the brush holder, a lug is attached to the end of the wire.

The basic types of handpieces used are shown in Table 2:

Examples of complete lug designations:

8PG2-10 is a plate closed tip with a diameter of 8 mm, under two wires with a cross section of 10 mm2;

5FG1-1,5. flag closed lug with a diameter of 5 mm, for one wire with a cross section of 1.5 mm2.

Replacing the disc in normal operation

Regular operation of the angle grinder requires regular replacement of grinding discs, which are a consumable. If the tool is already uncomfortable to work with, the worn out abrasive wheel should be replaced.

Important! Be sure to check the power supply is disconnected to prevent personal injury.

Step-by-step procedure

The wheel is fastened to the spindle head with the ratchet nut with M14 thread. The standard wrench has special jaws for hooking into the holes of the fixing flange.

To unscrew the nut, the spindle must be secured. For this purpose, there is a special lock located on the back of the angle grinder. Pressing the button locks the spindle with the cotter pin and prevents it from turning.

Insert the wrench into the holes. Hold the safety catch with one hand and turn it counterclockwise with the other, sliding the nut.

The direction of rotation of the disc is generally clockwise. But there are some models that have the opposite direction. Either way, unscrewing goes in the opposite direction to the rotation.

When the nut is slid, it can be effortlessly unscrewed by hand.

After intensive work with the metal tool, you may find a layer of burnt scale with abrasive inside the guard. Use a steel brush to remove any residue.

After cleaning, reassemble the lower flange and position it so that the grooves on the spindle and the grooves on the flange are aligned. The spacer is placed on top.

If your model does not have additional spacers, similar washers can be prepared from plastic or thick cardboard. Next, you need to properly place the disk on the angle grinder and cover it with a similar shim.

Important! Installed shims allow you to easily unscrew the nut, even if the disc is jammed or broken.

Use your hand to screw the upper locking pin anti-clockwise (counter-clockwise) while supporting the saw blade. Also tighten the spindle lock and screw down the flange until resistance is noticeable. Use an open-jaw wrench to tighten with a little more force. Do not overtighten the fastener, otherwise it might overtighten the disk and it might warp.

You can now continue to work. However, problems do occasionally arise and it is not easy to unscrew the disc on the angle grinder. How to change the disk on an angle grinder in such cases, let’s see further below.

What a solution to the problem is suggested by experts and amateurs

What is a gasket made of newspaper. This is a paper washer to the size of the nut. It is put on the installed disk, and the nut is screwed on top. This piece of paper was the stumbling block because the safety inspection always said that this solution was dangerous.

The safety authorities have the same attitude towards the installation of gaskets made of any other material:

But there is a solution, which does not contradict the safety requirements, and allows the normal installation and removal of the disk. This is a special nut, which consists of two elements. a nut and a pressure washer. The use of such a nut does not require any shims, because with it the disk does not jam.

If you do not have at hand a special key, the craftsmen offer to do without a key. This does not mean you can do without a wrench at all, but use a “gas wrench” or other tool. To change a jammed disc, squeeze the locking mechanism, squeeze the nut with a gas tool and unscrew it. You can change a jammed disc this way, but it’s a very inconvenient one-man operation.

There are also suggestions to clamp the disk with your hand and unscrew it that way. Maybe, but it is unlikely to change broken discs this way. It is better to use wrenches that are designed for removing and installing discs.

Some foreign power tool manufacturers, such as Bosh, produce angle grinder with easily removable nuts. They securely fix the disc on the tool shaft and are quickly and easily removed for disc replacement.

correctly, install, brushes, angle, grinder

Option 2. Brush replacement directly in the body of the angle grinder.

If the manufacturer has not equipped the tool with a quick brush change system, the angle grinder will have to be disassembled to implement this procedure. First of all, read the instruction manual of the tool and the schematic diagram, if they are included with the tool. Usually the body of an angle grinder consists of two parts fastened together. After the housing is disassembled, the old brush must be removed from the brush holder and replaced with a new one. Make sure the brush holder holds the brush securely against the collector. Try to use only original brushes that are suitable for your particular tool. However, if you do not have the opportunity to buy one and you could not find an analogue, the brush can be adjusted to the size you need. This is done quite simply. with a fine file. Take your time when adjusting, be careful when scraping off the brush. The main thing is that it did not end up being smaller in size than the original.

Separately, it should be noted that the replacement of brushes on the angle grinder is a very simple procedure. However, if you are going to perform it, make sure that your angle grinder is not already in the warranty period. Simply put, usually manufacturers are against any unauthorized introduction to their products. There are special service centers for such maintenance. If you break the guarantee agreement by penetrating into the tool, the producer refuses either free service or replacement of the tool. In short, there are different cases. After all every manufacturer has its own rules, so before you disassemble the angle grinder, we recommend to read the warranty card of the tool carefully.

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How to clean

The condition of the manifold significantly affects the service life of the brushes, significantly reduces spark formation, which will make the angle grinder work at parameters close to the nominal. Why do I have to clean it regularly?

One of the options for cleaning the manifold is shown below. Both consumables and tools are available:

The technique is quite simple. Important: Don’t forget to chamfer the blades, which is what the file is for.

Tapered pair. places to pay attention to:

Tooth integrity. With a tangential profile (inclined), the loss of a fragment of one tooth is not critical, t.е. will work, but ideally replace, especially the straight tooth pairs. Note the wear on the tooth surface. Over time, the tooth “pulls out”, sharpening towards the top. Edges usually work less, you can roughly navigate to them. Such defects are accompanied by increased operating noise.

As a budget solution (TIMELY, although there is nothing eternal at all. ), I practice changing the installation of the runout washer from the top (under the retaining ring) to the bottom (under the planetary gear). This action, decrease the clearance between idler and pinion, thus increasing the contact patch. In some lathes, especially Bosch, there is a metallic cushion (several tenths of a mm thick) between the flange and the gearbox housing, removing it has the same effect.

Keyway. Eventually the key, the shaft and the large pinion bore wear out. The nominal clearance should be within a few tenths of mm (so-called thermal). Checking is simple, put on the pinion shaft, with radial motions from side to side. Usually, it is the key itself that wears first and it is sufficient to replace the penny part. But it is worth carefully examine and grooves on the pinion and shaft. When replacing the spindle shaft bearing in the housing flange, I also recommend checking the condition of the copper bushing, which is also responsible for the alignment of the mechanism and the nominal position of the spindle shaft. Removed shaft, it is convenient to install in the sleeve and use as a lever, to assess the wear. In the “cold”, the bushing always has a small thermal gap (about 0.1-0.4 mm), which partially decreases at operating temperature (a feature of copper-graphite bushes, in the category described in detail). If the shaft displacement in the bushing is noticeably out of range, replacement in this situation (disassembling the mechanism and replacing the grease and the shaft bearing) would be more than appropriate, considering the small value of the bushing.

When assembling the gear housing and installing the flange, it is worth turning the mechanism by the spindle shaft. This action eliminates “tooth to tooth”. Otherwise, by tightening the flange screws, you can literally press out fragments of the aluminum alloy housing. Also, do not over tighten the nut fixing the drive pinion, because of the direction of rotation, it tends to self-tighten in most grinders with a tangential tooth profile (oblique)

It is recommended that the grease be replaced, specifically replaced and not added or partially replaced (it’s like changing dirty socks from left to right foot or vice versa). The interval, which is easy to follow: two changes of brushes. grease change. Surely everyone knows that with wear, the grease loses its properties, and the mechanism will wear out faster. Also, the result of any gearbox operation. metal microdust. The housing construction is not airtight, the smallest dust also penetrates and settles in the grease, which in total creates an abrasive environment, and it does its job 100%, ruthlessly wearing down even the highest quality hardened metal. It is worth thoroughly cleaning out the remains of old grease from all surfaces, not being lazy to get to hard-to-reach places. A piece of chipped tooth, retaining ring, key, housing, etc.д. and the aforementioned abrasives, can be mixed into the new grease and it will be a shame when a little thing like a small fraction, caught between the teeth of the bevel gear, causes irreparable damage.

Lubricant should be purchased according to the manufacturer’s recommendations (in the manual to the angle grinder or on the manufacturer’s website). ), in most cases a lithium based grease will be appropriate. Personally, I use NL Gi 2, a lithium-based grease for high-speed gears, in the gearbox mechanism. It’s stickier than it is held on the contact patch, even at high temperatures, not dripping like most counterparts. The modern market offers a variety of options, everyone will find the right fit for their needs. Also be guided by the rule of “golden mean” to determine the amount of grease (lack of leads to wear, and excessive to overheat during operation (worth laying, about 1/2 free space))

Tips for assembling an angle grinder

Perhaps it’s trivial or too superficial, but still. Before working, I download to my smartphone or laptop the original “blast-scheme” of this model, it does not hurt. When disassembling a previously unfamiliar mechanism or device, I place the hardware, which will not interfere in the future, in standard locations, if possible. For other situations, I use several containers, grouping together hardware and small parts by nodes and parts. In the disassembly process, according to the order of removing the parts, I put it in the proper order on the free edge of the workbench. These lines determine the order of assembly. Also, before disconnecting components such as buttons, regulators, stators, etc.п., Where there is a high probability of disturbing the correctness of the connection, before removing, take a picture on your phone for a “cheat sheet”, you can also mark the pairs of connections. These solutions, repeatedly saved me time and nerves, and found in the form of correctly made conclusions, analyzing their mistakes, but you are wiser and learn from mine.

After assembly, I fix the start button and put the running angle grinder on a flat, smooth surface for a couple of minutes. At idle, the brushes will properly rub against the manifold, taking its forum of circumference, the surface of the blades will finally form, the balls of the new bearings will rub with their tracks, and the warm grease will spread evenly over all surfaces. By the behavior of a working angle grinder on the surface, you can judge the vibration. Moving angle grinder, lets you know about the vibration, and smoothly working /- in a static place, about the minimum runout, t.e good) Also, after this test, should normalize the sound of the work, otherwise it is necessary to look for a problem and check the correctness of his repair.

In fact, maintenance work on the angle grinder, does not take much time (as even read this entire post), given that all necessary in the presence of. “But every minute you spend, it’ll pay off with a ration of.

The wisdom of the post: “Timely prevention. You can’t be sure,” “If you’re not sure, don’t do it,” “If you want to do it well, you’ve got to do it right. do-it-yourself”, “Kraylowo. leads to failure,” “Try to do it perfectly, it turns out badly,” “Saved money. earned”

Tips for assembling an angle grinder

It may be trivial or too superficial, but still. Before working, I download the original “blast-scheme” of the model to a smartphone or laptop, it will not hurt. When disassembling the previously unfamiliar mechanism or device, I put the metal parts that are not going to interfere later, if possible, in their regular places. For other situations, use several containers, grouping supplies and small parts by component. In the process of disassembly, according to the order of removal of parts, I lay down in a proper order on the free edge of the workbench. Such lines, determine the order of assembly. Also, before disconnecting components such as buttons, regulators, stators, etc.п., Where there is a high probability of violating the correctness of the connection, before removing, take pictures on your phone for a “cheat sheet”, you can also mark pairs of connections. These solutions, repeatedly saved me time and nerves, and found in the form of correctly made conclusions, analyzing my mistakes, but you are wiser and learn from my.

correctly, install, brushes, angle, grinder

After assembly I fasten the start button and put the working angle grinder on a flat smooth surface for a couple of minutes. At idle, the brushes will properly rub against the manifold, adopting its circumference forum, the lamellae surface will finally form, the new bearing balls will rub against their tracks, and the warm grease will spread evenly over all surfaces. By the behavior of a running angle grinder on the surface, you can judge about the vibration. The moving angle grinder, lets you know about the vibration, and smoothly working /. in a static place, the minimum runout, t.e good) Also, after this test, should normalize the sound of the work, otherwise you need to look for the problem and check the correctness of his repair.

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In fact, maintenance work on the angle grinder, do not take much time (as even read this entire post), given that all you need in the presence of. But every minute you waste is worth every minute.

Wisdom of the post: “Timely preventive maintenance. You don’t want to do it right”, “If you’re not sure, don’t do it right”, “You want to do it right”, “You don’t want to do it right”. Do it yourself.”, “Crank it up. leads to trouble”, “Try to do it perfectly, it doesn’t work itself”, “The money you save. earned.”

Useful tip for unscheduled angle grinder repairs

Many people wonder what to do if you can not find in the store exactly the same brushes as were installed in the angle grinder. You can just buy brushes of a larger size (1 mm difference is normal), and grind them to the right size.

To perform this operation as accurately as possible, you will need to make a simple device. On a piece of particle board, plywood (or other flat surface) with double-sided tape to fix the brush. In the corners of the master screws four self-tapping screws, sinking their heads below the surface of the brush at 0.5 mm.

In this case, the self-tapping screw heads act as lighthouses. After that, with the help of a bar with sandpaper to remove excess graphite. If you grind the brush by eye, you may get an uneven surface, which is undesirable.

For details on how to change the worn brushes on the angle grinder, you can see in the video on our website.


How to change brushes on the circular saw “Philent

Those who have worked with a hacksaw for hours do not need to explain the advantages of a circular saw

  • Finishing and carpentry work: cutting sheet materials (laminate, chipboard, OSB, plywood) and thin boards (platbands, linings, block-house, parquet).
  • Carpentry work: cross and lengthwise sawing of boards and logs up to 100 mm wide.
  • Generic jobs (log house construction, firewood procurement): cross and lengthwise cutting of 100. 200 mm wide logs and beams.

That’s why now we will take a swing at a review of several parts of the market. from small-sized models with a shallow depth of cut to prof models that can cut a thick beam with the least amount of time. What’s worth choosing when making your way around the tool store shelves in 2018?

The best compact circular saws

The circular saw from the “Chinese-Russian” manufacturer suddenly came out on top in this case ranking, although, no teeth, it has many big-name rivals. But practically the most part of brand circular saws under small disks (they are also rotary cutters) are battery-operated, so choosing a network circular saw for ourselves here we are actually going through only amateur models.

READ How to Choose a Wood Circular Saw

Brushes review of power tools fitolent

I noticed when working with Interskol saw some sparking in the brushes

After the inspection the verdict was. before it’s too late!

Interskol DP-1900 brushes replacement.

My second channel Cashback service with good.

Well, the price-performance-functionality ratio makes it a good circular saw. Of course, the manufacturer is not particularly bothered with ergonomics, but in the work it is comfortable enough, and the power of the 550-watt motor for discs with a diameter up to 85 mm is enough. Cutting depths of up to 25 mm are possible.

Unfortunately, the manufacturer did not provide for speed control. Therefore, when working with materials that give fine and light shavings, it is worth to immediately provide dust extraction, otherwise the cooling impeller of the high-speed collector motor will scatter dust all around.

Diold has a worm gearing, which is preferable to the belt gearing in the budget segment. The main thing is not to forget about high-quality lubricant and not to overload the saw so that the worm and the pinion gear driven by it will not be damaged.

READ How to properly sharpen a wood circular saw

for small wheels were found only in the “green” group of the amateur tools, and here the wheel is really small: 65 mm. With it, the PKS 16 Multi provides no more than 16 mm of kerf, and sometimes even a little less than 16 mm. So if you intend to work solely with thin sheet material, it will be in its place.

Let’s note right away the ergonomics: no complaints to Bosch here, everything is traditionally up to the mark. The main thing is not to mix up the saw with the iron and not to saw the ironing board, their grip is very similar. And it’s really more convenient than those saws which have to be held directly by the body of the electric motor, uncomfortably turning out the hand. It is also very convenient to change discs. just press the side lever to release platform and you will find the lock at the bottom of the body. Now it is possible to press it and safely unscrew a disk with an Allen key. And pushing the locking button automatically locks the power buttons. long live safety!

The specific design of the platform, which protrudes forwards strongly (plus the blade is covered by a light cover), made it necessary to add a tilting indicator-frame CutControl to monitor the cutting line. Because it is relatively far from the cutting point, even the smallest deviations become immediately visible.