DIY repair of grinder 125 interskol

In detail: do-it-yourself repair of LBM 125 interskol from a real master for the site my.housecope.com.

Recently they brought a grinder for repairs, it doesn’t work, and in general it works when it wants to. In general, Interskol devices are very reliable and durable, their quality, as a rule, is good and they work reliably and for a long time, well, since it does not work, we will repair it then.

Power consumption: 900 W
Rated voltage: 220V / 50Hz
Rotational speed: 11000 rpm
Circle diameter: 125mm
Rotary main handle: no
Weight: 2.2KG

Image - DIY repair of grinder 125 interskol

So, we open the device and see a bunch of dust and dirt that has accumulated over a long time of operation, we clean it all and wash it with napkins and degreasers.

We check the brushes, and all the electrical connections at the terminals by tightening and cleaning, take out the rotor of the collector electric motor and check it by visual inspection of the winding and plates so that nothing sticks, the bearings must be intact without cracks, and they must rotate freely without jamming, noise and backlash ...

Next, we proceed to the switch, it turned out, and became the culprit, here the switch button commutes two conductors of the circuit at once. We purge the lever drive itself with silicone grease so that it can more easily walk in its groove of the guide to the switch itself.

The switch can be removed and disassembled, I could not repair the burned-out half, so I closed one of the wires directly, and the second now serves to turn it on and off.

Over time, the contact went away in the switch, began to spark and heat up, and part of it melted.

You can, of course, replace the entire switch, which would be correct, but the owner wanted it as cheaply as possible, since the tool is not very expensive, and it’s not new, so I had to do this, a new switch costs about 400-500 rubles in the city, which not very cheap.

Video (click to play).

After assembling the grinder, be sure to test and check the operating modes at idle speed before giving it to the owner.

Many are familiar with the situation when a favorite tool stops working for no apparent reason. And if the grinder does not turn on, then, often, the reason for this is a simple breakdown, which can be quickly eliminated without special knowledge and tools. Next, we will consider simple ways to diagnose and repair a power tool using an angle grinder as an example. Initial state - the grinder does not start when the power button is pressed.

To complete the work, we need a multimeter with a dial function and a screwdriver. The first thing to check is the wire, or rather the plug and the place where the wire enters the body. Press the button and "massage" the suspicious areas. Most often, problems arise in the case. If this does not help and the grinder still does not work, go to the next step.

We disassemble the case. To be sure, you can turn on our tester in the dialing mode, and check the integrity of the wires from the plug to the entrance to the button.

Next in the electrical circuit is a button. Often it is the malfunction of this unit that is the reason that the grinder does not start. In order to check this unit, you need to turn it to the ON position, and "ring", as shown in the following photo:

In this case, the button "rang", which indicates its serviceability, so let's move on. This grinder uses a speed regulator, so it is also worth "ringing" it, having previously set it to maximum power.

The next thing to pay attention to if the grinder does not turn on are brushes. In large angle grinders, the brush holders are located outside, in our case - inside the case. We remove the brushes and examine them. It is necessary to make sure the integrity of the contacts on the brush itself.The main criterion for the performance of a brush is its degree of wear or size. In this grinder, it was their wear and tear that caused its failure. Therefore, replacing the grinder brushes will help eliminate the malfunction. For clarity, a comparison is made between new brushes and completely worn out ones.

If, in your case, all this turned out to be serviceable, and the grinder does not work, then the last thing that can be checked without a special tool is the anchor. To begin with, we "ring" between the iron parts of the armature and the collector lamellas. If it rings, then there is a breakdown of the insulation and the armature must be replaced.

Next, you need to measure the resistance between adjacent lamellas on the collector. It should be the same for all pairs. If, at any point of measurement, the resistance is several times higher, then we can talk about a break in the winding. It should be noted that such a malfunction rarely leads to a complete stop of the engine.

If, after carrying out the above diagnostics, it was not possible to identify the malfunction and the grinder does not turn on, then it seems that you will have to contact the master.

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Interskol UShM-125/1100 E Repair.
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rzd wrote:
He shot a video. Maybe someone will come in handy.

Commentary on the video.
I must say right away that it is difficult to comment on such things, since non-professionals do many things wrong, but I will try to talk about essential points.
So.
The author of the video admitted himself to not using the angle grinder for its intended purpose - at 3:15 he says that he sawed asbestos pipes for her, and apparently did not read the instructions - it is strictly prohibited there, if he brought the angle grinder to the service, he would be removed from warranty service ...
At 0:38, he says that everything in the switch melted, why it happened, and whether it was at all - it is impossible to say, because for some reason the floating switch did not hit the video.
Regarding the circulating retaining ring. At 9:07 am, the author shows that he disassembled the angle grinder, separating the gearbox from the motor unit, without removing the gear from the rotor axis, of course, he pulled out the retaining ring together with the bearing with this gear, cutting off the chips from the casting, which he found there. Therefore, I urge the owners of the instrument again and again - do not go there on your own, take the instrument to the ASC, where people know how and what to disassemble and repair.
Then you will not spend the whole day creating problems for yourself and then solving them.

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Serg wrote:
that he disassembled the angle grinder, separating the gearbox from the motor unit, without removing the gear from the rotor axis, of course, he pulled out the retaining ring with the bearing with this gear, cutting off the shavings from the casting, which he found there

I do not argue, I disassembled for the first time and not correctly. But what you say, took out the bearing together with the retaining ring, you understand what you said. If the retaining ring was in place, it is not realistic to do it. Well, if only to break it. And I just pushed it apart and cut it in half. Yes, and on the roller you can see the seat of the lock washer, covered with a huge layer of dust and this suggests that the lock ring has not been there for a long time and has ever stood at all (it has not been put in their grooves).
Not intended use. I sawed 5 pipes with a diameter of 100 mm. After sawing, I first wrapped the handle with foil. Well, how can this affect the switch? Is it a tool. No, the old switch had to be opened and shown.

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rzd wrote:
I do not argue, I disassembled for the first time and not correctly. But what you say, took out the bearing together with the retaining ring, you understand what you said. If the retaining ring was in place, it is not realistic to do it. Well, if only to break it. And I just pushed it apart with my hands and cut it in half.

This is not visible in the video, it is clear that the instrument is simply disassembled. Maybe you knocked him out with a hammer on a nut - by the way, there are some incomprehensible dents on it. On the other hand, there are no sawdust or wear marks on the gear pair, which would necessarily appear if the retaining ring was not installed from the factory.
The same is about the switch - there is no old one on the video, no photo, some words, there are a lot of them. But this is not evidence.
And enhanced advertising for the online store.
There is nothing to comment on.
In short, next time shoot the faults, not your emotions, they are of no interest to anyone.

Serg Well, you've arrived. Do you think I arranged all this trouble for myself? I understand you FOR INTERSCOL, in a place to apologize and say, yes it happens, and famous brands have and in general this video has no place on YouTube ,, I was also accused.
The video in the search on YouTube is on the first page. Let it be a shame, Interskol, for what they are doing. And people will make the right choice, I think.

Kvost wrote:
the ring itself was in incomplete engagement due to a mismatch in the dimensions of the seat groove

The size of the seating groove is good. When I cleaned it from dirt and the ring got up very well. On the video it is clearly visible, figs out with what. Maybe just as you say, in incomplete engagement, it was not completely planted.

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This angle grinder has helical gears. And their direction suggests that the moment of reactive force is directed along the armature towards its collector. Suppose that the retaining ring was poorly installed at the factory and it flew out of its seat. And now the question is, will the rear bearing (which is near the manifold) be able to ensure the normal operation of the gear pair, will it not break out of its seat? Therefore, the front bearing ceases to fully fulfill its function and does not ensure the retention of the armature from axial displacement.

Serg wrote:
This is not visible on the video.

We set the view to 1080 and starting from 10min 21sec. Everything is very clearly visible that everything is in dust and the ring was not there, and even more so, I did not remove the bearing along with the retaining ring through this hole.

_maximus_ wrote:
And now the question is, will the rear bearing (which is near the manifold) be able to ensure the normal operation of the gear pair, will it not break out of its seat?

It works, after all. Moreover, there is a seat on the bearing height by about half or even less.

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rzd wrote:
It turns out it can. It worked after all.

I just thought something, but this is, on the contrary, an advertisement for Interskol

Not every angle grinder will be able to perform its functions and will not fall apart if the retaining ring is also removed from it

rzd wrote:
Serg
Well, here we are. Do you think I arranged all this trouble for myself? I understand you FOR INTERSCOL, in a place to apologize and say, yes it happens, and famous brands have and in general this video has no place on YouTube, , they also accused me.

I tell you once again that your video contains more questions than answers - you can take it whatever you want - you want - as an accusation of rigging facts and running into INTERSKOL, if you want - as a guide to action for the future.
To get an apology, you had to behave differently from the beginning.

Vladimir, the comment about asbestos is due to the fact that angle grinders with a 90% probability are not subject to warranty service. There are also serious questions - the author wrote that he wrapped the handle with a stretch, as far as I understood - by the handle he means the motor unit - of course, the ventilation holes were also closed. If he continues this practice, the angle grinder will quickly fail and INTERSKOL will be to blame for this again.

rzd wrote:
I started answering in this thread. As in the topic Interskol = questions about tools, I was denied access.

The topic about INTERSKOL is closed for everyone, you need to spam less (this is not for you).
And here we ask you to clean it.

Serg. Post number 7. And I poured the dust there, after knocking out everything together with the bearing and retaining ring, as you said.

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There is a popular parable: He told me once - and I believed him; he said a second time - and I doubted; he told me a third time - and I realized that he was lying.

Serg wrote:
There is a popular parable: He told me once - and I believed him; he said a second time - and I doubted; he told me a third time - and I realized that he was lying.

I understand you perfectly well, the truth hurts your eyes, there is nothing to argue with, parables have gone. I understand that 10min 21 sec Not in your favor. What you have to answer, of course. there is nothing to be seen, well, to turn to folk parables. But the fact remains that there is a defect in the work during the assembly.

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You have got a wonderful visual aid on the topic "How not to shoot videos for specialized forums."

_maximus_ wrote:
This angle grinder has helical gears.

So what's next? On the Bosch earbuds, they are also helical. But in the case of a bosch grinder, this does not give any reason for further reflection - like what for. They work well anyway.

_maximus_ wrote:
Suppose that the retaining ring was poorly installed at the factory and it flew out of its seat.

How can you poorly install the retaining ring so that it falls out by itself? Stick it with snot? If it is inserted into the grooves and parted in the groove, then it would not fly out if the groove is normally made.

_maximus_ wrote:
And now the question is, will the rear bearing (which is near the manifold) be able to ensure the normal operation of the gear pair, will it break out of its seat? Therefore, the front bearing ceases to fully fulfill its function and does not ensure the retention of the armature from axial displacement.

Well, Maxim - mind you, you yourself wrote it. And it turns out that in interskol, such a design is simply necessary - well, so that retaining rings and all that. Because, for example, there is no such thing in Bosch and Aeg. He unscrewed the gearbox, took it off and nothing goes anywhere there, no rattles does not break. The plastic is probably just high quality. And then it turns out that all these design features of the interskol UHM - that something there will break otherwise if there is no stopper - because of poor-quality plastic. And the truth is, recently, the handle at 1050 was shown to have broken off on a typical problem, before that there was a humorous topic - the handles in a vice and the handles there just easily came off the handles. And there was also a mention in the topic about the dangers of the grinder as a human, the handle of the grinder fell off and almost completely did not do any trouble. Well, this is from what I remember.

... But what kind of dreamer-designer (grinder in his hands) came up with such a power button.

Two thin tendrils pull such traction with a decent effort. so they fell off.

What do you advise, gentlemen of the designer.

Dear Igor, let's add some specifics to this strange conversation.

Describe the work you performed using this angle grinder. It is desirable with an indication of the operating speed of angle grinders.
Here you write: I worked at maximum speed and without loading the lug.
This is possible only if you turned it on at idle speed and it burned out after 3 hours. Here, besides me, people from various services have gathered, and they are unlikely to believe in this miracle. works great at idle until the very end of the brushes. That is, I already have strong doubts about your objectivity.

As for the replacement tool, everything that is written in the ZOZPP applies to you as well. Demand.

Please provide the address of the service, the number and date of the receipt, the serial number of the instrument, your telephone number for communication, is your name Igor?

Regarding the words of the service - what kind of tool it is - professional / household - unfortunately, I cannot comment, because this is generally hearsay testimony. You never know what they told you there. unfortunately, the services are different, and the mood of the recipients is different. Can you prove these words? audio recording, at least. I was sent here from Ufa once, the service quickly stopped talking nonsense.

prof (using the tool for 8 hours a day without stopping with normal load)

The dominance of bloggers who did not hold anything heavier than a computer mouse in their hands and think that it is physically possible for the operator is a mode when he does not turn off the UShM-230 / 2600M for 8 hours (for example), you work her at least a couple of hours of clean time - then you as in the film "Dima Gorin's Career" will have to be removed from the angle grinder and taken to a warm place.

Hello!
Please tell us briefly about the protection of this tool from abrasive dust (generated when processing bricks, concrete).
To what extent is this dust contraindicated with angle grinders of your production?

Stone dust is contraindicated for any angle grinder, including this. Use dust extraction equipment.
In fact, a high concentration is contraindicated, and not just stone dust, because when cutting metal, the same abrasive metal-oxide dust is formed, which works in the same way as stone dust. It's just that there is less of it, and the second point is that metal is usually cut in the open air and is much smaller in volume than stone.

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Flaws;
Everything except speed control. It heats up like an iron for 5 minutes of work, the button is invented with scoops with crooked brains and hands, like this is a miracle
engineering thought is turned off from the slightest vibration, it is assembled blind and handless as soon as after such an assembly one grinder worked for me on a grinding with a cropping (round brush for metal or wood in the form of a glass) 1 year for 8 hours of continuous work, and the second by the same method 10 minutes. In the first, the speed control unit most likely burned out, and maybe the winding was burnt, and on the second, according to the conclusion of the "specialists" of the interskol service center, both the roter and the starter, and in fact, when I tried to turn the shaft by hand, the scraper in the area of the brushes, and in the gearbox. Having disassembled the first one to spit on the guarantee, about the second I can say that it was most likely not the rotor with the starter that burned out in it, but because of the curves of the collector's knobs, the knob was unscrewed on the shaft in the gearbox, which caused two worm gears to interlock, and in the area of the brushes on that the same reason for the lack of normal hands in production, the latch on the brush snapped off, as a result of which one brush worked for two more precisely, it worked, and the other, like a stick in a wheel, dangles and wedges the rotor.

In a word, Chinese bullshit collected by handy guys. And most importantly, I lost my guarantee for the second grinder, as her roter burned out and
starter in the course of 10 minutes of grinding the steel pipe. It is better to buy something branded for 2 tons more expensive than in five minutes you lose and
tools and the ability to get money back. Serial number of the thief UShM-125 / 1100E which burned out after 10 minutes of operation without even having time to warm up; No. 26348823 Was purchased at the “World of Instruments” store (IE Makeev AA) in the town of Sobinka, Vladimerskaya oblast. The store immediately disowned replacing this tool with the glory of the fact that it was not their difficulties and that they could only send it for warranty repair to the Interskol service, from where she came with a conclusion two weeks later about its unrepairability and refusal of warranty repair or replacement under warranty as I was hoping for. But it seems that now they will seek justice through the courts. Fortunately, he is not far from Sobenka.

It is a pity that the second angle grinder that you purchased was out of order so quickly. However, it is impossible to draw any conclusions on the basis of the failure of one copy, unfortunately, a marriage occurs in everyone, although this is an extremely undesirable phenomenon.

However, the first angle grinder, judging by your statement, worked for 1 year for 8 hours of continuous work - that's 250 working days a year, 250x8 = 2000 hours - a figure absolutely unrealistic for one set of brushes. Divide by 15 - then you get a very good result of 130 engine hours. Then you need to change the brushes - if you have not done this, then most likely the collector has failed and further along the chain.

As for the second angle grinder - you, apparently, have the conclusion of the ASC - post its scan here, please. Did you open the second angle grinder?

Please, write without any special errors, I hope it will not be difficult for you?
I deleted a duplicate of your message in the second topic, cross-posting with us, as elsewhere, is not welcome.

Good afternoon.
Limited ventilation is only one aspect. The efficiency is even worse, this is already serious.

The button is not because of this, unfortunately, it was a banal marriage. The current through the switch is less than at normal speed.
So you can use the regulator, I apologize for the marriage on behalf of the company.

Well, whatever they say and write, but Interskol is a folk instrument, I meet it everywhere - in brigades, at dachas, garage cooperatives, at construction sites. It is used by window, door installers, network engineers, installers, roofers, plumbers, and more.

Interskol makes quite suitable and durable instruments - a great alternative to the Chinese of unknown brands. In terms of quality and especially usability, Interskol does not match Kress, Hitachi or AEG, but in its price niche, first of all, it sits tightly, so you can completely trust their tool.

Here is one of the truly folk instruments - Bulgarian (Angle Grinder) Interskol UShM-125/900... The characteristic is laid down in the model name: disc 125 mm and power 900 watts at a price

It is a good walking tool with magnesium alloy gear housing. There are no bells and whistles in it - only two buttons. It is a two-position inclusion (tight, with the expectation of a fool), the second is the fixation of the spindle for changing disks.

The grinder is equipped with a protective semicircle that repeats the course of the disc, which is fixed with screws. There is no quick adjustment of the protection position, as on Bosch. The guard is close enough to the disc, so the diameter cannot be overestimated.

Wood discs (saws, with teeth) cannot be placed on this grinder, since it is not equipped with electronic speed control. The disc may crack from overheating and injure the operator.

The grinder handle is half plastic, average comfort, I would like a little longer. The additional handle can be installed in 2 positions: top or bottom. Although it is strange that toolmakers very often forget to make a mounting hole on the side, even though the Soviet Start grinder had three positions for attaching an additional handle.

Characteristics of the grinder Interskol UShM-125/900:

Power - 900 W
Disk rotation speed - 11000 rpm
Disc diameter max. - 125 mm
Weight - 1.9 kg

Why is the angle grinder called "grinder"? A short informative excursion:
In the 70s, the production of angle grinders was launched at the state enterprise Eltos-Bolgarka. Actually, this took place in Bulgaria, with which we had trade and political relations, and the entire CMEA instrument, along with tomatoes, green peas and “Ikarus”, went directly to the USSR. The name of the instrument at that time was long and unsonic, that's why the quite professional term “Bulgarian” has taken root in everyday life. Now this Bulgarian company has turned into Sparky.
Safety precautions when working with a grinder (angle grinder):

This video shows: How to replace the grinder body, change the stator, rotor, brush holders, brushes and bearing for angle grinders. Complete disassembly and assembly.
=============================================
Characteristics of the grinder (USHM) INTERSKOL USHM-125/900:
Country: Russia, China
MAIN CHARACTERISTICS:
Disc diameter 125 mm Other products
Minimum disk rotation speed 6500 rpm
Maximum disk rotation speed 11000 rpm
Bore diameter 22.2 mm
Spindle thread M14
FUNCTIONS:
Power button lock Yes
Spindle fixation Yes
ELECTRIC POWER SUPPLY:
Power supply type Network 220V
Power consumption 900 W
FRAME
Additional handle Yes
Handle type Two-position
Mains cable length 2 m
DIMENSIONS AND WEIGHT
Height 12 cm
Width 15 cm
Depth 33 cm
Weight 2.3 kg
The gear housing material is metal.
The color of the gearbox housing depends on the country of production (Russia - black, China - silver).

What exactly disappointed you?

Hello, where can I find a new case for the angle grinder 125/900? Mine broke

Uruzmag Kaitukov have you already changed the building? If not, then I need a stator. Won't you sell? )

Hello, in your region find the official representatives of Interskol, it may even be a service center, and you order through them.

Was it just me or a video from pieces? Moreover, it was assembled incorrectly.

This video shows: How to replace the grinder body, change the stator, rotor, brush holders, brushes and bearing for angle grinders.Complete disassembly and assembly.

Δημοσιεύτηκε στις Πριν χρόνο

What exactly disappointed you?

Hello, where can I find a new case for the angle grinder 125/900? Mine broke

Uruzmag Kaitukov have you already changed the building? If not, then I need a stator. Won't you sell? )

Hello, in your region find the official representatives of Interskol, it may even be a service center, and you order through them.

Was it just me or a video from pieces? Moreover, it was assembled incorrectly.

This video shows: How to replace the grinder body, change the stator, rotor, brush holders, brushes and bearing for angle grinders. Complete disassembly and assembly.

Don't forget to share vidos!)
Happy viewing!)

Sasha, what is the size of the brushes on this grinder?

in this video, the replacement of bearings / I saw how Alexander took the gearbox somewhere and somewhere or someone replaced the bearing and put it back and then here he is the repaired gearbox very informative

You need a gold chain, otherwise this one is hard to see.

And how to change the sleeve, how to pull it out?

And what if the bearing was replaced and the spindle backlash did not go away? Should I change the spindle shaft or the bronze bushing?

Alexander M. Brest thanks.

So you need to check which parts are worn out, and replace

Alexander, hello. Can you please tell me what kind of lubricant do you use for the angle grinder gearbox? I looked on your channel for a video on this topic, I did not find it.

worked a little. the plug is no longer native,

Exactly such a case will not pull out the gear in any way

I have interskol 115/900, the difference from 125/900 is not great. Shroud and anchor only.
In short, for the 2nd year of inactive use, the button began to fly off, it is poorly fixed. After the purchase for the 4th month, I took it under warranty to change the anchor because the winding wire somehow jumped out of it and cut off. Then I had to change the very e-button. Honestly, I’ve already lost count of how many times I changed the brushes, and I had to pick up my relatives anywhere. In addition, it growls for some reason.
There was an even larger angle grinder interskol. I gave it to my neighbor. She's also quirky.
In general, I concluded that interskol is not worth dealing with.
And yes, it quickly gets heavily clogged with dust.

I immediately had a needle bearing

A shitty apparatus made in China, how many such shit has gone over, never got caught with needle bearings in the editor, all were with a steel sleeve covered with a thin layer of bronze. At the expense of this device, I think the author knew what he pulled out for the sleeve, but did not spread. And the grinders were bought at different times, not one batch.