Peculiarities of repair of different brands of lathes

There is on the secondary market as an angle grinder Phiolent MSHU 2-9-125, which has a planetary gear ?hot? seating on the spindle shaft. Tension and force are nominal, but in the experience of online store, too much demand for the gear housing flange. Fiolent is famous for low unification, but that at each presser to buy an ORIGINAL flange for about 5 (for a piece of cast aluminum, factory-turned on the lathe and a maximum on the mill). Little value, and even detail scarce, which prompted me to give birth to this post.

Fit with guaranteed tightness (hot). no backlash fit planetary gear (large / driven), the inner diameter of which is less than the diameter of the shaft (the difference is about 0.05. 0.4 mm). This fit ensures a positive, no-play fixation of the pinion on the shaft, ensuring that it will withstand the radial loads of the angle grinder. As a rule, this type is inherent in the tool of the professional class, but today’s market has mixed the concepts and made the technology available even in the tool DIY class.

The main modules used

Before starting to repair the angle grinder, consider a few useful tips:

  • Before you start disassembling the angle grinder, carefully read its description, the assembly diagram and the order of work.
  • Be sure to adhere to the sequence of manufacturing operations.
  • Strictly observe safety precautions.

The most common cause of grinder breakage is a wire break near the handle. First you need to check the presence of voltage on the button, this is done with an ordinary voltage tester. Then we check the button itself for functionality.

about diagnosis and repair of the electrical part of the angle grinder.

How to remove a needle roller bearing or a destroyed plain bearing rim

Different bearings are used in the gearboxes of bucking machines. They are subjected to high loads and are the cause of malfunctions.

Trouble in the bearing can be detected by an increase in clearance on the spindle shaft. Disassembling the gear housing and removing the big gear shaft, you can see the needle bearing.

The needle bearing is not used in all lathes. In the same screwdriver in which it is installed, its disassembly can be done in several ways.

By removing the destroyed part of the bearing, the inner ring can be taken out with a machine tap. Engage a machine tap of the appropriate diameter in the chuck of an electric screwdriver and try to screw it into the bearing cage until the tap hits the bottom of the housing. Continue to turn the tap slowly into the cage. It will pull the cage up on the threads.

The second way is that the remaining rim of the destroyed needle bearing can be extracted with a special bolt and a retaining ring.

How to remove bevel gears of angle grinder gearboxes

Angle grinder gearbox repair begins with the removal of bevel gears. It is gears that are the main cause of angular grinder gearbox failures. In lathes most often it is necessary to change the small drive pinion mounted on the rotor shaft.

On the rotor shaft, helical gears can be attached in two ways:

  • The pinion is fixed by a keyed joint and clamped by a nut.
  • The pinion is fastened by means of a threaded joint. Both right- and left-hand threads are used.

Large driven helical gear is attached to the spindle shaft also in two ways:

In addition to replacing gears in grinders often need to replace a particular bearing. And there are at least three of them in the angle grinder.

Pressing the planetary gear

To begin the process logically, let’s look at the reasons why the unit needs to be pressed:

Any competent repair, involves replacing only the damaged parts, conducting a preliminary defectoscopy of the tool as a whole. With a high probability, preliminarily exclude unprofitable actions. With unprofessional approach, pressing the assembly, you risk the spindle shaft and gear housing flange (as practice shows, not an uncommon occurrence)

    The preliminary step will be “soaking” landing deep penetrating grease (WD-40 ideally / or any analogue) for 10 minutes, at least, it will not make it worse.

Features of designs of foreign manufacturers of angle grinder

In this chapter, we will consider the design features of boltcutters made under the brands Bosch, Hitachi and Makita, as well as the repair of the angle grinder with their own hands.

Repair of angle grinder Bosch

The Bosch angle grinder is a robust tool that gives you total peace of mind. But not every user treats the tool correctly. Repair of Bosch angle grinders most often involves replacing bearings.

All Bosch angle grinders are designed in the same way. Spindle shaft pos.25 is pressed into the helical bevel drive pinion pos.26 and rests in the gearbox housing pos.821 on the needle bearing pos.51.

If the bearing collapses there is a bearing rim inside the housing which is not easy to remove. We recommend two ways to disassemble the needle bearing. These are described in the section “How to remove the needle bearing”.

When wear or gapping occurs in pinion teeth, replace them both and only in pairs. When disassembling the gears, remember that the drive pinion is mounted on the rotor shaft on the threads, the LEFT one and it is fixed with the nut. driven large helical pinion pos.26 is pressed on the spindle shaft pos.25.

Hitachi angle grinder repair

Hitachi angle grinders are especially popular with Russian consumers. It’s easy to do. There are practically no homemade knockoffs of Hitachi machines on the market. Simple design allows you to easily perform repairs of any complexity.

Hitachi angle grinders have high reliability and don’t often come across the table of repairmen. The main reason to get an angle grinder Hitachi for repair is a gearbox breakage, namely, loss of teeth of gears.

Disassembles the gearbox of angle grinder easy. To disconnect the gear housing pos.3 from the stator housing pos.37 and loosen the carbon brushes.

remove, idler, pinion, angle

Remove the four screws pos.1 fastening the gear housing and stator housing. Separate gear housing and stator housing. Gear housing will detach along with the rotor pos.8.

To remove the gearbox cover pos.23, you need to unscrew four screws pos.24. Drives helical pinion pos.33 is fixed on the spindle shaft pos.26 by means of a key pos.25 and pulled off with a puller. Bearing pos.21 removable with a puller.

Repair angle grinder Makita

A feature of the Makita family of angle grinders is a quick-release protective cover pos.19.

Makita angle grinders more often than other machines get repaired. But the reason is the high percentage of fakes that flood the Russian market.

A real Makita is a reliable, durable tool. But, like all angle grinders, suffers from gearbox failure, its gears.

Gearwheels are replaced in case of gear jamming or breakage.

To repair a Makita 9069 or Makita 9558 HN angle grinder, the angle grinder must be disassembled.

If the gearbox is faulty, and this is determined by the appearance of play of the spindle shaft, gear jamming, slippage of the idler pinion, the gearbox should be disconnected from the stator housing. Release carbon brushes pos.35, unscrew the four screws pos.10 and disconnect the gearbox housing from the stator housing pos.37.

In the next step remove the four screws pos.18 holding the rotor cover pos.15. Driven gear pos.14 removable with the aid of the percussion hand. Pinion pos.43 is mounted by means of a keyway and secured by means of the nut pos.42. Rotor shaft bearings pos.3 removable with pullers.

Mechanical Damage

Bosch angle grinder designed for cutting, grinding, polishing works. Working in dusty conditions and under high loads is especially damaging to the life of the gearbox and in particular to the gears.

In addition to wear and breakage of the gear teeth the bearings and housing are mechanically damaged. Repair of angle grinder Bosch in terms of replacement of faulty bearings, restoration of the body to perform simple, if there is the desire and need.

Assembly of an angle grinder

Assembly of the angle grinder begins with the examination of all parts, assemblies, bearings, gears.

Beforehand, prepare a workplace with proper and good lighting, arrange the tools, lubricants, wipes.

What grease to use for a Bosch angle grinder

Repair of Bosch ears will not be quality, if you do not change the grease at its execution. For quality lubrication of Bosch angle grinder nodes it is recommended to use those lubricants that are offered by the tool manufacturer. But their high price makes you look for another way out, and it is there.

Domestic manufacturers of lubricants have developed special greases for gears and components of angle grinders.

They are not inferior to foreign lubricants in quality, and cost much cheaper. The only downside, our greases require more frequent changes.

Or you can use the grease made by your own hands.

Assemble the rotor

Assembly of the rotor involves pressing in bearings and installing the impeller. Lubricated bearings are pressed onto the shaft with a wooden spacer. The bearing near the manifold is covered by a rubber guard. This is the general algorithm for assembling the rotor shaft.

The individual models of the Bosch angle grinder have their own special features.

Assembling the Gearbox

Assembly of the gearbox begins with placing the rotor shaft in its housing. When the shaft is inserted in the housing, the drive pinion, washer and retaining nut are put on the shaft. The gear case with the inserted shaft must be placed in the stator case.

When you insert the collector bearing into the socket, press the gear case onto the stator housing. Check that the rotor can rotate easily in the bearings.

A spindle assembly with mounted bearing and pinion is mounted in the gear case cover.

It remains to insert the cover in place and check the quality of rotation of the spindle shaft. If the shaft rotates easily by hand, it is fashionable to tighten the screws that secure the rotor housing cover. The screws should be coated with sealing compound beforehand.

This is a general algorithm for reducer assembly. In some models, the repair of the Bosch angle grinder gearbox is slightly different.

  • Knowing the general scheme of the Bosch bolt cutters, you can safely dismantle the tool for lubrication;
  • The ability to repair the Bosch angle grinder with their own hands will allow you to extend the life of the tool, to replace the lubricant, carbon brushes on their own;
  • Follow the operating and maintenance schedule, and you will enjoy many years of trouble-free operation.

Gearbox fixtures

It is held by four bolts. They must be unscrewed not with extreme care remove the gearbox from the body of the angle grinder

Dismantling of the gearbox is necessary for its cleaning not to replace worn parts. How to remove the master gear from the rotor gear housing). This is one of the most important nodes of the angle grinder, which experiences tremendous stress during its operation.

To remove the rotor from the gearbox housing, you must. which holds the rotor. Use a special puller to remove the rotor. Such an operation involves some difficulties, if you do not have special skills, it is better to leave such work to professionals. You can not do without a puller here.

It should be said that for the simple removal of dirt, such a detailed disassembly is not necessary. As oil is only needed to replace a worn bearing or worn rotor.

To remove the armature you must first remove

Remove the armature with a special puller from the gearbox, pulling the brush out of the gearbox and carefully lifting the armature out by holding the pinion.

This operation requires some effort. Anchor removal from the housing must be carried out with extreme care as it is easily broken.

When, during operation, there is a strong sparking, a large heating of the housing, you simply need to take out the armature to clean the collector. The device is now ready to use again.

Assemble the tool with the new parts

After disassembling the tool and replacing all the broken parts, put it back together. Make sure you have all the tools, lubricants, clean rags and everything you need to put the finishing touches to the gearbox.

Assemble the rotor first. Press in the bearings and fit the impeller. Before doing so, carefully lubricate the bearings. Using a wooden spacer, press them on top of the shaft.

Cover the collector bearing with the rubber guard. This is the same diagram of how to assemble the rotary shaft.

Next reassemble the gearbox. Start this process by placing the gearbox on the rotor shaft housing. When the shaft is already inside the housing, put the drive pinion on it, then the washer and the lock nut.

Now install the gear housing, with the shaft in it, inside the stator housing. It is necessary to clamp both housings after the collector bearing is already in the socket. Next, check if the rotor rotates easily on the bearings.

The final step is to put the cover back where it was. Check how the spindle shaft rotates. If you determine that the rotation is easy, even from the movement of the hands, you can do screwing. They are used to fasten the cover to the body. Before that, lubricate all the screws, using sealant.


The home handyman occasionally have problems with the surface treatment that is unrealistic to approach with general-purpose equipment. It is possible that the part will be brittle with an impossible clamping force, or massive. It must be reworked on the spot. From an old angle grinder you can make a tool for machining small surfaces with a flexible shaft. You get the analog of a drill.

READ How to Make a Circular Saw from a Washing Machine

For the manufacture will require materials:

  • flexible shaft, which is purchased or selected from the available;
  • working tool holder attachment;
  • a pair of spherical roller bearings with 228 mm cross-section;
  • Working tool for processing with a shank diameter of 1-3.5 mm.

The presence of a flexible shaft will expand the functionality of the tool. With its help it will be able to get into the most hidden corners of the details, reduce the load on the hands.

Almost all of the home handyman’s supplies can be used as tools:

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