How to Remove the Gearbox of a Small Angle Grinder. How to remove the helical gears of the gearbox of an angle grinder

How to remove the gearbox of a small angle grinder

The peculiarity of the design of the Bosch angle grinder is presented in the application in the gearbox as a supporting bearing of the driven helical gear of the needle bearing.In Bosch angle grinders, the idler pinion on the spindle shaft is press-fastened.

In Bosch small power angle grinders in which spur gears are mounted in the gearboxes, shims are provided. This design makes it possible to regain contact with the gears by reducing the thickness of the shim. Helical gears wear much less than spur gears at higher tool speeds.

The operating environment of most rotary grinders is a dusty place. Dust is a major hazard resulting in failure of power tools, in love and angle grinders.

How to remove bearings from the rotor of a Bosch angle grinder

For disassembling bearings from the rotor.803 Bosch angle grinder is recommended to use pullers.

The bearing pos.15 next to the manifold is easy to remove, but to remove the bearing pos.14 from the impeller side is complicated by the fact that you need to perform a number of preliminary operations.

Bearing pos.15 is covered by a soft rubber socket. Similar rubber guard pos.33 closes also the bearing pos.14.

To remove the bearing pos.14 the nut pos.45, remove spur gear pos.17 and the plastic guard pos.33. With a bearing puller you can simply remove the bearing from the rotor shaft.

And if you do not have a puller? It could be helped by using vice, two iron bars and hammer with soft metal point.

Faults of the speed regulators

In CNC lathes of the series Bosch, in particular for low power, there are speed regulators. The speed regulator is accessed by opening the knob of the stator housing, held in place by one end screw.

Speed range of the speed controller can be adjusted with a potentiometer hidden in the knob panel.

It’s fairly easy to remove the defective regulator as it is only fastened to the guide rail.

Repair of the speed regulator angle grinder is a difficult process, the performance of which requires not only special knowledge but also tools and equipment.

If speed regulator is defective and no new one is available, disconnect input leads and install a bridge.

The reddish color shows the jumper that is installed if the speed regulator fails.

Stator Repair

Angle grinder repair Bosch includes the stator refurbishment. The main sign of stator failure is the spontaneous increase in speed of the running angle grinder, which is unrealistic to reduce adjustments.Stator coil burned in, changes color, becomes darker. The stator core also darkens with high temperature.

The stator is easier to rewind, although you need to follow certain rules and sequences.

If you have removed the stator case cover, closely inspect the condition of the carbon brushes and rotor collector lamellae.

The length of carbon brushes must be at least eight mm. By the way, Bosch angle grinders use carbon brushes with a “shot”, a device that stops the angle grinder when the length of the carbon brush.

The manifold lamellae are not required to have traces of carbon deposits or wear. Carbon deposits are simply removed with absorbent cotton soaked in alcohol.

Disassembling the gearbox of an angle grinder correctly, video

There are many companies that specialize in the production of angle grinder. The basic design principles of all brands of angle grinders are almost the same. However, there are some peculiarities that should be considered when repairing bolsters of a particular brand. The experience of such repair is presented by the masters in the video format, it is presented below.


Identify the cause of the malfunction angle grinder Fiolent in the following video helped disassemble the gearbox. After careful unscrewing of the fasteners on the gearbox housing, there was a large backlash of the spindle in the bearing unit support. Particles of the bearing cage confirmed the direction of repair work to replace the collapsed bearing unit.


The following video describes in detail how to disassemble the gearbox spindle of an angle grinder from one of Hitachi models. This is to replace a jammed bearing in the gearbox housing cover. In order to get to it you have to remove the pinion pressed on the shaft. Due to the small distance between the gear wheel and the gear cover, the puller jaws are ground to the required thickness in order to get into this gap. Important: Remove the pinion retaining ring before pressing it out.

How to disassemble the gearbox of angle grinder

The angle grinder disassembly process is inextricably linked to the angle grinder gearbox disassembly, as they form one whole. The angle grinder can also be disassembled without having to disassemble the gearbox, but in this case it would not be a complete disassembly. That’s why in the following we will consider the disassembly process of the angle grinder and the gearbox as a whole.

To perform this operation we need a screwdriver. I personally use a universal multi-function screwdriver with a ratchet mechanism.

Using a screwdriver to disassemble the angle grinder’s guard

To disassemble the angle grinder guard you need to unscrew the fastening bolts. For this model, 4 pcs fixing bolts. can be unscrewed with a screwdriver. Other models may require a wrench.

Read more at http://stroivagon.Which angle grinder to choose

Step 3. Removing the gearbox from the angle grinder housing.

The gearbox is held in the angle grinder housing (for this model) by four screws. Unscrew these screws with a screwdriver, then very carefully remove the angle grinder gearbox from the housing.

The rotor is rigidly fixed to the gearbox of the angle grinder

For this model the gearbox and motor rotor are fixed firmly to one another. To remove the rotor from the gearbox, the gearbox must first be disassembled. Therefore, our next step will be to disassemble the gearbox itself.

Using a screwdriver to disassemble the gearbox of the angle grinder

Gearbox of angle grinder is disassembled not only for repair of defective parts, but also for preventive maintenance.

The gearbox of the angle grinder is the most important component and experiences certain stresses during operation.

Grinder Repair. Replacing the (Gearbox) Gear Housing (Makita Part # 317814-3)

The idler gear (armature shaft gear).

Bearings that need to be lubricated to reduce frictional forces that occur during operation.

Step 5. View of the disassembled gearbox

Parts that make up the gearbox. an inside look.

To extract the rotor from the gearbox of the angle grinder, unscrew the nut that holds the rotor in the gearbox and use special extractors to pull the rotor rod out of the gearbox.

This operation is somewhat difficult and therefore I strongly recommend that you have it done in a repair shop. You need special tools and knowledge for disassembly. For preventive maintenance work to remove dust and dirt, you do not need such a detailed disassembly. Only use this kind of disassembly if a component fails, e.g. the rotor or the bearing.

The process of removing the rotor and bearing from the gearbox housing

Using the vise when disassembling the gearbox of an angle grinder

If you do decide to completely disassemble the gearbox, you will need a vise and the following to succeed:

Unscrew the nut on the gearbox side with a wrench (see photo).

Clamp the rotor case carefully in a vice and knock out the gear case with a wooden stick or light strokes of a hammer.

Change the position of the rotor in the vise and dislodge the bearing through a wooden board.

Rotor pinion and shaft design

To remove the pinion from the gearbox shaft, proceed as follows

clamp the rotor in a vice (firstly wrap it in a rag).

Then wrap rags around the pinion, clamp with a gas wrench and turn counterclockwise.

Remove the spindle and large pinion from the housing

Parts that make up the assembly

To disassemble the spindle housing, start by removing the large pinion with special pullers. Then clamp the housing in a vise and carefully (with light strokes through a board) knock the spindle with the bearing out of the housing. Further use special pullers or the method described above to dislodge the bearing.

It is very important to disassemble the reducer in proper time and replace the lubricant (usually it is lithol-24 grease) after intensive use. Timely replacement of grease can significantly extend the life of the angle grinder gearbox by preventing premature wear of its components.

When disassembling the angle grinder, especially during gearbox disassembly, it is very important to remember the position of all parts in the housing. This is essential for proper reassembly of the tool, because often there is a situation where disassembly becomes much easier than the reassembly. In order that you could better be able to absorb the lesson how to disassemble the angle grinder, especially for you, I have prepared a short video.

Instructions for repair of angle grinders with their own hands

Angle grinders (angle grinder), also called grinders, are a popular and reliable tool. But everything breaks down at some point. Perform the repair of angle grinder with their own hands is not difficult, if you have in front of you the instruction, telling a step by step order of repair angle grinder. Below you will find answers to any questions about repairing the gearbox, rotor, stator, carbon brushes of angle grinders.

Angle grinders among home craftsmen are especially popular. The possibility of changing of work tools allows to make cutting, grinding, polishing operations.

The presence of a soft starter makes the work of the tool safe and convenient. Angle grinder repair is uncomplicated and can be performed independently. For those who dare to carry out repairs to the angle grinder itself, you will need a scheme of angle grinder necessary type, tools, lubricants, and this manual.

Any repair of angle grinder with your own hands begins with the study of emerging failures. The design of the angle grinder is simple enough. The rotating rotor transmits, via a helical gear, the torque to the shaft (spindle) of the tool. The required working tool, be it a cutting stone, grinding or polishing wheel, is mounted on the spindle and the desired working operation is carried out.

By the way, about the shape of the tooth. On low-power angle grinders, straight spur gears are installed. Helical gears are used in bolsters with more than 1000 watts of power.

Angle grinders, like any tool, break down over time. The causes of malfunctions of the angle grinder can be different. They appear not only from improper use of the tool, but also from untimely replacement of carbon brushes, lubricants.

Regardless of the angle grinder model, all malfunctions occur in the same nodes. Faults of angle grinders are conditionally divided into mechanical and electrical. For novice repairers, faults are divided into simple and complex.

How to disassemble the gearbox correctly: Guidelines

When the gearbox completely refuses to work, it requires complete disassembly for parts replacement and thorough cleaning. To carry out the work, you need to prepare a locksmith’s vise. All work is performed in a certain technological sequence:

  • Use a wrench to loosen the bolt holding the gearbox housing.
  • Fix the body of the rotor with great care in a vise.
  • You extract the housing by lightly hammering.
  • Find a convenient position for the rotor to remove the bearing. The vise is clamped again.

Using a block of wood, the bearing is knocked out. To remove the pinion from the gearbox axle is necessary:

remove, gearbox, small, angle, grinder
  • The rotor is wrapped in a cloth and secured in the jaws of a vice.
  • The pinion is also wrapped with rags, using a gas wrench, turn it counterclockwise.
remove, gearbox, small, angle, grinder

Design Features

Metabo angle grinders have a number of patented design features.

  • The VibraTech handle, which reduces the vibration felt by the operator by up to 60%. This makes it quite comfortable to use the device for a long time.
  • Metabo S-automatic clutch for maximum safety at work. This design prevents dangerous jerks in the tool in the event of a jammed disk.
  • Quick clamping nut that allows you to replace the angle grinder’s wheel without using a wrench. Not all Metabo angle grinders are equipped with this device.
  • The disc brake allows you to fully lock the disc of the angle grinder within the first few seconds after you turn off the machine. Fitted on machines of the WB series.
  • The trigger is well sealed and prevents any electrical breakdown. It is also equipped with a safety fuse that prevents unauthorized activation of the device.
  • Slots in the housing ensure good ventilation of the motor and prevent it from overheating continually.
  • The gearbox in Metabo’s grinders is made entirely of metal, which allows heat to escape quickly and thus prolongs the life of the whole mechanism.

What angle grinder repair the user can do with their own hands

Although the angle grinder is not a tool of particular complexity, the user can perform repair work not on all nodes.

In addition to simple replacement of bearings or gear wheels, there are problems that cannot be solved without special equipment or tools.

  • To press out the idler pinion, you need a press. It is not possible to wind the rotor without a device.
  • Such malfunctions include failure of the rotor. For the average user this kind of trouble ends up in the service center.
  • For advanced users it is possible to rewind a burnt out rotor with some skill and understanding. But sometimes it’s easier to buy a new one than to rewind.

For most users, the repair of angle grinder with their own hands is limited to a certain range of faults.

Systematization of electrical faults of the angle grinder

  • The easiest fault, which does not turn on the angle grinder. breakage of the power cord. Most often there is a breakage in the power cord near the plug or in the inlet of the tool. The problem can easily be solved by replacing the power cord or removing the broken piece of wire.
  • Increased heat build-up in the carbon brushes area. The problem is most often caused by shortening the carbon brushes below their nominal size. The length of the carbon brushes must not be shorter than 8mm.
  • Angle grinder trigger stuck. The problem is caused by burnout of the internal contacts in the button. Remedies by completely replacing the switch with a new one.
  • Some angle grinder models have a device that enables infinitely variable speed adjustment of the angle grinder. The angle grinder’s speed regulator improves the grinder’s smooth startup and prevents the grinding tool from jamming. The angle grinder‘s speed regulator can be repaired by replacing it completely.
remove, gearbox, small, angle, grinder

Mechanical fault grouping of the angle grinder

  • The appearance of extraneous noises in the gearbox of the angle grinder, gearbox heating. Failure is caused by destruction of bearings, gear teeth wear, grease drying up. Remedied by replacing gears when tooth wear is high. If there is little wear on the gears teeth, you can try to correct it. Tooth profile corrected by hand, by filing with a round file and drill. Lubricant must be replaced with new grease each time the gearbox is repaired. New grease should be applied to carefully cleaned parts.
  • The bearing must be replaced if it is broken or if there is a large backlash. On some models, the bearing is interference fit on the spindle. Replacing requires special tools, such as a press. Parts must be cooled or heated.
  • Replacing bearings on the rotor is required if high runout occurs. Excessive runout can be easily seen on the rotor header and by the wear rate of the carbon brushes.

Simple malfunctions and ways of diagnostics and elimination by your own hands

If you have an angle grinder does not turn on when you press the “Start” button, then the inspection begins with an inspection of the power cable at the entrance to the tool.

Unscrew the cover of the angle grinder and check the continuity of the power cord with a tester or phase. Strictly obey safety rules.

If the power cord is intact and the angle grinder will not start, replace the start button.

If the angle grinder does not work when a new button is installed, check that the carbon brushes are properly seated and that they are firmly seated on the rotor head.

Complicated malfunctions and repair angle grinder with their own hands

The following types of failure require some knowledge and skill to fix:

Makita 9500nb angle grinder restoration part 1

  • Jammed or destroyed bearings.
  • Grinding gear teeth are sagging or fractured.
  • Open or short circuit in the rotor or stator.
  • Control circuit parts breakdown.
  • Rupture of the gear housing.

Usach Hitachi repair

Bulgarian Hitachi is especially popular among Russian consumers. All this than. There are practically no homemade knockoffs of Hitachi Bulgarians in the trade. Its simple design makes it easy to remove any difficulty.

Bulgarians Hitachi increased reliability is not seldom on the table of repairers. The main reason to get a Bulgarian Hitachi for repair is gearbox failure, to be specific, gear tooth formation.

Where to rewind electric motor armature

Electric motor armature can be qualitatively rewound only with special equipment. This technological operation is similar in complexity to the rewinding of the stator. Our workshop has all necessary tooling and equipment for rewinding collector motor armatures.

Anchor. is a movable constructional element that rotates at a high angular velocity. There is a considerable centrifugal force on it. Therefore, rewinding the motor armature should be supplemented by its quality balancing. After electric motor rewinding, impregnation and drying it is necessary to perform the final operation. dynamic balancing of the armature on a special balancing machine. Neglecting this will cause significant vibration, bearing and armature damage.

To work on the rewinding of the motor armature price will always be lower than the purchase of a new electric force unit. In many cases, rebuilding a motor armature is the only way to repair an electric drive, since picking up a new collector motor can be difficult because of the mounting location.

| Denial of responsibility | Contacts |RSS