As you know, there is nothing eternal and even the tools of branded manufacturers break down, not to mention the so-called "consumer goods". And an angle grinder (angle grinder) is no exception. By the way, they called the angle grinder “angle grinder” in the days of the Union, because then this tool was produced in Bulgaria and the first models were delivered from there. The angle grinder, as a tool, is very widespread due to its versatility and ease of use. There are also many varieties and models of grinders, however, the principle of operation and the device is fundamentally no different. Therefore, having considered the tool device, possible malfunctions and repair methods, they can be applied to any model of an angle grinder.
Angle grinder device relatively simple. The basis of the tool is its body, inside of which there is an electric motor, a starting device and a gear transmission to the spindle, on which various nozzles are mounted.
The case is made of strong shockproof plastic. Depending on the power, there are various dimensions and shape of the tool. Some models have an angular velocity controller, which is designed for the optimal choice of speed, for various types of work.
Another component may be a gearbox. The gearbox is designed to create optimal conditions for transmitting rotation from the rotor of the electric motor to the cutting or grinding wheel. This reduces the number of revolutions on the output shaft of the gearbox. Properly selected rotation speed and circle diameter are the key to the most effective tool operation.
A button to replace the working disk when pressed, which locks the disk in a certain position, preventing it from scrolling when removed.
The safety clutch serves as a limiter in the event of a sudden reactive torque. In another way, when a disk is jammed in the material, the angle grinder itself begins to rotate sharply, which can lead to injury to the worker. This coupling does not allow such rotation.
The electric motor consists of a standard stator and rotor. The stator is located in the guide tides of the plastic case, an angle grinder. On the back of the stator there is a special device called a brush mechanism. It contains copper – graphite brushes. Brushes are needed to transmit voltage to the rotor through the collector assembly.
The rotor is located inside the stator and is fixed in the housing in bearing units, which are made inserted directly into the tool housing. The front bearing assembly is usually made in a metal plate, or, this plate can be made of aluminum alloy.
The gear housing of the angle grinder is almost always made of aluminum alloy and has several threaded holes for attaching an additional handle. By turning the handle into various holes, you can change the location plane during operation.
The gearbox consists of two gears, with the help of which the direction of the output shaft changes by 90 degrees and the rotation speed decreases. The ratio of the number of teeth of the primary gear to the number of teeth of the secondary gear is called the gear ratio of the gearbox.
Typical malfunctions of grinders and diagnostic and repair methods
angle grinder suddenly stopped working.
The first thing to do is physically disconnect from the network and manually rotate the disk. If the disk does not spin or spin very tightly, immediately disassemble the instrument for visual inspection. If it turns easily, the most probable is that electricity does not reach the electric motor brushes. That is, the problem is either in the power plug, or in the wire itself, or in the button mechanism "Start". It is enough to disassemble the housing and "ring" cable with a conventional tester, or in any other way, for a break. After eliminating the break or replacing the wire, the angle grinder will work.
The start button and the power wire are in good condition, the angle grinder does not work.
Check brushes and brush holders. There may be a break or complete wear of the brushes. The resource of these devices is usually limited to several years, of course, it all depends on the intensity of use. Repair open or replace brushes.
Video: How to Connect a Button to an Angle Grinder
Further more serious malfunctions follow, respectively, and repair requires certain knowledge and skills.
When determining mechanical defects, an angle grinder should pay more attention to the condition of the plate (large gear), shank (gear on the shaft) and bushings. Uneven wear of the teeth or the shafts of the shafts indicates the immediate replacement of worn parts.
Breaking out the spindle lock button.
The reason is just one careless movement, namely, pressing (intentionally or accidentally) a button when the disk is spinning. Sometimes breakdowns occur due to attempts to remove a jammed disk using the button. Many grinders on the spindle, where the disk is mounted, have slots specifically for the usual open-end wrench, look at your angle grinder, most likely you have one. So, it’s better to use them and the open-end wrench, than the disk lock button.
Failure of the electric motor.
Often this happens with tools that work in dust and which are forced to rest in the sand or on the ground: sucked dust grinds the winding. However, you can kill the motor without dust. strong overloads, especially if the tool is low-power. Therefore, small grinders often burn out not only the anchor, but also the stator. Small grinders also have a breakdown of the electronic speed control unit. If you use an angle grinder to cut highly dusty materials, in particular slate, a well-worn stocking helps to protect the tool in place of the ventilation slots in the case.
Another sore spot for grinders (as well as other twisting power tools). Strong immunities against dust stand out few cars, and a high speed suggests rapid wear. In general, bearings are not the worst damage, they change easily. However, it is important to replace on time, otherwise there is a greater likelihood of a more serious breakdown, the repair of which is comparable to the purchase
If, when turned on, the disk starts to gain momentum and accelerates too much, there is definitely a coil closure on the stator winding. Stator repair is one of the most serious failures and requires appropriate skills. If you are not confident in your abilities, then it is more advisable to entrust it to professionals or use the services of a repair shop.
We begin the stator repair with the angle grinder by cutting the frontal parts of the winding, the remains of which are removed. Next, we make a new winding using a template sandwiched between two large plates on the axis, which can be inserted into an electric drill. The main thing is to achieve an identical number of turns made with the proper density and withstand the thickness of the wire. We insert two coils into the stator housing, we make the conclusions from the same winding wire, isolating them with flexible tubes of the corresponding diameter.
In models with power up to 1100 W, spur gears are usually used, mounted on an anchor, but an angle grinder with a higher power, for example, 1500 W, requires helical gear wheels. Both versions have a conical shape, since the axis of the gearbox rod intersects with the armature shaft, and transmission is possible only by angular engagement of the teeth.
As a rule, repair of the gearbox angle grinder consists only in the replacement of gears. If the disk gear is broken, then it will be very difficult to remove it for replacement; in the gearbox this assembly is best fixed.
Almost all modern models of drills, jigsaws, screwdrivers have a speed control. But not all angular grinders (grinders) are equipped with such a mechanism. In principle, a regulator is not needed for cutting metal with a cutting stone, but it is simply not replaceable for grinding. The proposed circuit of a homemade controller is very simple and reliable. There are not many details and they are not expensive. If you already have an angle grinder without a regular speed regulator, then you can easily improve it.
You can assemble it separately in a box with a socket and use it as a carrying case with a power regulator. And you can immediately assemble the regulator in the case of an angle grinder and pull out the handle of the resistor.
The power tool must not be allowed to operate for a long time under load at significantly reduced speed (this can be determined by ear) compared to idle speed, and moreover, the tool must not be clamped (blocked), otherwise it will burn out within a few seconds.
After operating at reduced speeds, do not immediately turn off the power tool. To prevent local overheating, it is necessary that it works for a while (more than 1 min.).
It is important to strictly observe the terms of lubricant replacement (addition) specified in the instruction manual and its quantity.
Prevention consists in completely or partially disassembling the tool, cleaning, lubricating and replacing (if necessary) some parts.
Timely replacement of relatively cheap parts that wear out quickly will allow you to save more expensive components of long-term use, which will ultimately lead to savings in the operation of the tool, eliminate premature repair and significantly extend the life of the tool.