An angle grinder or, as it is also called, an angle grinder is a versatile and easy-to-use tool that is used by both professionals and ordinary homeowners.
The versatility of this tool allows it to be used for working with various materials:
- Non-ferrous and ferrous metals.
- Artificial and natural stone.
- Silicate and ceramic bricks.
- Concrete.
- Ceramic tiles.
- Wood.
An angle grinder can be used both for cutting such materials and for grinding or processing them. You just need to choose the right wheels to use, which are intended for working with stone, concrete or wood. Most homeowners use grinders for sanding and cutting lumber. In this case, it is necessary to use special attachments for wood, while the grinders must maintain operation at minimum speed.
Purpose and scope of application of angle grinders
The term “grinder” to designate this construction tool appeared in the Soviet Union in the early 70s of the last century. Angle grinders received this name due to their place of origin; their production was established in Plovdiv.
The angle grinder was designed by Ackermann + Schmitt (FLEX-Elektrowerkzeuge GmbH) in Steinheim an der Mur in 1954. The angle grinder quickly gained popularity among specialists; one of the main factors for the success of the tool was its versatility.
The use of special equipment allows angle grinders to perform cutting and grinding operations on a wide range of different materials:
Ferrous and non-ferrous metals, as well as their alloys.
Natural and artificial stone.
Ceramic and silicate bricks.
Concrete and products made from it.
All types of facing ceramic tiles.
Sanding wood.
It is not recommended to use a grinder for cutting glass and wood; due to the high linear speed, heating occurs at the point of contact of the equipment and ignition is possible. In recent years, circular saws have been produced for working on wood with tips made from special refractory alloys. This equipment should be used very carefully and should not be allowed to overheat. The above list of materials determines the main areas of application of angle grinders.
This power tool is widely used:
- In construction.
- At enterprises related to metalworking.
- In car service workshops for body work.
The population has a lot of angle grinders in their hands; household owners actively use them to perform household work. With its help, cutting and grinding of the above materials is carried out. This power tool, in particular, processes welding seams and removes scale. The operation does not take much time and allows you to avoid unnecessary impact loads on the fresh joint.
Design of angle grinders, components
The design of angle grinders is characterized by a relatively simple and technologically advanced design, which made it possible to establish their production at many enterprises.
The angle grinder consists of the following parts:
The body, which is made of reinforced polymers. Such materials are characterized by high strength, resistance to wear and environmental influences. On the outer surface there is a button to turn on the tool with a lock. Some models have windows covered with hatches for replacing drive brushes.
An electric motor powered by a household network or batteries. Angler grinders use drives that can provide high shaft speeds. To cool the windings and other parts, a fan is installed on the front part of the axis.
Single-stage bevel gearbox in a separate housing made primarily of magnesium or aluminum alloys. It consists of bevel gears, the shafts of which are mounted on ball or plain bearings. The interaction of the parts with each other in the gearbox is ensured by the housing, which is filled with grease.
A spindle consisting of a shaft with a metric thread, a thick-walled washer and a nut for attaching a cutting disc or other equipment. On the gear housing there is usually a button on the opposite side that locks the shaft in place. This is necessary for dismantling and installing new equipment.
The removable handle is threaded and can be screwed into the gear housing in one of the selected positions. This is done for the convenience of holding the power tool while performing various types of work.
The protective casing covers part of the cutting disc and does not allow the sheaf of sparks that is formed during operation to fly away in all directions. The device protects the worker and surrounding objects from equipment wear products and material fragments formed during its processing.
The angle grinder is supplied to the consumer complete with a user manual and a special key for attaching the equipment. The latter is a steel strip with two pins that exactly match the holes of the fixing nut. In some cases, the manufacturer adds spare carbon brushes to the package.
Operating principle of an angle grinder
The angle grinder is driven by an electric motor, which is turned on by pressing a locking button or switch. Power is supplied from the network, as well as from a built-in or removable battery. Mostly, the tool is equipped with commutator electric motors, the stator winding of which has a high inductive resistance. This circumstance makes it possible to significantly reduce operating currents.
Spinning, the electric motor shaft rotates the drive gear in the gearbox, which drives the driven gear, and thus transmits force to the spindle. The mechanism body is made of magnesium or aluminum alloys to improve heat transfer. The gearing between gears is of two types: spur and helical (bevel Glisson system). The second option is preferable because it provides greater reliability and helps reduce noise.
More expensive and complex models use a release clutch installed between the engine and the gearbox. The main function of this unit is to prevent kickback when the disk suddenly stops due to jamming. This allows you to protect the operator from possible injury and the grinder components from damage. On such angle grinders, the spindle lock button can be pressed until it stops completely.
The choice of a design scheme in which the plane of rotation of the cutting disc or brush is parallel to the axis of the tool is explained quite simply. When an angle grinder operates, a significant torque occurs, tending to pull the tool to the side. This force is easily compensated by the operator due to the optimal positioning of the hands along and perpendicular to the axis.
The instrument is made up of the following parts
- The main drive point of the tool is an electric motor; the device does not work without it.
- Due to the gear unit, torque is transferred from the motor shaft to the spindle of the angle grinder.
- The supply of current to the electric motor and the process of closing the contacts occurs thanks to the power button.
- To secure the attachments to the unit you need a spindle.
- To connect the device to a power outlet, use a power cord.
The main reason for breakdowns and situations when it is necessary to repair angle grinders is improper use of the tool by craftsmen. There are two types of angle grinders according to their purpose:
- for household work;
- for regular work.
The category of household power tools is used only around the house without regular and prolonged loads. Household angle grinders made of low-strength materials should be operated for no more than 10 minutes without stopping, then allow the engine to cool for 10 minutes. Few people monitor the operating time of the unit, which is why various damage occurs in angle grinders. Undoubtedly, any household grinder can be a reliable assistant for a long time, provided that it is used correctly. Most often, experts advise not to repair a household grinder yourself; it is better to immediately contact service centers. Professional grinders, which are made from high-quality materials, are famous for the longevity of the device. Such devices are stable under long-term loads, operate continuously for up to 50 minutes and do not burn out.
Power, speed and tool diameter
Considering the significant difference in parameters between different models of angle grinders, the question arises, which is the best grinder to buy for home or work? It is necessary to decide: to perform, what operations it is necessary for, and what the volume of expected work is.
Rotational speed
One of the main parameters of an angle grinder is the linear speed of rotation of the wheel, which depends on the diameter of the wheel. The optimal value for this indicator is 80 m/s; a significant deviation in the speed of rotation towards an increase will lead to the destruction of the circle. A lower rotation speed causes rapid wear of the disc. There are five types of angle grinders, which vary in the size of the cutting wheels used.
The dependence of the spindle speed on the diameter of the working disk is as follows:
115 mm – 13290 rpm
125 mm – 12230 rpm
150 mm – 10190 rpm
180 mm – 8490 rpm
230 mm – 6650 rpm
Data on the permissible rotation speeds of the cutting wheel for each specific model must be indicated on a special plate that is attached to the body. The amount of torque must be sufficient to overcome the resulting friction force and maintain the required cutting speed. This characteristic is determined by the rated power of the electric motor of the angle grinder.
Angle grinder power
The rated power of angle grinders ranges from 650 to 2700 W, and depends on the diameter of the disc used. Accordingly, angle grinders designed for large diameter discs have more powerful drives. With these parameters, the electric motor provides sufficient force on the cutting edge of the wheel to effectively influence the material being processed.
For normal operation, it is necessary that the power consumption of an angle grinder with a disk diameter of 125 mm be at least 750 W. Moreover, the larger the diameter of the permissible equipment, the more powerful the engine should be. So in models with a tooling diameter of 230 mm, which are intended for intensive use on construction sites, the engine power consumption must be at least 2200 W.
Tooling diameter
Be sure to decide what diameter of the equipment will be sufficient for your needs. Remember that you cannot use circles whose diameter is larger than the permissible one. Of course, you can do this by removing the protective cover, but such manipulations are prohibited, as they can lead to injury to the operator.
It is especially dangerous to use an angle grinder without a protective casing when working with metal discs with hard-melting tips, which, if they fly apart, can cause significant harm to health, including death. If you have such a desire, just find on the Internet photos of people who were injured by neglecting safety when working with angle grinders and this desire will disappear forever.
The diameter of the equipment is deeply related to such a parameter as the depth of cut. This point is especially important if you are going to use an angle grinder to cut curb stones and other thick materials. The cutting depth of the model with a disc diameter of 125 mm is only 30 mm - 35 mm, depending on the model. This is because the dimensions of the gearbox will not allow you to completely immerse the circle in the material.
Of course, you can cut a curb stone by making cuts on both sides. But it is more difficult to make such a high-quality cut, and it will take more time. Therefore, if you have to constantly cut such materials, then you should look towards “grinders” with a maximum disc diameter of 230 mm.
Angles with a small working circle are of little use for cutting super-hard materials, and large models are inconvenient for grinding car bodies.
How to disassemble an angle grinder for diagnostics
In order to diagnose the electrical part of the angle grinder, as well as eliminate mechanical breakdowns of the device, you will need to disassemble it. Disassembly is carried out according to the following algorithm.
- Using a wrench, remove the disk or other attachment from the spindle of the unit.
- Unscrew the handle.
- Remove the protective cover.
- Open the special windows located on the sides of the angle grinder casing and remove the electric brushes, having first disconnected the terminals.
- Unscrew the gear housing from the angle grinder motor housing.
- Pull the gear housing lightly and remove it from the housing. In this case, the gear unit will be removed along with the rotor.
- After removing the armature, the motor stator will remain in the casing, which can also be easily removed for diagnostics after unscrewing the fasteners.
- To disassemble the gearbox, unscrew the screws holding the cover. After removing the cover, you will see the gears of the gearbox.
- To remove the anchor from the angle grinder, you will need to unscrew the nut located inside the gearbox.
- In order to remove the bearing from the armature, it is recommended to use a special puller. Otherwise, the shaft may be damaged.
For home or professional model
To determine which grinder to choose for the home and which for intensive work, you need to proceed from its technical indicators. All power tools, including angle grinders, are divided into household and professional, depending on the time of continuous use. Household angle grinder models are designed for occasional use of 30 - 40 minutes a day.
Professional models are designed for internal use of the tool throughout the day or work shift. Professional angle grinders have enhanced protection from dust, noise and a number of systems that are designed to ensure the comfort and safety of the operator.
If the angle grinder is intended for small household work, then you should pay attention to models with disc diameters of 115 mm, 125 mm or 150 mm. The most common model for home use is an angle grinder with a disc diameter of 125 mm. To understand how to choose an angle grinder for your home, you need to outline the range of tasks to be solved and the list of materials to be processed. Obviously, purchasing an expensive professional tool in this case is unjustified.
As for professional models, the undisputed leader here is an angle grinder with a disc diameter of 230 mm. When choosing such a model, you should pay attention to the engine diameter. The larger the engine diameter, the greater the torque the angle grinder can develop, and this is very important during grueling operation.
Therefore, if you are choosing between two approximately equal angle grinders, give preference to the one that has a larger motor diameter and only secondarily look at the power. Some manufacturers themselves indicate the torque in the tool's data sheet, but many ignore this parameter.
Purpose
The grinder was originally created for grinding surfaces. But due to significant design upgrades, it quickly began to perform such useful functions as cutting and processing any building materials, including cement, concrete, brick, tiles, slate and all types of metals.
According to the methods of performing work, angle grinders, like all power tools, are designed for operation in one of two modes:
- constant work in construction conditions with overcoming maximum loads during a full work shift - professional models;
- for single use with the organization of breaks at rated loads - a household tool.
This is one of the important differences to consider when purchasing. It affects the cost of the grinder.
Professional models
To ensure that the tool works for a long time in extreme conditions and is at the same time convenient, manufacturers use all sorts of technical tricks. For example, to slightly reduce the dimensions of the motor and its weight for the stator and rotor windings, insulated copper wire is not the usual round cross-section, but in the shape of a square.
Even the plastic composition for the body is selected in such a way that when heated to 140°C it does not transfer high temperature to the operator’s hands and at the same time does not lose its strength.
Expensive models of grinders have:
- vibration-proof inserts on the handles that prevent the development of occupational diseases;
- quick-release nuts SDS, allowing you to install working parts without using a special wrench;
- rotating rear handle;
- gear rotation function or the ability to move the front handle to one of three positions;
- special bearing design that ensures balancing of the working body;
- long power cord with a protective layer of durable insulation;
- the ability to regulate the speed of the working circle and a number of other useful functions.
Household tool
Grinders of this class are inferior in their characteristics to professional tools. However, they are produced according to strict technical standards, meet safety standards, and allow work to be carried out while observing breaks.
Additional systems to support tool operation
Angle grinders have become widespread due to their convenience, versatility and reliability. The design of the power tool includes a number of systems that are designed to ensure high performance and safety of working with the tool. The functionality of each model is determined by the manufacturer at the design stage; the list of additional options affects the cost.
That is why, next we will consider additional systems that ensure the operation of an angle grinder and determine how important their presence is for the effective and safe use of the tool.
Inrush current limiting system
When the electric motor is turned on, the load on the motor winding increases abruptly by 6-8 times, which can cause damage to it or trigger the protection. This also generates an impact torque, which is transmitted through the shaft to the gearbox and spindle. The starting current limiting system is an electronic circuit that provides a smooth increase in rotation speed.
The operating principle of this system is to gradually increase the voltage on the windings over a given time. Using an angle grinder becomes safe, and the service life of the electric motor and gearbox increases.
The absence of impact during startup improves cutting accuracy and eliminates the possibility of scoring during grinding.
System for maintaining a constant number of disk revolutions
When the cutting disc comes into contact with the surface being processed, friction occurs, which increases the load on the engine and reduces the rotation speed. The system for maintaining a constant number of disk revolutions compensates for resistance and ensures that the cutting speed is maintained. Stabilization of the spindle rotation speed is carried out through the use of a constant electronic circuit.
There are two ways to maintain speed in angle grinders operating under load: by current or by spindle speed. In the first case, a current consumption sensor is used, which records its value and, as it increases, the circuit increases the voltage on the windings.
Speed control involves the use of a tacheometric sensor that monitors the rotation of the angle grinder. When this indicator decreases, the electronic circuit increases the voltage and, as a result, ensures optimal rotation speed of the equipment. The choice of a method for maintaining a constant rotation speed occurs at the design stage and is carried out taking into account the positive and negative aspects of each method.
Not all models are equipped with such a system; we can say that its presence is desirable, but not necessary.
Restart locking system
During construction work, it is possible that a power outage occurs for a variety of reasons. The angle grinder's anti-restart system prevents the engine from starting unintentionally. When the grinder suddenly stops, the worker most often simply puts the tool aside without checking the position of the switch.
A sudden resumption of power supply in this case can result in injury to the performer or damage to valuable property. For angle grinders equipped with such a system, restarting occurs only after the starter is turned off and pressed again. In this case, the user will need to take the tool in his hands, which means his actions will be meaningful and controlled.
Having such a system is very important and necessary.
Automatic disk balancing system
When using angle grinders, especially with large-diameter equipment, discs or brushes wear unevenly. This leads to imbalance, which manifests itself in the form of vibration, which does not contribute to the accuracy of the operation. Runout negatively affects the condition of the bearings and reduces the service life of the electric motor.
The automatic disk balancing system compensates for the uneven distribution of the mass of the rotating equipment. To stabilize the tool, various technical solutions are used, mainly special bearing designs with fewer balls. This system makes the product more expensive and is usually used on professional models with large diameter discs.
If you are choosing a tool for intensive use on a construction site, then it is best to give preference to models equipped with this system.
Motor overload protection system
When using an angle grinder, the load on the electric drive is not constant and in certain periods can significantly exceed the design value. To protect the engine from overloads, grinders are equipped with special systems that forcibly stop the current supply. In this case, the tool simply stops working and to resume it you must first turn it off and then turn it on again.
There are two ways to protect angle grinders from overheating: by current or by temperature. In the first option, shutdown occurs when limit parameters are exceeded, which are recorded by the electronic module. In another design, a temperature sensor is installed on the engine, which interrupts the power circuit when the parameter goes beyond the set values.
The system ensures the longest tool life but does not in any way affect the quality and safety of the work.
Dust protection system
During the process of grinding surfaces or cutting materials using an angle grinder, a significant amount of dust is generated. It enters the housing with the air flow and causes increased wear; the most vulnerable are the bearings, brush assembly and outer surfaces of the rotor and stator. Metal particles formed during cutting can cause a short circuit between the turns of the winding.
The angle grinder protection system involves the use of the following design and technological solutions:
- Installation of meshes on ventilation openings, and on expensive professional models and filter elements.
- Armoring the stator windings and using cord bands on the rotor.
- The use of closed type bearings.
- The gearbox housing is made as sealed as possible.
- Pouring windings with epoxy resins.
Dust protection systems significantly increase the service life of angle grinders and make them safe during operation, preventing short circuits.
Kickback protection system when equipment jams
A sudden stop of the equipment leads to the generation of torque, which is aimed at turning the angle grinder. In this case, significant efforts arise, and it is impossible to hold the instrument in your hands, and this is already fraught with injuries to the upper limbs and other parts of the body.
The anti-kickback protection system when the equipment jams prevents such a situation from occurring. This is realized in two ways: mechanically or using electronics. In the first option, various types of couplings are used, which operate when there is a sharp increase in resistance to shaft rotation. The second method is based on constant monitoring of current values; if a certain value is exceeded, the power is turned off.
Various manufacturers have their own developments for implementing such protection; its presence is extremely important for professional models with a large circle diameter.
Adjusting the guard without using a key
In this regard, each manufacturer has its own ways of implementing such adjustment, but what they have in common is that changing the position of the protective casing is done quickly and without using a key. This is very convenient when performing certain types of work when you need to constantly change the position of the protective casing. As a rule, it is enough to bend the lever and move the casing to the desired angle.
When using housings that require a key to adjust, repositioning them is somewhat difficult. To make their work easier, users often resort to security violations. Do not clamp the casing completely or remove it altogether. The presence of a keyless casing adjustment system is designed not only to improve the work process but also to discourage the user from rash decisions that grossly violate safety regulations.
Speed adjustment
The spindle rotation speed is adjusted using a wheel located on the tool body. On cheap models, this adjustment may not be available at all. But as practice shows, when performing certain jobs, its presence is very important and allows for better cutting or grinding. For example, when sanding plastic and various paints and varnishes, if the equipment rotates too intensely, the surface being processed can burn.
Design and principle of operation
After connecting the power cord to the mains voltage and turning on the start button, the rotor of the electric motor begins to rotate. A gear transmission at its end transmits torque to the working circle.
When rotating under load, the disk material is subjected to significant loads and if the rules for handling it were violated during storage, it can break into pieces.
To ensure safe operation of the tool and prevent accidents, perform any operations with the angle grinder only with the protective cover installed.
Design Features
Inside the impact-resistant body of the angle grinder, there is the same commutator motor that is installed in the impact drill. It consists of a stator in whose bearings the rotor rotates. Its angular speed can reach 30 thousand revolutions per minute.
The difference lies in the connection of the working body, which rotates at an angle of 90O to the axis of the angle grinder shaft. The rotating head of the gearbox ensures rotation of the torque through a helical gear transmission. It is equipped with a damper bushing that dampens mechanical shocks of the nozzle transmitted to the engine bearings.
Airflow diagram
During prolonged operation with heavy loads, currents flow through the windings of the electric motor, heating the stator and rotor to high temperatures. To prevent burnout and destruction of wire insulation, a built-in forced-type cooling system is used.
Air masses are forced through the ventilation holes of the housing at the handle and are evenly driven along the electric motor, taking away excess heat from it. The heated air is discharged from the rotating head. For better heat removal, its body is made of light metal alloys.
When choosing an angle grinder for a home craftsman, pay attention to the location of the ventilation holes. During operation, they should not be covered with hands and are made with protection against sparks or dust from the material being processed.
Violation of internal air exchange can lead to a violation of the thermal balance, overheating of the windings, and breakdown of the electric motor.
Electrical diagram
In a simplified form, the connection of internal elements can be represented by the following picture.
The leads of the stator and rotor windings are connected to each other through brushes into a single serial circuit. Voltage is supplied to it through a two-pin switch.
Based on this principle, there are types of connecting electric motors with various electrical control and monitoring devices.
Handles of their types and adjustments
In their classic form, angle grinders have two handles, a main one and an additional one, which is mounted on the gearbox. But in this regard, the tool has many features that are worth considering separately.
One-handed and two-handed angle grinders
There are angle grinders with one and two handles. It should be noted right away that this does not mean that you will hold the tool with one hand when working. It’s just that in a one-handed angle grinder the second hand is located on the body. One-handed angle grinders are available with disc diameters of 115 mm and 125 mm. The main advantage of one-handed angle grinders is their short length, which allows the tool to be used in hard-to-reach places, for example during body work.
The main disadvantage is that they are more difficult to hold while working. Therefore, tools for large-diameter equipment come with only two handles. In any case, holding a tool by two handles is much more convenient and safe than holding it by one handle and the body. Before purchasing a tool, you should hold it in your hands to decide which option is preferable for you.
Attaching an additional handle
The gearbox housing has at least 2 holes for attaching an additional handle. It is optimal to have 3 holes - two on the sides and one on top. This is quite enough for the convenience of performing almost any work. Some manufacturers make more than 3 positions for attaching the handle; whether such functionality is needed is up to you to decide.
Additional handle attachment points.
Adjusting the main handle
The main handle can be rotated relative to the axis of the body. Most often there are 3 positions - neutral and 900 in both directions. This allows you to select the required coverage for better and more convenient work.
Angles of rotation of the main handle of the angle grinder.
Vibration damping handle
When using an angle grinder, vibration occurs, to dampen it a special vibration-damping handle is used. Not all models are equipped with such a handle. As a rule, these are more expensive or professional angle grinders. It may seem that this is not such an important detail, but from experience I can say that the operation of an angle grinder with an anti-vibration handle is much softer and more comfortable. Therefore, it is better if the tool is equipped with such a handle.
Grinder repair
To remove the rotor, it must be freed from the gearbox pos. This is fraught with overheating of the disk, its deformation and destruction.
Design features of the Makita grinder The grinder is an angle grinder, which received this name only in the vastness of the former USSR.
Nuts for fastening the disk are self-clamping SDS and conventional with key holes.
The higher the speed of its rotation, the more power the grinder has. The reason is just one careless movement, namely pressing a button intentionally or accidentally while the disk is spinning. If there is no current supply to the button terminals, the supply cable should be replaced. The operating principle of Makita angle grinders is based on the conversion of electrical energy into mechanical energy.
More on the topic: Standard communication cable depth
Purpose
The anchor needs to be repaired or replaced. It is most convenient to start diagnosing from the electrical current input area.
Insert the pre-lubricated LLB bearing into the bearing housing. Before you start repairing an angle grinder with your own hands, it is best to have in front of you a layout and electrical diagram and detailed instructions that correspond to a specific model.
Electrical component of the angle grinder design
Practical experience in ordering and arranging... Knitting. There is an axle lock button on the machine itself. Diagnostics of the rotor operation of an angle grinder Interturn short circuit, as a rule, occurs when the tool overheats during operation. At the front end of the armature there is a gear for transmitting rotation.
To install discs, a special key is supplied to the angle grinder, which secures the nut for clamping the disc. If this element fails, it is unlikely that an inexperienced worker will be able to restore the winding. How to read an electrical circuit In order to properly repair or carry out maintenance on an angle grinder, you must first of all learn to read the circuit diagrams of power tools, including the electrical circuit. Technical indicators The power consumed by the power tool is W. Diagnostics of an angle grinder Stops turning on How to find a break Tool repair
Cordless angle grinders - features of their choice
Autonomous grinders appeared on the power tool market relatively recently. Such designs use high-capacity lithium-ion batteries that can ensure the operation of the angle grinder for a short period of time. Such technical solutions are currently applicable only to angle grinders with a small disc diameter of 115 and 125 mm.
Using cordless angle grinders at home if there is an electrical outlet is not the best solution:
- Firstly, such models are quite expensive.
- Secondly, their battery life under load is limited.
- Thirdly, rechargeable batteries require constant monitoring and regular charging.
The only advantage of such a tool is the ability to use it in places where there is no power supply. For modern households, this is not a problem, which means choosing a cordless angle grinder is inappropriate. They are bought in case of emergency, when it is not possible to work from a power source.
The main parameter that you should pay attention to when choosing a cordless angle grinder is the battery capacity. Remember that angle grinders consume a fairly large amount of energy, so the larger the battery capacity, the more time you can work with the tool on one charge. All other selection criteria are the same for both cordless and corded angle grinders.
Diagnosis of a problem in the electrical circuit of an angle grinder
To identify the cause of a malfunction of an electric angle grinder, use an electronic multimeter and a screwdriver. A failure means the following problems:
- the tool overheats quickly;
- sparking of graphite brushes;
- speed is not regulated;
- rotation speed and power do not increase;
- The angle grinder does not start when the start button is pressed.
Advice! Grinders recommend starting to diagnose faults in the electrical circuit with the wire, and gradually move to the engine.
Diagnostics is carried out with a multimeter
Power cable
To check the power cable of an electric angle grinder, the multimeter should be switched to ohmmeter mode and set to the minimum resistance level. One multimeter probe is applied to the current-receiving rod of the plug, the second - to one of the supply contacts of the start button. Both fork rods are checked. If the cable is working, there will be a ring on each rod with the corresponding button contact. If this is not observed, the cause of the problem is in the wire and it needs to be replaced.
Start button
Testing the start button of an electric angle grinder is carried out using the same method - by ringing the input and output contacts. Only now you have to press the button. If a part fails, it cannot be repaired and a new one must be installed.
Speed control unit
If the rotation speed adjustment on an electric angle grinder is lost, this is indicated by the absence of noise when starting the angle grinder. Ringing the corresponding unit will confirm suspicions, but an inexperienced electrician is unlikely to be able to determine which part has failed.
Speed controller
Types of equipment for an angle grinder: rules for its use and selection
Angle grinders offer exceptional versatility with a wide range of different accessories. The equipment market is very large and can satisfy both the home craftsman and the professional. But even here there may be difficulties associated with selecting the size of the equipment. As mentioned earlier, the most common sizes are 125 mm and 230 mm angle grinders.
You can buy equipment for such a tool at any hardware store. But problems may arise with equipment for angle grinders 150 mm and 180 mm, since this type of tool is not very common. All produced equipment is intended for cutting or grinding a certain type of material or materials and its use on other materials is not allowed. This is the first thing you should pay attention to when choosing it.
The selection of equipment is carried out taking into account the nature of the work performed and the parameters of the angle grinder. It is not allowed to use equipment whose diameter exceeds the maximum permissible wheel diameter for this angle grinder model.
The range of equipment includes the following items.
Cutting wheels
Designed for cutting various materials. When using this type of equipment, the angle between the tool and the surface being processed must be strictly maintained. Cutting discs are used only for well-fixed parts. They come in abrasive and diamond types.
Abrasive cutting discs.
Most often, such circles are used for cutting metal, stone and concrete. The specification of such wheels is noted on their label and is indicated by letters and numbers, for example: A 24 S, where:
- The first letter “A” stands for the grain material from which the circle is made. A - corundum, AS - electrocorundum, C - silicon carbite (used in circles intended for cutting concrete).
- The number, in this case “24,” shows the grain fraction and indicates the specialization of the wheel. For steel this figure will be larger, and for non-ferrous metals it will be smaller.
- The last letter "S" shows the hardness of the ligament. The closer the letter is to the end of the alphabet, the higher the hardness of the ligament.
All these parameters must be selected for the material being processed. Otherwise, the disc may either burn or wear down too quickly. The main rule is that the harder the material being processed, the softer the bond should be.
Diamond cutting discs.
Diamond cutting wheels of various types are highly specialized and designed to be used only for working with certain materials:
- “Concrete” type for cutting all types of concrete, including reinforced concrete products.
- The asphalt type is intended for materials with a significant content of abrasives.
- The “building material” type is used for processing ceramic or silicate bricks.
- The “granite” type is used for working on super-hard building materials.
Based on the type of cutting edge, they are divided into segmented, solid and “turbo”:
Segmental
Solid
Turbo
Grinding wheels
Grinding discs.
Cup type grinding wheels.
Flap end grinding wheel.
Flap disc grinding wheel.
Cleaning Brushes
Cup brush with brass bristles.
Disc brush with steel bristles.
Safety regulations
When working with an angle grinder, you must remember that the rotation speed of the disk is from 6,650 to 13,290 rpm and its destruction is accompanied by the scattering of fragments. Therefore, it is strictly forbidden to remove the protective cover, and the operator must use special glasses. When working with power tools, the following safety precautions should be observed:
- It is not allowed to use equipment that does not correspond to the given model in size or has mechanical damage.
- Work gloves must be worn, as well as clear face and neck shields and eye goggles.
- There should be no people in the plane of rotation of the disk.
- To work with a certain material, use only specialized types of equipment.
- The power cord should be placed in such a way that it cannot be damaged.
Neglect of simple safety rules can lead to injury and even death due to damage to vital organs from disc fragments.
In order to understand how to choose an angle grinder (angle grinder) for your home, you need to know what exactly the tool is needed for and how often it will be used. If we take into account the average needs of the homeowner and the list of work being carried out, then we can recommend a network angle grinder with a circle diameter of 125 mm from a well-known manufacturer.
Typically, such a unit is sufficient to perform most jobs. In general, this tool is not very expensive and the market is oversaturated with supply. Therefore, all you have to do is determine your needs and compare several suitable models to make your choice.
Final Recommendations
Rules for installing the working circle
The inner diameter has a built-in metal ring. It is the base for installation on the bushing and its surface ensures precise alignment relative to the axis of rotation due to four protruding teeth.
The side surface of the ring serves to hold it on the surface of the circle. It is not a basic surface that ensures pressing of the disk inside the flange, if only for the reason that the cutting wheel can have a thickness of 1 mm, and the recess in the flange and nut is about three.
The circle is pressed against the annular protrusion of the flange with its end surface due to the force of screwing the nut, and is held by the plane that creates the greatest moment of resistance - at the periphery.
On the side of the circle there is a picture with technical characteristics. The inner ring, like the picture, can be applied on both sides or on one. This marking is specified by the manufacturer not for installing the disk, but for other purposes. However, some workers mistakenly believe that it is a guide to the direction of rotation.
Where to direct the sparks
According to the laws of inertia, fragments fly from the rotating circle. Their high temperature can burn through clothing material and cause skin burns. If the circle gets stuck in the part being cut, it may fall apart into pieces that will fly in the same way. To protect the operator of the grinder, a metal casing is installed.
When working, the tool should always be positioned so that at any time an unusual situation arises, the protective casing maximizes its function - it protects the human body from sparks and fragments falling on it.
Checking the condition of the brushes
Lifetime
The service life of carbon electrodes as reliable current conductors is approximately 80÷120 hours of operation. After this period, wear occurs and they need to be replaced.
Signs of defect formation on contacts are:
- the appearance of sparks forming a circular beam on the collector;
- noticeable reduction in engine power;
- obvious depletion of the length of the carbon rods or the formation of chips on the surface of their contact.
Clamping force
Factory adjustment ensures optimal contact force between the brush and the commutator plates. If the brush assembly is worn out or incorrectly replaced, it may be damaged in the direction of increasing or decreasing contact.
Increased pressure
Excessive pressure is created by the hard brush on the soft material of the commutator plate, leading to excessive heating of engine parts.
Reduced pressure
Additional electrical resistance appears at the contacts, which does not ensure reliable current flow when switching the windings located on the rotor. A spark discharge appears that can develop into an arc that damages the brush assembly, commutator, and motor.
Therefore, when replacing brushes, it is necessary to control their force and use original spare parts from the manufacturer.
To conclude the presentation of the material, we recommend watching the video of the owner of VselnstrumentiRu “How to choose an angle grinder.”
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