Do I Need To Adjust The Speed On The Angle Grinder

Models and their characteristics

Today, angular grinders equipped with speed control are in great demand among craftsmen. This type of tool is well suited for cutting, polishing and grinding workpieces. The construction market is represented by an angle grinder manufactured by both domestic and foreign companies. Models from several brands have proven themselves well.

  • Bosch GWS 850 CE. This device is lightweight for easy handling. The machine has a power of 850W and is good for polishing marble and granite. The set of the tool includes a disc speed regulator with six positions. The minimum speed of revolutions is 2800, the maximum is 11000 per minute, a special nozzle designed for high speed is used for processing wood with a machine. The manufacturer additionally equips the device with a handle, a wrench, discs and washers for attaching nozzles.

Do I Need To Adjust The Speed On The Angle Grinder

  • Makita GA5030. It is the lightest grinder (weighs 2 kg) and is designed for simple household work. Using the device, you can easily cope with cutting, grinding and polishing various materials. Thanks to the additional handle, the workflow is greatly simplified, this model can be used for discs with a diameter of 115 and 125 mm. The tool has a power of 1400 W, thanks to the speed control it is classified as a professional model. In addition, the angle grinder has a turn-on lock, a speed stabilization system, in order to protect the device from overheating during intensive work, it is recommended to turn it off periodically.
  • Metabo WEV 10-125 Quick. This modification is produced with the ability to change the speed and maintain a power of 1200 W, the design provides for an electronic engine overload protection system. The speed of rotation of the cutting wheel automatically changes depending on the type of work and is fixed at variable loads. Of all the 125 mm machines produced, this model is the best, it features a large number of revolutions and variable speeds. The angle grinder also has a safety clutch and replaceable brushes, which turn off when there is a voltage drop in the mains. In addition, the manufacturer has supplemented the tool with an overheating indicator, a stabilizer and a long cable.

The review of the popular angle grinder with adjustable speed can be completed by the modification of Hitachi G13SS. Due to its high power indicators and the possibility of using it with discs with a diameter of 150 and 230 mm, it takes a high rating among the types of this equipment. The device is perfect for both renovation and construction work. The device can cut metal workpieces and cut parts from different materials. A distinctive characteristic of the device is its narrow delight and light weight, which makes it comfortable to operate.

Why do you need a smooth start and speed control on an angle grinder

On drills and screwdrivers with similar capabilities, the rotation control mechanism has a trigger design. The peculiarities of the operation of grinders DO NOT allow the use of such devices, since the shape of the tool implies full palm coverage. In addition, safety requirements prohibit changing the set rotational speed of the disc of a working angle grinder.

Angle grinder with speed control and gradual start are highly reliable due to reduced stress on electrical components and mechanical part of the tool.

In conventional angle grinders, at the time of starting, an excess voltage is applied to the rotor and stator, which sharply increases the starting current on the coils. This has a negative effect on conductive elements. Despite the fact that manufacturers provide for work in this particular mode, voltage drops in the home network sooner or later lead to an inter-turn circuit.

An abrupt transition from a state of rest to an increased speed severely wears out the gearbox, forcing it to work in overload mode. Anyone who has ever used an angle grinder at least once knows the feeling when it breaks out of his hands at the moment of switching on.

The use of an angle grinder with a smooth start avoids voltage dips in the network. This means that switched on household appliances should not be subject to the risk of burnout.

Let’s consider the practical benefits of the speed control function:

  • There is a possibility of high-quality cutting of thin sheet products made of gestures or soft materials. Working at high speeds will lead to melting of the edges of the product from exposure to temperature.
  • Cutting Some ceramics are cut at low speeds. Otherwise, small particles may chip off at the site, which spoils the appearance of the workpiece and can lead to injury.
  • Grinding of different materials is carried out at different speeds. The adjusting mechanism will help to select the optimal operating mode without the risk of surface damage. This is especially important when polishing products with a low melting point.
  • The spindle speed depends on the consumables used. For example, diamond discs are operated at reduced speed to avoid overheating of the contact surface.

MILITARY AG900VS

Convenient and inexpensive angle grinder with a disc diameter of 125 mm and adjustable speed. Despite its very small size, it impresses with its power (900 W). The tool is fast and easy to handle the task at hand, be it grinding or cutting materials.

The ergonomic handle ensures safe working with the angle grinder. The discs can be easily removed and, conversely, fixed on the unit. It provides speed control. The tool does NOT overheat. The cord length is 2.5 meters.

  • Convenient to operate.
  • Good power.
  • Low price.
  • Small size.
  • Flimsy bearings.

Applicable disks size

All discs for grinders, including devices with a speed control function, are divided into two types: cutting and stripping. The diameter of the circles varies from 100 to 500 mm. The most common sizes are:

For oversized models, it is allowed to install discs of a smaller diameter, provided that the bore matches.

Remember: the larger the disk, the more massive the device will be. This will affect the cycle time.

Makita 9565CVK

Good angle grinder, reliable and functional. The powerful 1400 watt motor provides the user with incredible high productivity, no matter the type of work being done, be it grinding or cutting.

The compact size coupled with the light weight of the model makes it easy to operate the tool. The angle grinder provides automatic shutdown of brushes in case of severe wear, limitation of starting current, blocking of accidental activation.

  • Excellent performance.
  • Lightweight (1.8kg).
  • Multifunctional.
  • Convenient spindle stop button.
  • The cost.
  • Tough power button.

Tips for choosing

The angle grinder with speed controller is one of the most popular and widely used tools. Since this tool is represented by different modifications, it is difficult to make the right choice in favor of this or that device. The first step is to decide how the device will be used for domestic or professional purposes. In the event that infrequent and simple work is planned, then a small low-speed machine will do. For the simultaneous implementation of high-quality cutting and grinding of the material, it is best to opt for professional models.

In addition, it is worth paying attention to the following characteristics of the device:

  • Performance:
  • Minimum and maximum number of revolutions;
  • Additional functions;
  • Disk parameters that can be used with the instrument.

An important criterion when choosing is the frequency of operation of the device. For constant and intensive work, it is necessary to buy models in which the outer case is made of durable metal and supplemented with brass inserts. When installing the pipeline, it is advisable to use devices with the maximum level of protection against water and dirt.

AEG WS 13-125 XE

Great tool in compact size. It is moderately priced and powerful. The angle grinder perfectly copes with the tasks set, equally good at sanding surfaces and cutting off materials.

A feature of the model is a simple replacement of equipment (discs, brushes) and adjustment of the casing without the use of keys and a second additional tool. The handle included in the kit is comfortable to use, it does not vibrate and is securely fixed on the body.

  • Good power (1300 W).
  • Low noise level.
  • Comfortable to hold in hand.
  • Easy to change attachments.
  • Fairly heavy (2.4 kg).
  • Heats up quickly at low revs.
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Other functions

In addition to adjusting the speed and second useful properties, modern models are equipped with the following functions designed to increase work safety:

  • Protection against accidental activation. Two start buttons are installed on the angle grinder. Turning on occurs only when pressed simultaneously.
  • Load stabilizer. When cutting extremely dense materials, the electronic system automatically maintains the set number of revolutions. The function is useful for craftsmen who work with dimensional workpieces made of stone, marble or concrete.

Manual and electronic protection

Biting the disc during operation is the biggest nuisance. The angle grinder can pull out of your hands and cause serious damage. Possible reasons:

  • Contact of the circle with a foreign object;
  • Working with an object that is too strong;
  • Poor tightening of the spindle nut;
  • Exceeding the maximum number of revolutions of the nozzle;
  • Use of a disc whose material does NOT match the surface to be treated.

All this leads to the fact that the working nozzle breaks or scatters into parts. In the latter case, the fragments flying at high speed pose a danger to human health.

To reduce the risk of injury, manufacturers equip tools with anti-jam mechanisms.

All inexpensive models have a special casing to protect against disc fragments in case of jamming. These are international safety requirements.

Protection systems can be divided into two types:

  • Mechanical. Special couplings are installed on professional models with a speed control function. In the event of an overload or jamming of the disc during the transmission of torque, it begins to slip, preventing damage to the nozzle.
  • Electronic. In this case, a special safety unit is responsible for an emergency stop. Its principle of operation is based on reading electrical parameters during operation. An abrupt cessation of rotation is accompanied by a surge in current, to which the sensors instantly react, de-energizing the tool.

How to make a smooth start for an angle grinder with your own hands

Do-it-yourself speed regulator for an angle grinder: application features, schematic diagram, installation inside the case. What is soft start and how to connect it. Timing diagrams of the speed controller and soft start.

Almost all models of grinders in the lower price range do not have such useful options as adjusting the spindle speed and soft start. If you have a desire and some skills, you can make a speed controller for an angle grinder with your own hands, although it is much easier to purchase a ready-made electronic unit with several hundred rubles. The speed control expands the capabilities of the angle grinder and allows it to machine soft materials at reduced cutting speeds. In addition to the speed controller for an angle grinder, a very useful function is a soft start, which smooths out a sharp increase in current in the windings of an electric motor at the moment the voltage is applied to it. This prevents an abrupt increase in torque and “subsidence” of the supply network. In addition, smooth start-up Reduces shock loads on the motor and gearbox angle grinder, which protects them from premature wear.

Why do you need to adjust the speed of the angle grinder

Any angle grinder is structurally “sharpened” to work only with a cut-off or cleaning around a certain diameter. In total, there are six most common diameters in the range from 115 to 300 mm, which correspond to six groups of spindle speeds at idle speed. For example, an angle grinder with Ø125 mm wheels has a rotational speed of about 11 ÷ 12 thousand rpm, and with wheels Ø150 mm. 9 ÷ 10 thousand rpm. Such values ​​of the spindle speed are due to the fact that cutting discs are designed for high-performance processing of hard materials (metal, stone, ceramics) at cutting speeds up to 80 m / s.

However, when cutting, and especially when grinding soft and tough materials, completely different cutting parameters are required and, accordingly, the use of a tool with a speed controller. And this applies not only to wood and plastics, but also to steels, titanium and aluminum alloys. For example, processing of plastics and soft types of wood occurs at cutting speeds from 8 to 12 m / s, grinding of titanium and stainless steel alloys. within 15 ÷ 20 m / s, and even ordinary steel is polished at no more than 30 m / s. Therefore, the rotation speed of the grinding attachments in the grinders should be several times less than the passport one. It should be noted that in the bulk of the angle grinder speed controllers are in essence power controllers supplied to the angle grinder electric motor. That is, a decrease in the number of revolutions is achieved by reducing the power of the source by up to 15% of the nominal. But for grinding and cutting soft materials, this does not really matter, because in this case, a small power is required initially.

Schematic diagram of the speed controller

Ways of connecting the regulator inside the housing Angle grinder

There is more than enough space in the Grip part (rear handle) of an angle grinder to install a regulator with such dimensions. In low-power angle grinders, the free space is usually located closer to its end, and in more powerful ones. between the handle and the motor or in the handle itself (see photo below). Special skills are not required to install such a regulator, since it just needs to be included in the open circuit of the electric motor power supply.

The below shows the resuscitation of an old angle grinder equipped with a speed controller. Interesting push-button control of the number of revolutions with memorizing the value after turning off the supply voltage.

What is soft start

The electronic circuitry for smooth start-up of the angle grinder is based on the same principle as the speed controller circuit. It also uses a triac to limit the supply of power to the electric motor. But unlike the speed controller, the control pulses to the triac are formed NOT by manually setting the resistance in the RC-chain, but by an electronic circuit that forms a sequence of pulses with a decreasing delay duration. The diagram below shows how the pulse shift time decreases and the power supplied to the motor of the angle grinder increases.

Connection of soft start

The soft starter can be purchased in retail chains and independently mount any angle grinder inside the case. The below shows its installation on a new powerful angle grinder, purchased by the author for cleaning work. It is also interesting in that its author, with the help of a dial gauge, demonstrates the magnitude of the current jump when the angle grinder is turned on, first without a soft start, and then with this device.

The most advanced control device for an angle grinder is the load speed control system, which also functions as a speed controller and ensures a smooth start. On the Internet, you can find a scheme for making such a device on the U2010B microcircuit, but it is quite complicated even for those who have the initial skills of a radio amateur. Is it possible to purchase a ready-made speed control unit and how much does it cost? If anyone can answer this question, please share in the comments.

Circuit operation

The trimmer VR1 changes the charging time of the capacitor C1. When voltage is applied to the circuit, at the first moment of time (the first half-cycle of the input sinusoid), the DB3 and TRIAC triacs are closed. The output voltage is zero. Capacitor C1 is charging, the voltage across it increases. At a certain point in time, set by the R1-VR1 chain, the voltage across the capacitor exceeds the opening threshold of the DB3 triac, the triac opens. The voltage from the capacitor is transmitted to the control electrode of the TRIAC triac, which also opens. Current begins to flow through the open triac. At the beginning of the second half-cycle, the triac sine waves close until the capacitor C1 is recharged in the opposite direction. Thus, at the output, a pulse signal of a complex shape is obtained, the amplitude of which depends on the operating time of the C1-VR1-R1 circuit.

Features of mounting a finished block

When buying and installing a factory regulator inside an angle grinder, most often you have to modify the case. cut a hole in it to output the adjusting wheel. However, this can adversely affect the rigidity of the casing. Therefore, it is preferable to install the device outside.

The numbers on the adjusting wheel indicate the number of spindle revolutions. Meaning This is not absolute, but conditional. “1”. minimum speed, “9”. maximum. The rest of the numbers are for guidance when regulating. The location of the wheel on the body is different. For example, on a Bosch PWS 1300-125 CE, Wortex AG 1213-1 E or Watt WWS-900 angle grinder, it is located at the base of the handle. In the second models, such as the Makita 9565 CVL, the adjusting wheel is located at the end of the casing.

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The connection diagram of the regulator to the angle grinder is NOT complicated, but sometimes it is not so easy to pull the cables to the button, which is located on the second end of the device body. The task can be solved by selecting the optimal wire section or bringing it to the surface of the casing.

A good option is to install the regulator on the surface of the device or fasten it to a power cable. Everything does not always work out on the first try, sometimes the device has to be tested, after which some adjustments are made. And this is easier to do when access to its elements is open.

Speed ​​controller and soft start. what are you needed for

In modern angle grinders, two important functions are used to increase the reliability and safety of the tool:

  • Speed regulator. a device designed to change the number of engine revolutions in different operating modes;
  • Soft start. a scheme that provides a slow increase in engine speed from zero to maximum when the device is turned on.

They are used in electromechanical tools in the design of which a collector motor is used. They help to reduce wear on the mechanical part of the unit during switching on. Reduce the load on the electrical elements of the mechanism, starting them up gradually.

When the power is turned on, there is an abrupt transition from the rest state to the rotation of the disk at a speed of 2.5-10 thousand revolutions per minute. Those who have worked with an angle grinder are well aware of the feeling that the machine is simply “pulled out of hand”. It is at this moment that the overwhelming number of breakdowns occurs associated with the mechanical part of the unit.

The stator and rotor windings are not less stressed. The collector motor starts in short-circuit mode, the electromotive force is already pushing the shaft forward, but the inertia still does not allow it to rotate. There is a jump in the starting current in the coils of the electric motor. And although structurally they are designed for such work, sooner or later a moment comes (for example, during voltage surges in the network) when the winding insulation does not withstand and an interturn short circuit occurs.

When you include soft start circuits and changes in engine speed into the electrical circuit of the instrument, all of the above problems automatically disappear. Among other things, the problem of voltage “dip” in the general network at the time of starting the hand tool is solved. This means that the refrigerator, TV or computer will NOT be exposed to the danger of “burnout”. And the safety devices on the meter will NOT work and cut off the current in the house or apartment.

The soft start scheme is used in angle grinders of medium and high price categories, the speed control unit is used mainly in professional models.

Additional wiring diagrams increase the cost of the tool, but increase the service life and the level of safety during work.

Why the angle grinder is low speed?

The built-in disc speed control function allows you to delicately handle materials such as plastics or wood. Comfort and safety of work is increased at low revs. This function is especially useful in electrical and radio installation work, in car services and restoration workshops.

In addition, there is a strong belief among professional users of power tools that the simpler the device is, the more reliable it is. And the additional service “stuffing” is better to take out of the power unit. In this situation, the repair of equipment is greatly simplified. Therefore, some companies specially produce separate external electronic regulators, which are connected to the power cord of the machine.

Device manual

The basic rule when operating an angle grinder with a home-made speed controller is to observe the mode of work and rest. The fact is that the engine operating at the “regulated” voltage is especially hot. When grinding at reduced speeds, it is important to take frequent breaks so that the collector windings do NOT burn out.

It is also highly discouraged to turn on the tool if the speed controller is set to minimum. the voltage drop is NOT enough to spin the rotor, the collector lamellas will remain in short-circuit mode, and the windings will start to overheat. Unscrew the variable resistor to the maximum, then turn on the angle grinder, from below the speed to the desired value.

In addition, it should be understood that the adjustment of the speed of rotation on the angle grinder is based on the principle of a water tap. The device does NOT increase the number of revolutions, it can only lower them. It follows from this that if the maximum passport speed is 3000 rpm, then when the speed controller is connected, the angle grinder will operate in a range lower than the maximum speed.

How to make a do-it-yourself angle grinder speed controller

If you have an old angle grinder in your arsenal, don’t rush to write it off. Using a simple electrical circuit, the device can be easily upgraded by adding a function for changing the frequency of revolutions. Thanks to a simple regulator, which can be assembled by hand in a few hours, the functionality of the device will increase significantly. By reducing the rotational speed, the angle grinder can be used as a grinding and sharpening machine for various types of materials. There are new possibilities for the use of additional attachments and accessories.

Installing a homemade board

There are no ready-made installation recipes. Anyone who decides to equip an angle grinder with a regulator positions it according to their purpose and tool model. Someone inserts the device into the handle of the holder, someone into a special additional box on the case.

The space inside the housing of the angle grinder may vary from model to model. Some have enough free space to install the control unit. Secondly, you have to take it to the surface and fix it in a different way. But the trick is that, as a rule, there is always a certain cavity in the back of the instrument. It is designed for air circulation and cooling.

Usually this is where the factory speed controller is located. A DIY scheme can be placed in this space. To prevent the regulator from burning out, the thyristors should be installed on the radiator.

How to connect the device to an angle grinder, options

The connection of the regulator depends on which type of device is selected. If a simple circuit is used, it is enough to mount it in the mains supply channel of the power tool.

Smooth start plus and engine speed control

Technical details

After you select the right tool for its application, you can pay attention to the technical data. Depending on the power, the number of revolutions, the presence of “stop functions”, the device can floor not only functional, but also really safe.

Power. The minimum model is 0.5 kW. It is quite enough for solving many problems, because it copes with them in the same way as its powerful “brothers”. But there are several nuances.

  • A weak angle grinder will stall on contact with soft materials or with significant force. Cuts well, but slowly. When cutting thick metal, the choice of an angle grinder should be towards powerful devices over 1.8 kW.
  • A weak angle grinder serves much less because the load on the motor is high.
  • A weak tool cannot accelerate a large disc, it will stop immediately upon contact with material.

Rotational speed. In most cases, the tool will automatically adjust the speed. But some professional models have manual adjustment. this is unnecessary. It is NOT worth overpaying money for this, since the electronics will save your device from overheating and jamming, but manual adjustment is not always correct.

Fuse against starting and seizure. Be sure to take. The first will save you from premature start-up (if you plug the previously included tool into an outlet, it will not start), which is especially good if the light is often turned on / off. A second fuse is needed to shut off the angle grinder when it gets stuck. Both are mandatory and protect the worker from injury.

Scope and functionality

To begin with, let’s decide where and how you will use this device, since all the main parameters and functions of the angle grinder depend on it, and then we will move on to the technical characteristics and additional equipment. Let’s pay attention to the professional tool, protection from dust and moisture, disk size, the presence of additional handles.

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Protection from moisture or dust, is it necessary? Again, you must Pay attention to the scope of use. If you often work Not only in closed rooms, but also in open spaces, perform earthworks (for example, cut pipelines), then it is advisable to buy just such a tool. Its cost is 15-20% higher than usual, but under extreme operating conditions without protection, the engine will NOT last long. Another nuance is working in wet rooms. These can be basements, warehouses, vegetable stores, and the like. Increased moisture over time, we kill the motor winding. it burns out.

Disk size. An important criterion when using in hard-to-reach places. If you need to make a deep cut or drive a disc between two edges of the metal, then its size should be more than 15 cm. In addition, the cut is significantly accelerated with a larger diameter. There are 115, 130, 150, 180 and 230 mm discs. It is best to select the “golden mean”.

Additional handles. If you work with a large number of metal structures and are constantly moving the handles, then additional fastening and the handles themselves will be an advantage for you. You will be able to cut horizontal surfaces “under the right hand” without wasting time in thin sections or immediately switch to vertical cuts under the left hand.

How to choose a comfortable and convenient angle grinder?

Comfort is an important criterion when choosing. The first thing to pay attention to is the rubberized case. It allows you to securely hold the tool in your hand and prevent it from slipping. This can also prevent injury during work. Rubber pads are made on the entire handle, as well as on the back of the body for the other hand.

Anatomical shape is an important criterion, which will facilitate your work. Special grooves are made on the body for the fingers. This is very convenient if you have to work with one hand in hard-to-reach places.

The color of all controls and buttons is also important. The employee should easily find all the settings during the work. Before choosing an angle grinder for your home, pay attention to the availability of service from the manufacturer. Many Chinese models do not have spare parts at all in the domestic market. It is better to give preference to the “basic” models Bosh, Makita, Stern and the second similar devices.

Speed ​​controller for angle grinder: how to reduce speed and make a smooth start

The power tool in our workshop Occupies one of the main places. Each electrical device performs all functions in accordance with technical data. What else would you like? I really want the tool to NOT break down for a longer time or not break at all. As a person gets used to the second. a dog, so he gets used to the instrument.

One of the basic tools is the angle grinder, which we call the angle grinder. This is a versatile tool, which is capable of cutting, grinding, cleaning the surface, dusting the boards and it can be adapted to many operations.

Smooth start and speed control

Smooth start-up of power tools is the main guarantee of its longevity. Remember when a light bulb burns out? Most often at the moment of switching on. Because after connecting to the electrical network, the load increases sharply. The worn-out places of the spiral DO NOT withstand and it burns out.

The same processes take place in the angle grinder. At the moment of switching on, the current rises sharply, because the driving forces need not only to move the armature, but also quickly gain the required speed. The effect of such a hard start can be the most deplorable. a winding break.

To reduce the likelihood of tool failure due to a hard start, it is necessary to modify the angle grinder and equip it with a small built-in soft starter.

Another improvement is the rotation regulator. From their own practice, everyone knows how inconvenient it is to work with a tool, which does not have a rotation adjustment. If the electric drill is equipped with a camera, it is difficult to find the rotation speed and drill feed. This will either cause the drill to jam or break.

The lathe works in a similar way, in which there is a whole set of Special gears for adjusting the spindle rotation. This largely determines not only the safety of the cutter, but also the quality of material processing.

You can combine two advantages. smooth start-up and shaft speed control using an electronic circuit. It is quite possible to assemble it yourself and install it directly into the car body. With such a circuit, it will start smoothly, and not create overloads in the windings and the network. And with the same scheme, it will be possible to adjust the speed in order to select the mode of operation with any material.

If you cut metal with significant thickness and hardness, then you need to maintain high speed. But when processing surfaces of low-melting materials, high speed will do more harm than help the cause. It needs to be reduced. It is dangerous to work with stones or tiles at high speed. And here it is necessary to Slow down.

Even when the disc is wobbling, the rotation speed must be proportionally changed because the linear speed of the disc edge will decrease. You cannot do without a speed controller when working with a diamond cut disc, because at high temperatures it breaks down very quickly.

Everything suggests that if an angle grinder does not have a speed controller, then it must be made and installed in the machine.

How to make a speed controller with your own hands

In order not to complicate the perception of the principle of operation in complex terms, the principle operation of the circuit can be explained simply. It has a sensitive element that reads the load. Depending on the read value, this element controls the locking device.

The principle of operation is similar to that of a water tap. In this case, you are the sensitive element that controls the water tap. The flow of water, depending on the need, becomes more or less. The same process happens with the current.

It is necessary to correctly understand the moment that we will NOT be able to increase the rotation speed more than that which is indicated in the characteristics of the angle grinder. We can only reduce the turnover. If the maximum rpm is 3000, then the range in which we can adjust the rpm will be below this value.

In the simplest version, you can use a thyristor-based regulator circuit. He will feel and regulate. Two in one. This diagram has only five parts. It is very compact and fits easily into the case. Such a regulator will not work from zero rpm, but this is not necessary for an angle grinder.

If lower speeds are needed in the work, then it is necessary to use a different circuit on an integrated circuit, where the triac will be the locking element. Such a scheme will be able to regulate the speed from almost zero to the desired value.

And in that, and in another scheme, the main load falls on the shut-off element. It must be rated for voltages up to 600 V and for currents up to 12 A. If your grinder is more powerful than 1 kW, then the locking element must withstand a load of up to 20 A.

All the details of the thyristor circuit can be placed on a printed circuit board or simply by surface mounting. According to the second option, the parts are soldered onto the printed circuit board. The printed circuit board can be manufactured in different ways. It can be etched from foil-coated PCB, you can even cut a cutter, but it will turn out very roughly. In principle, she can be asked to make a familiar radio amateur for a very modest remuneration.

When the finished board is ready, you need to choose a convenient place in the angle grinder case to install it. It is desirable to install it so that it is convenient to use, and so that it does not interfere in the process of work.

Before installing the circuit in the car, you need to check it. To do this, instead of an angle grinder, an ordinary incandescent lamp must be connected to the output. An example with a power of 60. 40 W at 220 V will do. The efficiency will be obvious by changing the glow of the bulb.

Now it remains to mount the device in the selected place and make a test run of the angle grinder. It will stop breaking out of your hands during start-up, and the speed will be smoothly regulated by rotating the regulator.