How to connect the governor to an angle grinder

Making a speed controller for an angle grinder with your own hands

The simplest regulator can be assembled by hand. Those home craftsmen who understand a lot about electrical circuits may well make a speed controller using a simple circuit on semiconductors.

There are several ways how to make a regulator and embed this unit into an instrument; it can be installed both inside the body and attached externally, as a separate element. In any installation, he will be able to regulate the speed.

The external board can also be mounted in a separate plastic box with a plug and socket. In fact, this is the same carrying of the starting current, an angle grinder is turned on through it, and the speed is adjusted with a wheel on the box. It turns out to be an excellent polishing machine.

• Internal placement

This method is more complicated, but it makes it possible to fit into the case, which is compact and convenient.

• Before installing the circuit, you need to replace the keys that connect the instrument to the network.
• Free up space. Here you need to put electronic keys. a triac or thyristor to switch rotation speeds.

• You can also connect a soft start chip, which will make it possible to avoid a jerk at the start.

How to connect a regulator to an angle grinder to decrease or increase RPM

Every master has a good angle grinder. It is popular among professionals and in any household due to its easy operation and multitasking ability. The tool is conceived as a sander, but its unique bevel gear made it the most popular saw. By installing the appropriate discs, the angle grinder saws and cuts various materials, grinds and polishes surfaces, easily penetrating into hard-to-reach places.

Since materials for cutting and grinding come across different hardness and texture, then the speed of rotation of the disk during cutting should be different. Otherwise, the cutting wheel will not fulfill its task, or, moreover, it will jam in the material at the most inopportune moment and lead to engine failure.

The ideal option is a model with a built-in speed controller by the manufacturer. Buy angle grinder with speed control. the best solution.

For what tasks is adjustment necessary

angle grinder with speed controller are used:

• When grinding and cutting very thin sheets (metal or plastic). In this case, you need to reduce the speed to almost zero speed. The torque must be calculated so that the material does not melt.
• For cutting tiles, ceramics, artificial or natural stone. At the beginning of the cut, you need to increase the speed of rotation, then reduce, and at the end again increase the speed so that chips and cracks do not appear.

• When working with diamond-coated discs. With them it is better to cut at low speeds, so strong heating does not occur, and you can work longer.
• When working with polishing attachments, especially when finishing polishing.

The principle of operation of the speed controller

Soft start and speed control are additional functions. They are responsible for the comfort at work and the safety of the user. An angle grinder even without a regulator performs a wide range of tasks well, however, its disc rotates at maximum speed, which makes it impossible to perform tasks accurately and efficiently.

In a conventional typewriter, without a speed controller, the two stator windings are connected to the electrical network when the tool is turned on. Each of them is equipped with carbon brushes, they are pressed against the lamellas of the collector motor, closing the electrical circuit.

angle grinder with speed control. much more advanced and multi-tasking. it makes it possible to perform cutting or grinding very high quality, and most importantly. safely.

The electronic unit of the speed governor of the angle grinder is a switching system. It is based on a semiconductor triac or thyristor (this circuit works in a larger number of an angle grinder). expensive models of angle grinder are equipped with an integrated microcircuit, this is an expensive option, but more advanced and high-tech.

The change in the number of revolutions in both cases occurs by moving the variable resistor. It is installed inside the machine body and embedded in the electrical circuit break. between the start button and the stator windings. The integrated circuit is often located separately, in the break in the electrical wire.

The rotation speed is switched manually, for which there are corresponding keys on the case (buttons or a wheel).

Since the current is responsible for the torque on the spindle, in fact, the user decreases or increases it by switching speeds. Thus, by adjusting the current strength, you can reduce or, conversely, increase the rotation of the spindle and the speed of the cutting blade.

Pros and cons of a DIY regulator

On the plus side, your angle grinder will get additional features. You will be able to change the speed of rotation of the disk, decrease and increase the speed.

But home technology has several drawbacks:

• It gets very hot, so the load cannot be given for a long time. Recommended operating mode with intermittent shutdowns to cool the machine.
• Loss of power. Semiconductor regulators are good at adjusting the amperage and are excellent at changing the spindle speed. But at the same time, unfortunately, the power of the instrument decreases. Only the factory power regulator, installed by the manufacturer, keeps the engine power at 100%.

It is worth noting that the drop in power is relevant only when working with stone and ceramic tiles. And when cutting thin sheet materials, where it is very important to lower the speed, the loss of power is almost invisible.

How to properly connect the speed controller to the electric motor

The motor speed controller may be needed if you are assembling a machine or trying to improve the factory one. Incorrect connection can lead to a drop in power or even damage to the motor. Below you will learn how to install and assemble the power control governor.

Circuit of the speed controller for the electric motor

The simplest regulator circuit

Focus on this diagram. To reduce the speed of the electric motor, a PWM modulator is needed, it is also a triac. This is a microcircuit that modulates a PWM signal, allowing you to set its own frequency.

In this circuit, the U2008B microcircuit plays the role of a modulator. This is an inexpensive board designed specifically for adjusting the speed of an induction motor.

You will also need a diode and a resistor to lower the voltage. They are shown on the diagram with the signs D1 and R1. Also, in order to filter the incoming electricity, a power capacitor is needed, designated C1.

P1, R5 and R3 are voltage dividers designed to regulate voltage. The second resistor is needed to synchronize the internal blocks of the motor with the triac.

It is recommended that you install a conventional 1.5 amp fuse to keep the variable speed drive safe.

If you want to make a professional board, take this printable circuit:

It remains only to transfer it to foil-clad textolite and etch it. You can see the instructions here.

Factory Regulators

In some cases, it is more profitable to take a speed controller of a collector or asynchronous motor if you are going to upgrade industrial equipment.

The most common models:

1 Motor Speed ​​Controller 400W. Inexpensive (1300 rubles) PWM regulator with simple control. The main panel has an on / off button and a 10 step dimmer. It has high performance and is able to drive motors up to 400 watts. There is a good cooling and protection system inside. For him, the connection instructions will be described below.

2 KLS 4000-A1. Perhaps one of the most powerful Chinese rotational controls. Connection, as such, does not require. It is enough to insert the plug into the socket on the housing. There is a screen that displays the frequency of revolutions per minute. Perhaps this is the most convenient way to adjust the speed of a collector motor without losing power. from China. Sold in Russia with a 1.5-fold markup.

Thyristor speed controllers are in special demand among Russian home craftsmen.

They look like ordinary rheostats, but they have a large power reserve. However, you can do them yourself according to this scheme.

There are many disadvantages of this type of regulator:

• Semi-periodic waves. In this regard, the engine will constantly make noise during operation. This will not affect the operation of the engine, but the convenience of work is questionable.
• In principle, they are not suitable for high-power engines. They are useful for starting small motors like fan motors. You can forget about engines from a washing machine.
• Power stabilization is low enough, it is advisable to install an additional capacitor to smooth out voltage surges.

But there are also advantages:

Controller Specifications

The circuit will have the following characteristics:

• Working voltage. from 110 to 230 volts.
• Adjustment possibilities. 9. 99%. In general, this indicator depends on the chosen dimer.
• Load. up to 2.5 kilowatts.
• Working power. 300 watts without a radiator. If you set good cooling, you can increase it by 20-25%.

This circuit of the speed controller of a 220v collector motor is quite quiet and has a smooth start. Collecting it is quite simple.

Ways to connect the speed controller

How to connect the speed regulator? Consider Motor Speed ​​Controller 400W for 3 reasons:

How To Use An Angle Grinder. Ace Hardware

• This is the most popular speed controller.
• There are problems with its connection, due to the markup in Chinese.
• The connection is almost no different from being assembled by hand.

To begin with, it is worth studying the connection diagram printed on the side of the regulator or the passport of the device.

Now you need to use the pinout on the back panel. You will need to select the required conclusions. The CCW and COM pins are always short-circuited and do not need to be touched. To connect, you need to use the 3 bottom contacts. AS

AC is zero and phase (wires are installed arbitrarily, yet the current is alternating). A ground wire is inserted into the FG, if any.

In general, this is the end of the preparation. It remains only to insert the plug from the controller to the motor terminal block.

It is recommended to put a capacitor in the phase wire break.

It will help smooth out the incoming stress. It also doesn’t hurt to install a ferrite filter. It will help smooth out interference during work.

How to make a soft start and governor for an angle grinder

All budget options for an angle grinder have several disadvantages. First, there is no soft start system. This is a very important option. Surely all of you turned on this powerful power tool to the network, and when starting up, you watched how the incandescence of a light bulb, which is also connected to this network, falls.

This phenomenon occurs due to the fact that powerful electric motors at the moment of starting consume huge currents, due to which the mains voltage sags. This can damage the tool itself, especially those made in China with unreliable windings that may one day burn out during start-up.

That is, the soft start system will protect both the network and the tool. In addition, at the moment of launching the tool, a powerful kickback or push occurs, and in the case of a soft start system, this, of course, will not happen.

Secondly, there is no speed regulator, which will allow the tool to work for a long time without loading it.

The diagram below is from an industrial design:

It is introduced by the manufacturer into expensive devices.

Not only an “angle grinder” can be connected to the circuit, but, in principle, any devices. a drill, milling and turning machines. But taking into account the fact that the collector motor must be in the tool.

This will not work with induction motors. A frequency converter is needed there.

So, you need to make a printed circuit board and start assembling.

A dual operational amplifier LM358 is used as a regulating element, which, using a transistor VT1, controls a power triac.

So, the power link in this circuit is a powerful BTA20-600 triac.

During operation, the triac will heat up, so a heat sink must be installed on it.

So that there are no questions about the fact that the motor, when starting, can consume currents that significantly exceed the maximum current of the triac, and the latter can simply burn out, remember that the circuit has a soft start, and starting currents can be disregarded.

Surely everyone is familiar with the phenomenon of self-induction. This effect is observed when the circuit to which the inductive load is connected is opened.

It’s the same with this scheme. When the power supply to the motor is abruptly cut off, the self-induction current from it can burn the triac. And the snubber circuit dampens self-induction.

The resistor in this circuit has a resistance of 47 to 68 ohms, and a power of 1 to 2 watts. Film capacitor 400 V. In this version, self-induction as a side effect.

Resistor R2 provides current damping for the low voltage control circuit.

The circuit itself is to some extent both a load and a stabilizing link. Due to this, after the resistor, it is possible not to stabilize the power supply. Although the network has the same circuits with an additional zener diode, it makes no sense to use it, since the voltage at the power supply pins of the operational amplifier is within normal limits.

Possible replacement options for low-power transistors can be seen in the following picture:

The PCB that was mentioned earlier is only a board for the soft starter and does not have any RPM components. This is done on purpose, since in any case, the regulator must be brought out using wires.

The regulator is tuned using a 100 kΩ multiturn trimmer.

And the main adjustment is already using the resistor R5. It should be said that a scheme of this kind will not allow adjustment from zero, only from 30 to 100%.

If a more powerful regulator is needed, then it can be assembled according to the following scheme:

This circuit allows you to adjust the power almost from zero, but for an “angle grinder” it makes no sense.

First, the circuit must be checked for operability by connecting a 40-60 W 220 V light bulb as a load.

If everything is in order, then after disconnecting from the network, you immediately need to check the triac by touch. it must be cold.

Next, the board is connected to the “angle grinder” and starts.

If everything works fine. the “angle grinder” starts up smoothly and the speed is regulated. then it’s time to start testing under load.

Electronic device testing

Before connecting the block to the angle grinder, check it. Take a plug-in electrical outlet. Insert 2 wires into it, one of which connect to the board, and the other to the network cable. Connect another wire to the network board. As you can see, the regulator is connected in series in the electrical circuit. Connect a light bulb to the circuit and test the operation of the device.

How to make a speed controller for an angle grinder with your own hands?

• For what purpose is the angle grinder low speed?
• What is the angle grinder smooth start and speed controller for??
• How to assemble a regulator with your own hands?
• Electronic device testing
• Connecting the regulator to the angle grinder
• Installation of the regulator in the cavity of the angle grinder housing
• How to make a regulator from a dimmer?

If you have an old angle grinder among your tools, take your time to get rid of it. Using a simple wiring diagram, the tool can be improved by adding an option for adjusting the speed. Due to the usual control device, which you can create with your own hands within a few hours, the functions of the tool will significantly expand. By reducing the number of rotations per unit of time, the angle grinder can be used as a sharpening and grinding unit for different types of materials. There will be additional opportunities for using auxiliary equipment and attachments.

For what purpose is the angle grinder low speed?

The integrated wheel speed control option will make it possible to gently process materials such as wood or plastic. At lower speeds, comfort and safety are increased. This option is most practical in radio and electrical installation, service stations and studios engaged in restoration.

In addition, among professionals who use power tools, there is a judgment that the more trivial the device is, the more reliable it is. And the additional service “stuffing” is desirable to take out of the boundaries of the angle grinder. With this approach, equipment maintenance is greatly simplified. In this regard, some companies deliberately produce portable individual electric controllers that are connected to the network cable.

Installation of the regulator in the cavity of the angle grinder housing

The electronic device, assembled separately from the angle grinder, is encased in a dielectric material as all components are energized. A portable electrical outlet with a cable is fixed to the body. The handle of the variable resistance resistor is brought out to the outside. The regulator is connected to the mains, and the tool to a portable power outlet.

Connecting the regulator to the angle grinder

The frequency converter is connected to the instrument in series. If there is free space in the handle of the angle grinder, then this device can be placed there. The surface-mounted circuitry is glued with epoxy, which will serve as an insulator and vibration protection. Take out the variable resistance resistor with a plastic handle to adjust the speed.

What is the angle grinder for smooth start and speed controller?

In modern angle grinders, 2 necessary options are used that increase the characteristics and safety of the equipment:

• speed regulator (frequency converter). a device designed to convert the speed of the motor in different modes of operation;
• soft starter. a circuit that provides a leisurely increase in motor speed from zero to the limit value when the unit is connected.

They are used in electromechanical equipment, in the structure of which an alternating current electric motor with a collector is practiced. They help to reduce the wear of the mechanical part of the unit when it is turned on. Reduces the stress on the electrical components of the machine by bringing them into operation smoothly. As studies of the qualities of materials have revealed, a particularly strong development of contacting nodes is produced in the process of a sudden transition from a stationary state to rapid activity. For example, one start of an internal combustion engine in a car is equal to the wear of the piston and a group of sealing rings to 700 kilometers.

When power is applied, an abrupt transition is made from a stationary state to the rotation of a circle with a speed of 2.5-10 thousand revolutions in 60 seconds. Anyone who has used an angle grinder knows the feeling that the tool just “flies out of hand”. Just at this moment, most of the accidents associated with the mechanical part of the unit happen.

The rotor and stator windings are equally stressed. An alternating current electric motor with a collector starts in a short circuit mode, the EMF is already pushing the shaft forward, but the inertia force does not yet allow it to rotate. A jump in the starting electric current arises in the coils of the electric motor. Despite the fact that by design they are designed for such work, over time a moment comes (for example, with a voltage drop in the mains) when the winding insulator is not able to withstand and a short circuit occurs between the turns.

With the introduction into the electrical circuit of the instrumentation schemes for adapting a soft start and changing the frequency of rotation of the motor, all the above-described troubles spontaneously disappear. In addition, the issue of a sudden and significant decrease in voltage in the general power grid during the start-up of the tool is being resolved. Hence, it is clear that household electrical appliances will not be at risk of failure. And the automatic switches on the electric meter will not work and turn off the current in an apartment or house.

The soft start scheme is used in angle grinders of the middle and high price segment, the speed control unit is more and more in professional modifications of the angle grinder. Adjusting the speed makes it possible to process soft materials with an angle grinder, to carry out delicate grinding and polishing, since at high speeds the wood or paint will simply burn out. Auxiliary electrical circuit increases the cost of the toolkit, but extends the service life and the degree of safety in use.

How to assemble a regulator with your own hands?

A simplified and rather reliable frequency converter for an angle grinder is constructed with your own hands from available electrical parts. Below is a diagram showing all the required components for mounting on a printed circuit board of the device of interest to us.

So, we need:

• symmetrical triode thyristor (or triac, triac) DIAC (DB3);
• resistor (resistance) R1 (its parameters should be 4.7 kOhm);
• additional triac VT136 / 138 (TRIAC);
• capacitor C1 (400 V, 0.1 μF);
• additional resistance VR1 for 500 kOhm.

A similar scheme operates according to the following method.

• The charging time of the capacitor is modified by an auxiliary resistor (it is called the trimmer). When voltage is applied to the circuit, the triacs are in the closed position, and a zero voltage value is observed at the output.
• In the process of charging the capacitor, an increase in voltage is noted on it, which leads to the opening of the DB3 triac. As a result, the voltage falls on VT136 / 138. This thyristor element also opens up, and an electric current flows through it.
• After that, the symmetrical components are closed again and remain in a similar status until the capacitor is completely recharged in the opposite direction.
• Ultimately, at the conclusion, we acquire a deterministic signal of finite energy that is complex in its configuration. Its exact range is determined by the period of performance of the functions of the circuit capacitor. auxiliary resistance. resistance R1.

Triacs are usually located on a printed circuit board. It is easy to create it from PCB (multilayer extruded plastic is used, consisting of heat-insulating fiber and foil). Individual craftsmen cut the board with a cutter. It is practiced to place the circuit elements using the hinged mounting method. Triystres are mounted only on an aluminum or copper heat exchanger. It plays the role of a good heat sink.

The test of the assembled device is carried out using an ordinary 40-60 W incandescent lamp. Connect it to the circuit and start to regulate the glow power. If the brightness changes, then you have done everything correctly. Now you can start installing the regulator in the shell of the angle grinder. This is not very easy to do, since it is necessary to ensure that the auxiliary device does not interfere with you when using the angle grinder.

You will need to calculate the installation location of the homemade control device yourself, in accordance with the design features of the angle grinder. The installation of the circuit is performed:

• in an additional box mounted on the unit body;
• into the handle of the holder;
• into a small, empty niche (designed for cooling and air circulation) in the rear area of ​​the angle grinder.

The circuit itself is connected to the device by integrating it into the electric power supply channel of the angle grinder. With this, you, I suppose, will not have difficulties.

How to make a regulator from a dimmer?

A very effective and easy solution to this issue will be the creation of an external frequency converter. In the role of a converter, you can use a dimmer. a device for regulating the level of illumination. When creating, you will need an electrical outlet and a plug. I must say that the implementation of such a device can be performed in different ways. Particularly simple are 2: with and without a machine.

• Screw 2 wires to the ends of the electrical outlet so that one is longer. Then connect the long end to one of the pins on the plug. The end of the 2nd wire is fixed on the contacts of the dimmer, and its other output is connected to the 2nd contact of the plug.
• When using the 2nd option, it is required to make a number of modifications to the circuit, and specifically to place an automatic machine on the cord between the plug and the dimmer. Basically, ordinary switches are provided in the dimmers, but we need an automatic one, which, if something goes wrong, will turn off our device from the mains.

So, the frequency converter of the angle grinder is ready, and for practicality it can be placed in a specialized case or fixed on a wood panel. It should only be taken into account that such a device is homemade, and when working with the power grid, one must be careful.

How to make a speed controller for an angle grinder with your own hands, see the video below.

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 stand up 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 hard starting, it is necessary to modify the angle grinder and equip it with a small built-in soft starter.

Another improvement is the rotation regulator. Everyone knows from their own practice how inconvenient it is to work with a tool that does not have a rotation adjustment. If there is no such device in an electric drill, then it is difficult to choose 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.

Combine two advantages. smooth start-up and shaft speed control using an electronic circuit. It is quite possible to assemble it with your own hands and install it directly into the car body. With such a circuit, it will start smoothly without creating 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 it is necessary to maintain high speed. But when processing the surfaces of low-melting materials, high speed will do more harm than help the cause. It must be reduced. It is dangerous to work with stones or tiles at high speed. And here it must be slowed down.

Even when grinding the disc, the rotation speed must be proportionally changed, because the linear speed of the disc edge will decrease. You cannot do without a speed regulator when working with a diamond cut disc, because at high temperatures it collapses 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.

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

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

• Homemade from angle grinder
• Circular saw made of angle grinder
• DIY angle grinder repair
• Drill stand for a drill: how to make a holder, bed

One of the basic tools is an angle grinder, which we call an angle grinder. It is a versatile tool that can cut, grind, clean the surface, saw boards and can be adapted to many more operations.

How to make a speed controller with your own hands

In order not to complicate the perception of the principle of operation with complex terms, the principle operation of the circuit can be explained simply. It has a sensing element that reads the magnitude of the load. Depending on the read value, this element controls the shut-off 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 occurs with the current.

It is necessary to correctly understand the moment that we will in no way be able to increase the rotation speed more than that indicated in the characteristics of the angle grinder. We can only lower the turnover. If the maximum rpm is 3000, then the range in which we can adjust the rpm will be below this value.

In its simplest form, you can use a thyristor-based regulator circuit. He will both 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 microcircuit, 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 the other 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 circuit on the thyristor can be placed on a printed circuit board or simply surface-mounted. According to the second option, the parts are soldered onto a 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 it with a cutter, but it will turn out very rough. 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 case of the angle grinder 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. A copy with a power of 60. 40 W at 220 V will do. The efficiency will be obvious by the change in the glow of the light 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 adjusted by rotating the regulator.

Speed ​​controller for angle grinder. to make the machine more reliable and functional

The speed controller for an angle grinder is a useful mechanism that expands the functionality and prolongs the durability of the power tool.

• 1 Soft start and speed controller are mandatory devices
• 2 Why control the speed of the disc
• 3 Putting together the circuit. the easiest option
• 4 Operation of an angle grinder with a homemade regulator

One of the main places in the home workshop of any self-taught master is an angle grinder. an angle grinder, which in common people is called an angle grinder. With its help, you can qualitatively clean a variety of surfaces, grind them, cut and saw wood products. At the same time, every lover of independent performance of such work wants to make his domestic-made (or imported) angle grinder more reliable and functional. It is quite real.

angle grinder is designed for cleaning and sanding various surfaces

The key to long-term use of the angle machine is the function of its smooth start. When the tool is turned on, the amount of electric current increases. an angle grinder needs not only to start the electric motor, but also to quickly gain the speed required for operation. Naturally, such a sharp load negatively affects the units of the angle grinder, in particular, its electrical winding. The latter often breaks off. For this reason, many angle grinders fail after a few starts. It is possible to prevent such a problem on our own. It is necessary to modify the grinder by equipping it with a built-in soft start device and a speed controller. It is assembled on one microcircuit.

Many advanced (and, of course, expensive) angle grinders are initially equipped with a function of the working disc rotation regulator. In cheap models, the angle grinder, as well as in old devices, such a device is not provided. And its necessity among domestic craftsmen is not even discussed. Why? on this later.

If the angle grinder is used for cutting and cutting tiles, natural stone products, the high speed of rotation of the tool literally kills the power tool. In addition, with such processing, small particles begin to crumble from the material. This significantly impairs the quality and appearance of the tile or stone surface. With the function of selecting the required revolutions, the processing proceeds without a hitch. And the electric tool itself is completely protected from damage.

The angle grinder operates at a very high speed when cutting tiles and stone products.

Also, the rotation speed is important when working with metal products. For example, aluminum or tin blanks should be cut at minimum speed. Thick and hard metal, on the other hand, is processed at high speeds. Polishing and grinding work with an angle grinder cannot be done efficiently if the saw does not allow you to select the desired speed. You will simply ruin the surface to be treated. Try sanding wood or car body paint at high rotational speed and you will see what this is about.

As you can see, the refinement of the angle grinder makes the device much more functional. It becomes possible to work with any soft materials and delicate surfaces. And most importantly, the angle grinder becomes almost eternal. It will function for more than a dozen years.!

An elementary and very reliable speed controller for an angle grinder is made by hand from inexpensive electrical parts. Below is a diagram showing all the necessary elements for assembling the mechanism of interest to us on a printed circuit board.

We see what we need:

• symmetrical thyristor DIAC (DB3);
• resistor R1 (its resistance should be 4.7 kOhm);
• one more symmetric thyristor VT136 / 138 (TRIAC);
• capacitor C1 (400 V, 0.1 μF);
• additional resistor VR1 500 kOhm.

This scheme works according to the following principle. The charging time of the capacitor is changed by an additional resistor (it is called a trimmer). When voltage comes to the circuit, the symmetrical thyristors are in the closed position, and zero voltage is noted at the output. When charging the capacitor, an increase in voltage is observed across it, which leads to the opening of the thyristor DB3. After that, the voltage is supplied to VT136 / 138. This thyristor also opens, and an electric current passes through it. Then the symmetrical elements are closed again and remain in this state until the capacitor is fully recharged in the opposite direction. As a result, at the output we get a pulse-type signal of a complex shape. Its specific amplitude is determined by the operating time of the circuit capacitor. additional resistor. resistor R1.

How to Use an Angle Grinder

Thyristors are usually located on a printed circuit board. It is easy to make it from PCB (foil material is used). Some craftsmen cut the board with a cutter. It is allowed to place circuit elements using the surface mounting method. Symmetrical thyristors are installed strictly on a copper or aluminum heatsink. It plays the role of an efficient heat sink. The assembled mechanism is checked by means of a conventional 40-60 W incandescent lamp. Connect it to the circuit, start adjusting the brightness of the glow. If the heat changes, then you did everything right. You can now mount the regulator into the angle grinder body. This is not so easy to do. After all, you need to ensure that the additional mechanism does not interfere with you during operation of the angle grinder.

You will have to determine the installation location of the home-made regulator yourself, focusing on the design features of the angle grinder. Installation of the circuit in most cases is performed:

• in an additional box installed on the body of the device;
• into the handle of the holder;
• into a small cavity (designed for cooling and air circulation) at the back of the angle grinder.

The place of installation of a homemade regulator is selected in connection with the design features of a particular machine

The very connection of the circuit to the device is carried out by mounting it into the power supply channel of the angle grinder. I think you won’t have any difficulties with this.

When using an angle grinder with a self-assembled circuit, to select the speed of the disc, you must strictly adhere to the recommended operating modes of the device. He should be given frequent respites. This is especially important when processing any products at reduced speeds. This precaution is due to the intense heat generated by the angle grinder operating on modified voltage. If you use an angle grinder without a break, the manifold will not stand up, its windings will burn out.

Another important point. It is undesirable to start the grinder with the speed regulator set to the minimum value. In such a situation, the rotor will not have enough voltage (it will not spin). This will lead to overheating of the electric windings due to the fact that the collector lamellas will not come out of the short circuit mode (remain short-circuited). It will be right:

• set the regulator to the maximum value;
• connect the angle grinder to the network;
• reduce the rotational speed of the disk by the indicator required to perform the work.

Observe the specified recommendations for choosing the speed and starting the angle grinder, and then it will serve you for a long time and without accidents. With the modernized angle grinder, you can process products from any material!

Do-it-yourself speed controller and smooth start on an angle grinder

As a rule, budget angle grinders (angle grinder), popularly called an angle grinder, do not have adjustable electronic modules in their design, which include an engine speed controller and a soft start. The owners of such an angle grinder over time begin to understand that their absence dramatically reduces the functionality of the tool. In this case, you can refine the angle grinder by installing home-made devices on it.

What is the speed regulator and soft start for?

When power is supplied to the grinder motor, there is an abrupt increase in speed from zero to 10 thousand or more. Those who have worked with an angle grinder know very well that it is sometimes difficult to hold it in their hands when starting up, especially if a large diameter diamond blade is installed.

It is because of such abrupt increases in engine speed that the mechanics of the apparatus most often fail.

Also, during starting, a huge load is applied to the rotor and stator windings of the electric motor. Since a collector motor is installed in the angle grinder, it starts in a short-circuit mode: the electromagnetic field is already “trying” to turn the rotor, but it remains motionless for some time, since the inertia force does not allow it to be done. As a result, the starting current in the motor coils rises sharply. Despite the fact that the manufacturer has invested a certain margin of safety for the coils, taking into account overloads at start, sooner or later the insulation does not withstand, which leads to an interturn short circuit.

In addition to starting problems, the lack of rpm control causes some discomfort. For example, an angle grinder speed controller can be useful for certain types of work:

• when grinding or polishing any surfaces;
• when installing a large diameter tool;
• for cutting some materials.

In addition, when roughing with tines, there is a high probability of wire jamming in any gap. If the spindle speed was high, then the angle grinder may simply pull out of the hands.

If a power (speed) regulator with a soft start module is connected to an angle grinder, then all the problems described above will disappear, the service life of the device will increase and the safety of its use will increase.

Homemade regulator circuit

One of the most popular schemes for a soft start of the engine is an angle grinder with the ability to adjust the speed is presented below.

The basis of this regulator is the KR118PM1 microcircuit, as well as triacs, which are the power part of the device. Using this circuit, you can make a power regulator with your own hands, even without special knowledge in electronics. The main thing is that you know how to use a soldering iron.

This block works as follows.

• After pressing the start button of the unit, the electric current begins to flow, first of all, to the microcircuit (DA1).
• The control capacitor begins to charge smoothly and after a while gains the required voltage value. Due to this, the opening of the thyristors in the microcircuit occurs with a certain delay. It depends on the time it takes to fully charge the capacitor.
• Since the VS1 triac is controlled by the thermistors of the microcircuit, it opens just as smoothly.

The above processes occur in periods that are reduced each time. Therefore, the voltage applied to the motor windings does not increase abruptly, but slowly, as a result of which a smooth start occurs.

The capacity of the capacitor C2 determines the time for the electric motor to reach full speed. The capacitor capacity of 47 μF allows the engine to start in 2 seconds. When the angle grinder is turned off, capacitor C1 is discharged with 60 kΩ resistor R1 in 3 seconds, after which this electronic module is ready to start again.

If you replace the resistor R1 with a variable, then you get a speed regulator, which will reduce the engine speed.

It is important that the VS1 triac has the following characteristics:

• the minimum current strength for which it is designed should be 25 A;
• the triac must be rated for a maximum voltage of 400 V.

This circuit and the regulators made according to it have been repeatedly tested by many craftsmen on angle grinders with a power of up to 2000 watts. It is worth noting that this device, thanks to the KR118PM1 microcircuit, is designed for power up to 5000 W. So he has a considerable margin of safety.

Ideally, to solder the speed controller for an angle grinder, you will need to draw a PCB, etch the contacts with acid and then plunge them, drill holes and solder the radio parts. But everything can be made easier:

• solder all the details of the circuit by weight, that is, leg to leg;
• attach a radiator to the triac (can be made from sheet aluminum).

The regulator welded in this way will take up less space and can be easily placed in the housing of the angle grinder.

How to connect a regulator to an angle grinder

No special knowledge is required to connect a homemade power regulator, and any home craftsman will cope with this task. The module is installed in the break of one wire, through which power is supplied to the angle grinder. That is, one wire remains intact, and the regulator is soldered into the gap of the second.

In the same way, you can connect a factory power regulator worth about 150 rubles, which is often purchased by craftsmen in China.

Also, the regulator can be placed in an outlet and used to reduce the speed not only for an angle grinder, but also for other electrical appliances (drills, sharpeners, wood milling or lathe, etc.). This is done as follows.

The regulator is connected as described above. at a break in one of the wires of the supply cable.

The following photos show how the finished socket will look like, having a built-in speed regulator for an angle grinder, which can be used for other electrical appliances.

Any suitable sized plastic enclosure can be used in place of the junction box. You can also make a box yourself by gluing pieces of plastic with a glue gun.