How to make a smooth start on an angle grinder

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

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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.

make, smooth, start, angle, grinder

Almost all models of the angle grinder of the lower price range do not have such useful options as spindle speed adjustment 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 for 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 the current in the windings of the electric motor at the moment the voltage is applied to it. This prevents an abrupt increase in torque and “sagging” of the supply network. In addition, the smooth start-up reduces shock loads on the motor and gearbox of the 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 grinding wheel of 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 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 for an angle grinder 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, since in this case, a little power is initially required..

how to smooth rough wood by angle grinder

Schematic diagram of the speed controller

Modern circuits of speed controllers of an angle grinder are built on the principle of a semiconductor switch passing only a part of the power of one or both half-waves of alternating current. As a half-wavelength regulator in such devices, triacs (symmetrical thyristors) are used, therefore they are sometimes called triac regulators. The figure below shows a simplified diagram of such a device, sufficient to explain the principle of its operation, and to the right of it – diagrams of the full period of alternating current before and after regulation. Here, the shaded areas correspond to the power that is transferred to the electric motor from the power source through the triac regulator..

On the diagram, the wave icon indicates the source of alternating voltage, and the letter “M” – the angle grinder motor. In a simplified form, the regulator includes two RC circuits, a dinistor and a triac. When switch K1 is pressed, an alternating voltage is applied to the electric motor M and the regulator circuit. The current flowing through the variable resistor R1 begins to charge the capacitor C1. The time of its charge is determined by the resistance of the resistor R1, which depends on the position of its slider, which, in fact, sets the time parameters of the regulator’s operation. After the capacitor is fully charged, the voltage at the point of its connection to the dynistor rises to the nominal, the dynistor opens and supplies voltage to the control electrode of the triac. The capacitor C1 is discharged in this case. This moment on the diagram of the regulator operation is shown by a bold vertical line. After opening the triac, voltage is applied to the motor of the angle grinder in the first half cycle.

When the polarity of the alternating current is reversed, the voltage passes through zero, so the dinistor and triac close. In the negative half-cycle, everything is repeated, and the triac is also turned on with a delay determined by the parameters of the R1C1 chain. The regulator, even at idle, works with a certain delay in turning on the triac. This is due to the fact that, although the moment the current is applied by the resistance R1 to the capacitor C1 corresponds to the voltage crossing through zero, it must still rise to the level of the breakdown voltage of the dinistor. The figure below shows the dependence of the power supplied to the motor of the angle grinder on the time shifts of the control pulses of the dinistor. In the first case, the resistance of the resistor R1 is minimal, so the charge of C1 occurs quickly, and in the second, it is maximum, so the capacitor charges more slowly.

What is soft start

A smooth start-up of an angle grinder is an increasing voltage supply to its motor, at which it accelerates without starting current surges and with a gradual increase in torque. This mode protects the supply network from excessive power take-off and prevents it from “sagging”. This is especially true when the angle grinder is powered from autonomous voltage sources. In addition, it protects the motor windings from over-rated currents that can lead to their breakdown. With a soft start, the gearbox of the angle grinder does not experience shock loads, which protects it from premature wear.

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 not formed by manually setting the resistance in the RC circuit, 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 is shortened and the power supplied to the motor of the angle grinder increases..

Since the soft start and the speed controller work on the same circuitry, electronic units are produced that combine the functions of both of these devices..

There is more than enough space in the grip part (rear handle) of the 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). No special skills are required to install such a regulator, since it just needs to be included in the open circuit of the electric motor power supply..

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

Soft start connection

The electronic governor is mainly needed by DIYers to expand the capabilities of an angle grinder in terms of grinding and processing soft materials. Professionals, as a rule, use a specialized tool for certain types of work and use an angle grinder only for its intended purpose. The situation is different with a soft starter. For a low power household tool, this option is useful, but not required. But for professional angle grinders with drives over 1000 W, it is vital. In addition to the above performance improvements, soft start is critical to operator safety. an angle grinder with a Ø230 disc and a power of 2000 W weighs 5 ÷ 6 kg, and in order to hold it during the starting jerk, certain efforts and a stable position are required.

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The soft starter can be purchased in retail chains and independently mount any angle grinder inside the case. The video below shows its installation on a new powerful angle grinder purchased by the author for cleaning work. This video is also interesting in that its author, with the help of a pointer device, 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 the manufacture of such a device on the U2010B microcircuit, but it is quite complicated even for those who have the initial skills of a radio amateur..

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Models for angle grinder 600 W

For a 600 W angle grinder, starters with contact triacs are used, whose overload does not exceed 10 A. It is also worth noting that there are many devices with plates. They stand out for their security and are not afraid of high temperatures. The minimum frequency for a 600 W angle grinder is 30 Hz. In this case, the resistance depends on the installed triode. If it is used of a linear type, then the above parameter does not exceed 50 Ohm.

If we talk about duplex triodes, then the resistance at high speeds can be up to 80 ohms. It is very rare for models to have stabilizers that work from comparators. Most often they are attached directly to modules. Some modifications are made with wired transistors. Their minimum frequency starts from 5 Hz. They are afraid of overloads, but they are able to maintain high speeds at a voltage of 220 V.

Starters for angle grinder with 20 amp triac

Devices with 20A triacs are suitable for professional angle grinders. Many models use contactor resistors. They are primarily capable of operating at high frequencies. The maximum temperature of the starters is 55 degrees. Most models have a well-protected case. The standard circuit of the device assumes the use of three contactors with a capacity of 30 pF. Experts say devices stand out for their conductance.

The minimum frequency for starters is 35 Hz. They are capable of working in a DC network. Modifications are connected via adapters. Such devices are well suited for 200 W motors. Filters are often installed with triodes. Their sensitivity index is no more than 300 mV. Wired comparators with a protection system are quite common. If we consider imported models, then they have an integral converter that is installed with insulators. Current conductivity is provided at around 5 microns. With a resistance of 40 ohms, the model is able to consistently maintain high rpm.

Model for angle grinder with 15 A triac

The soft start for an angle grinder with 15 A triacs is universal and is often found on low power models. The difference between the devices is low conductivity. The circuit (device) of a soft start angle grinder involves the use of contact-type transceivers that operate at a frequency of 40 Hz. Many models use comparators. These elements are installed with filters. The rated voltage of the starters starts from 200 V.

Devices for 800 W Angle Grinder

800 W angle grinder works with low frequency starters. Triacs are quite often used at 15 A. If we talk about the circuit of models, then it is worth noting that they use expansion transistors, in which the current carrying capacity starts from 45 microns. Capacitors are used with and without filters, and the capacitance of the elements is no more than 3 pF. It is also worth noting that starters differ in sensitivity..

If we consider professional angle grinders, then 400 mV modifications are suitable for them. In this case, the current conductivity can be low. There are also devices with variable transistors. They quickly warm up, but are not able to maintain high speed of the angle grinder, and their current conductivity is about 4 microns. If we talk about other parameters, then the nominal voltage starts from 230 V. The minimum frequency for models with broadband triacs is 55 Hz.

Angle grinder starters 1000 W

Starters for this angle grinder are manufactured on triacs with an overload of 20 A. The standard device circuit includes a triode, a stabilizer plate and three transistors. The rectifier unit is most often installed on a wired basis. Capacitors can be used with or without a filter. The minimum frequency of the conventional model is 30 Hz. At 40 ohms, the starters are capable of supporting high overloads. However, problems can occur at low RPM angle grinder.

How to make a starter from a TC-122-25 triac?

It is quite simple to make a smooth start for an angle grinder with your own hands with a TC-122-25 triac. First of all, it is recommended to prepare a contactor resistor. Capacitors will require a single pole type. In total, three elements are installed in the starter. The capacity of one capacitor should not exceed 5 pF. To increase the operating frequency, a contactor is soldered on the plate. Some experts say that filters can improve conductivity..

The rectifier unit is used with a conductivity of 50 microns. It is capable of withstanding large overloads and will be able to provide high rpm. Further, in order to assemble a smooth start on an angle grinder with your own hands, a thyristor is installed. At the end of the work, the model is connected via an adapter.

DeWalt DW745 soft start module install

Smooth start for a do-it-yourself angle grinder: diagram. Soft starter angle grinder, connection

Many power tools fail due to motor wear. Modern models of angle grinder have a soft starter. Due to him, they have ways to work for a long time. The principle of operation of the element is based on a change in the operating frequency. In order to learn more about the starter device, it is worth considering the diagram of the standard model.

Diagram of the device for an angle grinder with a triac 10 A

The smooth start circuit of an angle grinder, made by hand, involves the use of contact resistors. The polarity ratio of modifications, as a rule, does not exceed 55%. Many models are manufactured with blockers. A wired filter is responsible for protecting the device. Low frequency transceivers are used to pass the current. The process of lowering the threshold voltage is carried out on a transistor. The triac in this case acts as a stabilizer. When connecting the model, the output resistance at an overload of 10 A should be about 55 ohms. Starter covers are semiconductor-based. In some cases, magnetic transceivers are installed. They handle low RPM well and can maintain nominal frequency.

Making a soft start

The circuit is assembled on a printed circuit board with dimensions of 45 x 35 mm, the board is laid out as compactly as possible so that it can be built into the body of a tool that requires a soft start. It is better to solder the power wires directly to the board, but if the load power is small, then you can install the terminal blocks, as I did. The board is made by the LUT method, photos of the process are presented below.

It is advisable to tin the tracks before soldering the parts, so their conductivity will improve. The microcircuit can be installed in a socket, then it can be removed from the board without any problems. First, resistors, diodes, small capacitors are soldered, and then the largest components. After completing the assembly of the board, it is imperative to check it for correct installation, ring the tracks, wash the remaining flux.

Smooth start for do-it-yourself angle grinder

This article will discuss the smooth start-up diagram of an angle grinder from the available parts. Since a soft start is not installed in the whole tool, this can be corrected and independence to assemble a simple soft start scheme for an angle grinder and do it yourself. This device will help you upgrade your tool and make it less dangerous and more convenient..

If you often work with a tool, then you probably faced the following problem: the engine, whether it be an angle grinder, circular saw, planer or other equipment, starts up very sharply. Such abrupt starts are fraught with a lot of troubles: firstly, there is a high starting current, which does not have the best effect on the wiring, and secondly, a sharp start of the engine quickly wears out the mechanical parts of the tool, and thirdly, the ease of use decreases, when starting an angular the grinder has to be held firmly, and it strives to get out of the hands. In expensive models, a soft start system is already built in, which easily copes with all these troubles. But what if this system does not exist? There is a way out – to assemble the soft start circuit yourself. In addition, it will be possible to use it with incandescent bulbs, because most often they burn out exactly at the moment they are turned on. A smooth start will significantly reduce the possibility of a light bulb burning out quickly.

Soft start circuit

On the Internet, a soft start circuit is often found, built on a rather rare domestic microcircuit K1182PM1R, which is not always easy to get now. That is why I propose an equally effective circuit for assembly, the key link of which is the available TL072 microcircuit; instead of it, you can also put the LM358. The time it takes for the engine to reach full speed is set by the capacitor C1. The larger its capacity, the more time it will take to overclock, the best option is 2.2 uF. Capacitors C1 and C2 must be rated for at least 50 volts. Capacitor C5 is at least 400 volts. Resistor R11 will dissipate a decent amount of heat, so its wattage should be at least 1 Watt. In the circuit, you can use any low-power transistors, T1, T2, T4 have an n-p-n structure, you can use BC457 or domestic KT3102, T4 has a p-n-p structure, BC557 or KT3107 will fit in its place. T5 – any semistor suitable for power and voltage, for example, BTA12 or TC-122.

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First launch and tests

After the board is completely ready, you can check it for operability. First of all, you need to find a low-power light bulb of 5-10 watts and connect it to the 220 volt network through it. Those. the board and the lamp are connected to the network in series, and the OUT output remains unconnected. If nothing burned out on the board, and the light did not light up, you can connect the circuit directly to the network. The same low-power light bulb can be connected to the OUT output for testing. When connected, it should smoothly gain brightness to the maximum. If the circuit works properly, you can connect more powerful electrical appliances. With prolonged operation, the seven-core may heat up slightly – there is nothing to worry about. If there is free space, it will not hurt to install it on the radiator.

Hazardous mains voltage is present on the board during operation, therefore, precautions must be taken. Under no circumstances should you touch the parts of the board when it is connected to the network. Before switching on, make sure that the board is securely fixed and that no metal objects can fall on it, which could lead to a short circuit. For reliability, it is recommended to fill the board with varnish or epoxy resin, then even moisture will not be afraid of it. Successful build!

Making a soft start

It is advisable to tin the tracks before soldering the parts, so their conductivity will improve. The microcircuit can be installed in a socket, then it can be removed from the board without any problems. First, resistors, diodes, small capacitors are soldered, and then the largest components. After completing the assembly of the board, it is imperative to check it for correct installation, ring the tracks, wash the remaining flux.

General information

The stator of the electric motor is an inductor, therefore, there are resistances with active and reactive components..

When electric current flows through radioelements. having resistance with an active component, losses occur associated with the conversion of part of the power into a thermal form of energy. For example, the resistor and stator windings of an electric motor have resistance with an active component. It is not difficult to calculate the active resistance, since the phases of the current (I) and voltage (U) coincide. Using Ohm’s law for a section of a circuit, you can calculate the resistance: R = U / I. It depends on the material, cross-sectional area, length and temperature..

If the current passes through the reactive type of elements (with capacitive and inductive characteristics), then, in this case, a reactive R appears. An inductor that has practically no active resistance (the calculations do not take into account the R of its windings). This type of R is created due to the Electromotive force (EMF) of self-induction, which is directly proportional to the inductance and frequency I passing through its turns: Xl = wL, where w is the angular frequency of the alternating current (w = 2Pif, and f is the frequency of the network current) and L is the inductance (L = nn / Rm, n is the number of turns and Rm is the reluctance).

When the electric motor is turned on, the starting current is 7 times higher than the nominal current (current consumed during the operation of the tool) and the stator windings are heated. If the stator coil is old, an interturn short circuit may occur, which will result in the breakdown of the power tool. To do this, you need to use a soft starter for the power tool..

One of the methods to reduce the starting current (Ip) is switching the windings. To implement it, you need 2 types of relays (time and load) and the presence of three contactors..

Starting an electric motor with star-connected windings is possible only with 2 contactors not simultaneously closed. After a certain time interval, which is set by the time relay, one of the contactors is disconnected and another one, not previously activated, is turned on. Thanks to this alternation of turning on the windings, the starting current decreases. This method has a significant disadvantage, since when two contactors are simultaneously closed, a short-circuit current occurs. However, when using this method, the windings continue to heat up..

Another way to reduce the starting current is frequency control of the start of the electric motor. The principle of this approach is the frequency change of the supply U. The main element of this type of soft starter is a frequency converter, consisting of the following elements:

  • Rectifier.
  • Intermediate chain.
  • Inverter.
  • Electronic control circuit.

The rectifier is made of powerful diodes or thyristors, which acts as a converter U of the mains supply into a constant pulsating current. The intermediate circuit smoothes the pulsating DC current at the output of the rectifier, which is collected on the large capacitors. An inverter is required to directly convert the signal at the output of the intermediate circuit into a signal of amplitude and frequency of the alternating component. An electronic control circuit is needed to generate signals necessary to control a rectifier, inverter.

Operating principle

During the start of the collector-type electric motor, a significant short-term increase in the consumption current occurs, which is the reason for the premature failure of the power tool and its delivery for repair. The electrical parts wear out (the current is 7 times higher) and the mechanical parts (abrupt start). To organize a “soft” start, you should use a soft starter (hereinafter referred to as the soft starter). These devices must meet the basic requirements:

  • Smooth increase in load.
  • The ability to start the engine at regular intervals.
  • Providing protection against linear surges U, phase failure (for a 3-phase electric motor) and various interference of the electrical component.
  • Significantly increased service life.

The most widespread are triac soft starters, the principle of which is smooth regulation of U by adjusting the opening angle of the triac transition. The triac must be connected directly to the motor windings and this allows the starting current to be reduced from 2 to 5 times (depending on the triac and control circuit). The main disadvantages of triac soft starters are as follows:

  • Complex schemes.
  • Overheating of windings during prolonged start-up.
  • Problems with starting the motor (leads to significant heating of the stator windings).

The circuits become more complicated when using powerful motors, however, at low loads and idle, it is possible to use simple circuits..

Soft starters with open loop controllers (in 1 or 3 phases) are widely used. In models of this type, it becomes possible to preset the start time and U value before starting the motor. However, in this case, it is impossible to adjust the amount of torque under load. With this model, a special device is used to reduce the inrush current, protect against loss and phase imbalance, as well as against overloads. Factory models have the function of monitoring the state of the electric motor.

The simplest single-phase control circuits are executed on one triac and are used for tools with a power of up to 12 kW. There are more complex schemes that allow you to adjust the power parameters of a motor with a power of up to 260 kW. When choosing a factory-made soft starter, it is necessary to take into account the following parameters: power, possible modes of operation, equality of permissible currents and the number of starts in a certain period of time.

Smooth start for do-it-yourself angle grinder

This article will discuss the smooth start-up diagram of an angle grinder from the available parts. Since a soft start is not installed in the whole tool, this can be corrected and independence to assemble a simple soft start scheme for an angle grinder and do it yourself. This device will help you upgrade your tool and make it less dangerous and more convenient..

If you often work with a tool, then you probably faced the following problem: the engine, whether it be an angle grinder, circular saw, planer or other equipment, starts up very sharply. Such abrupt starts are fraught with a lot of troubles: firstly, there is a high starting current, which does not have the best effect on the wiring, and secondly, a sharp start of the engine quickly wears out the mechanical parts of the tool, and thirdly, the ease of use decreases, when starting an angular the grinder has to be held firmly, and it strives to get out of the hands. In expensive models, a soft start system is already built in, which easily copes with all these troubles. But what if this system does not exist? There is a way out – to assemble the soft start circuit yourself. In addition, it will be possible to use it with incandescent bulbs, because most often they burn out exactly at the moment they are turned on. A smooth start will significantly reduce the possibility of a light bulb burning out quickly.

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We make a soft-start carrier for a power tool

If you often use a power tool, then you have probably used an angle grinder (angle grinder) with and without soft start. Agree, a power tool with a smooth set of revolutions is much more pleasant to use, and it lasts longer than usual. In this material, I will tell and show how you can modify a conventional carrier so that the power tool connected through it has a smooth start.

Why soft start is better

Before proceeding with the rework process itself, I want to say a few words about the benefits of a soft start. So, a soft start allows:
1. Less wear on the gears of the mechanism, because at the start there is no initial impact on them.
2. There is no inrush current, which has a beneficial effect on the performance of your entire supply network.
3. In a power tool with a soft start, the stator and rotor windings are less likely to fail..
4. With a smooth start, the power tool does not pull out of your hands, which is good from a safety point of view.
So the advantages of a soft start are obvious, now let’s move on to the very finalization of the carrying.

In order to complete this work, we will need:
Block KRRQD12A, carrier (about how to assemble a high-quality carrier is written on the channel), an external installation socket, a soldering iron with solder, a small piece of PVA 32.5 wire, a stationery knife, heat shrink (or electrical tape), a piece of plywood and an hour of free time.

What is block KRRQD12A

The most important element in our entire design is the KRRQD12A soft starter, which is precisely designed for the modernization of power tools. This unit is designed for an operating current of 12 amperes, which fits perfectly into the amperage of our sockets (16 A).
Note. There is also a KRRQD20A (rated for 20 Amp) on sale, which is outwardly indistinguishable from a 12 Amp unit, but I do not recommend it for installation in an outlet, as this can lead to overheating of the outlet contacts due to excess amperage.

So, now we disassemble our carrier and inspect the insides:
As you can see in this carrying, the contacts are fixed on a screw clamp, and in order not to push two wires under one clamp, I decided to solder the wires to the pads on the contact jaws.After that, in the carrying case we make a neat hole for our new wire and it can be closed.
Next, we take an external outlet, place it next to the fixed carrier.
Then we attach our KRRQD12A block according to the following scheme: yandex.ru
That is, the unit is connected in a sequential manner. The junction of the wire from the carrying with the block is soldered and insulated using heat shrink.

Then just plug in the socket and carefully place the KRRQD12A unit in the case as follows: Now just carefully close the covers. That’s it, you can consider the process of our modernization completed. Now it remains to check everything for performance:

As you can see from the video, we have got a modernized carrier with an additional soft start unit, which will allow you to turn on the power tool both in the usual way and with a soft start.
Source: zen.yandex.ru

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

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 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..

Homemade regulator circuit

One of the most popular schemes for a soft start of the engine is an angle grinder with adjustable 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 scheme, 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 switched 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 that 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 power 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 an ESC for an angle grinder, you will need to draw a PCB, etch the contacts with acid and then plow 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..

If there is very little space in the angle grinder, then the adjuster can be placed outside the tool, as shown in the following photo..

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, which has 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.