A grinder, or grinding machine, is often simply necessary on the farm to perform metal work. In addition, it can be used to clean both wooden and stone materials. It is difficult to imagine performing industrial work without an angle grinder. This is a tool that is suitable for both a professional in his work and an amateur in household work.

When doing work with your own hands, it is important that the power tool has a smooth start. This is especially true if you often have to work, and the network cannot withstand the voltage of the tool.

Budget options for angle grinders - angle grinders - have a number of disadvantages:

1. The power tool does not have the ability to have a smooth, soft start. This can lead to power outages, since the angle grinder consumes a large amount of electricity in the first seconds after switching on. There is also a huge probability of damage to the electric motor and breakage of the tool after not a soft start, but a sharp, jerky one.
2. Power tools, especially simple Chinese ones, do not have a speed regulator (by adjusting the speed you can ensure long operation of the tool without putting a load on it).

Therefore, when choosing a tool, it is very important to pay attention to such parameters as speed adjustment and availability soft start. In addition, when choosing an angle grinder, you should pay attention to power. The main indicator here is the volume of work performed.

If the work is not large-scale and not frequent at the household level, then a power tool with an adjustment of 125 mm and a power of between 600-900 W is suitable.

For large-scale work on an industrial scale, you should use an angle grinder that is approximately twice as powerful. More to the main indicators except technical characteristics, refers to safety. The grinder must be safe. What does it mean? Firstly, as already mentioned, the presence of a soft start, which prevents voltage surges during switching on. Automatic fuses necessary for emergency stopping of the motor during a system failure. The fuses serve as a regulator when the circle jams. Provides protection from dust. It is necessary when using an angle grinder frequently to prevent dust from accumulating in the tool.

The heat dissipation function is important. The heat sink protects against overheating. During operation, especially if the work is long, the machine body is subject to strong heating so that there is no overheating and heat removal is necessary. When overloaded, the angle grinder stops - this happens during heating, approaching 200 o C. Well, balancing the disk serves to reduce unpleasant vibration and beating of the tool during operation, old worn disks are especially susceptible to this effect. Paying attention and paying attention to safety when choosing a tool and when further working with it is very important.

When choosing a tool, it is worth noting that there are grinders with one and two handles. Here you should rely solely on convenience. Two-handed models will most likely be more comfortable to hold, but such tools are heavier in weight; one-handed models will also have to be held with two hands, but such angle grinders are smaller in size and weight.

Bosch is the leader in the power tools market. The tools of this company have all the necessary characteristics from convenience to safety. Another advantage of Bosch tools is that there is good ventilation.

Bt136 600E: voltage regulation switching circuit

Manufacturers do not burden cheap angle grinders that do not have sufficient power with voltage control switching circuits, otherwise such angle grinders would no longer be cheap. When starting the grinder, if it is smooth, the process is carried out through an adapter connected by contacts to the rectifier block. The rectifier block converts the current.

But sometimes it makes sense to modernize an angle grinder using an established scheme. The electrical circuit is assembled quite simply. It is not difficult to make, and you can, if desired, connect not only an angle grinder, but any other tool to the finished circuit. However, the tool must have a commutator motor, not an asynchronous one.

A homemade approach to creating a circuit would be as follows:

• To get started, you should download the board if you don’t have it;
• The Bt136 600E triac is used as the power link;
• During operation, the triac will heat up; to avoid this, a heat sink is installed;
• The resistors used provide resistance to current, providing current suppression;
• The regulator is adjusted using a multi-turn trimmer resistor;
• To check, connect a light bulb;
• After connecting, the light bulb must be turned off - the triac must be cold;
• Connecting the resulting circuit to the grinder.

If the board is connected correctly, the triac and resistors of the angle grinder should start smoothly, and the use of the rotation speed should be regulated. After this, you can test the grinder in action. Such knowledge may be needed when repairing electric motor faults. For example, when voltage increases or improper balancing occurs.

Do-it-yourself speed controller for an angle grinder

If you use your ingenuity to create a speed controller with your own hands, you can use soldered control boards from a sewing machine or vacuum cleaner. In addition, the components for the regulator are inexpensive and can be easily purchased if possible. It is worth noting that the device requires a gearbox to support a certain number of revolutions and speed. If the speeds are high, then the reason is most likely in the stator. The stator requires repair. Repairing the stator is possible at home.

The operation of a commutator motor is ensured by any type of electrical voltage. When changing the voltage power, you need to reduce or increase the number of revolutions. Changing this number helps thyristor regulator rpm

Regulator assembly steps:

• First, you need to unscrew the handle of the grinder, evaluate the place and figure out where to place the elements of the circuit (if there is no space, then you can make the device in a separate box);
• The resistor can be made of aluminum;
• Provided the triac does not heat up too much, a small radiator is sufficient;
• Next, the structure is soldered.

Finally comes the sizing epoxy resin for fastening. Homemade device can work for years. There are cases when the device accelerates at higher speeds after switching on - this means the stator winding is short-circuited. In this case, a turn short circuit occurred. The stator requires repair, most often it requires rewinding.

What are the typical malfunctions: the winding breaks or burns, a short circuit occurs, the insulating surface breaks through.

Making a speed controller

An electric angle grinder is impossible without a speed controller, so that it is possible to reduce the speed.

The regulator circuit from a physics point of view looks like this:

• Resistor – R1;
• Trimmer resistor – VR1;
• Capacitor – C10;
• Triac - DIAC;
• Triac - TRIAC.

The electronic regulator can be not only built-in, but also remote for convenience. In Bosch angle grinders, the electronics set the speed from almost 3 thousand to 11.5 thousand. There is no load on the meter's power, all indicators are taken into account. Reducing the number of revolutions and increasing them is not difficult for the tool. Adjustable rotation speeds are simply necessary when working with an angle grinder.

Making a soft start for a power tool with your own hands (video)

Only at first glance, it seems that an angle grinder may never be needed in life, that situations when it will come in handy, much less when it will have to be repaired, will not arise. Of course, you can turn to professionals, or you can identify the problem yourself and try to fix it.

A smooth start for any power tool is very important for the following reasons. First, it helps protect your electrical device from breakdowns, which means fewer trips to the repair shop, which means virtually no downtime and increased productivity. Secondly, having a soft start for the electric motor saves you money that could otherwise be spent on paying repairmen or buying a new tool.

In contact with

This article will look at making a soft start for an electric motor with your own hands using the example of an angle grinder or, in other words, an angle grinder.

Why do you need a soft start unit?

Due to some design features, starting the grinder leads to the appearance of dynamic loads to the device. Since the mass of the disk with which it is carried out useful work, is high enough, then on commutator motor and the gearbox of the device is subject to powerful inertial forces, which leads to the following negative factors:

1. During the start, which is especially sharp, inertial forces very strongly influence the body of the device, which may cause injury: You simply don't hold the tool and release it. Therefore, when starting the electric motor of the angle grinder, always hold it with both hands.
2. During the start, the electric motor is subject to an overload caused by the supply high voltage current What does this lead to? First of all, the motor winding suffers and accelerated wear of the brushes occurs, which will not happen if you make a block for a soft start. Otherwise, be prepared for the fact that one not very wonderful day something will happen in the engine. short circuit caused by complete wear of the brushes. This, in turn, will force you to shell out money for repairs or buy a new sander.
3. Rapidly applying torque to the gearbox during startup will cause accelerated wear on the gears in your grinder's gearbox.
4. Also keep in mind that jumping the angle grinder can destroy the blade, the fragments of which can cause serious harm to you, so never work without a cover for protection.

To make it more clear to you which elements of the grinding machine suffer most from a sudden start, look at the diagram below.

Of course, some companies that produce grinding machines equip their devices with a soft start block at the factory. However, equipping with a soft start is an unaffordable luxury for angle grinders in the budget price segment, so if you do not want to buy an expensive power tool, then you are in danger of encountering the problems described above.

However, there is a way out and it is quite simple: make your own device for a soft start according to one of the possible schemes. If there is free space in the body of your device, then you can use a ready-made soft start device and put it in the grinder.

Making a soft start for an angle grinder with your own hands

One of the most commonly used schemes for manufacturing a starting device is based on microcircuit KR118PM1 and triacs that make up the power section. Using this scheme, you can make a soft start unit without having specialized skills and without deep knowledge of electrical engineering. The only important thing is that you know how to solder.

Graphically, this diagram looks like this.

DIY device you can connect to absolutely any power tool, designed for a voltage of two hundred and twenty volts. Soft start block, created on the basis of this scheme, does not need to be turned on with a separate button, but can be connected to the standard button of the grinding machine. If your angle grinder has free space inside the case, you can install the unit in it or make a separate case for it and connect it to the power tool through a gap in the power cable.

The best option for connecting a soft starter unit and your grinder will be as follows: you apply voltage to the input of the block (connector XS1) from a power source with a voltage of two hundred and twenty volts. A plug from an angle grinder is connected to the output of the block (connector XP1).

Operating principle of the soft starter

1. After you press the power button on the grinder, voltage appears in the circuit, which is initially sent to the microcircuit, which is designated DA1 in the diagram above. The capacitor, which regulates the voltage, gradually increases it until the operating value is reached. Due to the operation of the capacitor, the thyristors in the microcircuit open with some delay and slowly transmit voltage to the power section in triacs VS1.
2. The process described above occurs in periods that become shorter and shorter if you count them from the moment of startup. As a result, the voltage supplied to the grinding machine increases slowly, and not abruptly, which determines the smooth start of the electric motor.
3. The time during which the engine reaches operating speed is depends on the capacity of the capacitor used C2. As a rule, a capacity equal to forty-seven microfarads is enough for the angle grinder to start smoothly in two seconds. Usually this period of time is enough to remove the overload from the electric motor and gearbox.
4. After you finish work and turn off your device, resistor R1 discharges capacitor C1 with its resistance. If the value of resistor R1 is sixty-eight kilo-ohms, then the discharge takes only three seconds. You can then use the soft starter again as it is ready to start the sander again.

If you want to upgrade the unit to a device regulating the speed of the electric motor, then replace the constant resistor R1 with a variable one. In this case, you can adjust its resistance, and therefore influence the engine speed.

Triac VS1 in your block must meet the following characteristics:

• The minimum current it allows is twenty-five amperes.
• The maximum voltage for which it is designed is four hundred volts.

This circuit, tested by many craftsmen, was tested on a grinder with a power equal to two kilowatts, and has a power safety margin of up to five kilowatts, which is made possible thanks to the KR118PM1 microcircuit.

Many power tools fail due to wear and tear on the motor. Modern models of angle grinders have a soft start device. Thanks to it, they are able to work for a long time. The operating principle of the element is based on changing the operating frequency. In order to learn more about the starter device, it is worth considering the diagram of the standard model.

Soft starter

The standard soft start circuit for an angle grinder consists of a triac, a rectifier unit and a set of capacitors. To increase the operating frequency, resistors are used that allow current to pass in one direction. The starter is protected by a compact filter. models maintain low. However, in this case, much depends on the maximum power of the motor installed in the angle grinder.

How to connect the model?

The soft start of the angle grinder is connected via an adapter. Its input contacts are connected to the rectifier block. In this case, it is important to determine the zero phase in the device. To secure the contacts you will need to check the functionality of the starter using a tester. First of all, negative resistance is determined. When installing a starter, it is important to remember the threshold voltage that the device can withstand.

Device diagram for an angle grinder with a 10 A triac

The do-it-yourself soft start circuit for an angle grinder involves the use of contact resistors. The polarity coefficient of modifications, as a rule, does not exceed 55%. Many models are produced with interlocks. A wired filter is responsible for protecting the device. Low frequency transceivers are used to pass 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. Covers for starters are suitable on a semiconductor basis. In some cases, magnetic transceivers are installed. They handle low speeds well and can maintain the rated frequency.

Model for grinders with a 15 A triac

Soft start for an angle grinder with 15 A triacs is universal and is often found in low-power models. The difference between the devices is their low conductivity. The soft start circuit (device) of an 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. Rated voltage Starters start at 200 V.

Starters for angle grinders with a 20 A triac

Devices with 20 A triacs are suitable for professional grinders. Many models use contactor resistors. First of all, they are able to operate at high frequencies. The maximum temperature of the starters is 55 degrees. Most models have a well-protected case. The standard device circuit involves the use of three contactors with a capacity of 30 pF or more. Experts say that the devices stand out for their conductivity.

The minimum frequency for starters is 35 Hz. They can work online direct current. Modifications are connected via adapters. Such devices are well suited for 200 W motors. Filters are quite often installed with triodes. Their sensitivity indicator is no more than 300 mV. Quite often there are wired comparators with a protection system. If we consider imported models, they have an integrated converter that is installed with insulators. Current conductivity is ensured at around 5 microns. With a resistance of 40 Ohms, the model is capable of stably maintaining high speeds.

Models for angle grinder 600 W

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

If we talk about duplex triodes, then the resistance at high speeds can reach up to 80 Ohms. Very rarely, models have stabilizers that operate from comparators. Most often they are attached directly to the modules. Some modifications are made with wired transistors. Their minimum frequency starts from 5 Hz. They are afraid of overloads, but are able to maintain high speeds at

Devices for angle grinders 800 W

800 W grinders work with low frequency starters. Triacs are quite often used at 15 A. If we talk about the circuit of the models, it is worth noting that they use expansion transistors, whose 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 grinders, then modifications of 400 mV are suitable for them. In this case, the current conductivity may be low. There are also devices with variable transistors. They warm up quickly, but are not able to maintain high speeds of the grinder, and their current conductivity is about 4 microns. If we talk about other parameters, the rated voltage starts from 230 V. The minimum frequency for models with wideband triacs is 55 Hz.

Starters for angle grinders 1000 W

Starters for these angle grinders are made using 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 wire base. Capacitors can be used with or without a filter. The minimum frequency of the conventional model is 30 Hz. With a resistance of 40 ohms, starters are capable of supporting large overloads. However, problems may arise at low speeds of the angle grinder.

How to make a starter using a triac TS-122-25?

Making a soft start for an angle grinder with a triac TS-122-25 with your own hands is quite simple. First of all, it is recommended to prepare a contactor resistor. Capacitors will be required of the single-pole type. A total of three elements are installed in the starter. The capacitance 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 increase conductivity.

The rectifier block is used with a conductivity of 50 microns. It is capable of withstanding large overloads and will be able to provide high speeds. Next, to assemble a soft start on an angle grinder with your own hands, install a thyristor. At the end of the work, the model is connected via an adapter.

Assembling a model with VS1 series triacs

You can assemble a soft start for an angle grinder using a VS1 triac with your own hands using several rectifier blocks. The capacitors for the device are suitable for the linear type with a capacity of 40 pF or more. You should start assembling the modification by soldering the resistors. Capacitors are installed in series order between insulators. The rated voltage of a high-quality starter is 200 V.

Next, to make a smooth start for the angle grinder with your own hands, take a prepared triac and solder it at the beginning of the circuit. Its minimum operating frequency should be 30 Hz. In this case, the tester must display a value of 50 ohms. If there are problems with overheating of the capacitors, then you need to use dipole filters.

Model for angle grinders with regulator KR1182PM1

To assemble a soft start for an angle grinder with the KR1182PM1 regulator with your own hands, you need a contact thyristor and a rectifier unit. It is more expedient to use a triode for two filters. It is also worth noting that to assemble the starter you will need three capacitors with a capacity of at least 40 pF.

The sensitivity indicator of the elements must be 300 mV. Experts say that the triac can be installed behind the lining. You also need to remember that the threshold voltage should not fall below 200 V. Otherwise, the model will not be able to operate at lower speeds of the angle grinder.

When choosing an angle grinder, a person thinks about the long service life of the tool. It is believed that the more expensive the tool, the longer it will last. But sometimes there is not enough money for an expensive purchase and you have to purchase an inexpensive model. Inexpensive models of angle grinders do not have a speed regulator. Other devices, such as drills, screwdrivers and hammer drills, have a speed control. And the angle grinder only has a power button. Thus, the angle grinder breaks faster, because under the influence of a sharp start, the gearbox and winding wires of the armature fail.

The following situations are possible:

• The action of a high load on the gearbox axis causes an inertial jump, leading in some cases to the tool falling out of the hands.
• The amount of torque during the start-up period contributes to wear of the gearbox gears.
• Destruction of the circle due to overload.

You can upgrade the tool and end up with a grinder with soft start. You can do the modernization yourself. A soft start for an angle grinder can be made with your own hands in two ways. The first method involves purchasing a ready-made device, which already has a speed controller and slows down the start of the engine at startup. This device is placed inside the device. The second method is to make a circuit that will make the start smoother. If the power cord breaks, the circuit is connected to the break.

Circuit manufacturing plan

The angle grinder's soft start circuit involves the use of the well-known KR118PM1 microcircuit for phase adjustment. The design contains semistors. Multiplying the operating frequency is achieved by installing resistors that pass current in one direction. The advantage of this scheme is its simplicity and the absence of special adjustments after assembly. This method can be used by anyone who does not have special skills, but works with a soldering iron.

Basic principles for designing a circuit:

• When choosing capacitor C3, the acceleration time can be increased;
• The installed resistor R1 with a resistance of 68 kOhm does not require replacement with a variable resistance, as it ensures smooth starting of models of various powers (0.6–1.5 kW);
• If you want to equip it with a power regulator, resistor R1 is replaced variable resistance. A value of more than 100 kOhm does not help reduce the output voltage. The angle grinder switches off when the microcircuit legs are shorted;
• When using a semistor of the TS-122-25 type, models with a power of 0.6–2.7 kW start smoothly. And also in this case there is a power reserve in case of jamming. For models up to 1500 W, less powerful semi-sectors (VT139 and W140) will be sufficient.

Circuit operation process

When the start buttons are closed, current flows to the microcircuit. The voltage across the main capacitor begins to increase. It reaches the operating value as it charges. Depending on the charge of the capacitor, the thyristors open. The opening of the VS1 semistor is also carried out with delay. A separate half-cycle of alternating voltage is characterized by a decrease in delay. As a result, the voltage at the input to the tool increases smoothly. Based on this, the engine starts smoothly. As a result, the speed does not increase quickly and the gearbox does not receive inertial surges.

The installed capacitor C2 facilitates starting within 2 seconds. This time is enough to start functioning, and a quick start does not increase the load. Turning off the tool leads to the discharge of capacitor C2 through resistance R1. With a capacity of 68 kOhm, the discharge period lasts 3 seconds. After this, you can start the device again.

The value of the current moving through the input of the semistor VS1 is regulated by resistor R2. Capacitor C1 is considered a control part of the microcircuit. Resistors and capacitors are attached to the legs of the microcircuit by soldering.

Connecting the soft start function

This microcircuit is comparable to any device that provides a voltage of 220 V. Power is supplied to the XP1 connector.

The assembled circuit is placed in a plastic container. Suitable for this junction box. A socket and a wire with a plug are connected to the block. The device resembles an extension cord. The socket accepts the angle grinder plug. The functionality is checked using a tester. First, negative resistance is determined.

Complicated collection method

If you have certain skills or experience, you can make a complicated smooth launch scheme. This serves as a typical circuit for the XS-12 module. This circuit is installed in many models of power tools, even at the manufacturer. If you want to adjust the speed, you need to install a trimming and adjusting resistor with a capacity of 100 kOhm and 50 kOhm, respectively. But there is another way - to place AC voltage 470 kOhm in the middle of the resistor-diode section. The resistor capacity is 47 kOhm.

The microcircuit is powered from a voltage of 5–35 V. An auxiliary semiconductor diode DZ is not required, since the power circuit produces no more than 25 V. It is recommended to connect a 1 MΩ resistor simultaneously with capacitor C2.

It should be remembered that when turning on a tool connected to the circuit, the load must be removed. Otherwise the soft start may burn out. First you need to wait until full promotion is achieved, and then start working.

To extend the life of an angle grinder, sometimes you don’t need to spend money on an expensive model. It will be enough to develop a smooth start of the angle grinder with your own hands. Then your tool will have reliability and a long service life. Moreover, the above scheme has been repeatedly used by many craftsmen.