How To Reduce The Speed Of An Angle Grinder Without Losing Power

Typical speed regulator circuit

This is how the governor board assembly looks like

The engine speed regulator is not just a variable resistor that steps down the voltage. An electronic control of the magnitude of the current is required, otherwise, with a drop in speed, the power will proportionally decrease, and, accordingly, the torque. In the end, a critically low voltage value will come, when, with the slightest resistance of the disk, the electric motor simply cannot turn the shaft. Therefore, even the simplest regulator must be calculated and executed in the form of a well-developed circuit.

And more advanced (and accordingly expensive) models are equipped with regulators based on an integrated circuit.

Integrated circuit of the regulator. (most advanced option)

If we consider the electrical circuit of the angle grinder in principle, then it consists of a speed controller and a soft start module. Power tools equipped with advanced electronic systems are significantly more expensive than their simple counterparts. Therefore, not every home craftsman is able to purchase such a model. And without these electronic blocks, only the winding of the electric motor and the power key will remain.

The reliability of modern electronic components of the angle grinder exceeds the resource of the motor windings, so you should not be afraid of purchasing a power tool equipped with such devices. The only limit can be the price of the product. over, users of inexpensive models without a regulator sooner or later come to install it on their own. The block can be purchased ready-made or made by yourself.

Angle grinder with speed control: power tool capabilities

If the angle grinder is not equipped with a speed controller, can I install it myself? Most angle grinders (angle grinder), among the common people of Bulgarians, have a speed controller.

The speed controller is located on the housing of the angle grinder

Consideration of the various adjustments should begin with an analysis of the electrical circuit of the angle grinder.

The simplest diagram of a grinding machine

advanced models automatically maintain rotation speed regardless of the load, but more often tools with manual disc speed control are found. If a trigger-type regulator is used on a drill or an electric screwdriver, then such a regulation principle is not possible on an angle grinder. Firstly, the features of the instrument suggest a different grip when working. Secondly, adjustment during operation is unacceptable, therefore, the speed value is set with the motor off.

Why generally adjust the rotational speed of an angle grinder?

When cutting metal of different thickness, the quality of work is highly dependent on the speed of rotation of the blade. When cutting hard and thick material, the maximum rotation speed must be maintained. When processing thin sheet metal or soft metal (for example, aluminum), high speed will lead to melting of the edge or rapid blurring of the working surface of the disc;
Cutting and cutting stone and tiles at high speeds can be dangerous. In addition, the disc, which rotates at high speeds, knocks out small pieces from the material, making the cutting surface chipped. over, for different types of stone, different speeds are selected. Some minerals are just processed at high speeds;
Grinding and polishing is basically impossible without speed control. Incorrectly setting the speed, you can ruin the surface, especially if it is a paintwork on a car or a material with a low melting point;
The use of discs of different diameters automatically implies the mandatory presence of a regulator. Changing the disc Ø115 mm to Ø230 mm, the rotation speed must be reduced by almost half. And it is almost impossible to hold an angle grinder with a 230 mm disc rotating at a speed of 10,000 rpm in your hands;
Depending on the type of crowns used, stone and concrete surfaces are polished at different speeds. over, with a decrease in the rotational speed, the torque should not decrease;
When using diamond discs, it is necessary to reduce the number of revolutions, since their surface quickly breaks down from overheating. Of course, if your angle grinder works only as a pipe, angle and profile cutter, you will not need a speed controller. And with universal and versatile use, the angle grinder is vital.

Making a speed controller with your own hands

Attempts to adapt a conventional dimmer to adjust the brightness of the lamp will do nothing. First, these devices are designed for a completely different load. Secondly, the principle of operation of the dimmer is not compatible with the control of the winding of the electric motor. Therefore, you have to mount a separate circuit, and figure out how to place it in the instrument case.

Homemade speed controller

The simplest thyristor speed controller can be easily made by yourself. To do this, you need five radio elements, which are sold on any radio market.

Wiring diagram of a thyristor speed controller for your instrument

The compact design allows you to place the circuit in the case of an angle grinder without compromising ergonomics and reliability. However, this arrangement does not allow the torque to be maintained when the rpm drops. The option is suitable for reducing speed when cutting thin sheet metal, polishing work, processing soft metals.

If your angle grinder is used for processing stone, or you can install discs larger than 180 mm on it, you need to assemble a more complex circuit, where the KR1182PM1 microcircuit is used as a control module, or its foreign analog.

Electrocircuit of speed control using the KR1182PM1 microcircuit

This scheme controls the amperage at any speed, and allows you to minimize the loss of torque when they decrease. In addition, this scheme treats the engine more carefully, extending its resource.

The question of how to adjust the speed of the tool arises when it is stationary. For example, when using an angle grinder as a circular saw. In this case, the connection point (automatic machine or socket) is equipped with the regulator, and the speed is adjusted remotely.

Regardless of the method of execution, the speed controller of the angle grinder expands the capabilities of the tool and adds comfort when using it.

Power speed regulator

Work principles

The 220 V motor speed controller without power loss is used to maintain the initial set shaft speed. This is one of the basic principles of this device, which is called a frequency regulator.

With it, the electrical appliance operates at the set engine speed and does not reduce it. Also, the motor speed controller affects the cooling and ventilation of the motor. Power sets the speed, which can be either increased or decreased.

The question of how to reduce the speed of a 220 V electric motor was asked by many people. But this procedure is pretty simple. One has only to change the frequency of the supply voltage, which will significantly reduce the performance of the motor shaft. You can also change the power supply to the motor by using its coils. Electricity control is closely related to the magnetic field and motor slip. For such actions, they mainly use an autotransformer, household regulators, which reduce the speed of this mechanism. But it is also worth remembering that engine power will decrease.

Engine types

Engines are different in characteristics. This means that this or that technique works at different frequencies of the rotation of the shaft that starts the mechanism. The motor can be:

Single phase,
Biphasic,
Three-phase.

Mostly three-phase electric motors are found in factories or large factories. At home, single-phase and two-phase are used. This electricity is enough to operate household appliances.

Description of the electric motor speed controller without power loss

Each of us at home has some kind of electrical appliance that has been working in the house for more than one year. But over time, the power of technology weakens and does not fulfill its direct purposes. It is then that you should pay attention to the insides of the equipment. Basically, problems arise with the electric motor, which is responsible for the functionality of the equipment. Then you should turn your attention to a device that regulates the engine power speed without reducing their power.

Shaft rotation

Engines are divided into:

Asynchronous,
Collector.

The speed controller of an asynchronous electric motor depends on the connection of current to the mechanism. The essence of the operation of an asynchronous motor depends on the magnetic coils through which the frame passes. She pivots on sliding contacts. And when, when turning, it turns 180 degrees, then according to these contacts, the connection will flow in the opposite direction. Thus, the rotation will remain unchanged. But with this action, the desired effect will not be obtained. It will enter into force after a couple of dozen frames of this type are introduced into the mechanism.

The brushed motor is used very often. Its operation is simple, since the transmitted current passes directly. because of this, the power of the electric motor turns is not lost, and the mechanism consumes less electricity.

The washing machine motor also needs power adjustment. For this, special boards were made that do their job: the engine speed control board from the washing machine is multifunctional, since when it is used, the voltage decreases, but the rotation power is not lost.

The circuit of this board has been verified. One has only to put bridges from diodes, choosing an optocoupler for the LED. In this case, you still need to put the triac on the radiator. Basically, engine tuning starts from 1000 rpm.

If you are not satisfied with the power regulator and lack its functionality, you can make or improve the mechanism. To do this, you need to take into account the current strength, which should not exceed 70 A, and heat transfer during use. Therefore, you can install an ammeter to adjust the circuit. The frequency will be small and will be determined by the capacitor C2.

Next, it is worth adjusting the regulator and its frequency. When exiting, this pulse will go out through a push-pull transistor amplifier. You can also make 2 resistors that will serve as an output for the computer’s cooling system. To prevent the circuit from burning out, a special blocker is required, which will serve as double the current value. So this mechanism will work for a long time and in the right amount. Power control devices will provide your electrical appliances with many years of service at no extra cost.

How to make it yourself?

There are various options for adjustment schemes. Let’s give one of them in more detail.

Here’s how it works:

Originally, this device was designed to adjust the commutator motor in electric vehicles. It was about one where the supply voltage is 24 V, but this design is applicable to other motors.

The weak point of the circuit, which was determined during tests of its operation, is its poor suitability at very high amperage values. This is due to some slowdown in the operation of the transistor circuit elements.

It is recommended that the current be no more than 70 A. In this circuit there is no current and temperature protection, therefore it is recommended to build in an ammeter and monitor the current strength visually. The switching frequency will be 5 kHz, it is determined by the capacitor C2 with a capacity of 20 nF.

At the same time, it is recommended to select the value of R1 in such a way as to correctly adjust the operation of the regulator. From the output of the microcircuit, the control pulse goes to a push-pull amplifier on transistors KT815 and KT816, then it goes to transistors.

The printed circuit board has a size of 50 by 50 mm and is made of one-sided fiberglass:

This diagram additionally shows 2 45 ohm resistors. This is done for the possible connection of a conventional computer fan to cool the device. When using an electric motor as a load, it is necessary to block the circuit with a blocking (damper) diode, which, by its characteristics, corresponds to twice the value of the load current and twice the value of the supply voltage.

Operation of the device in the absence of such a diode may lead to damage due to possible overheating. In this case, the diode will need to be placed on the heat sink. To do this, you can use a metal plate that has an area of 30 cm2.

Regulating switches work in such a way that the power losses on them are small enough. In the original circuit, a standard computer fan was used. To connect it, a limiting resistance of 100 Ohm and a supply voltage of 24 V were used.

The assembled device looks like this:

When manufacturing a power unit (in the lower figure), the wires must be connected in such a way that there are a minimum of bends in those conductors through which large currents pass. We see that the manufacture of such a device requires certain professional knowledge and skills. Perhaps in some cases it makes sense to use a purchased device.

Adjustment

Now let’s talk about how you can regulate the speed of the collector motors. Due to the fact that the speed of rotation of the motor simply depends on the magnitude of the supplied voltage, then any means of adjustment that are capable of performing this function are quite suitable for this.

Let’s list a few of these options for example:

Laboratory autotransformer (LATR).
Factory adjustment boards used in household appliances (you can use in particular those used in mixers or vacuum cleaners).
Buttons used in the construction of power tools.
Smooth-acting household dimmers.

However, all of the above methods have a very important flaw. Together with a decrease in speed, the power of the motor also decreases. In some cases, it can be stopped even with just your hand. In some cases, this may be acceptable, but for the most part, it is a serious obstacle.

A good option is to perform speed control by using a tachogenerator. It is usually installed at the factory. In case of deviations in the speed of rotation of the motor, the already corrected power supply corresponding to the required speed of rotation is transmitted to the motor through the triacs. If the motor rotation control is built into this circuit, then power loss will not occur here.

How does it look constructive? The most common rheostat regulation of rotation, and made on the basis of the use of semiconductors.

In the first case, we are talking about a variable resistance with mechanical adjustment. It is connected in series to the collector motor. The disadvantage is the additional heat generation and additional waste of battery life. With this method of adjustment, there is a loss of motor rotation power. It is a cheap solution. Not applicable for sufficiently powerful motors for the reasons mentioned.

In the second case, when using semiconductors, the motor is controlled by supplying certain pulses. The circuit can change the duration of such pulses, which in turn, changes the rotation speed without losing power.

Device

The collector motor usually consists of a rotor (armature), stator, brushes and a tachogenerator:

The rotor is the rotating part, the stator is the external magnet.
Brushes made of graphite are the main part of the sliding contacts through which voltage is applied to the rotating armature.
A tachogenerator is a device that monitors rotation characteristics. In case of violation of the uniformity of movement, it corrects the voltage entering the motor, thereby making it smoother.
The stator can contain more than one magnet, but, for example, 2 (2 pairs of poles). Also, instead of static magnets, coils of electromagnets can be used here. Such a motor can work from both direct and alternating current.

The ease of adjusting the speed of the collector motor is determined by the fact that the rotation speed directly depends on the value of the applied voltage.

In addition, an important feature is that the axis of rotation can be directly connected to rotating tools without the use of intermediate mechanisms.

If we talk about their classification, then we can talk about:

DC brushed motors.
AC brushed motors.

In this case, we are talking about what kind of current the electric motors are powered by.

The difference is how these connections are organized.

It is customary to distinguish between:

Parallel excitation.
Sequential excitement.
Parallel-sequential excitation.

Power speed regulator

Shaft rotation

Engines are divided into:

When using an electric motor in tools, one of the serious problems is adjusting the speed of their rotation. If the speed is not high enough, then the action of the tool is not effective enough.

If it is too high, then this leads not only to a significant waste of electrical energy, but also to a possible burnout of the instrument. If the rotation speed is too high, the performance of the tool may also become less predictable. How to fix it? For this purpose, it is customary to use a special speed controller.

A motor for power tools and household appliances usually falls into one of 2 main types:

Collector motors.
Asynchronous motors.

In the past, the second of these categories was most prevalent. Now, about 85% of motors used in electrical tools, household or kitchen appliances are of the collector type. This is explained by the fact that they have a greater degree of compactness, they are more powerful and the process of managing them is simpler.

The action of any electric motor is based on a very simple principle: if a rectangular frame is placed between the poles of a magnet, which can rotate around its axis, and a direct current is passed through it, then the frame will turn. The direction of rotation is determined according to the "right hand rule".

This pattern can be used for the operation of a collector motor.

The important point here is the connection of current to this frame. Since it rotates, special sliding contacts are used for this. After the frame rotates 180 degrees, current flows through these contacts in the opposite direction. Thus, the direction of rotation remains the same. At the same time, smooth rotation will not work. To achieve this effect, it is customary to use several dozen frames.

Work principles

The 220 V motor speed controller without power loss is used to maintain the initial set shaft speed. This is one of the basic principles of this device, which is called a frequency regulator.

With it, the electrical appliance operates at the set engine speed and does not reduce it. Also, the motor speed controller affects the cooling and ventilation of the motor. Power sets the speed, which can be either increased or decreased.

The question of how to reduce the speed of a 220 V electric motor was asked by many people. But this procedure is pretty simple. One has only to change the frequency of the supply voltage, which will significantly reduce the performance of the motor shaft. You can also change the power supply to the motor by using its coils. Electricity control is closely related to the magnetic field and motor slip. For such actions, they mainly use an autotransformer, household regulators, which reduce the speed of this mechanism. But it is also worth remembering that engine power will decrease.

Electric motor speed controller without power loss

The board for adjusting the revolutions of collector electric motors on the TDA1085 microcircuit allows you to control the motors without losing power. A prerequisite is the presence of a tachometer (tachogenerator) on the electric motor, which allows the motor to provide feedback to the control board, namely the microcircuit. In simpler terms, so that it would be clear to everyone, something like the following happens. The motor rotates with a certain number of revolutions, and a tachometer installed on the electric motor shaft records these readings. If you start to load the engine, the shaft speed will naturally begin to drop, which will also be fixed by the tachometer. Now let’s look further. The signal from this tachometer goes to the microcircuit, it sees this and gives a command to the power elements to add voltage to the electric motor. Thus, when you pressed on the shaft (giving a load), the board automatically added voltage and the power on this shaft increased. Conversely, let go of the motor shaft (remove the load from it), she saw this and reduced the voltage. Thus, the revolutions remain not low, but the moment of force (torque) is constant. And most importantly, you can adjust the rotor speed in a wide range, which is very convenient in the use and design of various devices. Therefore, this product is called "Board for adjusting the speed of collector motors without power loss".

But we saw one peculiarity that this board is applicable only for collector motors (with electric brushes). Of course, such motors are much less common in everyday life than asynchronous ones. But they are widely used in automatic washing machines. This is why this circuit was made. Especially for the electric motor from the washing machine automatic machine. Their power is quite decent, from 200 to 800 watts. Which allows them to be widely used in everyday life.

This product has already found wide application in the household of people and has widely covered people engaged in various hobbies and professional activities.

Answering the question. Where can you apply a washing machine motor? Some list was formed. Homemade wood lathe; Grinder; Electric drive for concrete mixer; Sharpener; Electric drive for honey extractor; Straw cutter; Homemade pottery wheel; Electric lawn mower; Wood splitter and many other things where mechanical rotation of any mechanisms or objects is necessary. And in all these cases, we are helped by this board "Adjusting the speed of electric motors with maintaining power on the TDA1085".

Crash test of the speed control board

The board for adjusting the revolutions of collector electric motors on the TDA1085 microcircuit allows you to control the motors without losing power. A prerequisite is the presence of a tachometer (tachogenerator) on the electric motor, which allows the motor to provide feedback to the control board, namely the microcircuit. In simpler terms, so that it would be clear to everyone, something like the following happens. The motor rotates with a certain number of revolutions, and a tachometer installed on the electric motor shaft records these readings. If you start to load the engine, the shaft speed will naturally begin to drop, which will also be fixed by the tachometer. Now let’s look further. The signal from this tachometer goes to the microcircuit, it sees this and gives a command to the power elements to add voltage to the electric motor. Thus, when you pressed on the shaft (giving a load), the board automatically added voltage and the power on this shaft increased. Conversely, let go of the motor shaft (remove the load from it), she saw this and reduced the voltage. Thus, the revolutions remain not low, but the moment of force (torque) is constant. And most importantly, you can adjust the rotor speed in a wide range, which is very convenient in the use and design of various devices. Therefore, this product is called "Board for adjusting the speed of collector motors without power loss".

This product has already found wide application in the household of people and has widely covered people engaged in various hobbies and professional activities.

Crash test of the speed control board

This product has already found wide application in the household of people and has widely covered people engaged in various hobbies and professional activities.

Sources:

http://instrument.Guru/elektrichestvo/opisanie-regulyatora-oborotov-elektrodvigatelya-bez-poteri-moshhnosti.html
http://crast.ru/instrumenty/regulirovka-oborotov-kollektornogo-dvigatelja-bez
http://elektroplata.ru/blog-news/TDA1085

Angle Grinder angle, grinder, losing, reduce, speed