How to Connect an Angle Grinder Without a Speed ​​Control

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

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

how to connect an angle grinder without speed control

angle grinder designed for cleaning and grinding various surfaces

The key to long-term use of the angle grinder is the function of its smooth start. When you turn on the tool, the magnitude of the electric current increases. The angle grinder needs to not only start the electric motor, but also quickly gain the required speed for the work. Naturally, such a sharp load negatively affects the angle grinder nodes, in particular, its electrical winding. The latter often breaks off. For this reason, many angle grinders fail after several starts. Realistically to prevent such a problem on their own. It is necessary to modify the grinder, equipping it with a built-in soft start device and a speed controller. It is assembled on a single chip.

Many advanced (and, of course, expensive) angle grinders are initially equipped with a function for regulating the rotation of the working disk. In cheap models of angle grinders, as well as in older devices, such a device is not provided. And its need is not even discussed among home craftsmen. Why? About it further.

If an angle grinder is used for cutting and cutting tiles, natural stone products, the high speed of the tool literally kills the power tool. In addition, with this treatment, small particles begin to crumble from the material. This significantly degrades the quality and appearance of the tiled or stone surface. With the function to select the required speed, processing takes place without a hitch. And the electric tool itself is completely protected from breakdowns.

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When cutting tiles and stone products, the angle grinder operates at a very high rotation speed

Also, rotation speed is important when working with metal products. For example, aluminum or tin blanks should be cut at minimum speed. But thick and hard metal, on the contrary, is processed at high speeds. Polishing and grinding work using angle grinders and it is completely impossible to effectively perform if the saw does not allow you to select the desired speed. You simply spoil the processed surface. Try to polish the wood or paintwork of the car body at a high speed of disk rotation, and you yourself will understand what is at stake.

As you can see, the revision of the angle grinder makes the device significantly more functional. There is an opportunity 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!

Video: How to Connect an Angle Grinder Without a Speed ​​Control


Elementary and very reliable in use, the speed controller for an angle grinder is made with your own hands from inexpensive electrical components. Below is a diagram that shows all the necessary elements for assembly on a circuit board of the mechanism of interest to us.

We see that we will need:

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

Such a scheme works according to the following principle. The charge time of the capacitor is changed by an additional resistor (it is called a tuning). When voltage comes to the circuit, the symmetric thyristors are in the closed position, and zero voltage is noted at the output. When charging a capacitor, an increase in voltage is observed on it, which leads to the opening of the thyristor DB3. After which 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 completely recharged in the opposite direction. As a result, at the output we get a pulse-shaped signal of complex shape. Its specific amplitude is determined by the operating time of the circuit capacitor. additional resistor. resistor R1.

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Thyristors are usually located on a printed circuit board. It is easy to make of PCB (using foil material). Some craftsmen cut the board with a cutter. It is allowed to place circuit elements by the method of wall mounting. Symmetric thyristors are installed strictly on a copper or aluminum radiator. It plays the role of an effective heat sink. Checking the assembled mechanism is carried out using a conventional incandescent lamp 40-60 watts. Connect it to the circuit, begin to adjust the brightness of the glow. If the glow changes, then you did everything right. Now you can mount the regulator in the body of the angle grinder. This is not so easy to do. After all, you need to ensure that the additional mechanism does not interfere with the operation of the angle grinder.

You will have to determine the installation site of the homemade controller yourself, focusing on the features of the design of the angle grinder. Installation of the circuit in most cases is carried out:

  • in an additional box installed on the device;
  • into the handle of the holder;
  • into a small cavity (it is intended for cooling and ensuring air circulation) in the back of an angle grinder.
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The installation site of a homemade controller is selected in connection with the design features of a particular machine

The connection of the circuit to the device itself is carried out by mounting it into the power supply channel with an angle grinder. With this, you, it seems, will not arise.

When using an angle grinder with a self-assembled circuit to select the speed of the disk, you must strictly adhere to the recommended operating modes of the device. He should be given frequent respite. This is especially important when processing any product at reduced speed. This precaution is due to strong heating angle grinder, operating on a modified voltage. If you use a angle grinder without respite, the collector will not stand up, its windings will burn out.

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

  • set the regulator to the maximum value;
  • connect the angle grinder to the network;
  • reduce the speed of rotation of the disk by the indicator necessary for the performance of work

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