Makita Speed Angle Grinder
If the angle grinder is not equipped with a speed regulator, is it possible to install it yourself?
Most angle grinders (angle grinders), in the common people of the grinders, have a speed control.
The speed controller is located on the angle grinder body
Consideration of the various adjustments you need to start with the analysis of the electrical circuit of the angle grinder.
simplest electrical diagram of a grinder
advanced models automatically support rotation speed regardless of the load, but more often there are tools with manual adjustment of the disk speed. If a hammer type regulator is used on a drill or an electric screwdriver, then this principle is not possible on a angle grinder. Firstly. the features of the tool suggest a different grip when working. Secondly, adjustment during operation is unacceptable, therefore, the speed value is set when the motor is off.
Why do I need to adjust the speed of rotation of the disk with an angle grinder?
- When cutting metal of different thicknesses, the quality of work greatly depends on the speed of rotation of the disk.
If you cut hard and thick material. it is necessary to maintain maximum speed. When processing thin sheet metal or soft metal (for example, aluminum), high revolutions will lead to edge melting or rapid washing of the working surface of the disk;
- Cutting and cutting stone and tile at high speed can be dangerous.
In addition, a disk that spins at high speeds knocks small pieces out of the material, making the cutting surface chipped. over, for different types of stone, different speeds are selected. Some minerals are processed at high speeds;
- Grinding and polishing are not possible in principle without speed control.
Incorrectly setting the speed, you can spoil the surface, especially if it is a paint coating on a car or material with a low melting point;
- The use of discs of different diameters automatically implies the mandatory presence of a regulator.
Changing the Ø115 mm disk to Ø230 mm, the rotation speed must be reduced by almost half. And it’s almost impossible to hold an angle grinder with a 230 mm disc rotating at a speed of 10,000 rpm;
- Polishing of stone and concrete surfaces depending on the type of crowns used is carried out at different speeds. over, with a decrease in the rotation speed, the torque should not decrease;
- When using diamond blades, it is necessary to reduce the number of revolutions, since from overheating their surface quickly fails.
Of course, if your angle grinder works only as a pipe cutter, angle and profile, a speed control is not required. And with the universal and versatile use of angle grinders, it is vital.
Video: Makita Speed Angle Grinder
Typical speed controller circuit
This is what the RPM board looks like.
The engine speed regulator is not just a variable resistor that reduces the voltage. Electronic control of the magnitude of the current strength is necessary, otherwise, with a decrease in speed, the power, and accordingly the torque, will be proportionally reduced. In the end, there will come a critically small amount of voltage when, at 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 scheme.
And more advanced (and therefore expensive) models are equipped with regulators based on an integrated circuit.
Integrated circuit controller. (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 master is able to purchase such a model. And without these electronic units there will be only an electric motor winding and a power button.
The reliability of modern electronic components of angle grinders exceeds the resource of the motor windings, so you should not be afraid of acquiring a power tool equipped with such devices. The limiter can only be the price of the product. over, users of low-cost models without a regulator sooner or later come to their independent installation. The block can be purchased ready-made or made independently.
DIY speed controller
Attempts to adapt a conventional dimmer to adjust the brightness of the lamp will not work. Firstly, 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 electric motor winding. Therefore, you have to mount a separate circuit, and figure out how to place it in the tool body.
Homemade speed controller
The simplest thyristor speed controller can easily be done independently. To do this, you need five radio elements that are sold on any radio market.
Circuit diagram thyristor speed controller for your instrument
The compact design allows you to place the circuit in the angle grinder housing without compromising ergonomics and reliability. However, this scheme does not allow you to save torque when the speed drops. The option is suitable for reducing speed when cutting thin tin, carrying out polishing work, processing soft metals.
If your angle grinder is used for stone processing, or you can install disks larger than 180 mm on it, you need to assemble a more complex scheme, where the KR1182PM1 chip, or its foreign counterpart, is used as a control module.
The circuit diagram of speed control using a chip KR1182PM1
This scheme controls the current strength at any speed, and allows you to minimize the loss of torque when they are reduced. In addition, this scheme treats the engine more carefully, prolonging 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 is equipped with a regulator (automatic machine or socket), and the speed is adjusted remotely.
Regardless of the method of execution, the rotary angle grinder expands the capabilities of the tool and adds comfort when using it.