- What is a grinder: device and technical characteristics of the tool
- How to choose the right grinder
- Diameter of used circles
- Spindle speed
- Tool power
- Additional options for comfortable work
The grinder, she is an angle grinder, allows you to cut, grind, polish various materials. But the convenience of working with the tool and its effectiveness depend on how correctly it is selected for the tasks at hand. In this article, we’ll talk about how to choose a grinder for home use..
What is a grinder: device and technical characteristics of the tool
This instrument appeared in the union about four decades ago. Its popular name “Bulgarian” comes from the name of the country that began to supply the first models to the USSR. In fact, the angle grinder appeared much earlier. In the 40s, the German manufacturer AEG launched the mass production of these power tools, and almost 30 years later the Bulgarian plant Elprom-Lovech established their production and supply to the union on the basis of the acquired patent.
Today, the grinder is an integral attribute not only in the industry, but also in almost every garage. It can be used to cut metal, stone, concrete and other materials, clean, grind and polish surfaces, sharpen garden tools and tools. This multifunctionality has led to the well-deserved popularity of angle grinders.
The device of grinders from different manufacturers in the main units does not differ significantly, with the exception of minor features. Any angle grinder consists of the following basic modules:
- Tool body – usually it has increased resistance to damage.
- Metal housing angular gearbox.
- Electric motor.
- Control electronics – start button, spindle speed controller, soft start module.
- Protective cover.
More expensive and professional models may have additional modules that help protect the device from breakdowns – release couplings, electric motor protection systems when the tool is jammed in the material, noise suppression filters. It should be noted that for the production of such grinders, better and stronger materials are used that will last longer..
The principle of operation of the angle grinder is to transfer the rotation of the motor rotor through a gearbox to a spindle with a cutting disc when you press the start button.
How to choose the right grinder
The choice of an angle grinder is mainly dictated by the planned frequency of its use. It makes no sense to spend money on a large powerful unit, the task of which will be to cut metal corners or pipes a couple of times a week, working with it for 15–20 minutes. It’s another matter if you are considering daily use in a garage workshop or when building a house. The tool for these tasks must withstand heavy loads and continuous operation. It is also important to evaluate the properties and parameters of the materials on which the work will be mainly carried out. After such an analysis, there will already be a certain understanding of which grinder to select according to the technical characteristics.
The characteristics by which it is customary to classify angle grinders have a certain relationship with each other. So, the maximum diameter of the disc affects the power of the grinder and the speed. The more powerful the engine, the more weight the tool will have, but the depth of cut also increases with the diameter of the disc..
Diameter of used circles
The diameters of cutting discs for angle grinders are in the range of 115–230 mm. According to this parameter, it is customary to divide all grinders into three groups: small, medium and large.
The first group includes tools with which circles up to 125 mm can be used. These grinders are very popular in everyday life, since they are small in size, light in weight and allow you to solve most of the same tasks as a large tool within the limits of the circle diameter.
Medium angle grinders include models with a permissible diameter of used circles from 150 to 180 mm. Tools of this class are already able to work for a longer time without the danger of overheating and failure. They are well suited for construction work, repairs, plumbing, but their weight and dimensions complicate their everyday use..
Large grinders, on which wheels up to Ø 230 are used, are designed for daily intensive work and are more suitable for industrial use or processing materials with high hardness. It makes no sense to consider such a tool for small household needs..
This parameter is inversely proportional to the previous one. The larger the disc diameter, the lower the required revolutions. This is due to the limitation of the linear speed of the cutting edge of the disc during rotation. The maximum value for safe operation is 80 m / s. Exceeding this parameter can lead to rupture of the disc, which can be dangerous for the life and health of the operator. At low line speed, the wheel is subject to more wear with a loss of productivity.
Usually the optimum speed is set by the manufacturer according to the largest allowable disc diameter. But since the discs tend to wear out, it will not be superfluous to have a function that allows you to manually adjust the speed. This will allow you to use the full potential of even those discs that have some wear..
Perhaps the most important parameter for determining tool performance. Power directly depends on the size of the circles that are allowed for use with a particular model..
Household grinders have engines with a power of 0.75–1.4 kW. Power below 0.75 kW is often not enough even for simple tasks, and grinders with an engine of about 1.5 kW are already relatively heavy. Therefore, the best option for a household angle grinder would be a 0.8-0.9 kW engine.
For regular work and continuous loads, more powerful grinders with motors from 2 kW are used. Such a tool has good resistance to overheating and is capable of working in cycles for several hours with interruptions. In addition, the torque of such grinders is higher than that of household ones, which also has a positive effect on productivity. This allows them to run at lower revs with larger circles at the same potential..
Additional options for comfortable work
Here, perhaps, you need to start with security. It is very important that the tool has a good comfortable grip. Not only the convenience of working with the grinder, but also its safety will depend on how well thought out the ergonomics of this part. The rubberized grip with grooves for fingers will not slip out of your hands when jerking or pushing the tool during operation. It is preferable to buy a tool with an additional handle, if it is provided by the design. It will also improve comfort and safety..
The soft start system is designed for a uniform set of revolutions when the grinder is turned on. In this mode, the tool smoothly reaches the working speed, which has a positive effect on the service life of the units. This function also helps to eliminate line voltage drop at start. It is possible to visually check the correctness of the soft start operation only with a heavy wheel.
Disc jamming protection is implemented through a special release clutch, which is triggered when the disc gets stuck in the material. This function can prevent possible breakage of tool assemblies and destruction of the wheel. In expensive models, an electronic system is used, which is responsible for the emergency stop of the engine in such cases..
Less common features such as automatic disc balancing, disc brake, detachable power cable, quick access to brushes, main handle adjustment. These functions have not yet received widespread adoption, but each of them adds convenience to the operation of the tool. How important they will be for specific conditions should be assessed independently. Everything depends on the final cost of the grinder.
When choosing a grinder, it is important to pay attention to the length of the power cord and the quality of the insulating material. The margin of length should be sufficient so that the cord does not break and is not too taut during operation. The insulation material must retain its properties at different temperatures. Poor quality insulation can lose its elasticity at subzero temperatures, leading to its destruction and the risk of electric shock.
We told you about safety with angle grinders in the article “Safety when working with a grinder”, and about correct work with a grinder “How to work correctly and safely with a grinder”.