Rotation speed
The speed of rotation of the working attachment, which is capable of providing a grinder of the appropriate design (for example, angle — see "Type"). If the device has speed control, this paragraph shows the range of such adjustment, from minimum to maximum.
It makes sense to compare by this parameter units belonging to the same type and having the same maximum diameter of the disk (or other working nozzle). The latter is due to the fact that the larger the disk, the faster its edge moves (at the same speed); i.e. a larger diameter requires less RPM for the same performance/efficiency. In general, when comparing different models, the following should be taken into account. The higher rotation speed is well suited for large volumes of work (because it improves productivity) as well as for fine polishing with “delicate” nozzles. A lower setting, in turn, improves accuracy (reduces the chance of removing excess material), as well as provides more torque and allows you to more effectively deal with hard, stubborn materials. More detailed recommendations for different types of work and different nozzle diameters can be found in special sources; here we note that an increase in the rotation speed, usually, affects the cost of the machine compared to analogues (since this requires a more powerful engine). In addition, discs and other attachments may have maximum RPM limits.
More features
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Soft start. A function that provides smooth spin-up of the grinder motor, with relatively little acceleration. This is achieved by limiting the starting current. The soft start serves two purposes: it prevents the tool from jerking, reducing the risk of letting it go, and it reduces the load on the mains, avoiding large power surges.
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Speed controller. Possibility to limit the maximum number of engine revolutions. In fact, this function is a smooth speed control; it is useful when full speed is not required, such as delicate jobs where accuracy is more important than productivity. Note that this function is found in all types of grinders — including those with a vibration or belt principle of operation (see "Type"): even in such units, the vibration frequency or belt speed is determined precisely by engine speed.
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Maintain momentum. The ability to maintain a given number of revolutions regardless of the load on the working nozzle. This function is implemented by automation, which accordingly adjusts the engine power — increases it with an increase in load and reduces it with a decrease. A constant rotation speed has a positive effect on both the quality of processing and the service life of the working nozzles and the entire tool.
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Protection against accidental activation. The ability to block the power button,
...preventing it from being accidentally pressed. This allows you to safely move the switched off tool from place to place during work breaks without fear of accidentally turning it on. Also, this feature will be useful if there are small children nearby. And in some models, the protection can also turn on when the power is turned off (for example, network failures) — thanks to this, when the power is restored (which can happen at the most unexpected moment), the tool will not start working without the user's command.
— Electronic engine protection. A safety system that turns off the tool when the load on it increases critically. The specific way in which such protection works may vary. For example, in some models, it turns off the engine with a sharp increase in the load on the working nozzle — for example, when the disc is jammed in the material; this avoids sharp jerks of the tool, its breakage, disc destruction and other unpleasant consequences. In other models, protection reacts to overheating or a critical excess of current. There are also tools that combine both of these options.
— Brushless motor. The presence of a brushless motor in an electric grinder (see "Power supply"). Such motors are considered more advanced than traditional collector motors (with brushes): they are more economical in terms of energy consumption, less noisy and do not spark, which is important in conditions of increased fire danger. The main disadvantage of brushless motors is their high cost.
— Engine brake. A special brake that stops the rotation of the motor shaft after power is turned off. Thanks to such a device, after finishing work, you do not need to wait until the grinder nozzle finishes rotating by inertia — the rotation stops in just a couple of seconds (whereas without a brake, this may take several tens of seconds). This not only increases the safety of work, but also has a positive effect on the service life of the tool.
— Safety clutch. A protective clutch that prevents damage to the engine when the load on it is significantly increased — for example, in the event of a jammed disc. Such a coupling connects the working nozzle and the motor shaft. It can be disposable or reusable: in the first case, when overloaded, the clutch is destroyed and needs to be replaced, in the second, it is disconnected, and to continue working, it is enough to connect it back.
— Backlight. This feature is definitely desirable when working in low light conditions. However, it can also come in handy in bright external light: the place of work is often in the shade (for example, from the instrument itself), and it can be difficult to work in such conditions without special lighting.
— Display. Own display, which can display various information about the operation and status of the device. Such a screen provides additional convenience and visibility, but in general this is a rather specific function that is extremely common in modern power tools.
— Synchronization with a smartphone. The ability to connect the instrument to a smartphone or other gadget (such as a tablet) via Wi-Fi or Bluetooth. Such a connection is usually used to adjust the operating parameters; doing this through a mobile application is often more convenient than through the controls on the instrument itself.
— Anti-vibration system. Damping system that reduces the level of vibrations that occur during operation. The presence of such a system has a positive effect on both the quality of work and convenience: strong vibration of the tool leads to rapid fatigue, the anti-vibration system helps to avoid this.
— Rotary main handle. The possibility of turning the main handle of the grinder around the longitudinal axis. This function is found mainly in corner models (see "Type") — it provides additional convenience, allowing you to adjust the position of the handle to the specific situation. This can be important for working in non-standard positions and hard-to-reach places.
— 3-position additional handle. An additional handle mounted on a removable mount and having three installation options: on the left (traditional option for right-handed holding of the tool), on the right (for left-handers) and on top (for specific cases — situations when you need to periodically change the grip, work in hard-to-reach places, etc.). P.). This feature provides advanced options for customizing the instrument to your own preferences. It is found mainly in corner models (see "Type").
— Keyless disk replacement. The ability to change discs in a grinder (usually an angle grinder, see "Type") without the use of keys and other additional tools. The convenience of this function is obvious: you do not need to keep the key with you all the time, make sure that it is not lost, etc. However the keyless mount is considered somewhat less reliable than the key mount, so it is rarely found in heavy professional models.
— System of fastening X-LOCK. An advanced attachment system used on some angle grinders (see "Type"), predominantly manufactured by Bosch and Makita. This system is somewhat more expensive than the traditional 22mm nut or washer mount, but has a number of advantages over it. Firstly, X-LOCK provides the simplest and fastest installation: no need to fiddle with additional parts or tools, just put the disk on the spindle and press it until it clicks; in turn, to remove the working nozzle, it is enough to press the button that turns off the latch. Secondly, you can install the nozzle with only one, correct side to the tool — the mounting design will not allow otherwise. The main disadvantage of machines with this system is incompatibility with cheaper and more common discs for a standard 22 mm mount; and equipment for X-LOCK is not yet available in every hardware store.
— Collet chuck. Special design chuck used in straight grinders (see "Type"). The clamp of such a cartridge consists of several elastic petals (usually 2 – 3), which, when tightened, are compressed, fixing the working nozzle. The main advantages of collets are the speed and convenience in changing nozzles, simple design and low cost.
— Coolant supply(coolant). Possibility of supplying coolant to the place of work. This function is found mainly in machines for stone and concrete (see "Type"), because it is for these materials that water cooling is most relevant: it not only prevents overheating, but also prevents the formation of dust. To supply water to the machine, a nozzle is provided, which is led to the working nozzle, and a pipe for connecting to a water hose.
— Connecting the dust collector. The ability to connect a container to the tool to collect dust and other contaminants that occur during operation. Such a container can be supplied with the machine, but this is not necessary, this point should be clarified separately. Anyway, the dust collector, although it does not provide one hundred percent protection against pollution, however, significantly reduces their amount and facilitates cleaning after work. Dust collectors can be both reusable and disposable.In box
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Additional handle. Separate handle for a second hand. Theoretically, such equipment could make the instrument more comfortable to hold with two hands. However, in fact, the absence of an additional handle is often not critical: many tools without it are either intended to be held in one hand (like some straight grinders, see "Type"), or have other adaptations for a second hand (for example, a ledge on the body). So to answer the question of whether you need an additional handle, you need to take into account the type and size of the grinder, as well as the features of the planned work. Also note that by default such a handle is designed for right-handers, and the possibility of its use with left-handed holding should be specified separately.
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Charger(charger). A device for charging the battery in a grinder with the appropriate type of power supply (see "Power supply"). Also in this paragraph, a specific model of the charger is usually specified. In itself, the presence of a "charger" in the kit eliminates the need to look for and buy it separately; at the same time, such a charger is optimally suited to at least the “native” battery, and often also to other compatible batteries. And data on the model will be useful, first of all, in case the complete charger is lost or fails and you have to buy the same or similar one instead. In addition, knowing the charger model, you can find detailed data abo
...ut it and evaluate its characteristics and features (compatibility with various batteries, additional functions, etc.). At the same time , the “without charger” package is also very popular — see below for more on it.
— No charger. This feature is indicated exclusively for battery models (cars with other types of power supply — see "Power Source" — by definition do not have a charger, there is no need to specify this point for them). The meaning of this configuration is that modern grinders most often use standard batteries, which are also suitable for other power tools of the same brand and are designed, respectively, for standard “chargers”. Thus, if the "household" already has a battery tool, then the charger for it may be suitable for the grinder, you will not need to overpay for the second copy of the charger. And even if the charger is not available, usually, it can be purchased separately without much difficulty (moreover, some tools also allow you to choose the most suitable model of such a device from several options).
— Case / bag included. The presence of a case or bag for storing and transporting the tool. The case is a suitcase and is made of durable material, usually there is a place not only for the machine itself, but also for working attachments and other additional accessories. The bag is soft, which allows it to be compactly folded when there is no need for it. Check the availability of a case or bag immediately before buying.
— Dust collector. Container for collecting dust and other contaminants that occur during operation. See "Advanced — Connecting the dust box" for details.
— Barbell. A long rod significantly expands the "radius" of the tool: with such equipment, you can reach a great height, process a large area without rearranging the platform or other stand, etc. Such features are relevant primarily when processing walls, so the vast majority of grinders with rods in the kit are wall grinders(see "Type").Noise level
Approximate noise level generated by the grinder during operation. Note that this indicator is quite approximate, because. actual "loudness" can vary markedly depending on the type and shape of the material being processed, the surface it is placed on, and other circumstances. In addition, different manufacturers may use different measurement methods. Nevertheless, this indicator makes it possible to assess how comfortable this or that model is in operation and whether special hearing protection is required.
The most “quiet” modern grinders give out about 65 dB — this is comparable to loud speech at a distance of 1 m; in the loudest, the noise level reaches 107 dB — this is the volume of an industrial workshop.
Weight
The total weight of the grinder; for battery models (see "Power Source"), usually, it is indicated without taking into account the battery.
This indicator has two meanings. On the one hand,
light weight has a positive effect on manoeuvrability and reduces fatigue during work — especially when processing vertical surfaces and ceilings, as well as in other situations where the tool has to be held on weight. On the other hand, for grinders with a vibrational principle of operation (see "Type"), used for processing horizontal surfaces, a significant weight is considered optimal: it allows the tool to fit closer to the material being processed, and also contributes to stability and retention. So when choosing such a model by weight, it is worth considering the features of its intended application.