Comparison Makita 9911 vs Bosch GWS 850 CE Professional 0601378792

The type of grinder determines the design features and the operation of its working mechanism.

— Corner. One of the most common and versatile types of grinders. The name is due to the device of the working mechanism, in which the drive axle and the spindle with the working nozzle are located at an angle of 90 degrees and are connected through a gearbox. It is this type of grinders that is unofficially called "grinders". The working tool is a grinding wheel. Angle grinders are used for grinding, polishing, roughing and stripping metal, concrete, brick, cement, marble and granite products. Design features also allow the use of such a tool for cutting metal and cleaning welds.

— Direct. In straight grinders, the drive shaft of the electric motor and the spindle with the working nozzle are located on the same axis, which led to the name. Most often they are used for small and precise work, they are convenient for processing hard-to-reach surfaces (the length of the spindle is of great importance). As a working tool, finger and conical grinding wheels, cutters, brushes can be used. Not designed for use with large grinding wheels such as those used in angle grinders.

— Tape. The working element of such grinders is a sanding belt connected into a ring and moving along guide rollers. Such devices are designed for rough processing and leveling of flat surfac...es, as well as the preparation of edges and bevels. Tape models have a fairly high performance, but are not designed for accurate delicate processing; in addition, they are intended mainly for relatively narrow parts, the width of which does not exceed the length of the tape (brush / drum devices are better suited for large surfaces — see below). Also note that grinders of this type do best with wood, although sanding belts are also available for other materials, including metal, concrete, plastic.

— Eccentric. In eccentric grinders, the working tool (sanding sheet) performs two movements simultaneously: rotational and vibrating. Due to this, high quality processing is achieved with good performance. These machines are well suited when a large amount of material has to be removed during fine finishing work. Unlike vibration grinding, they allow you to process not only flat, but also convex and concave surfaces.

— Vibrating. Orbital sanders use a vibrating sanding sheet driven by an eccentric on the motor shaft. With a relatively low productivity, such a scheme provides high accuracy and quality of processing. Vibration grinders are used for fine finishing of flat surfaces.

— Delta grinding. In fact, they are a kind of vibration grinders (see above), but they differ from them in the shape of the grinding sheet: it is triangular, resembling the Greek letter “delta” in shape (hence the name). Due to this, as well as their small size, these machines are well suited for working in hard-to-reach and difficult places, such as corners, edges, curves, etc.

— Multifunctional. Machines operating on the vibration principle, however, combining the capabilities of several varieties at once. Such versatility is realized through interchangeable soles, which, usually, are supplied in the kit. Thanks to such accessories, a multifunctional grinder is able, at a minimum, to turn from a conventional vibrating (with a rectangular sole) to a delta vibrating (with a triangular one) and vice versa; and some models are also equipped with a round nozzle and can also work in the eccentric format. Such a tool will be the best choice for those who have to deal with a wide variety of tasks for a vibration format machine: one universal machine with a set of interchangeable accessories is much cheaper than several more traditional tools with similar characteristics. On the other hand, a multifunctional model handles worse with each specific task than a specialized unit of a similar cost. Simply put, at the same price, a universal machine “can” more, but a specialized one (vibrating, delta grinding, etc.) is more effective in its particular area.

— Polishing. A type of angle grinder specifically designed for finishing various surfaces. Technically capable of working in grinding mode, however, the main function is still polishing and final finishing of the material.

— Brush / drum. Grinders of this type are generally similar in layout to angle grinders (see above), and the main difference is that the working nozzle does not have the shape of a flat disk, but of a characteristic cylinder, the length of which noticeably exceeds the diameter. If such a cylinder has hard bristles (usually metal) — the machine is called a brush, in other cases — a drum; however, there is no fundamental difference between these varieties, in addition, many models allow the use of both types of nozzles. This nozzle format is especially suitable for processing large flat surfaces, for which tape machines are poorly suited; specifically, the brushes are very effective, in particular, when removing paint and varnish coatings. On the other hand, removing paint is just one of many tasks that sanders have to deal with; and with other types of work available for this type of machine, vibration (including delta grinding) and eccentric models (see above) also do a good job. In addition, rotating cylindrical nozzles are not particularly accurate, they are not suitable for delicate work that requires care and precision. That is why grinders of this type are relatively rare nowadays.

— Wall grinder. A specific feature of most wall grinders is an elongated design that includes a characteristic rod (see "Complete set"). This allows you to grab a large section of the wall without moving from your place, as well as work at high heights without using stools or other similar supports. However, wall grinding models are produced without a rod. Such devices, usually, are a slightly modified version of the angle machines described above. Of the differences, in addition to the use of a rod, one can also mention the method of attaching the working nozzle — it is installed on Hook-and-loop or other similar devices, similar to how it is done in an eccentric tool.

— Grinder for concrete. Most stone/concrete grinders are similar in design to angle grinders (see above), although there are other variations. Anyway, such tools are quite powerful, and their design is designed for long-term operation in difficult conditions: for example, overload protection is often found (see "Additional"), a system for supplying water to the place of work, etc. can be provided.

Power delivered during work directly to the working nozzle. High power, on the one hand, contributes to performance, on the other hand, it significantly affects the dimensions, weight and price. Therefore, it is worth choosing a tool for this parameter, taking into account the specifics of the planned work; recommendations on specific power values for different types of work can be found in special sources.

The power consumed by the grinder during operation. Usually more than the output (useful) power (see above) due to losses during the conversion of energy from electrical to mechanical. However, the general patterns in this case are the same: a more powerful tool, on the one hand, is usually more performant, on the other hand, it is heavier, larger and more expensive. In addition, the total electricity consumption depends on this indicator; however, grinders, even the most powerful ones, consume relatively little energy, and difficulties can arise only when connecting a high-performance professional tool to weak electrical wiring.

Note that it is much easier to determine the consumed power than the useful one; therefore, only this parameter is often indicated in the characteristics, without specifying the useful power. In general, it is quite possible to compare grinders of the same type using it (see above): a modern tool has approximately the same efficiency, and in most cases the useful power values bare related in the same way as the consumed values.

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.

The maximum disc size that can be installed in a grinder of the appropriate design (see “Type”). Most models are capable of working with nozzles of smaller diameter, but a rim that is too large simply will not fit on the tool due to size limitations.

The larger the disc, the larger the processing area and the depth of cut provided by the grinder. On the other hand, rotating a larger attachment requires corresponding power, which, in turn, affects the price, dimensions and weight of the entire tool. So you should choose according to this parameter taking into account the specific tasks for which you plan to use the machine. Detailed recommendations on this matter can be found in special sources; Here we note that discs are conventionally divided into small (up to 125 mm), medium (up to 230 mm) and large (230 mm or more).

Belt speed provided by the grinder. For more information about belt units, see "Type". In this paragraph, both one value and a range can be given — if the device has a speed control (see "Additionally — Speed regulator").

Other things being equal (primarily the same belt width), a higher speed has a positive effect on productivity. On the other hand, to ensure such a speed, a more powerful engine is needed, which accordingly affects the weight, price and energy consumption of the entire tool. In addition, the low belt speed contributes to accuracy: the chance of removing excess material is reduced. So it’s definitely worth looking specifically for a “fast” grinder only if it is to be used often and for large volumes of work. In other cases, a slower model may well be the best option. More detailed recommendations on this matter (including for different materials and types of work) can be found in special sources.

The length of the belt or sheet for which the grinder is designed.

Working nozzles in the form of sheets are used in units with a vibrational principle of operation, in the form of tapes — respectively, in tape ones (for more details on both, see "Type"). Anyway, this paragraph does not indicate the working length of the tape / sheet (that is, the length of the surface adjacent to the material being processed), but the total — that is, the size of the nozzle itself. This size in itself determines only the compatibility of the grinder with certain sheets / tapes. At the same time, clamp-like fastenings (see "Sheet fastening"), used in most classic vibrating instruments, often allow you to install sheets of slightly longer lengths than indicated in the specifications. Hook-and-loop models (mostly delta sanders) technically accept both longer and shorter sheets, although in fact this is not recommended at best. But in tape tools, the length of the tape must exactly match the parameter specified in this paragraph — even a slight deviation can lead to incompatibility.

As for the working length of the tape / sheet, it inevitably turns out to be less than the total (for sheets — not much, for tapes — quite significantly). However a longer tape/sheet often has a greater working length; however, with the same general dimensions of the nozzle, its working size in different tools may be different; it is indicated in the item "Sole Size" (see below).

The width of the belt or sheet for which the grinder is designed.

Working nozzles in the form of sheets are used in units with a vibrational principle of operation, in the form of tapes — respectively, in tape ones (for more details on both, see "Type"). Anyway, this paragraph does not indicate the working width of the tape / sheet (that is, the width of the surface adjacent to the material being processed), but the total — that is, the size of the nozzle itself. This size in itself determines only the compatibility of the grinder with certain sheets / tapes. At the same time, clamp-like fasteners (see “Sheet fastening”), used in most classic vibrating instruments, usually fix the sheet only in front and behind, so that in such instruments the restrictions on width are not as strict as, for example, on length: the sheet may be somewhat wider, and somewhat narrower than the nominal size. However, such possibilities should be clarified separately, and for a full guarantee it is better to clarify whether a particular machine allows deviations in width. The situation is similar with delta sanders, where Hook-and-loop is traditionally used: a discrepancy in width technically does not prevent the installation of a nozzle, but not all models allow this. As for the band tools, they may allow the installation of a narrower band — but not a wider one.

As for the working width, it, usually, corresponds to the general one, or (in some vibration models) differs slightl...y from it. Anyway, the working width is given under Sole Size (see below).

— 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.

— 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.

— 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.

— 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.