Comparison Makita BO3711 vs Makita 9910

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.

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 frequency of vibration of the working attachment, which is capable of providing a grinder of the appropriate design (a classic example is vibration, see "Type"). If the device has an oscillation frequency adjustment, this paragraph gives the range of such adjustment, from minimum to maximum.

A higher frequency (with the same amplitude — see below) improves overall performance, especially when working with hard, stubborn materials, and also contributes to efficiency in delicate finishing (such as polishing). In turn, a lower frequency reduces the likelihood of making a mistake by removing an excessive amount of material. There are also more specific points related to this parameter; them, as well as recommendations for choosing the frequency for different jobs, materials and types of sanding sheets, can be found in special sources. Here, we note that individual sanding sheets may have their own limitations or recommendations regarding the operating frequency.

The amplitude of oscillations made during the operation of the nozzle of an eccentric, vibration or delta grinding type machine (see above). Along with the frequency (see above), it is one of the most important indicators of such machines. Higher amplitude provides more intensive processing, which has a positive effect on performance; on the other hand, for delicate work, it is desirable to have a small oscillation amplitude(less than 2 mm).

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).

The size of the sole provided in the tool.

This parameter is indicated for two types of grinders — most models with a vibrational principle of operation (namely, for vibration and delta grinders, as well as multifunctional ones), as well as belt units. For more information about both, see "Type", here we note that the sole as such is only available in vibrating tools — in tape tools, we are talking about the size of the section of the tape that is in direct contact with the material. Simply put, the size of the sole is the size of the working surface of the machine.

The larger the size of this surface, the more performant the machine, the better it is suitable for large volumes of work. And tape models, we recall, are used mainly for processing oblong parts and during operation they are usually located across such a part; so that for such machines it is highly desirable that the length of the tape be not less than the width of the surface to be treated — otherwise, accurate processing can be quite difficult. On the other hand, a large sole inevitably affects the dimensions, weight, and most often the cost of the tool, besides, it can make it difficult to use in cramped conditions. Yes, and consumables for such soles (sheets, tapes) require larger ones — and, accordingly, more expensive. So when choosing according to this indicator, it is worth considering the features of the intended application; if you wish, you can refer to special sources for detailed r...ecommendations on this matter.

Also note that for multifunctional models (see "Type") in this paragraph, several options are most often given — for each specific sole. However, there are models where only one set of sizes is indicated. This can either mean that both main vibration nozzles (rectangular and triangular) have the same dimensions in length and width — or that the data is indicated for a non-removable triangular sole, on which a larger rectangular one is put on if necessary. Such details can often be clarified directly from the photographs of the goods, in extreme cases — from the manufacturer's documentation.