Comparison Scheppach DS930 vs Scheppach DS920

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 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).

— 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.

— 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 da...ta about 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").

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.