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.
Oscillation speed
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.
Oscillation amplitude
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).
Tape/sheet length
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).
Belt / sheet width
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).
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.
Power cord length
The length of the network cable can tell you how far from the outlet you can operate the device. Therefore, for domestic use, it is more relevant to choose models with a short cord, for construction work or use in production, in the garage a
longer cable is better.
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.
