Comparison Jet JSSG-10 230 mm / 200 W vs Makita GB602 150 mm

without sharpening discs

Type, in other words, the general purpose of the machine.

— Sharpening. In accordance with the name, the main purpose of such units is to sharpen the cutting edges of various tools — from knives, chisels, etc. to saw blades and chains of mechanical saws (for more details, see "Sharpening"). Such processing is carried out due to the rotation of the abrasive disc. The traditional, familiar to many grinding machine (grindstone) has two discs on the sides of the casing with the engine; however, there are often models that differ in design (especially among specialized units, for example, for sharpening chains).

— Grinding. Grinding in the general sense is called all machines for grinding — semi-finishing and finishing of various surfaces. However, only aggregates that are not related to surface grinding are included in this category (for the latter, see below). Such machines can use different types of work items. One of the most popular options is a sanding belt mounted on two pulleys and moving due to their rotation; such a tape can be located both horizontally and vertically (“on the edge”). Another common type of work item is a disk on which sanding paper is attached. At the same time, unlike a grinding machine, the role of the working surface is played not by the edge of the disk, but by the round surface itself; this, in particular, allows you to vary the intensity of processing by moving...the workpiece closer to the centre of the circle (where the speed of movement is lower) or vice versa. There are also combined models — for two rotation modules (see below), combining both types of work items. A separate category are spindle grinders working with sleeves (see "Working element").

— Grinding and grinding. Models that combine the capabilities of grinding and grinding machines (see above). Usually, such a unit is similar to a classic grindstone with two rotation modules, in which a sanding belt or brush is installed instead of one of the discs. Thus, both sharpening and grinding can be performed on one machine. The downside of this versatility is that both in terms of grinding and grinding capabilities, such machines are inferior to specialized models. Therefore, this option is designed mainly for situations where versatility is more important than advanced functionality.

— Grinding and polishing. Machines designed both for sharpening tools and for polishing — fine finishing of the surface of the material being processed, making it smooth and shiny. Polishing can be carried out according to the same principle as sharpening — using a rotating disk; therefore, most often machines with a polishing function are positioned as combined grinding and polishing machines. Such units are often equipped with an engraver on a flexible shaft (see below). Note that they are usually somewhat smaller than "pure" grinders, use smaller discs and are less suitable for rough work.

— Polishing. This type of machine tool is similar in design to the grinding and polishing machines described above; the key difference is that the polishers only use smooth polishing pads, and are not designed for abrasive sharpening tips (even if it is technically possible to install such a sharpening tip). Such units are less versatile than grinding and polishing units, and they do not have key advantages over them; therefore, purely polishing machines have not received much distribution.

— Surface grinding. A type of grinding machine, designed primarily for the processing of flat surfaces, including conjugated. Such aggregates are fundamentally different from the "ordinary" grinding (see above) in design and mode of operation. They use a working element in the form of an abrasive disk fixed above the desktop; this table, in turn, is fixed on a massive frame, and the workpiece on it is installed in a special fixture and moves under a rotating disk during processing. Surface grinders make it easy to process large surfaces, but they are very massive, bulky and expensive, and therefore are considered professional (and even industrial) class equipment.

Rated power of the electric motor of the machine. The more powerful the engine, the higher the speed and intensity of processing can be, the larger discs can be used with the machine and the better it is suitable for working with hard, stubborn materials. On the other hand, a powerful motor consumes a lot of energy (which may require special connection — see "Power") and significantly affects the dimensions, weight and price of the entire unit. Therefore, manufacturers choose this parameter based on the type (see "Machine") and the desired characteristics of speed, productivity, etc. In fact, this means that engine power is rather a secondary parameter, and when choosing, it makes sense to pay attention to more practical points — disk diameter, rotation / movement speed, etc.

Types of tools and other devices for which the unit with sharpening functions is designed to work (see "Machine")

— Chains. Grinding machines for sharpening the working blades of chain saws — the actual chains. The teeth on such chains require special processing — in particular, the use of thin discs. The machines themselves also have a specific design — most often the rotation module (it is one) is installed in an inclined position on a fixed base and can be raised / lowered (although there are other design options).

— Drill. Units for this purpose, usually, have nests where drills are inserted during processing; each socket is designed for a different drill diameter. Theoretically, the drill can be sharpened on a universal machine (see below), but this requires certain skills — while processing on a specialized machine, on the contrary, is extremely simple.

— Knives. In this case, we mean models that have specialized equipment for working with knives, scissors and other similar bladed tools. Such equipment ensures that the tool being sharpened is held in the optimal position relative to the disk and reduces the risk of “messing up” during sharpening, making this type of machine generally more convenient than universal ones (which are also often used for sharpening knives). On the other hand, knife equipment may not be suitable for some specific...jobs.

— Milling cutters and drills. Machine tools designed to work with drills and cutters, usually, are rather complex units equipped with clamps with an abundance of adjustments. This allows you to easily set the optimal position of the tool being sharpened, and also provides other features necessary for this type of work. At the same time, the design features of such machines make them suitable for universal sharpening, this option, usually, is also indicated in the characteristics.

— Saw blades. Models for sharpening circular saw blades have two distinctive features: a small blade thickness that allows you to work without problems in the space between individual teeth, and a special attachment for the saw blade — usually in the form of a freely rotating axis with a clamp. The disk is fixed on this axis, after which each tooth is processed in turn by the disk.

— Universal. In this case, traditional sharpening is meant using a rotating disk of a rather large thickness, in which the tool to be sharpened is processed by the side of this disk and is held, usually, manually. This sharpening method is really suitable for a very wide variety of tools and fixtures, with a certain skill and the availability of appropriate disks, drills, knives and even saw blades and chains can be sharpened in this way. The main disadvantage of universal sharpening can be called the manual hold itself: it is less reliable than using clamps, and besides, the operator requires a rather high accuracy of movements — otherwise, the quality of sharpening can be worsened, or even ruin the tool. However, some machines with this function are equipped with fixtures for workpieces.

There are grinders that combine several types of sharpening described above — for example, models in which one of the rotating modules is supplemented with a mount for saw blades, or units with recesses of various shapes — for knives and drills.

Regular diameter of the disk (see "Working element") used by the machine for dry processing (see above). When grinding and polishing, usually, we are talking about the maximum diameter of the disk that can be installed on the tool — a larger nozzle will either be ineffective or not fit into the dimensions of the seat at all, but a smaller diameter disk, usually, is installed without problems (of course, if the hole diameter matches — see below). For grinding machines, the diameter of the disc corresponds to the diameter of the sanding pad, which is necessary for the full use of the disc.

The larger the regular disk — the heavier and more powerful the machine, usually, the better it can cope with complex work of a large volume. At the same time, for small everyday tasks like periodically sharpening knives or chisels, a small disc is quite enough.

The bore diameter of the dry cutting discs (see above) used by the machine. In order for the nozzle to be used normally with the machine, it must match it not only in diameter and thickness (see the relevant paragraphs), but also in the size of the mounting hole.

The thickness of the "dry" blade (see "Dry Machining") for which the machine is designed. Usually, we are talking about the maximum thickness of the disc that can fit on the seat — most models allow the use of thinner nozzles.

Note that this parameter depends on the type of sharpening (see above): working with chains and saw blades involves a small thickness of the discs, universal sharpening is the opposite. And for grinding models, the thickness of the disc is not relevant at all, even if the disc is provided in the design; see "Machine" for details.

The nominal speed of rotation of the disk for dry processing (see above), provided by the machine; for models with adjustable rotation (see below), the maximum rotation speed.

For the same disc diameter and material, a higher speed provides more intensive processing, and a slower rotation contributes to accuracy and precision. In addition, optimal speeds depend on the composition of the disc and the material being processed; detailed recommendations with specific figures for a particular situation can be found in special sources.

A separate category is grinding machines with disk-shaped working elements: in such units, the actual speed of movement of the disk surface relative to the workpiece depends on how close the contact point is to the centre of the disk.

Wet processing involves the supply of water or other liquid to the working element during operation. This mode is found only in models with grinding functions (see "Machine"). The disc rotates at a relatively low speed. Due to the combination of water cooling and low speed, the risk of overheating and spoiling the machined tool is reduced to almost zero; in some cases (for example, when sharpening blades made of carbon tool steel), this is especially important. In addition, “wet” sharpening is more accurate, the process waste does not scatter around so much. On the other hand, the low rotation speed of the disk imposes its own limitations on the use of this method, and the machines turn out to be heavier, bulkier and more expensive than completely “dry” counterparts.

Regular diameter of the disk (see "Working element") used by the machine for wet processing. Unlike dry sharpening, in this case, this parameter most often describes not the maximum, but the optimal diameter of the nozzle for a given machine: a disc that is too small may simply not reach the liquid poured into the working bath.

If the machine is purchased for infrequent everyday use, this parameter can be ignored; but for large volumes of work it is recommended to use larger discs.