Comparison Bosch PAM 220 0603676020 vs Bosch DWM 40 L Professional 0601096603

Working length of the tool. The meaning of this parameter may be different, depending on the type (see above) and design features. So, for bubble levels, rules and inclinometers, the total length is indicated, while in sliding models (see "Functions") data are given for the maximum length, unfolded. For goniometers, on the contrary, the length is indicated by the size of the main bar, that is, in the folded state; and for hydraulic levels, a slightly different parameter is used — the length of the hose, it is given separately (see below).

In general, the longer the tool — the larger the surface it can measure or (in the case of rules) process, the more advanced and professional this model is considered. On the other hand, a longer fixture will also be more expensive and cumbersome, and in cramped conditions, problems may arise up to the complete impossibility of use. Therefore, when choosing, you need to take into account the specifics of the work and the scale of the proposed measurements. For example, for ordinary home repairs, a level of 40 – 50 cm is quite enough, for the construction of a small extension, you should choose a larger model, by 70 – 80 centimeters, and the length of high-quality bubble levels can exceed 3 m. At the same time, very small instruments of this type are also produced — from 7 cm. Such pocket levels can be useful, for example, for calibrating a geodetic instrument that...does not have its own alignment tools. And you can carry it in your pocket, bag, tool box. But the rules, by definition, are made long — from 1 m.

Tool width. In fact, the width of the rib corresponds to the width of the front panel — that is, the main operating panel, from which the "vertical" and "oblique" capsules are visible, on which the digital display is located, etc.

The large width adds strength to the tool and reduces the chance of deformation, but makes it difficult to use in narrow spaces: for example, a mirror capsule may be required to control the vertical in a narrow gap (see "Functions"). Note that long tools are inevitably made wide — otherwise it would be impossible to provide the necessary strength.

Tool size in thickness, from front to back. In fact, this is the smallest slit in which this fixture can be placed during measurements (although some measurements may require a mirror capsule, see "Functions"). Therefore, for work in cramped conditions, it is worth using thinner models. At the same time, note that long and heavy tools are inevitably made quite thick — to ensure strength and resistance to deformation.

The measurement accuracy provided by the level, or rather, the maximum error that can occur during measurements.

In this case, linear accuracy is meant, measured in millimetres per metre. The meaning of this parameter can be described using an example as follows: if the tool has a length of 1 m, an accuracy of 1 mm / m and shows a flat horizontal line, the difference in height between its edges will be less than 1 mm. In the case of levels, such an indicator is clearer than the error in degrees. And for goniometers and inclinometers, the accuracy in mm / m is indicated mainly for horizontal and vertical measurements; for angular measurements, the accuracy in degrees is relevant (see below).

The higher the accuracy, the better the tool, the less measurement errors it gives, however, this parameter also affects the price accordingly. Therefore, it rarely makes sense to specifically look for a high-precision level — for most work, an error of 1 – 2 mm per metre, provided by modern models, is considered quite acceptable.

Note that in the characteristics it is customary to indicate the minimum value of the error. This must be remembered in light of the fact that the measurement accuracy may vary in different modes — for example, for a folding tool (see "Functions") it is higher in the folded position.

The accuracy of angle measurements provided by the tool, or rather, the maximum error in degrees that can occur during measurements. This parameter is given for devices originally intended for measuring angles — goniometers and inclinometers (see "Type"). With such measurements, linear accuracy (in millimetres per metre) is not applicable.

The lower the error, the more accurate the instrument will be, the smaller the difference between the actual angle value and the instrument readings can be. On the other hand, high accuracy has a corresponding effect on the price. Therefore, when choosing, you need to take into account the specifics of the work — how important high measurement accuracy is for them.

— Scale for measuring length. Own scale for measuring length, printed on a level or other tool; Essentially a built-in line. Constantly using a level instead of a ruler does not make sense because of the bulkiness, but this function can still be useful — for example, in situations where you suddenly need to measure something, but there is no ruler at hand.

— Mirror capsule. The presence of a mirror capsule in the design of the tool. Such a capsule is, in fact, a regular vertical control capsule, supplemented with a special mirror. The usual "vertical" capsule is possible only from the front (wide) side of the instrument; thus, a tool without a mirror is useless for vertical control in cramped places, the width of which is less than the width of the rib (see above). But in the presence of a mirror capsule, the level can be inserted into the slot with a narrow side, and the position of the bubble will still be visible thanks to a special slot with a mirror installed in it.

— Hole for gripping. The presence of a special slot in the design of the level, which allows you to comfortably hold it in your hands. In devices with a large length of such slots, two can be provided, for both hands. Anyway, holding by the slot is often not only more comfortable, but also more reliable than the usual outside grip.

— Magnetic base. The presence of a magnetic base in the design of the tool. Such a...base allows you to tightly “stick” to metal surfaces, which not only reduces the risk of dropping the tool, but also has a positive effect on measurement accuracy. Usually, powerful neodymium magnets are used in the design, capable of holding the level even in the “on the ceiling” position. At the same time, this function is far from always relevant, so the same model can be produced in two versions — with and without a magnetic base.

— Impact site. The ability to use the level for impact work — in other words, to knock directly on it, transferring the blow to the material under the level. This function can be very useful when laying tiles, bricks, etc. — it allows you to trim the material with the help of blows and at the same time control the quality of laying with the help of a level. Usually, the shock platform has the form of a sloping surface on one side of the level; often it is supplemented with a rubber lining that reduces wear. In the absence of such a platform, it is impossible to knock on the instrument — you can damage it.

— Digital display. The presence of a digital display in the tool design. This function is not required for classic levels — bubble capsules are enough to control the horizontal / vertical. But for a goniometer (see "Type"), the display will be useful — it affects the total cost, but provides much greater accuracy than a mechanical scale. Inclinometers, by definition, have this function. Please note that the display requires batteries of one type or another (see "Power").

— Backlight. The presence of illumination in the design of the level. It can be both for the digital display (see above) installed in the instrument, and for capsules. This feature makes level operation independent of ambient light and will be especially useful in low light conditions — by turning on the backlight, you can easily see the values in twilight or even in complete darkness.

— Extendable design. The ability to lay out the tool, increasing its working length. This feature is found mainly in "large-caliber" levels with a working length of 3 m or more. On the one hand, in some situations, such a length is indispensable from a practical point of view, while making a clumsy tool of this size does not make sense — the design would be too bulky and inconvenient to store and transport. Folding allows you to significantly reduce the length — usually, by more than a third, for example, from 320 cm to 180 cm. On the other hand, an additional mechanism adversely affects the accuracy of measurements — often when unfolded, it is lower than when folded; and as the moving parts wear and loosen, the error increases even more. Therefore, manufacturers try to do without a sliding structure as far as possible and provide it only when it is practically impossible to do without it.

— Laser pointer. The presence of a laser pointer in the tool design. This function is found exclusively in inclinometers — the laser beam plays the role of continuing the tool, increasing the working length to 20 – 30 m (see "Measurement range"). This provides many additional possibilities: for example, you can determine the attachment point of a long inclined beam by installing an inclinometer at the location of the beam base and tilting it to the required angle — a laser mark will indicate the attachment point of the upper end of the beam.

The presence of a case or cover in the tool kit.

A case is a container made of rigid material, sometimes with a carrying handle; cover — soft case. These devices are similar in purpose — they protect the instrument from negative factors such as dust, moisture, temperature changes, etc., as well as from unnecessary contacts with foreign objects (which could damage both the instrument itself and these objects). At the same time, the cases are stronger and more reliable, and the covers are more convenient to transport, because. are more compact and can even "squeeze" somewhat.

You can store or transport the tool in an impromptu package, but the complete one is usually more reliable and convenient — all the more, you don’t need to look for and select it yourself.