Marking caliper: device, types, tips on the choice

The most famous tool for accurate measurements is a caliper, it is simple and at the same time allows you to do measurements, the limit of the error of which does not exceed hundredths of the millimeter. One of the varieties is a marking caller (VCD), designed for both linear dimensions and surface markup with great accuracy.

Principle of operation

This device is arranged in the same way as the usual caliper. He has a rod – a rod from solid alloy with a division scale inflicted on it. A sliding frame is attached to the rail, which you can move along the bar. There are 2 sponges with attacks from carbide plates with a marking caller – One of them is fixed, is one of the ends of the bar. Other is on the frame and moves with it.

Between the sponges, you can clamp the measured part, while the frame is fixed with a special screw. Usually, the caliper has another couple of sponges designed to withdraw internal sizes.

Some models are equipped with a depthine meter that allows you to measure the depth of holes, grooves and grooves. The most important element of the device, due to which the measurement accuracy is achieved, this is a reference device.

The easiest option is nonius, which is a conventional division scale applied to one of the edges of the slot frame. Instead of nonius, a clock type dial or special computer can be a reference device. The marking option of the instrument has a design identical to the described, and a few more features.

  • Circular layout system. This device is needed for convenience when conducting marking works.
  • The material of high hardness sponges and their pointed form, which makes it possible to mark the markup of metal and increases accuracy, minimizing the deformation of sponges.

    The main technical conditions define GOST 166-89. The most important characteristics that should be considered when choosing, such.

    • measurement range. Calcirculators with carbide sponges 250 mm, 300 mm and 400 mm refer to tools with the widest range in this category.
    • Permissible error limit. Depending on the range and the accuracy class, it takes values ​​from 0.05 mm to 0.1 mm. For models with a large range (1000 mm or more) error can reach 0.2 mm.

    Calcarcules with a digital reference device more accurately mechanical.

      At the same time, both types of tools require calibration (zero mark setting), protection against pollution, frame skew to avoid accuracy loss.

      Varieties

      When choosing a specific type of measuring device, it is logical to consider its cost and its own needs. There are three main types of calipers on sale.

      The most simple and cheap models – Nonius. Have 2 scales, one of them is applied to the frame as in the design described above. To determine the linear size, you need to fix the sponges in the desired position (they must compress the measured part or tightly lay down to the inner edges of the hole, grooves, grooves), then remove measurements. Division on the rod, which turned out to be the left of the nonius zero position, shows how many millimeters is the measured length. To determine the fractional part, you need to multiply the sequence number of the first coincided with the main risk of risks on nonius on the price of its division. Then lay first and second.

      In order not to perform such an operation with each measurement, you can buy a caliper with a dial. It will allow you to see the value immediately, by the position of the arrows on the watch scale. Two described modifications refer to mechanical. Both are distinguished by durability and sufficiently high accuracy. From time to time it is necessary to check whether the zero of the nonius (or the dial arrow) coincides with the zero of the rods with closed sponges. If not – the device is not calibrated.

      In addition to these varieties there is a third type – electronic caliper. For counting distance between sponges, a special computer with a sensor having a fixed discrete step (usually 0.01). These models are more accurate, their calibration is performed with one click of the electronic scale button on zero. But they cost more, and their service life is less. They require periodic replacement of batteries.

      For domestic purposes, you can approach the mechanical caliper, and the digital tool is good for more professional measurements.

      There are slightly more special cases of the design of the device that you can consider if you have specialized measurements and markup tasks. For example, models with elongated sponges for measuring internal hard-to-reach areas or to determine the inter-axis distances.

      How to choose?

      If you want to choose a stancircle for marking, which will suit you in the best possible, first of all note the quality. Among the best manufacturers of these tools – Swiss brand TESA, Japanese Mitutoyo, German Firm MAHR. In the domestic market, the Chelyabinsk Instrumental Plant (CHIZ) and Kirov Instrumental Plant (Krin) are confidently.

      It is worth take into account the functional features of each of the models. There is a standard device configuration, it is marked by a special designation of the SC-I. This is a simple variant with two measuring sponges. If you need to do measurements, such as hole diameters, pipes, any internal dimensions, it is better to stop your choice on the SC-II with an additional pair of sponges designed just for this.

      Models with a dial (circular scale) are distinguished by marking Shto. If you do not seek to buy the most cheap version of the caliper, it makes sense to choose from them, because it is easier to work with the dial than with the divisions of Nonius. If your goal is to buy an expensive tool with higher accuracy indicators, then you will fit the Digital Device of the Shtsz, with which you can perform measurements and markup up to 0.02 mm.

      Depending on what range you are going to produce measurements, choose a tool with an optimal length of the rod.

      There are compact models for sizes not more than 20 cm, but if you want to shoot exact dimensions, say, during construction, you can buy a specialized caliper with a length of the rod up to 1 m and more. Just keep in mind that he can have more measurement errors.

      Finally, do not forget about the specifics of the surface, for the markup of which the caliper will be used. Steel used in mechanical engineering, titanium and various solid alloys are difficult to place a conventional tool. You can choose a model with the labeling of the STCT – with sponges from alloying hardness. They can be subject to higher loads without risk damage.

      Many are concerned about the question, is there any danger to get marriage or fake. The chance of what it happens, boils down to zero, if you buy or order a tool in the official brand store. It is quite another thing if you buy from the supplier without a dealer license. Maybe they are selling cheaper, but in this case the products can really be counterfeit. The same applies to many cheap Chinese models of caliper. When buying, be sure to check whether the frame is easily moving, whether it does not fall into the skew, whether the zero corresponds to the nonius (or the arrow on the dial) the beginning of the main scale with closed sponges.

      How to redo the usual caliper in the markup, look next.

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