The dial gauge is a device designed for relative measurements of shape deviations, external dimensions, and surface locations. It represents a system of connecting gears and levers that enhance the movement of the rod and transform these movements into readings. In most watch-type devices, moving the measuring rod of the device by one millimeter corresponds to one turn of the arrow. In this case, the division price, and therefore, the value of the movement of the rod, which the device allows you to reliably measure, is 0.01 mm. The measurement limits are 0-5 mm and 0-10 mm. Sentinel indicators come in three accuracy classes: zero, first, and second. Zero-type devices allow the smallest measurement error, and the second class - the largest error.
For the purpose of relative measurements in the field of metalwork and tool production in labor-intensive places and in the manufacture of various parts, a lever-gear indicator of especially small overall dimensions is used.
The dial indicator is also used to measure the runout of cylindrical parts or to check the parallel sides of the product, for example, prisms. In order to determine the runout value, the part must be installed on the centers of a special device.
All watch indicators are unified. Models of devices are splashproof based on three stones, with unloading in the event of an impact on the rod, with a measuring range of 0-25 mm and 0-50 mm.
The dial gauge is capable of measuring the depth of drilled holes. Such devices, like micrometers, have an accuracy of 0.01 mm. The small arrow of the device indicates millimeters, and the large arrow indicates hundredths of a millimeter. To measure the inner diameter, use a special device worn on the indicator.
The hour indicator is used to determine the deviation in size or position of the part being checked. Due to the fact that the dial is divided into 100 parts, the countdown is made with an accuracy of 0.005 mm. The dial of the device has a two-sided calibration from zero: divisions to the right side indicate the deviation of dimensions in the direction of increase, respectively, to the left - in the direction of decrease.
To measure linear values, deviations of the geometric shape, as well as the relative positioning of the surfaces of the parts, a dial-type indicator with additional devices is used. Such measurements are carried out using the method of absolute measurements, when the measured value does not exceed the limit of measurement of the scale of the device, and by the method of relative measurement, by checking with an end measure of length.
There are indicators based on the use of gearing. In such devices, a spring-loaded measuring rod and a gear rack are structurally made as a single unit. The rack is meshed with a 16-toothed wheel.
In conclusion, we note that watch-type indicators are the most common and widely used measuring devices in the designs and elements of control devices. These devices with a division value of 0.01 mm are used extremely rarely - firstly, from the fact that the control of parts and workpieces does not require such high accuracy, and secondly, due to the rapid wear of measuring devices when working in blacksmithing conditions stamping and foundries.