Indicator (distance amplifying instrument)

A dial gauge is a mechanical instrument for measuring lengths or length differences. It is used for example for comparison, flatness, position or runout measurements. Gauges are manufactured with either an analog or a digital display.

For gauges with dial gauge and analogue display the longitudinal movement of the probe by means of rack and pinion is transmitted to the pointer. Thus, the pointer of the dial indicator can repeatedly turn in a circle. The number of revolutions is indicated by a further pointer, such as the hour hand of a clock indicating the number of rotations of the minute hand. The rack ratio has the advantage that the indicator has a relatively large measurement range. A disadvantage of the measured value transmission method, however, is that a massive measuring portion size is exceeded ( ie, that which must be determined measure on the DUT greatly exceeds the distance range of the rack ) with rigid locking of the dial gauge will cause gear damage or damage to the rack. Thus, repeated exceeding of the measuring path of the rack to inaccuracies, or run the so-called " trailing pointer ", which manifests itself in an extremely delayed return pointer. This means that no more tests can be performed, which relies on the value differences, so concentricity and flatness measurements.

In addition, a dial indicator is characterized in that it can also be used in traction both in print and as such return shall be the measuring rod by a spring. Thus, the measuring force applied is substantially constant.

Gauges achieve an accuracy of about 1/ 100 mm (10 microns) with a typical range of 5 to 60 mm.

For gauges with accuracy of 1/ 1000 mm ( 1 micron ) is called a dial indicator, these have by design a lower measuring range.

Have gauges, as well as micrometers and probe, hardened surfaces or bullets with which they touch the object to be measured.

Strap gauges allow for easy measurement of the thickness of sheet-like articles. For this purpose, the two measuring surfaces are pulled apart and held the object to be measured in between. After releasing both surfaces lie back onto the object and the pointer shows the thickness of the material.