The classic version of the sensor is called a dial sensor, and has a display similar to the face of a clock with hands. The hands indicate graduations on a circular scale on the dial, which represent the distance of the measuring tip from the zero setting. Dial gauges are typically used for relative, rather than absolute, measurements.  For example, to make sure the jaw of a vise is perpendicular to the direction of machine movement, pull the dial sensor arm over the jaw as it moves in the direction of travel.  The sensor will read how much the vise jaw is deviated from perpendicularity. It is more difficult to see relative movement on digital sensors than on an analog dial. A dial sensor is a measuring instrument used to measure linear displacement. Depending on the reading system, dial sensors can be divided into dial sensors, in which the reading is done through a clock, and electronic dial sensors, in which the reading is done directly on an electronic LED display.

The inner workings of a mechanical dial sensor are similar to the precision dial mechanisms of wristwatches, except that a rack-and-pinion gear is used to read the position of the probe, rather than a pendulum. There are teeth on the stylus of the sensor, along which the pinion gear slides. When the stylus moves, the pinion drives a mechanism that rotates the clock hand. Springs preload the gear mechanism to minimize the error of play in the reading. Because the mechanisms are delicate, a robust housing is required for the sensors to operate reliably in harsh environments, such as metalworking in machine tools.

Most electronic sensors have a switch to change the in/mm unit system and have a "hold" function to lock peak readings on the digital display. The supplied batteries provide up to 250 hours of operation.

Application of dial sensors

Dial sensors are used by engineers in many ways, some of which are outlined below:

• For setting the workpiece in the machine (lathe, milling machine, grinding machine),
• For checking spindle runout in a machine tool,
• For measuring surface roughness,
• To adjust the ignition,
• For measuring the depth of indentation in electrical discharge machining (EDM),
• For measuring height differences on a surface plate.
• For measuring the runout of brake discs and hubs.

Advantages of analog dial sensors

• The dial gauge is the most flawless tool for making linear measurements.
• It is a very effective measurement tool in ensuring the quality of the workpiece.Due to the tight tolerances, the dimensions of the tool are very small, so it can be used in mass production without problems.
• The dial gauge is also useful in checking dimensions.
• Moreover, dial sensors can also be used to measure several deviations by aligning them with other attachments.
• In addition to round shapes, conical surfaces can also be measured effectively.

Disadvantages of analog dial sensors

• The precision of dial sensors is often lost due to machine vibration.
• Space constraints can lead to installing the tool at an angle, thus losing the precision of the measuring device, the exception being 3D sensors and diatests.
• A major drawback of this tool is the parallax effect.