dialindicator

A dial indicator, also known as a dial gauge, is a precision instrument used to measure small linear distances by translating the displacement of a spring-loaded plunger into rotation of a circular dial pointer. It is widely used in machining and metrology to assess runout, alignment, flatness, and depth.

Construction and ranges: The device consists of a spring-loaded plunger or contact point, a rigid housing, and an internal gear train that drives a circular dial with graduations. Common sizes offer ranges such as 0-1 inch (0-25 mm) or 0-2 inches (0-50 mm), with resolutions typically 0.001 inch (0.01 mm) or finer on higher-end models. The unit may feature interchangeable contact points, a bezel for reference, and a zero-setting mechanism to enable relative measurements.

Operation: The plunger moves as it contacts a surface, and this motion is amplified by the internal gearing to rotate the dial pointer. The user can set the dial to zero at a reference surface for relative measurements, or read an absolute displacement depending on the setup. Some indicators include a revolution counter to track overtravel beyond a single dial rotation.

Types and variants: The standard plunger indicator is the most common form. Variants include digital dial indicators with electronic readouts, and test indicators with shorter travel used for gauge seating and alignment. There are also specialized forms with different tip configurations or long stems for depth-related measurements.

Applications and care: Dial indicators are used to check runout on rotating parts, measure deviations in flatness or parallelism, set up and align machine components, and verify depths. Proper care involves keeping the contact point clean and intact, avoiding excessive force, and calibrating against known standards to maintain accuracy. Temperature stability and regular verification against gauge blocks are recommended.