A dial indicator is a precision mechanical measuring instrument that utilizes the lever-gear amplification principle. It is primarily used to measure minute dimensional variations, geometric errors, and the relative positional accuracy of workpieces.

1. What is dial indicator 

**Main Structural Components**

**Stylus/Probe:** Directly contacts the workpiece and senses minute displacements.

**Lever System:** The core transmission mechanism that amplifies and transfers the stylus displacement.

**Gear Mechanism:** Further amplifies the displacement and drives the rotation of the pointer.

**Dial and Pointer:** Display the measurement results; one full revolution of the pointer typically represents a displacement of 0.1 mm or 0.2 mm.

**Bezel:** A rotatable ring used for zero-point adjustment.

**Clamping Shank/Dovetail Mount:** Used to secure the dial indicator to a base or stand.

**Spring:** Provides the measuring force and ensures the return of the stylus.

2. Working Principle of the Lever Dial Indicator

This type of dial indicator achieves visualization of minute displacements through a two-stage amplification system. When the probe contacts the workpiece and generates a minute displacement, the lever system first performs the primary amplification of this displacement.

The displacement amplified by the lever is then further amplified by a gear mechanism, driving the pointer to produce a noticeable angular movement on the dial.

The deflection angle of the pointer is proportional to the displacement of the probe, allowing users to directly read precise measurement values from the dial scale.

This design enables the lever dial indicator to magnify displacements of only a few micrometers to a level clearly visible to the naked eye, thereby achieving high-precision measurement.