Dial Gauge: Features and Types

This page introduces the features and types of dial gauges, as well as the dial gauges used at TDC.

For more detailed information about the measuring instruments we use, please refer to the “Measuring Instruments” page.

What is a Dial Gauge?

A dial gauge is a precision measuring instrument used to accurately measure short linear distances. It is typically mounted on measuring fixtures (stands) or precision equipment for use.

Dial gauges are commonly used to measure deviations from a reference point or to ensure alignment. They are widely utilized in manufacturing environments where dimensional accuracy is critical.

Additionally, dial gauges are used in conjunction with machine tools, such as lathes, to measure the runout of rotating shafts or objects attached to them.

Features of Dial Gauges

Unlike calipers or micrometers, dial gauges are not used as standalone tools. Instead, they are fixed to a stand or the object being measured.

When properly mounted, dial gauges can measure not only dimensional changes but also geometric tolerances that represent three-dimensional shapes, such as flatness, roundness, inclination, coaxiality, and concentricity.

Despite their intricate internal structures, dial gauges are easy to use. When employed with the correct measuring techniques, they provide highly reliable measurements, making them an essential tool in many manufacturing environments.

Types of Dial Gauges

Dial gauges can be broadly categorized into two types: analog and digital.

• Analog Dial Gauges
  Analog dial gauges convert the linear or arc motion of a spindle equipped with a contact point into rotational motion via gears, displaying the magnitude of the movement with a scale and needle. The measurement range is short, typically 0–10 mm, and these gauges are primarily used for comparative measurements.
• Digital Dial Gauges
  Digital dial gauges use an encoder to read the linear or arc motion of a spindle equipped with a contact point. The measured values are displayed on an LCD or digital screen.

Here, we introduce three representative types of dial gauges:

• Dial Indicator（Analog）
• Dial Test Indicator（Analog）
• Digital Indicator

Dial Indicator

A Dial Indicator transmits the vertical movement of the spindle, caused by detecting the unevenness of the target object, to the dial. The internal gears, known as the “rack gear” and “pinion gear,” enable the needle to display the displacement.

With its ability to accommodate a longer stroke, the Dial Indicator is ideal for measuring objects with significant variations. It is particularly well-suited for metalworking tasks such as centering during lathe operations or aligning surfaces when using milling machines.

Dial Test Indicator

In the Dial Test Indicator, which uses the principle of leverage, the angle of the spindle is transmitted to the dial via internal gears, and the needle displays the displacement.

Due to the thinner spindle, it can measure in narrow spaces where a Dial Indicator would not be able to measure.

Compared to the Dial Indicator, the Dial Test Indicator has the disadvantage of a shorter measuring range but offers the advantage of higher resolution. For this reason, it is used for precision comparative measurements, such as checking the runout of rotating shafts or assessing the accuracy of machine tools.

Digital Indicator

The device that displays the changes in the dial gauge digitally is called a Digital Indicator.

It uses a digital linear scale with a photoelectric system internally. Since it can be damaged by dropping or impact, it is important to handle it with care.

How to Use a Dial Gauge / Usage Examples

Measuring with a Single Dial Gauge

With just one Dial Gauge, you can measure groove depth, step height, and thickness from a reference surface.

1. Set the Dial Gauge to zero at the reference surface.
2. You can measure the unevenness, height, and depth from the reference surface in numerical values.

Note: When using a granite surface plate, place the workpiece on the surface plate, set the surface plate as the reference zero point, and measure the height of the workpiece in numerical values.

Measuring with Multiple Dial Gauges

By mounting multiple Dial Gauges on a long bar, you can measure the flatness of a surface.

1. Fix multiple Dial Gauges at the same height on a reference plate or reference bar.
2. Set the Dial Gauges to zero using a flatness master or straightness master.
3. By placing the setup on the workpiece, you can check the flatness and straightness of the surface.

Precautions for Dial Gauges

While Dial Gauges are commonly used in many industries, they have the following precautions due to their nature and structural characteristics:

• Prone to measurement errors
• Not suitable for mass inspection
• Difficult to mount on metalworking machines
• Requires significant effort for recording and utilizing measurement results

Prone to Measurement Errors

Dial Gauges can experience inaccurate measurements if the attached arm bends or if the angle at which it contacts the workpiece is incorrect.
Due to the installation position, setup, and measurement method, measurement errors are more likely to occur, which is considered a disadvantage.

Not Suitable for Mass Inspection

Dial Gauges are mounted on stands or precision equipment for measurements.
As a result, when there are many measurement points or inspection items, the process becomes time-consuming, making it unsuitable for mass inspection.

Difficult to Mount on Metalworking Machines

Dial Gauges are sensitive to contamination from oil, liquids, and dust, which limits the installation options.
They are difficult to mount on metalworking machines such as cutting or pressing machines due to these limitations.

Requires Significant Effort for Recording and Utilizing Measurement Results

Many Dial Gauges cannot record the results directly to devices like PCs. Typically, the measurement values obtained with a Dial Gauge must be read manually from the needle and then recorded either by hand or through manual data entry.

As a result, there is a significant potential for human error during transcription or entry, and the process from measurement to recording and data utilization requires considerable effort.

For Precision Measurements Requiring Strict Accuracy, Contact TDC

At TDC, we possess ultra-high-precision measuring equipment and are capable of conducting measurements at the nanoscale.
For more information about our measuring instruments, please refer to the “Measuring Equipment” page.

• Precision Measurement of High-Accuracy Parts
• Need to perform mass inspections
• Want to conduct measurements on metalworking machines
• Interested in utilizing measurement result data

If you have any of the above requirements or need highly accurate measurements, please feel free to contact TDC.

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