Bore gauge is a collective term describing tools used for measuring the internal diameter of holes, cylinders, pipes and divots in materials like wood, metal, and plastic. They have a range of applications across industries, including automotive, construction, engineering, aerospace, and many more.

This guide will discuss everything business owners need to know about bore gauges, including a more detailed look into what they are, how they work, and how to use them.

What is a bore gauge?

As we touched on above, bore gauges are instruments designed for accurately measuring the diameter of a hole or bore. The tools come in various sizes and specifications, taking measurements as small as 0.2mm and as large as 152mm and beyond.

Some other common names for bore gauges include internal micrometres, telescoping gauges, bore mics, cylinder tests, and hole tests.

A typical bore gauge has a steel or chrome construction, with both rigid and expanding versions available. Within these categories, there are four main types:

  • Telescopic gauges, where transfer the internal dimensions of a bore to a remote measuring tool,
  • Beam gauges, which measure larger internal and external diameters,
  • Small-hole gauges, where the gauge is usually set smaller than the hole to be measured,
  • Dial bore gauges, which are similar to telescopic gauges but feature an analogue or digital readout.

How bore gauges work

Regardless of the type of bore gauge you’re using, they all follow similar working functions.

Let’s start with telescopic bore gauges. These tools are T-shaped with a long, tapered end and horizontal handle. As you insert the gauge into the bore and lock it in place, you’ll need to rock the handle to determine the exact internal diameter of the hole. The rocking movement will compress the two anvils giving the bore’s dimensions. You’ll then need another tool, like a calibre or micrometre, to read the measurement from the locked gauge.

Dial bore gauges work in much the same way, but they make the process easier thanks to the in-built dial that displays the reading for you.

How to use a bore gauge

For the sake of this explanation, we’ll focus on the most popular type of bore gauge on today’s market, which is the dial bore gauge.

To use a dial bore gauge, follow these simple steps:

  1. Zero the gauge by measuring it with a micrometre set to the bore’s precise size. When the zero mark aligns with the micrometre’s needle, you’ll be ready to go.
  2. Insert the gauge into the hole to your desired depth, rocking it back and forth until it’s secure.
  3. Eventually, the pointer on the bore gauge’s dial will begin reversing itself. Record the measurement where the pointer sets itself and remove the gauge from the bore.
  4. To obtain your final value, you’ll need to subtract or add the measurement value from the number you calibrated the indicator to. Whether you add or subtract will depend on which direction the pointer moved to when it began reversing.

Conclusion

To summarise, there are various bore gauges available on today’s market, each with distinct functions and features. If you’re looking for a measurement tool that’s simple and easy to use, a dial bore gauge is an ideal choice.