What Is a Bore Gauge Used For?

In precision mechanics we find special tools, different from classic screwdrivers and hand tools. One of these is called bore gauge - sometimes micrometer - and it is very important to have all the necessary knowledge to understand what it is and what it is for. Especially if you need to work with holes and circumferences. In fact, the bore gauge is fundamental for measuring circular width.

For example a cylinder through which the piston must pass. Now you might ask yourself: "But can't you do the same work with a normal ruler? Or maybe with a caliper?". In a world where precise measurements are not needed yes, and even if the caliper seems a more balanced solution than the ruler, the result would be inferior to what the bore gauge can offer. Let's find out why and how to use it.

What is a bore gauge, a definition

The bore gauge is a measuring instrument used in the field of precision mechanics. Specifically, this tool is used to measure the internal diameter of cylindrical holes while respecting the hundredth or even the thousandth of a millimeter.

So if you need a extremely precise measurement you cannot do without this tool which presents itself as a rod equipped with an analog or digital measurement and interchangeable heads of different sizes and shapes.

How is a bore gauge made? Here are the components

The main advantage of a bore gauge, in addition to its precision, is the simplicity of construction and use. Basically, the structure is very simple: there is a rod that allows you to reach even the deepest points that connects the measuring system (analog or digital) with the measuring head that comes into contact with the hole surface. There is an important aspect to consider here.

The best models offer the possibility to choose which head so as to adapt the tool to the surface. Obviously there are models suitable for larger cylinders, like those of an automobile, but also those that are used for small holes.

What is the difference compared to a caliper?

Let's skip the comparison with the ruler, decidedly commonplace when measuring the diameter of a cylinder. But there could be doubt about the caliper: well, compared to this tool the bore gauge manages to find the diameter even of the internal areas and not just the edges.

That's why this tool is a protagonist in the mechanical, automotive and aerospace industries - but also in individual workshops that work with different types of motors - for quality control and the production of precision components.

How to use a bore gauge, the guide

The method for using the bore gauge is fairly simple: make sure it is properly calibrated and that the working area is clean. Where there is contact with the tool there should be no residue of dirt or grease. Insert the bore gauge into the hole you want to measure, keeping it as centered and parallel to the cylinder as possible: read the values when you have maximum stability.

Types of bore gauges available on the market

There are different types of bore gauges that satisfy all needs, even those of specific sectors. Setting aside the extremely professional models in use in industrial departments, we can evaluate a series of models available to the public that can meet every single need. Like, for example, the rectification of the pistons of a motorcycle or an automobile.

The particularly widespread models are the classic centesimal bore gauges with analog reader and interchangeable tips, insulating wooden grip and check rings. The alternative is the digital model, even more precise and practical to use to obtain measurements with resolution 0.002. One of the most useful accessories in these cases is the extension to reach the most difficult points.