Used to describe the collection of tools used for accurately measuring holes, bore gauges are a key tool in any engineer or machinist’s collection. Bore gauges come in a variety of forms and sizes to measure the diameter of a range of holes both easily and accurately.

Bore gauges are typically made of steel and are a precision tool made to be accurate within micrometres. Various forms of gauge are found for different levels of accuracy with more basic, solid gauges suitable for slotting into a hole to determine its size. These solid gauges are similar to a set of drill bits where the user has a range of pre-set sizes to work from.

Alternatively, expanding gauges are used for a more accurate measuring solution. Often found with either two or three anvils, these adjustable gauges can be set within a hole and then measured when removed to find the exact diameter. This style of gauge paired with a precision calliper will ensure you always have the most accurate measure.