What is a feeler gauge?

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Feeler Gauge A feeler gauge is a hand-held measuring tool.

It has a number of folding metal strips (also known as blades, or leaves) which are machined to specified thickness levels.

Measurements are given in millimetres or inches and can be found in a central location on each individual strip.

Wonkee Donkee Feeler gauge used to check tappet clearance A feeler gauge fits into small gaps, often less than 5.08mm (0.200″).

The gauge gives you an idea of how wide a gap is by physically filling the space with metal strips which have a known thickness value.

Feeler gauge sizes Feeler gauges can take measurements as small as 0.02mm (0.0008″) and as large as 5.08mm (0.200″).

The size of a feeler gauge as inscribed on the tool refers to its thickness.

How do feeler gauges differ from other measuring devices?

Wonkee Donkee Feeler gauge used to check piston ring gap A feeler gauge is different from many other measuring devices as it provides you with a visual clue of how wide the gap you are measuring is by physically filling the gap with metal strips.

Feeler gauges are ideal for use in spaces where other measuring devices, such as a tape measure or caliper could not fit.