A feeler gauge is an instrument used to measure gap widths between two flat surfaces, where it is difficult to reach. Feeler gauges are found in metrology section.
Feeler gauge consist of some small lengths of steel (leaves or blades) of different thicknesses with measurements labeled on every leaf. Leaves on it are flexible enough that, even if they are all on the similar hinge, some can be stacked jointly to gauge mean values. It’s familiar to have two sets of imperial units and metric measurements though the pictured set has together size recorded on each leaf.
A similar tool with wires of particular diameter instead of flat leaves is used to set the gap in spark plugs to the correct size; this is done by changing the gap until the leaf of the correct thickness just fits between the flat surfaces.
There are many different types of feeler gauges. Some of them are:
- Go-No-Go feeler gauge: It has a thick base and a thinner tip. The thinner end of the gauge can ‘go’ into the gap and the thicker body will not ‘no go.’
- Straight leaf feeler gauge: A straight leaf feeler gauge has leaves that are consistently parallel.
- Metric Feeler Gauge: It gives measurements in hundredths of a millimeter.
- Imperial feeler gauge: It gives measurements in thousandths of an inch.
- Tapered feeler gauge: A tapered leaf feeler gauge has leaves that thin out towards the tip.
- Feeler strip: It work identically to feeler gauge blades. The exception is that they are not connected in a set, and either end can be used to measure. They are separate for quick and easy use.
- Offset Gauge: In this gauge blades are bent toward the tip for easier access to most motor vehicle applications and work in restrictive areas.