A Feeler Gauge
refers to a tool
typically used to check clearance
s and tolerance
s in machine
s such as an automotive engine
. Usually such a gauge comprises a package of rigid metal strip
s of increasing thickness
es. The thickness is printed or engraved on each strip. A typical automotive gauge might start at 0.001'' and increase to perhaps 0.04'' with steps of 0.001''.
To check clearances one starts with the skinniest strip and slips it in the gap to be checked, and then goes to the next biggest strip, and so on, until the next highest gauge won't slip into the gap. The clearance then lies between that gauge and the previously used one.
Plastigage is a compound of plastic-like consistency also used for such a purpose, typically in situations where the parts must be connected and the fasteners tightened to specified torque. Crankshaft and rod bearing clearances are a good example.
I love how this got softlinked to Words that sound dirty but really aren't ...