Glossary of Gaging Terms


The readout of an air or electronic gage system. It displays readings on a scale as dimensional values. When connected to air or electronic gage tooling, readings are amplified many times, allowing the user to easily read the size being measured.



The resultant non-movement on the display of an air amplifier that occurs when one nozzle of a two-nozzle tool is closed toward the workpiece and the other nozzle equally compensates for that movement.



An air or electronic amplifier featuring a vertical bargraph display.



Refers to air tooling designed to measure Close-To-Shoulder. As an example, an air plug used to measure counterbores. Removal of front center post on air plugs below 2.510" becomes a blind hole design.


Full Scale Value (FSV)

The numeric equivalent of the graduated display. FSV is usually 1-1/2 to 2 times greater than the tolerance being measured to show approach or oversize conditions.



The visual increase of size that is created by an amplifier. In systems where the air amplifier has adjustable magnification, this is accomplished by adjusting the flow or back-pressure within the amplifier to agree with the master sizes. On systems that have an air amplifier with fixed magnification, it is essential that the air gage tooling is precise so that full amplification can be achieved.



The orifice in the air gage tooling that emits the air which blows against the part being measured. The diameter size of the nozzle is dictated by the air gage system used. The quantity and location of nozzles are determined by the measurement application.


Nozzle Drop

The engineered distance that a nozzle is recessed below the surface of the air gage tool. Nozzle drop is governed by the air gage system. A deeper nozzle drop can provide longer wear life of the air gage tool.



The smallest increment on the full scale display of the amplifier. For example, the Edmunds air and electronic columns have a full scale with 100 graduations. Therefore, the resolution is 1/100th of the full scale value. Restriction - A device used to control air pressure or flow within an air gage amplifier. This may be done with a fixed orifice of a precise size, with adjustable needle valves, or with both.



The process of positioning the magnified spread on an amplifier to a desired relative position on the scale. Zero is generally at midpoint of the full scale, but the spread may be positioned anywhere on the scale.


Zero Size

The desired midpoint or nominal size of the feature being measured as it relates to the scale. On back-pressure systems, zero is usually the midpoint between the minimum and maximum allowable size. On the flow system, the zero size is generally the minimum size.

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