A ring gauge, or ring gage, is a cylindrical ring of a thermally stable material, often steel, whose inside

diameter In geometry, a diameter of a circle is any straight line segment that passes through the center of the circle and whose endpoints lie on the circle. It can also be defined as the longest chord of the circle. Both definitions are also valid for ...

is finished to gauge

tolerance Tolerance or toleration is the state of tolerating, or putting up with, conditionally. Economics, business, and politics * Toleration Party, a historic political party active in Connecticut * Tolerant Systems, the former name of Veritas Software ...

and is used for checking the external diameter of a cylindrical object. Ring gauges are used for comparative gauging as well as for checking,

calibrating In measurement technology and metrology, calibration is the comparison of measurement values delivered by a device under test with those of a calibration standard of known accuracy. Such a standard could be another measurement device of know ...

, or setting of gauges or other standards. Individual ring gauges or ring gauge sets are made to variety of tolerance grades in metric and English dimensions for master, setting, or working applications. There are three main types of ring gauges: go, no go, and master or setting ring gauges. Go ring gauges provide a precision tool for production comparative gauging based on a fixed limit. Go gauges consist of a fixed limit gauge with a gauging limit based on the plus or minus tolerances of the inspected part. A go ring gauge's dimensions are based on the maximum OD tolerance of the round bar or part being gauged. A go plug gauge's dimensions are based on the minimum ID tolerance of the hole or part being gauged. The go plug (ID) gauge should be specified to a plus gaugemakers' tolerance from the minimum part tolerance. The go ring (OD) gauge should be specified to a minus gaugemakers' tolerance from the maximum part tolerance. No-go or not-go gauges provide a precision tool for production comparative gauging based on a fixed limit. No-go gauges consist of a fixed limit gauge with a gauging limit based on the minimum or maximum tolerances of the inspected part. A no-go ring gauge's dimensions are based on the minimum OD tolerance of the round bar or part being gauged. The no go ring (OD) gauge should be specified to a plus gaugemakers' tolerance from the minimum part tolerance. Master and setting ring gauges includes gauge blocks, master or setting discs, and setting rings are types of master gauges used to calibrate or set

micrometer Micrometer can mean: * Micrometer (device), used for accurate measurements by means of a calibrated screw * American spelling of micrometre The micrometre ( international spelling as used by the International Bureau of Weights and Measures; ...

optical comparator An optical comparator (often called just a comparator in context) or profile projector is a device that applies the principles of optics to the inspection of manufactured parts. In a comparator, the magnified silhouette of a part is projected up ...

s, or other gauging systems. Working gauges are used in the shop for dimensional inspection and periodically checked against a master gauge.

Accuracy grades

Similar to gage blocks, ring gauges are sold under different accuracy grades. The higher the grade, the lower the allowable variance from the nominal diameter. This diameter tolerance varies, within each grade, based on the nominal diameter. US standard grades are defined per ANSI/ASME B89.1.5.

References

{{Reflist Metalworking measuring instruments