Plain ring gauges are manufactured from the finest steel and are ground and precision lapped after a heat treatment process which includes a sub-zero stabilisation cycle to ensure dimensional stability.
Plain setting ring gauges are manufactured to BS 4065:1966 for inch sizes and BS 4064:1966 for metric. There are three grades, B, A and AA.
These gauges are intended for use as masters to set the numerous types of instrument used in the manufacture of internal diameters. These instruments generally use two or three points of contact or, in the case of air gauging, there is no point of contact.
BS 4065 – Total tolerance per grade of ring
American standard ANSI/ASME B89.1.6M.2002 includes four classes:- z, y, x and xx, xx being the highest degree of accuracy normally available.
ANSI/ASME B89.1.6 – Total tolerance per grade of ring
Customers should specify disposition of tolerance e.g. + tolerance, - tolerance or bilateral.
Variations due to out-of-roundness, taper and out-of-straightness must not exceed one half of the total tolerance in combination. Any single geometric error must not exceed one third of the tabulated values.