Thread ring gages are used to check an external threaded part.
The most common classes of fit are:
-2A...a general purpose class of fit (sometimes used as a before
plate for a 3A) and
-3A...used to check parts with "closer" tolerance requirements.
Other classes of fit and special pitch diameters are available upon
The part being checked is generally acceptable when it does not
enter the NOGO ring gage more than 1½ to 3 turns dependent
upon customer specifications. NOGO ring gages have an annular groove
around the outside for identification.
The GO thread ring gage checks all functional geometries of the
threaded part with the exception of the major diameter. The products'
thread should freely enter the GO thread ring gage for the entire
length of the threaded portion.
This page is a modified page extracted from Dynamics of Gaging published by Regal-Beloit Corporation.The data is provided for general information only. The intention is to provide accurate information; regardless; errors may exist in the supplied information. If accuracy is critical, base your final decisions on the data provided in the root documents: ANSI/ASME B1.20.1; ANSI B1.20.5;and ANSI SAE AS71051 which are copyrighted documents. To purchase copies visit an Authorized Reseller.
Original Posting: 5/4/2005
Last Revision: 8/9/2018
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