The 1986 edition of this Standard was a combination of ANSI B1.3-1979 and ANSI B1.3M-1981. These
earlier versions of this Standard were based upon the following instructions as defined by the B1
Committee at its meeting on October 7, 1976, which charged the B1.3 Subcommittee with the
responsibility of preparing these documents.
The Subcommittee was to prepare a catalog of gages and gaging systems so that each gage or gaging
system would be defined only in terms of the dimension(s) controlled and so that any material of an
editorial nature that could be construed as giving preference to one gage or gaging system over
another would be eliminated, as outlined in the following three statements:
(a) All references to referee gaging methods are to be eliminated from all B1 documents.
(b) A catalog of gaging systems is to be prepared by the B1.3 Subcommittee so that any description
of the gage relates only to the specific dimension(s) it controls. All material of an editorial
nature that could be construed as giving preference will be eliminated.
(c) The level of dimensional acceptability shall be determined by the threaded product application
and specified by American National Standards or other product standards, or by procurement drawings
Subsequently, the Subcommittee decided to combine these previous standards into one document and
designate it ANSI/ASME B1.3M-1985, Screw Thread Gaging Systems for Dimensional Acceptability - Inch
and Metric Screw Threads (UN, UNR, UNJ, M, and MJ).
This revision includes the following specific changes:
• elimination of internal snap gages
• addition of best wire size radius contacts to minimum material thread groove measurement
• clarification of out-of-round indicating gaging in Tables 1 and 2
• addition of a reference to ANSI/ASME B46.1, Surface Texture, to provide roughness average
guidelines to be used for the evaluation of the surface texture of threaded products
• addition of linear and coordinate measuring machines to the equipment included for thread
• clarification that all System 23 checks are not all mandatory
• clarification relating to the measurement of changes in diameter size because of
Suggestions for improvement of this Standard will be welcome. They should be sent to Secretary,
ASME B1 Main Committee, 345 East 47th Street, New York, NY 10017.
This revision was approved as an American National Standard on October 12, 1992.
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