- Author
-
U.S. Department of Commerce
- Title
- Report of the National Screw Thread Commission.
- Coporate
- Department of Commerce, Washington, DC
- Report
-
Miscellaneous Publication No. 141; 4th Edition,
April 10, 1933,
179 p.
- Keywords
-
standards
|
machinery
|
fire hoses
|
wires
|
specifications
- Identifiers
- screw threads for bolts, machine screws, nuts, tapped holes; uniform pitch screw thread series for high pressure fastenings, railroad applications, machinery components; screw threads of special diameters, pitches, and lenghts of engagement; American National hose-coupling and fire hose coupling threads; American National pipe threads; American National screw, bolt, and nut proportions; screw threads for oil well drilling equipment; American National standard hose connections for welding and cutting torches; American Naitonal rolled threads for screw shells of electric sockets and lamp bases; derivation of tolerances; wire methods of measurement of pitch diameter; control of accuracy of thread elements in the production of threaded product; class 5, wrench fit for threaded studs (tentative specifications); common practice as to thread series and class of fit for screws, bolts, and nuts; American National Acme screw threads (tentative specifications)
- Abstract
- Progress in commercial screw thread practice, which is based very extensively on the standards established by the National Screw Thread Commission, has been such as to require several revisions and some additions to the standards promulated in the Commission's 1928 report. This report, the fourth to be published, embodies necessary changes. The experience of the Commission demonstrates that technical standards, to be useful, cannot be static, but must be revised and adapted to meet changing requirements. Major revisions of the previously published standards consist in: The addition of the 1 3/8-, 3 1/4-, 3 1/2-, 3 3/4-, and 4-inch sizes to the coarse-thread series; the addition of the 1 3/8-inch size to the fine-thread series; the elimination of all sizes above 1 1/2 inches from the fine-thread series; the elimination of the small machine screw sizes from class 4, close fit; the addition of four sizes and pitches to the hose-coupling threads; the revision of tolerances for pipe thread gages; and the revision of the specifications for Acme threads, including a new recommended series of diameters and pitches. The volume of the report has been reduced by the elimination of standards for body dimensions of bolts, nuts, and screws, and standards for the design of gage blanks, except by reference to the latest revisions of other published standards for these products. New material added to the body of the report includes specifications for an 8-pitch and a 16-pitch thread series for special applications, which, together with the previously published 12-pitch series, are presented as a separate section. These series, demanded by industry constitute in effect an amplification of the fine-thread series, and are a substitute for the sizes above 1 1/2 inches in that series which have been deleted. A new table of tolerances for gages used in the inspection of class 4, close fit product is also included. In the appendixes the recommended practice for threading tool's has been deleted. The Commission's purpose to stimulate much needed activity in the standardization of taps, die-head chasers, and other threading tools has been fulfilled. Published standards for such tools, which have received general recognition, are referred to in the report. The assistance and cooperation of many individuals, manufacturers, and users of screw-thread products, tools, and gages, and of the American Society of Mechanical Engineers, the Society of Automotive Engineers, the American Standards Association, and several of the sectional committees organized under its procedure, the Federal Specifications Board, the United States Army, the United States Navy, the Bureau of Standards, the National Board of Fire Underwriters, the American Petroleum Institute, the International Acetylene Association, the Gas Products Association, and the American Gage Design Committee, are gratefully acknowledged by the Commission.