- Author
-
U.S. Department of Commerce
- Title
- Report of the National Screw Thread Commission. Revised, 1924, Authorized by Congress, July 18, 1918, H.R. 10852 as Approved August 19, 1924.
- Coporate
- Department of Commerce, Washington, DC
- Report
-
Miscellaneous Publication No. 61
February 11, 1925
179 p.
- Keywords
-
standards
|
machinery
|
fire hoses
|
wires
|
specifications
|
measuring instruments
- Identifiers
- screw threads for bolts, machine screws, nuts, tapped holes; screw threads of special diameters, pitches, and lenghts of engagement; national hose-coupling and fire hose coupling threads; national pipe threads; wood screws; derivation of tolerances; wire methods of measurement of pitch diameter; control of accuracy of thread elements in the production of threaded product; design and construction of gages
- Abstract
- This report is the first revision of the progress report of the National Screw Thread Commission published in 1921. The initial accomplishment in the standardization of screw threads in the United States was the report under date of December 15, 1864, of the special committee appointed by the Franklin Institute on April 21, 1861, for the investigation of a proper system of screw threads, bolt heads, and nuts to be recommended by the institute for adoption and general use by American engineers. In its report this committee recommended a thread system designed by William Sellers. This thread system specified a single series of pitches for certain diameters from one-fourth inch to 6 inches, inclusive. The threads had an included angle of 60 deg and a flat at the crest and root equal to one-eighth of the pitch. This system came into general use and was known as the Franklin Institute thread, the Sellers thread, and commonly as the United States thread. The accomplishments realized in the adoption of the Franklin Institute, or United States standard thread, in 1864 were brought about largely by the great need of standard threads by American railroads for the development of their lines and equipment. In May, 1868, this thread was adopted by the United States Navy. In recent years numerous organizations have carried forward the standardization of screw threads. The American Society of Mechanical carried forward by the British Engineering Standards Association, an organization formed in 1901. While the United States standard thread system fulfilled a great need in the period of the development of our great railway systems, it did not fully meet the requirements of modern manufacture because of the need for additional standard sizes and pitches developed in other industries, and especially because of the need for definitely specified limiting sizes of threaded parts. To fulfill the first of these needs, a thread system having finer pitches than the United States standard system was recommended by the Society of Automotive Engineers, and a machine-screw thread series which provided smaller sizes of screws than the United States standard threads was recommended by the American Society of Mechanical Engineers. The progress of machine design and manufacture has established an extensive use of these fine thread series. With the great extension of quantity production in this and other countries, particularly during the World War, the need for national standard limiting dimensions was emphasized, as one of the pre-requisites of quantity production is standardization of form and dimensions of parts, in order that interchangeability may be established. This is especially important in the matter of screw-thread parts, since there are two mating parts that must fit and these parts in many cases are made in different places. Standardization of screw threads is important to both the manufacturer and the user of a machine, as the user should be able to buy locally a screw or nut for replacement in case of breakage or wear.