Wrllimn Sellers and The United States Standard Screw Threads at The Franklin Institute: A Mechanical Engineering Heritage Site

Sunday, June 12,2005 6:00pm Philadelphia, Pennsylvania

The Franklin Institute ( ScienceMuseum

Celebrating ASME's 125M Anniversary ASME Historic Mechanical EngineeringLandmark Designation The Franklin Institute Jordan Lobby Sunday, June 12,2005,6:00 pm

Welcome Kenneth A. Kroos Past Vice President, Mid-AtlanticRegion

Introductions and Kenneth A. Kroos Recognitions Harry Amen President, ASME

History and Heritage John K. Brown Program ASME History and Heritage Committee

William Sellers and John Alviti The ScrewThread Senior Curator, The FranklinInstitute Standard

Plaque Presentation Harry Amen

Acceptance Steven L. Synder VP,Exhibit and Program Development The Franklin Institute

Closing Kenneth A. Kroos

Exhibit Overview Steven L. Synder

Please join us for the ASME Summer Annual Meeting Opening Reception followingthe cere- mony. Preview Sir Isaac bLoft, an exhibit co-sponsored by ASME which aims to encourage young people to explore scienceas a field of interest and as a potential career.

In honor of ASMEysdesignation, a special display of fourteenof the Sellers Collectionof Mechanical Drawingswill be available for display in the gallery area ofSir Isaac 5Loft and in Harcourt Lounge. The entire collection consistsof nearly 890 drawings from the Sellers company datingfrom 1848to 1914. The United States StandardScrew Threads 1864 William Sellers at The Franklin Institute

By the 1850s,American machinery makers built a rangeof sophisticated tech- nologies. Textile machines,metal planers, steam engines, locomotives,rotary print- ing presses, and a myriad of otherhigh-technology products powered an era infatu- ated with machines. But infatuation turned tohstration when those machines broke down. The country lacked any national or industry standardsfor the most basic mechanicalelements, the nuts andbolts that createda functional machine from disparateparts. So when a bolt broke ora nut was lost, the user had to make a new one to fit its mate or to send fora replacementfrom the builder. No one coulddeny the value ofa national standard for these essential fasteners. Indeed by that time the world's industrialleader, GreatBritain, was adoptinga com- prehensive systemof screw threadspromulgated in 1841 by that nation's leading maker of machine tools,Joseph Whitworth(1803-1887). His American counterpart, tool builderWilliam Sellers(1824-1905) of Philadelphia, understoodthe value of Whitworth's standard,a clear improvement over thevarious "mongrel"threads that U.S. machinerymakers had adopted. But Sellers decidedto improve upon Whitworth's approach, creatinga system of threads adapted toAmerican needs. In April 1864 Sellerslaid out his proposed system of screw threads in a paper delivered atPhiladelphia's Franklin Institute. Sellers simplifiedWhitworth's design by adoptinga thread profileof 60 degrees(versus 55 degrees),which was easier for ordinary mechanics and machinists to cut. In additionto this profile, Sellers offered systematic approaches to thread pitch (the number of threads perinch), form, and depth, as well as rulesto proportion hex nuts- for each fractional sizefrom 114- inch to 6-inch diameterbolts. The Franklin Institutewas America's leading forum for developingthe art and science ofmechanical engineeringin this era before the founding ofthe ASME, and Sellerswas its president. On December15, 1864, a special committee of the Institute endorsed the Sellers or Franklin Institute threads.To aid their adoption throughoutthe United States,the Institute lobbied theU.S. Army, Navy (whose Bureau of Steam Engineeringwas a leading mechanical innovator),and the master mechanicsof America's largest railroads. The new thread standards did not sweep the nation overnight.The inertia of old approacheswas difficultto surmount, whilethorough adoptionrequired newlypre- cise taps and dies as well as reliably dimensioned steelbar stock. But by the 1880s, the system hadtriumphed, as machines with interchangeable parts- from type- writers to locomotives- flooded the nationaleconomy. Knownoriginally as the Sellers or Franklin Institute threads,they became the UnitedStates Standard threads. Other systems of screw threads have sincecome into widespreaduse. But downto the present day, William Sellers' innovationremains a ubiquitous

over, please standard. Take a quarter-inchnut from a Portland, Maine,hardware storeand it will reliably fit a quarter-inch boltin Portland,Oregon. The economy and simplicity of this elegantly rationalsystem representsWilliam Sellers' legacy andthe enduring quality of fine mechanical engineering.

John K. Brown Associate Professor Department ofScience, Technologyand Society School of Engineering and Applied Science UniversiQof Rrginia

The Historyand Heritage Programof ASME The Historyand Heritage LandmarksProgram ofASME (the American Society of Mechanical Engineers)began in 1971. To implement andachieve its goals,ASME formed a History and Heritage Committeeinitially composed ofmechanical engineers, historiansof technologyand the curatorof mechanicalengineering at the Smithsonian Institution,Washington, D.C. The Historyand Heritage Committee providesa public service by examining,noting, recording and acknowledgingmechanical engineering achievementsof particular significance. For furtherinformation, pleasecontact ASME, Three ParkAvenue, NewYork, NY 10016-5990, 1-2 12-591-7740.

Foundedin 1880as the American Societyof Mechanical Engineers, today's ASMEis a 120,000-memberprofessional organizationfocused on technical, educationaland research issues of the worldwide engineeringand technology community. In 2005,ASME cele- brates 125 years of continued service and leadership- setting the standard- for profes- sional engineering societiesworldwide.

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