The History of Threads

Monday, 1 May 2023
Many people consider Archimedes to have invented the screw thread around 250BC.  However, Archytas of Tarentum (428BC-350BC) first applied the screw principle in presses to extract oil from olives.
Examples of these presses were found in the ruins of Pompeii.  Archytas has been described as the founder of mechanics and was a contemporary of Plato.
Milestones in the evolution of the bolt and nut threads of today include:
1750: Antoine Thiout introduced the innovation of equipping a lathe with a screw drive.
1760: J and W Wyatt patented the first Thread System.
1770: Jesse Ramsden made the first Screw Cutting Lathe.
1840: Joseph Whitworth, in an effort to standardise screw threads, and to reduce interchangeability problems proposed his 55-degree thread form.   This set a fixed number of threads per inch, for a range of diameters.  His proposals eventually became standard practise in Britain in the 1860’s.
1864:  William Sellars, in the USA independently proposed a 60-degree thread form, and various thread pitches for different diameters.   This subsequently was developed into the American Standard Course Series (NC) and the Fine Series (NF).  This thread form had flat roots and crests, making it easier to cut than the Whitworth Standard that had rounded roots and crests.
About the same time there were a number of metric threads being developed in Europe, with flank angles of 47.5, 53, and 60 degrees.
The ISO form evolved from these (and the Unified American threads), with a 60-degree flank angle, and flat crests with rounded roots.
The literature and research have been compiled by Boltmasters Australia from various academic and technical resources; thank you for reading.