Fasteners History

How often do we take the simple screw for granted?

 

It is believed by some that the screw thread was invented in about 400BC by Archytas of Tarentum, regarded as the founder of mechanics and a contemporary of Plato.

 

One of the first working examples of the screw thread principle are those used in olive and fruit presses recov­ered from the ruins of Pompeii. Archimedes (287 - 212 BC developed )

he screw principle and used it to construct devices to raise water, although the water screw may in fact have originated in Egypt before the time of Archimedes.

The Romans applied the Archimedean screw to mine drainage and the screw was described in the first century AD in Mechanica of Heron of Alexandria.( 1700–1948 )

Getting more serious about screws

It wasn’t until the eighteenth century that the screw thread began to take on its true importance and huge advances in the sophistication of its manufacture were made.

They were still being cut by hand and depended solely on the eye and skill of a craftsman. But then, around 1750, Frenchman Antoine Thiout introduced the innovation of equipping a lathe with a screwdrive which allowed the tool carriage to move longitudinally and semi-automatically.

In 1760 W. Wyatt patented a factory made screw system and in 1770 Jesse Ramsden built the first satisfactory screw cutting lathe.

Screws with fine pitches were now essential in manufacturing precision instruments that would allow the construction of steam engines, machine tools and surveying instruments that, in turn, assisted in the con­struction and development of canals, roads and bridges.

Increasing demand, therefore, deemed it necessary for screw threads to be factory made, but firms were developing screw thread designs for their own works and the lack of thread standardisation made fastener interchangeability problematical.

This remained the case until Manchester-based toolmaker Joseph Whitworth began collecting sample screws from a large number of British workshops. In 1841 he put forward two proposals for stan­dardisation to the Institute of Civil Engineers.

The principal features of the British Standard Whitworth (BSW) thread-form are that the angle between the thread flanks is 55 degrees and the thread has radiuses at both the roots and the crests of the thread. The British Standard Fine (BSF) thread has the same profile as the BSW thread-form, but was used when a fine pitch was required for a given diameter.

   

During the next 20 years Whitworth’s threads displaced the existing collection, becoming standard practice in Britain.

In 1864 in America, William Sellers independently proposed another standard based upon a 600 thread-form and various thread pitches for different diameters. This was adopted as the US standard and subsequently developed into the American National Coarse (ANC) and National Fine (NF) threads. 

Around the same time metric thread standards were being set throughout Europe, with a number of different flank angles adopted...the German Loewenherz had an angle of 530 8’ and the Swiss Thurythread 47.50. After some debate the international (metric) standard evolved based on a 600 flank angle.

1948 - 2002

In November 1948 the Unified thread was agreed by the UK, the USA and Canada to be used as a single standard for all countries using inch units. It was only as recently as 1965 that the British Standards Institute issued a policy statement requesting that organisations should regard the BSW, BSF and BA threads as obsolescent with the first choice replacement for future designs being the ISO metric thread and the ISO inch (Unified) thread second choice.

Metric threads are designated by the letter M followed by the nominal major diameter of the thread and the pitch in millimetres (eg M10 x 1.0 indicates that the major diameter of the thread is 10mm and the pitch is 1.0mm). The absence of a pitch value indicates that a ‘coarse’ thread is specified (eg M10 indicates a coarse thread of 10mm diameter - with its pitch calculated at 1.5mm).

Today the range and variety of screw threads and the number of ways in which we all use screws is incalculable. Needless to say, as one of the Brazilian Manufacture sources dedicated 100% to Global Automotive segment.

SELF TAPPERS AND DRIVE SCREWS

Combi • Hammer drive • Hexagon head threadforming • Pozi Sems unit • Slotted • Special • Standard high grade • Standard imperial Standard metric • Torx  - internal & external

SET SCREWS AND FLANGE SCREWS

Flange • Hexagon head • Pozi • Sems unit Serrated flange  • Special • Standard high grade Standard imperial • Standard metric • Torx – internal & external 

SOCKET SCREWS

• Cap • Flange • Set • Shoulder Special • Turned part

Credit – Anixter/USA 

JR Santiago

Business Director