British Standard Whitworth

These are the first instance of mass-production techniques being applied to marine engineering, as the following quotation from the obituary from The Times of 24 January 1887 for Sir Joseph Whitworth (1803–1887) shows: The Crimean War began, and Sir Charles Napier demanded of the Admiralty 120 gunboats, each with engines of 60 horsepower, for the campaign of 1855 in the Baltic.

There were just ninety days in which to meet this requisition, and, short as the time was, the building of the gunboats presented no difficulty.

He took them to pieces and he distributed the parts among the best machine shops in the country, telling each to make ninety sets exactly in all respects to the sample.

The orders were executed with unfailing regularity, and he actually completed ninety sets of engines of 60 horsepower in ninety days – a feat which made the great Continental Powers stare with wonder, and which was possible only because the Whitworth standards of measurement and of accuracy and finish were by that time thoroughly recognised and established throughout the country.An original example of the gunboat type engine was raised from the wreck of the SS Xantho by the Western Australian Museum.

[citation needed] American Unified Coarse (UNC) was originally based on almost the same Imperial fractions.

However, the top and bottom 1⁄6 of each of these triangles is cut off, so the actual depth of thread (the difference between major and minor diameters) is 2⁄3 of that value, or h = p/(3tanΘ) = 0.64032738p.

This arc has a height of e = Hsin Θ/6 = 0.073917569p (leaving a straight flank depth of h − 2e = 0.49249224p) and a radius of r = e/(1 − sin Θ) = 0.13732908p.

Whitworth and BSF spanner markings refer to the bolt diameter, rather than the distance across the flats of the hexagon (A/F) as in other standards.

[8] During World War II the smaller size hexagon was adopted more widely to save metal[9] and this usage persisted thereafter.

[citation needed] Fixings for garden gates traditionally used Whitworth carriage bolts, and these are still the standard supplied in UK and Australia.

[citation needed] British Morris and MG engines from 1923 to 1955 were built using metric threads with bolt heads and nuts dimensioned for Whitworth spanners and sockets.

[14] In the 2011 movie Cars 2 by Disney / Pixar, the vital clue to the discovery of the villain, Sir Miles Axlerod, is that he uses Whitworth bolts.

Whitworth thread form
Two spanners, both nominal size 5 ⁄ 8 in, with a diagram superimposed to show the logic that allows them both to be nominal size 5 ⁄ 8 in when their actual sizes are clearly different (across-flats distance vs screw diameter). The across-flats definition is the common standard today, and has been for many decades. The larger spanner in this photo is from the 1920s or earlier. Its face was polished to allow the size stamp to show well in the photograph. This example is American, but it illustrates the way that spanners for Whitworth fasteners were typically labelled.