27-08-2013, 04:35 PM
Sir Joseph Whitworth
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(1803 - 1887), English Engineer,
born in Stockport, Cheshire
Sir Joseph Whitworth is best known in connection
with his development of a rationalised system of
screw threads and for the screw threads that bear his
name; British Standard Whitworth (BSW). He
proposed this thread system in 1841 and the relevant
British Standard is BS 84: 1956. However, the
principal contribution of this exceptionally talented
engineer was his introduction of new standards of
accuracy in manufacturing to a degree previously
unknown.
By 1830 a skilled mechanic could be expected to work
to an accuracy of only one sixteenth of an inch but by
1840, thanks to Joseph Whitworth, an accuracy of one
ten-thousandth of an inch was a practical proposition.
Subsequently, Whitworth devised an instrument (a
bench micrometer) that could measure to one
millionth of an inch. He also introduced a standard for
the flatness of plane surfaces, which was essential
for fine engineering work and for the manufacture of
surface plates used for marking out purposes.
Joseph Whitworth was born in Stockport, Cheshire, on
the 21 December 1803 and he was the son of Charles
Whitworth, a schoolmaster (another source says that
he was a Congregational minister), and Sarah. He
was Christened on the 8 February 1804 at Churchgate
Independent on Orchard Street, Stockport.
Joseph Whitworth only received an elementary
education and during this period of his life he did not
distinguish himself. On leaving school he became an
indentured apprentice to an uncle who was a cotton
spinner in Derbyshire. This was only a four-year
apprenticeship and on completion of this he worked
for another four years as a mechanic in a factory in
Manchester. He then found employment working for
Henry Maudsley (1771-1831), inventor of the screw-
cutting lathe. Maudsley's factory was on Westminster
Bridge Road in London and here he worked alongside
other men who were also destined to become famous
engineers, such as James Nasmyth (1808-1890),
inventor of the steam hammer, and Richard Roberts
(1789-1864), inventor of a self-acting spinning mule.
Under Maudsley's tuition, Whitworth developed
immense skill as a mechanic. Here he developed a
method of creating truly flat surfaces and he
developed machine tools for turning, shaping, milling,
slotting, gear cutting and drilling, all to a high degree
of accuracy. He also introduced a box-casting system
for the iron frames of machine tools that increased
their rigidity, while reducing their weight.