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UNC and UNF fasteners in Britain

Arran Cameron
Somebody will know the answer to this…


Almost all British machinery manufactured before 1950 used Whitworth, BSF, or BA fasteners. Manufacturers moved towards using metric fasteners in the 1970s and these have been the most commonly available and used family since 1980, although the proposal to use metric fasteners dates back 1965. Whitworth and BSF officially became obsolete in 1948 following an agreement between the UK, US, and Canada to standardise on the American UNC and UNF fasteners for future use. UNC and UNF fasteners were used in British machinery manufactured in the 1950s, 60s, and 70s where they gradually replaced Whitworth and BSF before themselves being replaced by metric fasteners.


1. Were UNC and UNF fasteners used across most industries in the UK or were they largely confined to specific industries such as automotive and machine tools? Were they regularly used in railways or shipbuilding?

2. Were the numbered sizes smaller than ¼ inch commonly used or did industry stick with BA fasteners until they moved to using metric fasteners?

3. Were UNC and UNF fasteners commonly used in construction? What are the most common family of fasteners used to hold together 1960s tower blocks and university buildings?

4. Was it easy to buy UNC and UNF fasteners from hardware and DIY shops in the 1960s and 70s or did they move directly from selling Whitworth and BA fasteners to metric fasteners?
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    Arran,

    I can't give a definite answer but my memory from shipbuilding is that shipyards moved across to metric measurements in the late '70s (with one example I remember at Scott Lithgow in Port Glasgow "We need another section of cable tray for here, 300mm by 6 feet") but my memory was that this was a transition from BS Whitworth. As I didn't experience any UK built ships built between 1960 and 1979 I can't be sure there wasn't an intervening period of UNC/UNF.

    By the way, BA was actually a metric thread standard but it didn't really catch on elsewhere so I think it was assumed to be imperial by most people. However I don't recall seeing it used anywhere.

    On availability, certainly when I was buying my first tools in the late '70s and early '80s metric was readily available, but when faced with an existing bolt, thread guages were a necessity as there were so many different possible options that you needed to have bolt diameter and thread pitch in order to look up what you were faced with. I seem to remember that it was possible to buy the right nuts and bolts, but that is not the same as it was easy to do so.

    I may have some old bits and pieces at home to help here so if I am able to look them out I may be able to add some more info.

    Alasdair
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    Arran,

    I can't give a definite answer but my memory from shipbuilding is that shipyards moved across to metric measurements in the late '70s (with one example I remember at Scott Lithgow in Port Glasgow "We need another section of cable tray for here, 300mm by 6 feet") but my memory was that this was a transition from BS Whitworth. As I didn't experience any UK built ships built between 1960 and 1979 I can't be sure there wasn't an intervening period of UNC/UNF.

    By the way, BA was actually a metric thread standard but it didn't really catch on elsewhere so I think it was assumed to be imperial by most people. However I don't recall seeing it used anywhere.

    On availability, certainly when I was buying my first tools in the late '70s and early '80s metric was readily available, but when faced with an existing bolt, thread guages were a necessity as there were so many different possible options that you needed to have bolt diameter and thread pitch in order to look up what you were faced with. I seem to remember that it was possible to buy the right nuts and bolts, but that is not the same as it was easy to do so.

    I may have some old bits and pieces at home to help here so if I am able to look them out I may be able to add some more info.

    Alasdair
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