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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?
  • 0
    Yes, Andy, mine was also a Renault 4, though I did not attempt anything as ambitious as removing the engine. An interesting point was the lock-nutting arrangement, used on the clutch adjustment and similar. It used adjacent sized spanners, probably recognising that spanner sets usually came in 1 mm intervals and a handyman might be less likely to have two spanners of exactly the same size. In reality, only certain spanner sizes are "standard", relating to the corresponding standard sized bolts. A set of metric spanners would probably tackle nearly all nut sizes at a pinch, though I still have a set of BS ones.


    Rust was usually what killed cars in those days.  Things have certainly improved and you seldom see a rusty car nowadays and plenty of twenty-plus-year-old ones are still running around. What finishes cars nowadays are usually MOT issues, serious mechanical failure or accident damage, where repair is not economical.


    I had fun with my Renault 4 too, a versatile, practical and comfortable car. I sold it on before rust became a problem.
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    Denis McMahon:

    I was used for many other purposes, including bicycles.



    I always thought they used British Standard Cycle threads before many of them were replaced with metric threads. Modern day components made in the US often use UNC and UNF threads.
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    In the 1960s bicycles were a bit of a mixture of thread types. BA seemed to be used for some of the smaller bolts, e.g. fixing mudguard stays to frame. The system was also slightly confused by the similarity of BSC to BSF in some sizes. I once had to replace a lost bolt on a prop-stand, and I used a 1/4 inch BSF one, easy to obtain. I "cleaned up" the thread with a  tap and it fitted OK. In reality it was probably a replacement for a BSC bolt. Both BSC and BSF 1/4 inch are 26 threads per inch, with a slight difference in thread profile. Indeed these are very similar to 0BA and M6, which have thread pitches of 1 mm or 25·4 threads per inch. I read somewhere that one type will screw onto the other provided the threaded section is not too long.


    I believe that the British Cycle threads are still used on "cycle specific" parts, such as threads associated with bearings, for which the fine thread form is highly suitable.
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    Denis McMahon:

    In the 1960s bicycles were a bit of a mixture of thread types. BA seemed to be used for some of the smaller bolts, e.g. fixing mudguard stays to frame.




    Manufacturers and installers of aftermarket accessories probably used whatever fasteners they could obtain most easily at the lowest price.






    I believe that the British Cycle threads are still used on "cycle specific" parts, such as threads associated with bearings, for which the fine thread form is highly suitable. 




    There are still a few BSC thread sizes in regular use today although nuts fit metric spanners. A 5/16" Whitworth spanner is the size that fits pedals as well as axle nuts on small children's bikes, and is by co-incidence almost the same size as a 15mm spanner. A 17mm spanner fits the nuts used on 3/8" diameter axles (often erroneously referred to as 10mm) but this is a standard metric spanner with no Whitworth equivalent.


    Female BMX hubs are attached to the frame with a strange hybrid bolt that is 3/8" UNF (24 TPI as opposed to 26 TPI for BSC of the same diameter) with a 17mm head. 



     

  • 0

    Denis McMahon:


    1.  I served my time in the 1960s in the electricity supply industry. There, Whitworth and BSF were dominant and in continuing use by plant manufacturers.  I came across American Unified fasteners mainly on motor cars. At the time I put this down to the dominance of American organisations like Ford and GM. Ford was later a key player in the automotive industry's conversion to Isometric.

    Established industries with a large quantity of infrastructure - like railways and utilities - were slow to change fastener standards due to issues of backwards compatibility with whatever already existed. The automotive industry was more agile in comparison and could change fastener standards whenever a new model or vehicle platform was designed.



    2. I believe that the smallest Whitworth size was 1/8 inch. I came across this size in domestic appliances but it was rarely found in the industrial environment, where the BA series was more popular for fasteners of this size. Whitworth sizes were popular from 3/16 inch upwards.

    Whitworth fasteners are available in 3/16 and 1/8 inch. There is also 5/32 inch but this is long obsolete except as a Meccano fastener. BSF fasteners are available in 7/32 and 3/16 inch. There was a general rule in industry that Whitworth and BSF fasteners smaller than 1/4 inch were used on heavier mechanical assemblies or those using a significant number of larger Whitworth and BSF fasteners, and larger BA fasteners were used on electrical and precision mechanical assemblies or those using a significant number of smaller BA fasteners.

    4. I have long thought that a lot of obsolete stuff, surplus to industry's requirement, gets dumped on the home DIY market. The move from Whitworth to Isometric was somewhat sporadic, with Unified occasionally getting in the way. I remember once around 1975 in a hardware store, asking for some Isometric fasteners, and being told, rather pompously, "They will never catch on for years yet." Six months later, the  same shop was selling almost exclusively Isometric

    During the 1950s, 60s, and 70s most medium sized towns had at least one industrial surplus shop selling electrical and mechanical components. It was commonplace for owners of smaller independent DIY and hardware shops to prowl them and stock up with items being sold at a lower price than the manufacturer's prices. That resulted in Whitworth / BSF, and some Unified, fasteners ending up on the DIY market many years after industry had moved over to metric fasteners. The larger DIY chains like B&Q and Wickes bought new merchandise so there was probably a time when they were selling mostly metric fasteners whilst smaller independent DIY and hardware shops were mostly selling Whitworth fasteners.
  • 0
    Thanks, Arran, for the clarification on Whitworth fasteners. I vaguely remember 5/16 Whitworth on domestic appliances, but was not sure.


    As a lad I had many happy hours with Meccano. I built, among other things, cranes, steerable motor cars, a transporter bridge (two examples still working in the UK as far as I know), and a loom which actually worked. I took it to school and my teacher was most impressed!  Happy days!
  • 0
    Denis, I was slow to pick up on your CEGB comment, but an advertisement in an E&T on-line email that I received recently for The Uniper Academy reminded me of its heritage. http://www.cegbmidreg.co.uk/ptc/leaflet/ptccover.htm

    I trained at the Plant Training Centre as an Apprentice and returned some year later as an Instructor/Training Officer, before moving to Whitehall Road Leeds (North East Region) to head up the Electrical Department there.  Post-privatisation Powergen moved the Plant  Training Centre a few miles from Drakelow to Ratcliffe on Soar, whereas National Power went from Leeds, to Bricket Wood, to Didcot, to Ferrybridge within 5 years. Redundancy seemed a more attractive option in the end!  Incidentally my successor at Drakelow ended up at National Grid and as far as I know is still there.      


  • 0

    Denis McMahon:

    My first experience of Isometric fasteners in industry was in 1973 when I worked for a while for a subsidiary of Philips.




    There are differences between the head sizes for ISO / ANSI metric fasteners and DIN metric fasteners. There are also JIS metric fasteners with small heads.

    ISO / ANSI metric

    M10 16mm

    M12 18mm

    M14 21mm

    DIN metric

    M10 17mm

    M12 19mm

    M14 22mm


    DIN metric head sizes are more common although I have encountered ISO / ANSI metric on cars built since the late 1990s. The DIN metric sizes includes M7 with an 11mm head, so beloved by the French that no French car is complete without one, but nobody outside of France uses them. A 7/16 inch AF spanner also fits them.

    JIS metric

    M8 12mm

    M10 14mm

    M12 17mm

    M14 19mm

    M16 22mm


    A 14mm head is also found on some M10 fasteners with a fine thread.


     



     

  • 0

    Roy Bowdler:
    Denis, I was slow to pick up on your CEGB comment, but an advertisement in an E&T on-line email that I received recently for The Uniper Academy reminded me of its heritage. http://www.cegbmidreg.co.uk/ptc/leaflet/ptccover.htm

    I trained at the Plant Training Centre as an Apprentice and returned some year later as an Instructor/Training Officer, before moving to Whitehall Road Leeds (North East Region) to head up the Electrical Department there. . .


     




     

    Thanks Roy for that interesting link about the training centre at Drakelow. I was based in the North Eastern Region and was posted to various power stations there at various times. There was a training centre at Stella South power station, now gone, but the one you describe at Drakelow was certainly on a much bigger scale. I never visited Drakelow but I recall that from the railway there was an ash silo visible, which I believe could be something to do with Drakelow. I left the CEGB to do a degree.

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