UNC and UNF fasteners in Britain

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.

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.