I was wondering if you can help? I'm trying to get hold some older stock 3/16 BSF nuts (like GKN/Nettlefolds), I believe 2BA is also a close alternative. I don't suppose anyone has any spare that they would be willing to sell?
I'm aware that you can get 'modern' BSF nuts in this size, I have a few myself but I don't think they just quite the same dimensionally. The originals seem marginally taller.
I've added a couple of pictures showing a used one that I have along with a modern one.
My understanding was that bolt heads and nuts of both Whitworth and BSF were reduced in size during WW2 in an effort to save on steel. They never returned to the original size.
I have pre war spanner’s that do not fit modern equivalents or some nuts on my Austin whilst the same spanner do fit those that were original.
Whilst I've never worried about this sort of detail I did come across this company on line who may be able to help although I don't think they list 3/16" BSF.
02-07-2023, 08:30 PM (This post was last modified: 02-07-2023, 08:32 PM by Stuart Giles.
Edit Reason: punctuation
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Most pre-war British Standard nuts were the same height as the nominal diameter -e.g. 3/16" BSF nut would be 3/16 tall etc. Also, Most pre war nuts were 'bar turned' i.e. they were made from hexagonal bar on a lathe; they usually have a chamfer on one side only. Modern nuts are produced in a stamping process; which is why they have a chamfer on both sides. WRT alternatives, 10-32 UNF is a lot closer to 3/16" BSF than 2BA.
03-07-2023, 12:49 PM (This post was last modified: 03-07-2023, 12:50 PM by Parazine.)
(02-07-2023, 06:04 PM)Denis Sweeney Wrote: My understanding was that bolt heads and nuts of both Whitworth and BSF were reduced in size during WW2 in an effort to save on steel. They never returned to the original size.
I have pre war spanner’s that do not fit modern equivalents or some nuts on my Austin whilst the same spanner do fit those that were original.
Almost correct!
It was World War 1 when the sizes were reduced, a 3/16" Whit thread, for example used a nut with a 3/16" Whit hexagon before this. After the change, a 1/4" Whit thread used a 3/16" hexagon. There was a period where the reduction only applied to BSF sizes, hence the dual marking of spanners.
Trying to explain to people who have only ever dealt with metric spanners sizes is challenging!
My memory may not be as good as it never was (according to she who must obeyed...) but nearly some 40 years ago when I first purchased Ruby, one of the first items on my list of stuff to buy were sets of Whitworth and BSF spanners etc and was then sadly dismayed by constantly struggling to find the right spanner.
My curiosity led me to digging up info at that time I am pretty sure it was changed in WW2, I do have the original paperwork somewhere but as it is not to hand and following Parazine's comment, I have looked again this afternoon.
Now if you can believe Wikipedia.......... certain branches of industry reduced the sizes of Whitworth nuts under the designation "Auto-Whit" and these were formalised by the British Engineering Standards Association in 1929 as standard no.193 (original Whit standard no.190 and BSF standard no.191)
It then goes on to say "....during WW2 the smaller hexagon size was adopted more widely to save metal and this usage persisted thereafter."
The piece then goes on to say that it is common today to encounter a Whitworth hexagon which does not fit a nominally correct spanner.
Thank you for all your replies. I find the info very interesting. I was aware that is a slight difference between 'modern' nuts and the originals, but I never thought about the two wars having an influence on it, but that makes perfect sense. I just assumed it was due to poor quality manufacturing (attention to detail) as is the case with many products produced today. I have recently purchased an old book (from the 1930's) that is dedicated to screw threads and systems. I've yet to read in great detail but I've found the attached extract. It doesn't add much to the discussion but I thought it would be of interest.
I'll go and measure the 'used' original I have, I'm sure it will correlate with the information discussed here.
John - Thank you for the link, I've contacted this company now and it would appear they can supply me with some and they seem to be produced like the originals.
Stuart - Thanks for the info on the alternatives, its useful to know and I understand your concerns Chris. I was only considering close alternatives as I was struggling to find any being produced like the originals. I don't intend to use these for a 'tolerance critical purpose' or mechanical part. I'll always try and endeavour to find the correct like for like nominal replacement.
03-07-2023, 08:08 PM (This post was last modified: 03-07-2023, 08:16 PM by Tony Griffiths.)
Another point: when turned from hexagon bar nuts have a beautiful "all-machined" look and one at odds with the rough "commercial" finish of those stamped. I might be wrong, but the only ones I can find today turned from bar are in stainless steel, a material that brings in its train certain problems.
