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 Bolt thread standard: Whitworth?
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Rob Bell

United Kingdom
70 Posts

Posted - 16/05/2018 :  18:07:52  Show Profile
Apologies for the daft question - all my tools are metric! There are a number of fasteners on my M-type that need replacing, so I'll need to order some suitable replacements.

The question is what is the thread standard? Whitworth or BSF??

Thanks!

bloodysalmon

United Kingdom
1195 Posts

Posted - 16/05/2018 :  18:20:32  Show Profile
Hi Rob,
I am sure others will fill in the gaps, but principally the triple MMM MG's are all BSF, except for the fuel pipes being BSP. There are only a few BSW.

Chris Blood (D-type Salonette)
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LewPalmer

USA
2311 Posts

Posted - 16/05/2018 :  18:51:41  Show Profile
Correct. However, the heads on BSF and Whitworth are the same, except the Whitworth one is one size smaller than the corresponding BSF. In other words, you only need one set, not two.

Lew Palmer
PA1169, PB0560
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Rob Bell

United Kingdom
70 Posts

Posted - 16/05/2018 :  20:54:59  Show Profile
Absolutely perfect: thanks! :)
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Nick Dean

United Kingdom
196 Posts

Posted - 16/05/2018 :  21:07:08  Show Profile
Rob, if you have a local recycling centre, and they sell items , check for BSF spanners, ring & open enders, or ebay. A lot of our older generation are giving up on the tools and there are some bargains to be had. Good luck,
Nick.

N A Dean
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Cooperman

United Kingdom
481 Posts

Posted - 16/05/2018 :  21:42:14  Show Profile
Another good source are Boot Fairs. Although don't go to one like this.





John Cooper M 628
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Malcolm Eades

United Kingdom
329 Posts

Posted - 17/05/2018 :  08:54:15  Show Profile
I got a lovely set of BSF spanners quite cheaply in a local "antique" shop (but mostly just bric-a-brac) where there is a stall-holder who specialises in old tools.

Malcolm
M Type

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Simon Johnston

United Kingdom
3253 Posts

Posted - 17/05/2018 :  10:22:17  Show Profile
quote:
Originally posted by LewPalmer

However, the heads on BSF and Whitworth are the same, except the Whitworth one is one size smaller than the corresponding BSF. In other words, you only need one set, not two.


Before the war BSW and BSF bolt head sizes were the same, i.e. a 1/4" spanner fitted a 1/4" BSW bolt head and a 1/4" BSF bolt head and the spanners were simply marked '1/4"'. During the war, as a steel saving measure, BSF bolt heads were reduced in size by one step so that a 1/4" BSF bolt now needed a smaller spanner, i.e. a 3/16" one. From then on spanners were marked with both bolt head sizes, e.g. 3/16" BSW (or more usually, just 3/16" W) and 1/4" BSF. It isn't clear why BSW bolt heads weren't also reduced in size but perhaps they weren't used in the same quantity as BSF and thus the steel saving would have been minimal in relation to the cost of the changeover.

Simon J
J3437
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KevinA

New Zealand
355 Posts

Posted - 17/05/2018 :  10:42:27  Show Profile
Actually Simon I think it is a bit more complicated than that. I've heard the same war-time stories but they don't really hold up. I have original bolts from veteran (my examples 1904), edwardian (mine are mainly 1912-14) and various vintage and post vintage and quite frankly the standardisation for the whitworth is non-existant.
If you read many of the modern references the nut height is defined, as is the across flats etc. This is either not true, or at least wasn't followed. The simple fact is that for whitworth as long as the threads conformed the rest was optional, in practice at least.

BSF however was the first time in the UK that standards were maintained so most things from circa 1930 on are likely to be pretty good.

The moral of my soapbox rantings is ignore ones with just whitworth markings and only work with spanners marked BSF. You won't go far wrong.



Edited by - KevinA on 17/05/2018 10:44:23
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Westbury

United Kingdom
644 Posts

Posted - 17/05/2018 :  10:57:35  Show Profile
Hello, Forum.

Whilst on the subject of fasteners, could anyone please tell me when aerotite lock nuts were introduced ? Despite all my efforts I cannot find a definitive answer to this question. I would imagine they would almost certainly have been developed for aircraft applications but whether before, during or post WW2 I know not.

Any views would be most welcomed.

Chris.
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Rob Bell

United Kingdom
70 Posts

Posted - 17/05/2018 :  14:09:13  Show Profile
Luckily I do have a small collection of spanners, open and ring, that I found in a rusting, water filled tool box. I guess that they date from the early 1960s - and mostly not in bad condition, but some of the chrome plate has come off. A Mixture of BSF, BSW and some others. All made in West Germany, which surprised me - I had thought that tools of this period would be mostly British?

I also found a British made 1/2" ratchet in the same box. Unsurprisingly it was seized solid, but I thought, for fun, why not give it a good douse with penetrating oil followed by some old engine oil. To my amazement, it is now free and works a treat. Rather a course ratchet mechanism - but feels like it has been engineered to last for ever!

I'll have to look out for a socket set too: thanks for the car boot sale/ flea market tips! :D
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Simon Johnston

United Kingdom
3253 Posts

Posted - 17/05/2018 :  14:48:15  Show Profile
Kevin,

The reduction in bolt head sizes was made under War Emergency B.S. 916 : 1940. Paul Crawford of the University of Dundee did some considerable research into spanner sizes and his article is well worth perusing - see https://www.sat.dundee.ac.uk/psc/spanner_jaw.html

In general, spanners from 'our' era, i.e. the 1930s, don't have W marked on them - they are simply marked with the size, 1/4", 5/16". etc. It was only after the war when the two sizes of BSW and BSF were used that we get the 1/4" W/ 5/16" BSF marking.

I wouldn't be at all surprised to find that bolt sizes from the vintage and veteran era were not standardised (as I recall, Bentley crank cases had the nuts and studs numbered for that very reason to ensure that they went back together properly)but by the 1930s they were.

Simon J
J3437
P.S. The wartime specification is quite hard to track down so here it is.





Edited by - Simon Johnston on 17/05/2018 15:04:37
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mingle54

France
1 Posts

Posted - 02/06/2018 :  12:06:30  Show Profile
I think Simon, you have got it the wrong way round. Before the war BSF heads were 1 size smaller than the head of a BSW bolt, ie a 5/16 BSF bolt was 0.525" across the flats where as a 5/16 BSW bolt was 0.6" across the flats (the same size as a 3/8 BSF bolt). During the war the head size of the BSW bolt was reduced to the same size as the head of a BSF bolt ie a 5/16 BSW bolt head became 0.525" across the flats, reportedly to save steel. This is confirmed on the website you refer to and also from the "Old" and "New" standards of BS 190 1924 and BS 916 see http://www.oldengine.org/members/diesel/Tables/WhitAF.htm which compares BS 190 to the later BS 1083 (BS 1083 only differs from BS 916 in the thickness of the head, nut and locknut but not the across flats size). This is also confirmed by comparing the heads of new BSF and BSW bolts which are now the same size. Some spanners in the 1930s may only have been marked with "W" or "BSW", but many were certainly marked with the different BSW and BSF sizes.

Michael Inglehearn
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Simon Johnston

United Kingdom
3253 Posts

Posted - 02/06/2018 :  12:24:46  Show Profile
Interesting references, Michael. I shall read and digest!

Simon J
J3437
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MG Maverick

United Kingdom
900 Posts

Posted - 02/06/2018 :  13:13:50  Show Profile
Maybe imperial spanners are available with the logo which would be a nice touch. Here is one from the toolkit of my other cars. ?


Chris

J2353
J4129




Edited by - MG Maverick on 02/06/2018 13:18:13
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Cymber

United Kingdom
904 Posts

Posted - 03/06/2018 :  22:02:48  Show Profile
An interesting account as to how BSF bolts came to have a size smaller hexagon than BSW which has left me puzzled. I don't recall my PA having large headed BSF bolts when I first stripped it in the late 1950s in fact it still has some of its original bolts.

Maurice.
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