Hi Everyone,
What I am trying to do is to work out what the head size is on a bolt with the designation A.STD 312 120 (from a Hurricane drawing). Can any light be shed on what this designation means and how to decode other designations like it?
I believe this is a 1/4″ BSF bolt with a head size between the flats of 11.4mm.
The other information I have is that this bolt goes in a 1/4″ hole and the parts manual says the conversion for a similar(?) bolt, A.Std 312/10 is 6.A1./1E as per attachment below.
Grasping the only recognized piece of information, the “E” I have guessed that this is a 1/4BSF bolt based on:
http://forum.keypublishing.co.uk/showthread.php?t=31764&highlight=bolt+numbers and http://www.lasaero.com/article/a-a25
The following site then suggests that a 1/4BSF bolt has a distance between the flats of 11.4mm:
http://www.vintagevehicle.com.au/Interesting%20Things.htm
Have I guessed right?
Excerpt from the Hurricane parts manual:
[ATTACH]168158[/ATTACH]
Hope everyone had a Wonderful Christmas with lots of aeroplane related gifts (even better if others were thoughtful enough to purchase them for you……) and wishing everyone a Happy and Healthy New Year.
Regards,
By: StevSmar - 1st January 2009 at 14:49
Thanks for your help
Hi Bruce and Radarsdesk,
Thank-you both for answering my question.
Interesting to read the historical evolution of bolt standards that you provided Radarsdesk. Reminds me for some reason of the troubles Packard had when manufacturing the Merlin- apparently that was quite a task.
You have confirmed what I suspected that the “E” in the RAF Stores Section and Reference Number designates this as 1/4″BSF.
Bruce, the Brown Brothers catalogue that you have scanned and posted is excellent, it tells me everything I need to know about BSF bolt and nut dimensions. Thanks for your generosity in scanning this.
Regards,
By: radarsdesk - 31st December 2008 at 21:03
Hi Steve,
Can’t help on the A.Std designation. but:
The column designated Ref No is the RAF Stores Section and Reference Number (Section 28, BA/BSF bolts being later designated section 28D), therefore sec/ref 28D/7240 equates to part number A1/1E which is a MILD STEEL hex head aircraft bolt 1/4″ BSF. AP1086 lists this bolt in having a minimum length under the head of 0.58″. The 6 prefix for the British Standard series that the bolts were produced to, therefore the full part number is 6A1/1E.
The A1 series bolt was superceeded by the A15 series bolt in 1940 (with suffix Y for High Tensile and Z for Stainless Steel) ie. an A15Y/1E bolt having a sec/ref of 28D/7145.
The A15 series bolt was then superceeded by the A25 series bolt in 1962 for High Tensile and A26 for Stainless Steel, an A25/1E bolt having a Sec/Ref of 28D/12707, the full part number being 2A25/1E for example denoting the Aerospace British Standard.
The letter part of the part number denoting diameter of 1/4″ (2A25 being the British Standard for BA & BSF Bolts) and the 1 denoting plain length of 0.10″
Hope that helps
Best regards
Dave
By: Bruce - 31st December 2008 at 18:44
Almost,
A.Std is a Hawker designation, and would cover bolts of their own manufacture.
The alternative 6.A1 was superceded by A25 post war. They are similar in most respects, and are what everyone uses now.
A25/1E has a plain shank under the head of 0.1″ and is a 1/4″ BSF bolt.
If you find the previous thread on the Brown Brothers catalogue, you will find a link to a download. Help yourself!
Bruce
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December 31, 2008 at 5:06 pm