I have noted reference to "Admiralty Thread" over what is now a considerable period of time in old car circles

I have searched, so far without success, in such tomes as "Machinery Handbook" and other standard engineering references, for some actual information about it.

I have talked to a chap who was once involved in British Torpedo "mechanics" and he had never hear of it.

I would love to shift it out of the Apocrypha category and find some substantiated references to it.

Some of the threads which are at times claimed to be “Admiralty Thread” eg 20 tpi track rod end on some cars, are UNF form. Whilst their origins may well have been in some way connected originally to “Admiralty” specs., those threads are in fact listed as a “Unified” ( Extra, or Extra, Extra Fine I think) in “Machinery Handbook”.

Given the references to it in these pages, perhaps someone could steer me in the direction of where I might glean some further edification on the subject.

Regards,

Barry R.
on

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Barry,

You may put your chapters from the Apocrypha back on the shelf, together with the dreaded Machinery’s Handbook, and be assured that there is indeed a “British Admiralty Fine Thread” .

Machinery's Handbook probably does not recognise British Admiralty since it is an American publication!!!

British Admiralty Fine Threads
(Whitworth Form)

Diameter.............TPI

Under 1/2"............24
1/2" & under 3/4".....20
3/4" & under 1".......14
1" & under 2".........12
2" & under 4"..........8
4" & over..............6

You may read of this and other wonderful engineering at ‘Peter & Rita Forbes' Engine Webpages’ which is to be discovered thus ....

http://www.oldengine.org/members/diesel/Tables/front.htm

go to 'Machinery Tables' and then to 'British Admiralty Fine'

This is truly a magnificent site, and well worth an evenings browsing.

I do so hope that you did not catch anything nasty whilst in the cellar the other day

Mike

Many thanks Mike,
I will have a look there!

I wonder if there is a UK (or should I say Great Britain and Her Dominions?) equivalent to "Machinery Handbook"

Regards

Barry R.

I thought it would be in my 'Molesworth' pocket book of enginnering formula, 28th Edition (circa 1912), but no, could be in the full edition.

Sandy

Machinery's Handbook still hasn't recognised the R8 taper - which is probably the most common milling machine taper in the world. It's far from perfect.

Charles

Thanks for the responses.
Have had a look at the "ancient engines" site, and their list of Admiralty Threads, but with one exception, (3/4"X 14 tpi)the sizes and pitches there don't line up with the A7 "specials"

I have now found the follwing site:


http://www.watchman.dsl.pipex.com/thread.html

This seems to have a fairly comprehensive listing.

I now need to find a bit more background info, and from what I have seen, but not yet read, it looks as though the Admiralty Threads may have their origons as far back as the Crimean War period.

If there is anyone who has any definite references to the Austin/Admiratly Threads/First World War story I would appreciate any details.

Regards to all,

Barry R.

It was mentioned in the A7 Clubs magazine (aka Grey Mag) but it could have been anytime in the past 20 years....

Charles

Thanks Charles,
I have the complete run of those, so it looks as though I should buy one of those rubber "thumbing" devices!

Regards,

Barry R