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+--- Thread: Radius arm thread (/showthread.php?tid=404)
RE: Radius arm thread - David Cochrane - 02-11-2017
(02-11-2017, 11:13 PM)Ruairidh Dunford Wrote: Good to see my memory is not all gone to pot David - can you answer the question about Whitworth form for me please?
Stuart has given a very comprehensive & erudite answer! I always understood that the 'admiralty' threads had a Whitworth tooth form, but I am willing to be corrected.
RE: Radius arm thread - Ruairidh Dunford - 02-11-2017
Thanks Stuart, very helpful - I got myself into a right fankle there!
Alastair - looks like had found exactly what you needed, not as rare as I'd believed!
RE: Radius arm thread - Ruairidh Dunford - 02-11-2017
Thanks as well David.
RE: Radius arm thread - Alastair - 03-11-2017
Thanks everyone! I'll be in touch David.
Has anyone ever compiled a list of all the various threads used on the 7?
Alastair
RE: Radius arm thread - Ruairidh Dunford - 03-11-2017
Your Club site has the details here Alastair: http://www.austin7.org/Data%20Pages/Tech%20Data/
RE: Radius arm thread - Alastair - 03-11-2017
Hanging head in shame! Our local group the Unstoppables, awarded me the annual Pratt trophy (a somewhat less than concours Pratts can, suitably mounted) at our pre-Christmas do the other day for transgressions during the past year, and this is further justification... It was the third year running and I must further admit I nominated myself this time, having gone to the wrong pub for the do.
At least we've resolved the die problem!
Thanks again everyone,.
Alastair
RE: Radius arm thread - Austin in the Shed - 03-11-2017
For the radius arm threads,and others on the car it might be worth investing in a BSW/BSF thread restoring file.Cromwell tools for example sell one to clean up 8 different pitch internal and external threads for £21.Usually the radius arm threads get bruised when knocking them out of the axle and with a thread file its easier to pick up/dress the damage than trying to get a die to start and stay in pitch when threading.
RE: Radius arm thread - Amilcar John - 03-11-2017
I used a thread restoring file by Sykes Pickavant from ebay - which probably means I have a more casual approach to thread form etc.
Does that make me a bad person?
RE: Radius arm thread - David Cochrane - 05-11-2017
(03-11-2017, 01:58 PM)Amilcar John Wrote: I used a thread restoring file by Sykes Pickavant from ebay - which probably means I have a more casual approach to thread form etc.
Does that make me a bad person?
Personally I think that you would be a better person if you'd got one from me
(BT940 here)
RE: Radius arm thread - Dennis Nicholas - 06-11-2017
According to Newnes Engineer's Reference Book (sixth edition 1954)
Admiralty fine thread (Obsolete) Whitworth Form) 5/8 is 20 Tpi.
British Standard Whitworth 55 degree angle 5/8 is 11 Tpi. (Whitworth form threads).
British Standard Fine 55 degree 5/8 is 14 Tpi. (Whitworth form threads)
So it seems we have established that the Herbert Austin threads were 5/8 16 Tpi (with a Whitworth 55 degree form ???)(that is with rounded tops and bottoms to the threads).
BSW, BSF and now Perhaps we could have HAT (Herbert Austin Thread)