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Kleftiwallah
Joined: 27 Oct 2016
Posts: 222
Location: North Wiltshire
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 Posted: Tue Jul 25, 2017 4:15 pm Post subject: Threadform has me fummoxed! |
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The securing threaded shafts of a British Jaeger speedometer have me flummoxed. 34 T.P.I. and 3/16" diam', my 'very near' reads 0.190" or 4.84mm.
I've been through Mr F.J. Camm's Newnes Screw Thread Tables and I'm beat.
Anyone any ideas what this thread is? ? ?
Over to you Chaps and Chapesses. 
Cheers, Tony.
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V8 Nutter
Joined: 27 Aug 2012
Posts: 587
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| Posted: Tue Jul 25, 2017 7:07 pm Post subject: |
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| Are you sure it's 34 T.P.I.? A number 10 A.N.F has the same diameter but 32 T.P.I. Having said that I seem to remember reading somewhere some American threads were changed in the 1930's |
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47Jag
Joined: 26 Jun 2008
Posts: 1480
Location: Bothwell, Scotland
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| Posted: Tue Jul 25, 2017 10:19 pm Post subject: |
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I would agree with V8 that it is more likely to be 32 tpi x 3/16" which also happens to be 2BA which is the same as 10/32 unf. The only difference is in the size of the nuts. 2BA will have smaller 5/16" SAE or 2BA spanner size and 10/32 will be 3/8 SAE spanner size. IMHO British Jaeger is more likely to be 2BA.
Art |
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Paul fairall
Joined: 17 Nov 2016
Posts: 429
Location: North west Kent
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| Posted: Tue Jul 25, 2017 10:32 pm Post subject: |
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| 47Jag wrote: | I would agree with V8 that it is more likely to be 32 tpi x 3/16" which also happens to be 2BA which is the same as 10/32 unf. The only difference is in the size of the nuts. 2BA will have smaller 5/16" SAE or 2BA spanner size and 10/32 will be 3/8 SAE spanner size. IMHO British Jaeger is more likely to be 2BA.
Art |
10/32" ? 5/16"
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Kleftiwallah
Joined: 27 Oct 2016
Posts: 222
Location: North Wiltshire
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| Posted: Wed Jul 26, 2017 11:37 am Post subject: |
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Thanks for all those interesting and educational replies.
I got by with an M5 X .8.
Cheers all. Tony.
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V8 Nutter
Joined: 27 Aug 2012
Posts: 587
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| Posted: Wed Jul 26, 2017 2:07 pm Post subject: |
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| I never thought to look at British threads, I just assumed a publication by F.J. Camm would have covered everything. I must have tapped hundreds of holes 2BA when I was an apprentice, come to think of it, I broke more than a few taps. |
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ukdave2002
Joined: 23 Nov 2007
Posts: 4104
Location: South Cheshire
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| Posted: Wed Jul 26, 2017 8:11 pm Post subject: |
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Jaeger / Smiths instruments used BA threads.
Dave |
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47Jag
Joined: 26 Jun 2008
Posts: 1480
Location: Bothwell, Scotland
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| Posted: Wed Jul 26, 2017 10:59 pm Post subject: |
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Paul,
The Yanks use wire gauge to express diameters under 1/4". So 10/32 would be a 10 gauge (3/16") with 32 TPI. The 5/16 is the SAE size of spanner/socket the also fits 2BA.
Art |
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jp928
Joined: 07 Jun 2016
Posts: 249
Location: Australia
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| Posted: Fri Jul 28, 2017 8:11 am Post subject: |
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As long as the the threads are short and a bit soft M5 is close enough to 10-32 - a 0.8mm pitch gives 31.75 tpi. I use M5s in American 10-32 model aero fittings when I am pressed.
jp 26 Rover 9 |
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Paul fairall
Joined: 17 Nov 2016
Posts: 429
Location: North west Kent
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| Posted: Fri Jul 28, 2017 6:30 pm Post subject: |
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| 47Jag wrote: | Paul,
The Yanks use wire gauge to express diameters under 1/4". So 10/32 would be a 10 gauge (3/16") with 32 TPI. The 5/16 is the SAE size of spanner/socket the also fits 2BA.
Art |
so 10/32 is not a fraction of an inch then.
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47Jag
Joined: 26 Jun 2008
Posts: 1480
Location: Bothwell, Scotland
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| Posted: Fri Jul 28, 2017 8:28 pm Post subject: |
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Paul,
NO. Perhaps I didn't express it correctly. Maybe it should read 10-32.
Art |
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Paul fairall
Joined: 17 Nov 2016
Posts: 429
Location: North west Kent
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| Posted: Fri Jul 28, 2017 9:41 pm Post subject: |
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| 47Jag wrote: | Paul,
NO. Perhaps I didn't express it correctly. Maybe it should read 10-32.
Art |
so 10 is the wire gauge and 32 is tpi. Jeez, what's wrong with measuring something by its diameter. Even cable is measured millimeters squared not wire gauge. That was fine when people were used to looking at something and recognizing its wire gauge size.
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Bitumen Boy
Joined: 26 Jan 2012
Posts: 1735
Location: Above the snow line in old Monmouthshire
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| Posted: Sat Jul 29, 2017 10:21 am Post subject: |
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| Paul fairall wrote: | | 47Jag wrote: | Paul,
NO. Perhaps I didn't express it correctly. Maybe it should read 10-32.
Art |
so 10 is the wire gauge and 32 is tpi. Jeez, what's wrong with measuring something by its diameter. Even cable is measured millimeters squared not wire gauge. That was fine when people were used to looking at something and recognizing its wire gauge size. |
And then of course there's the problem of which wire gauge! IIRC there's an American wire gauge as well as a Birmingham wire gauge and the Standard wire gauge. There may be others, who knows..?  |
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Paul fairall
Joined: 17 Nov 2016
Posts: 429
Location: North west Kent
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| Posted: Sat Jul 29, 2017 5:27 pm Post subject: |
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I will stick with my micrometers
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