[modeleng] Re: coarse threads

Hi All,
As well as the BSP and NPT threads why is it that all the UNC and Whitworth 
threads are all the same pitch except the half inch,whit is 12 TPI and UNC is 
13 TPI the form changes from 55 Dregees to 60 Degrees but if you need to clean 
up an old thread either whit or UNC taps and die would do to get things started.

yours John Burridge


> Message Received: Jan 27 2007, 04:46 AM
> From: "Alan Stepney" <alan@xxxxxxxxxxxxxxxx>
> To: modeleng@xxxxxxxxxxxxx
> Cc: 
> Subject: [modeleng] Re: coarse threads
> 
> Here, 27tpi is used for, or used to be used for brass pipe gas threads.
> Our pipe threads are 28 , 19, 14, 11 tpi according to size.
> Alan Stepney
> 
> http://www.alanstepney.info
> Model Engineering & steam engine information pages
> ----- Original Message ----- 
> From: "Jesse Livingston" <fernj1@xxxxxxxxxxxxx>
> To: <modeleng@xxxxxxxxxxxxx>
> Sent: Saturday, January 27, 2007 2:45 AM
> Subject: [modeleng] Re: coarse threads
> 
> 
> Alan,
> 
> Try and find a lathe that will cut 27 tpi.  You will have to look at a lot
> of them before you will see one with that number of threads and yet it is a
> very common one.  Where???  On 1/8" pipe fittings, that's where.
> 
> Unka Jesse the Tennessee Redneck Machinist
> 
> 
> 
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