Subject: Re: UNF?? Thead Form Question

From: Charlie Greenman <[email-masked]>
Date: 6 Jun 1996 12:31:03 GMT

5/16-32 is NEF (Extra-file-thread series)

Basic pitch diameter is 0.2922
      minor diameter is 0.2719
Helix angle at basic pitch diameter is 1o 57'

This is from ASA B1.1-1949

(actually from Tool Engineers Handbook, 1949, first
edition. Truly a GREAT book.)

Charlie

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From: [email-masked] (Jim Hanrahan)
Date: Wed, 12 Jun 1996 21:49:01 GMT

Someone wrote:

>>> All UNxx thread forms are 60 degree, non-truncated forms.  Both the
>male and female threads are cut with a 60 degree tool, that comes to a
>full point. <<

In article <[email-masked]> [email-masked] (Scott Logan) writes:

>Sorry, but I think you may be mistaken.  UN series threads ARE
>truncated.  According to Machinery' Handbook, the crest of an external
>UN thread is truncated by a height of .125H, the root by .1667H.  An
>internal thread is truncated .25H on the minor diameter and .125H on the
>major diameter. H=cos30*pitch

I agree with Scott. The full "V" thread was the old American National thread 
form which has been superceded by the Unified National.

--------------------------------------------------------------
  Jim Hanrahan, PE, CP-IA         Naval Surface Warfare Center
  [email-masked]      Annapolis, Maryland, USA