Re: size of drill and tap for grease zerk

Posted by Tim PloughNman Daley on January 01, 2006 at 07:33:36 from (206.148.168.167):

In Reply to: size of drill and tap for grease zerk posted by souNdguy on December 31, 2005 at 11:36:53:

Happy New Year Sounder Man-

Misconceptions about NPT taps always amaze me. NPT ( National Taper Thread ) American Standard Taper Pipe Thread. Key word is TAPERED. Slope is exactly 3/4" per foot. Tap size refers to orrifice opening of the mating part, not the actual tap major diameter. 1/8 NPT actually has 27 threads per inch, but they don't measure NPT that way. Perhaps that is why a 1/4-28 tap works- for a while - until you screw in the fitting too far and strip out the major diameter. Someone mentioned Interfernce Fit threads- which are NOT tapered Pipe Threads. They are straight threads used on manifold studs but are similar to NPT threads because they are meant to be screwed in once and allow the thread to "crush" itself over and form a seal. HTH

Tim Daley (MI)
*8N15513*

Replies:

• Re: size of drill and tap for grease zerk soundguy 04:47:06 01/02/06 (3)
  • Re: size of drill and tap for grease zerk Tim PloughNman Daley 16:35:58 01/03/06 (2)
    • Re: size of drill and tap for grease zerk soundguy 04:29:38 01/04/06 (1)
      • Re: size of drill and tap for grease zerk Tim PloughNman Daley 04:58:39 01/04/06 (0)
• Re: size of drill and tap for grease zerk Tim PloughNman Daley 07:52:27 01/01/06 (0)

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