3/8npt threaddimensions in mm

So I realize that I will need to use the coil command to cut the threads into the surface, but I'm just not sure of the specifics of the thread shape, spacing, hole diameter or tapering, etc....  If anyone has modeled npt threads before or knows of a source to get the relevant information, please let me know!

I've never under stood why the standards never give any dimensions for major (external) or minor (internal) diameters for pipe threads - just pitch at the various 'L' locations.  It seems to be treated as forbidden knowledge, even though in the case of NPTF (aka Dryseal), the thread crests are very important to control to achieve leak-free joints (L-effing-OL).  You have to back out the dimensions from an SAE standard for external thread blank dimensions and from form tool manufacturers' data sheets for internal thread dimensions.

NPT threadchart

I don't mean to highjack from the OP, but some RP materials (and RP Processes) post-process better than others.  By cutting the threads in the model then it is a matter of "chasing" the threads with a tap in post-processing to clean them up.

1NPT threaddimensions in mm

While playing with the model I have come across with a strange thing. Changing amount of revolutions to 8 in Coil1 gives me an error message. Please see the attached. Any other amounts are just fine. Can anyone confirm this?

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I am re-creating a pin, that is ported for an auto greaser. The fitting used for this is 2021-2-4S. In my pin model, I created a 1/8-27 NPT hole using the Inventor 2012 hole command and setting my parameters. See attached image

Far below normal precipitation has caused a drought and increased fire danger levels. All of Connecticut is currently in a Stage 2 Drought Advisory. Residents are encouraged to be mindful of water consumption and use extra caution to prevent fires. An emergency burn ban remains in effect at all state parks, forests, and wildlife management areas, prohibiting the use of all outdoor grills, firepits, campfires, etc.

NPT threadangle

I don't know if this will work with your 3D printing process, but this will work for me, my machinist will be able to build this pin.

Thanks for the help so far folks.  Two reasons why I want to model the threads in inventor instead of tapping the hole myself later:

Out of curiosity, what is your objective with this exercise? For rapid-prototype parts, I normally model the tap drill hole, but cut the threads with a hand tap.

1/2npt threaddimensions in mm

So I realize that I will need to use the coil command to cut the threads into the surface, but I'm just not sure of the specifics of the thread shape, spacing, hole diameter or tapering, etc....  If anyone has modeled npt threads before or knows of a source to get the relevant information, please let me know!

I despise taper pipe threads with the white-hot intensity of a thousand suns.  Even if you do make them correctly, testing an assembly featuring these ports or fittings ensure you're wearing them out even before the customer receives them!  I'm becoming increasingly serious when advocating my company add a line-item charge if a customer wants NPT ports.  Bluntly, I believe the main reason they're still being used (ignoring 1/8-27 for grease fittings and high-temp environs) is that the fittings are cheaper!  Only by charging more for these ports equivalent to the price difference in pipe and SAE fittings can this scourge on mankind finally be wiped out.

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SolidWorksNPT threadexternal

NPT threaddimensions PDF

1) the material that comes out of the 3D printer is quite brittle, so I'm reluctant to use a drill tap for fear of breaking the part

I have a similar problem... 3D printing a 1/8-27 NPT external thread.  Personally, I'm concerned about how these 3D printed (ABS plastic) NPT threads will perform; I believe they want to consider using these in production, not simply for prototyping... but I digress.  There is (to me) a lot of ambiguous minutiae in the details I'm finding for the actual physical description of the thread (various charts found on the web, machinists handbook, so on).  Attached is my best effort based on what I know at present.  I very much welcome feedback.

I plan on 3D printing a model that has NPT threads, 1/8-27.  From previous posts, I've learned that I need to physically model the threads because threads using the Hole feature are merely visual representations and will not carry over to an STL file.

1) the material that comes out of the 3D printer is quite brittle, so I'm reluctant to use a drill tap for fear of breaking the part

I plan on 3D printing a model that has NPT threads, 1/8-27.  From previous posts, I've learned that I need to physically model the threads because threads using the Hole feature are merely visual representations and will not carry over to an STL file.