NPT thread on a curved surface
SOLIDWORKS Forums
12 hours ago

Hello.

I am trying to implement a 1/16" NPT thread on a curved surface.

I have used the hole wizard and a tapered tap option to tap a hole where I want in tapered pipe tap, but since it's on a curved surface SW won't allow me to thread a curved a surface.

This leads me to believe that I may need to tap and thread the hole manually, but I am unsure of how to go about doing that to a production level standard (as I understand the thread profiles are not to be used for production quality stuff, which is what I am trying to do)

 

Does anyone have any idea where I could start going about solving this issue?

I am very new to the aspect of creating production-quality threads, let alone non-linear NPT tapered thread so I am trying to do it correctly from the start.

I have attached a model of the surface I am trying to thread.

 

Thanks in advance for any help/direction.


Categories: Modeling and Assemblies, Parts and Features

Comments
Last comment By: Paul Salvador   Fri, 15 Feb 2019 19:35:07 GMT
Re: NPT thread on a curved surface

Hi,

As Chris said a spot face will work, and would be the best option IMO, to ensure enough threads for your fitting, another option is to add a plane at the quadrant of the curved surface and select that for the face for the hole wizard.

 

Regrds,

By: Jim Moses  Thu, 07 Feb 2019 13:58:08 GMT
Re: NPT thread on a curved surface

Evidently you're using a newer version that 2017, as I can't open your file.

You can use a plane tangent to the surface, or put a spotface on the curved surface, as said above.

Very rarely do you need to show the actual threads, though.

Hole wizard will show the callout, and usually, that is all that is needed for production.

By: David Sloop  Thu, 07 Feb 2019 14:12:02 GMT
Re: NPT thread on a curved surface

Hello,

 

I'm on SW2018 so the attached must be SW2019.

Can you save your test as a Parasolid (x_t) file and upload that?

Or add some screen shots?

 

Kevin

By: Kevin Chandler  Thu, 07 Feb 2019 14:26:17 GMT
Re: NPT thread on a curved surface

Has anyone ever seen this one before?  I opens the file but I'm unable to do anything because all the commands are grayed out.

 

Chris

By: Christopher Estelow  Thu, 07 Feb 2019 14:58:04 GMT
Re: NPT thread on a curved surface

Christopher Estelow wrote:

 

Has anyone ever seen this one before? I opens the file but I'm unable to do anything because all the commands are grayed out.

 

Chris

It was made with a version newer than what you opened it with.

By: Danny Edwards  Thu, 07 Feb 2019 15:07:21 GMT
Re: NPT thread on a curved surface

Christopher Estelow wrote:

 

Has anyone ever seen this one before? I opens the file but I'm unable to do anything because all the commands are grayed out.

 

Chris

As Danny Edwards mentioned, if you're on the last SP of 2018, you're permitted to open SW2019.

By: Kevin Chandler  Thu, 07 Feb 2019 15:10:56 GMT
Re: NPT thread on a curved surface

Cool.....every other time I tried to open a future version it just had the pop-up.

 

Chris

By: Christopher Estelow  Thu, 07 Feb 2019 15:14:43 GMT
Re: NPT thread on a curved surface

Thanks for the help with the spotface, it really does help
Any idea about my question regarding executing the production quality threads?
Ive attached it as a parasolid as someone suggested to the original post

By: Muamin S.  Thu, 07 Feb 2019 23:14:14 GMT
NPT thread on a curved surface

Hello.

I am trying to implement a 1/16" NPT thread on a curved surface.

I have used the hole wizard and a tapered tap option to tap a hole where I want in tapered pipe tap, but since it's on a curved surface SW won't allow me to thread a curved a surface.

This leads me to believe that I may need to tap and thread the hole manually, but I am unsure of how to go about doing that to a production level standard (as I understand the thread profiles are not to be used for production quality stuff, which is what I am trying to do)

 

Does anyone have any idea where I could start going about solving this issue?

I am very new to the aspect of creating production-quality threads, let alone non-linear NPT tapered thread so I am trying to do it correctly from the start.

I have attached a model of the surface I am trying to thread.

 

Thanks in advance for any help/direction.

By: Muamin S.  Thu, 07 Feb 2019 02:49:26 GMT
Re: NPT thread on a curved surface

Hello,

 

If I understand correctly, you want actual 1/16 NPT threads cut into your part.

The Thread command doesn't do NPT I don't believe.

 

So I think you'll have to find a 1/16 NPT pipe nipple (any NPT fitting with a male thread) as a 3D model.

Locate this model into your part per an engagement standard, such as:

Basic Dimensions, American National Standard Taper Pipe Threads, NPT, (ANSI B2.1-1968) 

Then do a Combine>Subtract.

 

I went to McMaster as they have NPT 3D models, but their smallest size is 1/8 NPT.

 

Kevin

By: Kevin Chandler  Fri, 08 Feb 2019 21:30:07 GMT
Re: NPT thread on a curved surface

Why do you want "production quality threads"?  If you spot-face this cylinder, you aren't going to have enough wall thickness left to produce a sealable "production quality thread".

By: Josh Brady  Fri, 08 Feb 2019 21:32:41 GMT
Re: NPT thread on a curved surface

I do this all the time, work in plumbing and create 3D printed prototypes that require production quality threading. From my experience, McMaster Carr 3D models are actually inaccurate - when printing a McMaster file, often something will be just barely off to prevent you from using it in a prototype.

 

You have to use the helix and cut sweep command instead of the thread tool to create a production quality thread. NPT threads taper at angle of 1.7899 degrees, and each size has standard diameters. You can use McMaster parts for reference, but ultimately just take a look at the wikipedia page here: National pipe thread - Wikipedia

 

Sketch a circle with diameter equal to the effective thread diameter if it's an internal thread, or actual outside diameter if external. Create a tapered hole (1.7899 taper angle) from this sketch. Create a tapered helix with the desired height and pitch from this sketch. In your case, the pitch would be 1/27 threads per inch. Ensure that the orientation is correct (clockwise vs counterclockwise, typically threads are clockwise but you may have to switch the orientation depending on the way the model is built) Sketch the thread profile on a plane coincident with the axis of the helix and the beginning of the helix, and pierce the sketch to the beginning of the helix. (You can google how to derive dimensions for thread profiles, too much to explain here) Ensure that you add a taper to the thread profile, see McMaster threads for reference. Then cut-sweep it along the helix. Also, add a chamfer to the edge of the appropriate length. I usually do my helix, sketch the thread profile, add the chamfer, then sweep the cut.

By: Victor Carosi  Fri, 08 Feb 2019 22:20:55 GMT
Re: NPT thread on a curved surface

Thanks for the help, I am trying to prototype some threads, and 1/16 NPT is one of them among other things like AN fittings.

I appreciate this help very much, ill give it a crack

I am very new to this so the whole McMaster thing is something I've never heard of, thanks for mentioning it.

By: Muamin S.  Sat, 09 Feb 2019 23:57:17 GMT
Re: NPT thread on a curved surface

I would print the part with just a thru hole and then cut the threads into it.  That way you are guaranteed it will be the right size.

 

Chris

By: Christopher Estelow  Mon, 11 Feb 2019 13:51:54 GMT
Re: NPT thread on a curved surface

If the proportions are correct on the image you posted, your wall thickness is only 1/8".  For a 1/16-27 NPT thread, you are already short of 4 threads engagement.  Spot face it and you're in the neighborhood of 2 threads.

By: Josh Brady  Mon, 11 Feb 2019 14:17:39 GMT
Re: NPT thread on a curved surface

Josh Brady wrote:

 

If the proportions are correct on the image you posted, your wall thickness is only 1/8". For a 1/16-27 NPT thread, you are already short of 4 threads engagement. Spot face it and you're in the neighborhood of 2 threads.

For me I would punch the hole and add a pipe Nipple of the thread size he needs to their would be enough threads.  But not sure I've even seen one that small.

By: David Nelson  Mon, 11 Feb 2019 15:08:39 GMT
Re: NPT thread on a curved surface

I would definitely recommend what David said if the walls are too thin.

 

Chris

By: Christopher Estelow  Mon, 11 Feb 2019 15:12:56 GMT
Re: NPT thread on a curved surface

Kevin Chandler wrote:

 

Hello,

 

If I understand correctly, you want actual 1/16 NPT threads cut into your part.

The Thread command doesn't do NPT I don't believe.

 

So I think you'll have to find a 1/16 NPT pipe nipple (any NPT fitting with a male thread) as a 3D model.

Locate this model into your part per an engagement standard, such as:

Basic Dimensions, American National Standard Taper Pipe Threads, NPT, (ANSI B2.1-1968)

Then do a Combine>Subtract.

 

I went to McMaster as they have NPT 3D models, but their smallest size is 1/8 NPT.

 

Kevin

It doesn't specifically say NPT here, but if you drop it onto a part:

By: Dan Pihlaja  Fri, 15 Feb 2019 15:20:56 GMT
Re: NPT thread on a curved surface

Dan Pihlaja wrote:

 

Kevin Chandler wrote:

 

Hello,

 

If I understand correctly, you want actual 1/16 NPT threads cut into your part.

The Thread command doesn't do NPT I don't believe.

 

So I think you'll have to find a 1/16 NPT pipe nipple (any NPT fitting with a male thread) as a 3D model.

Locate this model into your part per an engagement standard, such as:

Basic Dimensions, American National Standard Taper Pipe Threads, NPT, (ANSI B2.1-1968)

Then do a Combine>Subtract.

 

I went to McMaster as they have NPT 3D models, but their smallest size is 1/8 NPT.

 

Kevin

It doesn't specifically say NPT here, but if you drop it onto a part:

I thought the OP was looking to get a cut thread modelled in? Yes?

HW taps are cylindrical/conic only, true?

 

Kevin

By: Kevin Chandler  Fri, 15 Feb 2019 17:18:03 GMT
Re: NPT thread on a curved surface

Kevin Chandler wrote:

 

Dan Pihlaja wrote:

 

Kevin Chandler wrote:

 

Hello,

 

If I understand correctly, you want actual 1/16 NPT threads cut into your part.

The Thread command doesn't do NPT I don't believe.

 

So I think you'll have to find a 1/16 NPT pipe nipple (any NPT fitting with a male thread) as a 3D model.

Locate this model into your part per an engagement standard, such as:

Basic Dimensions, American National Standard Taper Pipe Threads, NPT, (ANSI B2.1-1968)

Then do a Combine>Subtract.

 

I went to McMaster as they have NPT 3D models, but their smallest size is 1/8 NPT.

 

Kevin

It doesn't specifically say NPT here, but if you drop it onto a part:

I thought the OP was looking to get a cut thread modelled in? Yes?

HW taps are cylindrical/conic only, true?

 

Kevin

You are correct.   I missed that entire portion of it.  *sigh*.

 

Anyway, I wouldn't use the built in thread for this at all then.

Instead, if you really need the threads modeled in (99% of the time you do NOT need them modeled in), then use a sweep instead.  Start the sweep a few millimeters above the curved surface and cut inward.

By: Dan Pihlaja  Fri, 15 Feb 2019 18:52:22 GMT
Re: NPT thread on a curved surface

Victor Carosi    ...agree, have pre sketch and simple model to reference!  (image showing sketch for spot face and surface model reference(s).. depending on the type of thread used)

2thrds 1.png

By: Paul Salvador  Fri, 15 Feb 2019 19:35:07 GMT
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