Modeling threads for 3D printing 3

[Trietsch]

Hello,

What is the best way to get threads in a .stl file so they can be printed? I realize that these threads may not function unless the printer is very accurate.

Using NX6.0.5.3 and TCuA8.3, once of my sites is looking to purchase a 3D printer so I don't have a specific machine yet.

Thanks it advance.

 

[capnhook]

For external threads, model them "fat", then clean them up with a thread die.

Internal threads can usually be easily tapped.


Have fun.....

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[Trietsch]

Thank you for the response. Do you know of a way for NX to model/show the threads? This way the RP machine will attempt to create them without the need for secondary processing.

 

[cowski]

Insert -> Design Feature -> Thread
Choose the detailed type and it will create threads on your model.

www.nxjournaling.com

 

[Trietsch]

Cowski,

Thank you for the response, is there a way to show the threads from the hole tool? i.e. I want to show 1/4 - 20 threads 5/8" deep. Do I have to look up the thread's parameters in order to show them detailed?

 

[capnhook]

This way the RP machine will attempt to create them without the need for secondary processing.

Believe me, you are going to have to at least chase the 1/4" - 20 threads with a tap. Order one now so that you will have it when the time comes.

Proud Member of the Reality-Based Community..

[green]To the Toolmaker, your nice little cartoon drawing of your glass looks cool, but your solid model sucks. Do you want me to fix it, or are you going to take all week to get it back to me so I can get some work done?[/green]

 

[cowski]

Not that I know of, but then I'm an infrequent user of the thread and hole functions.

I wouldn't be surprised if a future version of NX combined the 2 functions, it looks like the thread dialog is due for an update...

What you can do is create your threaded hole with the hole function then add the thread feature that references the existing expressions from the hole feature. That way if the values of the hole feature change, the thread will update accordingly.

www.nxjournaling.com

 

[Trietsch]

Haha, I fully agree capnhook, however there are those in management that would like to think otherwise so I will have to prove it to them with a physical part. Good thing maintenance has a complete tap and die set on hand.

All that aside, do you know of a way for NX to display (and ultimately export) the threads without manually typing the major/minor diameter and pitch? I played with NX8.5 a bit to see if it was just something I am missing in NX6, however I don't see this functionality on the horizon, I can't be the only one that wants this.... can I?


Cowksi,

I'm glad you posted this as you are the #2 MVP here, second only to John and he works directly with the developers. Perhaps this is being shown in the UK Users group today in "what's new in NX9" the remainder of my CAD/PLM admin group resides in the UK and were in attendance..


For now I supposed the machinist handbook will be my friend to cross reference a standard thread size to its geometric features.

Thank you all for the posts! At least I am not the only one that doesn't see this option.

 

[JohnRBaker]

To answer you question with respect to the 'Hole' feature function, which I assume that you've created a 'Threaded Hole' feature, NO there is no option to show detailed threaded using the 'Threaded Hole' function. You will need to create a 'General Hole' first (the diameter of the hole is critical as it must match the tap-drill size, which for a 1/4-20 is 0.2094 inches). Once you have the holes created then do what cowski stated above, use the Insert -> Design Feature -> Thread... function to create the thread faces.

That being said, I also agree with cowski that you'll need to chase those threads with an actual 1/4-20 tap to get anything even close to usable for threads that small and even then I wouldn't expect good results. Now if the 3D Printing technology that you're using produces an actual SOLID part that is not just a hollow shell, like some RP methods do, then you might be better off just modeling the pilot hole and skipping the threads in the NX model altogether and physically add them using that 1/4-20 tap AFTER the printed model is created.

John R. Baker, P.E.
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Product Engineering Software
Siemens PLM Software Inc.
Industry Sector
Cypress, CA
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To an Engineer, the glass is twice as big as it needs to be.

 

[cowski]

I also agree with cowski capnhook that you'll need to chase those threads

Fixed.
For the record, it was capnhook's suggestion (which I also agree with).

www.nxjournaling.com

 

[Trietsch]

John,

Thanks for the comments, I too anticipate current RP technology will be far too lacking for a 1/4-20 thread. And after the first part or two I'll likely have convinced everyone here that we should add such things as a secondary step and leave some extra on the plastic RP parts to remove afterwards.

For future reference, any luck with standard thread sizes appearing in NX design feature > thread? Perhaps I’ll be luck enough for you to show this to me at the Indiana RUG this year for NX9 goodies..

 

[cowski]

...I too anticipate current RP technology will be far too lacking for a 1/4-20 thread.

I actually have a couple parts from our FDM machine that I used the thread function to model in 10-32 threads (I thought, why not? I'll give it a try). I can thread a 10-32 screw in with no secondary cleanup. The fit is slightly loose, but it was good enough for the intended purpose. The results of your experiment may surprise you, but I agree that for the best fit you will want to make the hole undersize then drill & tap as necessary.

www.nxjournaling.com

 

[capnhook]

If you are using the powder-based technology, you can infuse the matrix with a couple of drops of cyanoacrylate. After it cures, chase the tapped hole with the tap. It will give you stronger threads.

You are right, Trietch....after the first part or two it will be obvious what you will have to do. Threaded inserts like those used in the injection-molding world work AOK, too.

Proud Member of the Reality-Based Community..

[green]To the Toolmaker, your nice little cartoon drawing of your glass looks cool, but your solid model sucks. Do you want me to fix it, or are you going to take all week to get it back to me so I can get some work done?[/green]

 

[JohnRBaker]

There are no plans at the moment to update/replace the current 'Detailed Thread' function in NX. However, there is a little trick that you can do which will make this a lot simpler. First go ahead and create your normal 'Threaded Hole' feature and then go to the Insert -> Design Feature -> Thread... function and set the 'Thread Type' to 'Detailed' and select the pilot hole that is already in the model and hit OK. Now granted, you will have TWO 'threaded' features in your model but since one is 'symbolic' and the other 'detailed', the system doesn't really care. And starting with NX 8.0, if you don't mind doing one extra step you can eliminate the first 'symbolic' thread feature. Just create the 'Threaded Hole' feature as described above, but before adding the 'Detailed' thread, edit the 'Threaded Hole' and change it to a 'General Hole' which will remove the 'symbolic' threads but the size of the 'pilot' hole will be unchanged and therefore will be ready for you to add the 'Detailed' thread. I know it's a bit of a kludge, but it gets the job done and works now.

John R. Baker, P.E.
Product 'Evangelist'
Product Engineering Software
Siemens PLM Software Inc.
Industry Sector
Cypress, CA
Siemens PLM:
UG/NX Museum:

To an Engineer, the glass is twice as big as it needs to be.

 

[SDETERS]

You could also use the thread function then take those surfaces and do an offset of a certain number. I think I usually use .003-.005 or so. This way it is a looser thread fit. So the pitch stays and your fastner threads in nice. We have a Z-corp machine and we tap our threads.

 

[mmauldin]

Another trick is to not accept the NX defaults for the the minor diameter. I force the minor diameter on external threads as small as NX will accept, then do an overall offset to make the body smaller. .003" works well for our Objet machine.

For internal threads I control the minor dia by the hole size.