Creating Internal and External threads that can screw into each other

[Anonymous]

Let's say I want to model and 3D print a nut and a bolt which can screw together. What's the best way to create external threads(bolt) which can scew into internal threads(nut)? I understand how to use the Thread utility by selecting faces. However, it's not clear if the utility treats internal vs external threads differently. One thread would need to be extruded from the base cylinder while the other needs to be cut from the base cylinder.

Note:I'm using physically modeled threads because the parts will be printed.

Thanks.

[innovatenate]

In the thread tool, there is a Modeled thread option. If checked, this will generate the 3D geometry for the thread in the model. I have heard that they will work when 3D printed. 

In the Thread dialogue you can spacify the Size, Designation, and Class of the threads. Does this answer your question?

Thanks,

[Anonymous]

Hello Nathan,

Thank you for the reply. I'm aware of the modeled option.

My Question:

I have created both a bolt and a nut with the "modeled" option enabled. They both have the same Size, Designation, and Class of thread. Will the bolt screw into the nut when I print it? The utility would need to extrude the external threads and cut the internal threads(or vice versa), otherwise the bolt won't fit in the nut. With Inventor, you have to account for this when manually creating a bolt-nut combination.

[innovatenate · Accepted solution]

I have not tested this myself. However, I have heard from other users and coworkers that the the threads will fit together and function when 3D printed. You may have to look at the end conditions of the thread to insure that they will fit together smoothly. 

I have also sent a report for development to investigate B class internal threads. Thanks for posting this and let me know if I've missed anything or if you have any further questions.

Thanks,

[Anonymous]

Thank you Nathan! This answers my question. I guess this means that external threads are extruded, while internal threads are cut.

Another question on threads: Is it possible to extend the number of thread types in the utility? I want to try some thread sizes that are not present in the utility. 

[Anonymous]

Thank you, I was exporting to STL without Modeled checked and couldnt figure out why Cura wasnt showing my thread. You are a legend. 🙂

[jeffL6CDH]

I have this problem also, but with an important "twist".  I'm modeling and will be printing only the female receiving threads.  The male threads will be tapped (physically cut) into an existing 1/4 inch diameter metal rod. So there will be no extruding added to this metal part.  What is the correct size hole to receive this rod?  I'm guessing that I will have to create a hole slightly larger than 1/4 inch for the smooth, untapped portion of the rod, and then create a "sleeve" deep inside this hole that is SOME AMOUNT narrower than the rod, into which receiving threads can be cut so as to accept the tapped end of the rod.  But what amount narrower??  Am I even on the right track?

[Anonymous]

I have the same question.

I used exact same thread for inside and outside:

But after printing they didn't screw into each other:

[etfrench]

You can either tune your printer so that it prints with the necessary tolerances for the threads, or  you can edit the threads to give more tolerance.

Use the Press/Pull command on each flank of the threads to reduce their size.  You can also do a Press/Pull on the major and minor diameters.  You'll need to experiment with different offsets to find the settings that will work with your printer.

Here's a thread that I just printed. 

It's a metric trapezoidal 22mm thread.  Each flank of the threads were reduced by .05mm.  The major diameter was reduced by 1mm (about half the height of the thread).  The flat on the male piece allows it to lay flat on the print bed and print with no support.

Here's the default 22mm x 8 thread:

[adamjames95]

Hi @Anonymous ,

Here is a link to a workflow I use to create threads in Fusion 360:

https://www.youtube.com/watch?v=dSS3SWLIuZk&t=71s

Hope this helps!

-Adam James