Tips/Techniques 3DP typical machine threads

[PeterT]

This got touched on elsewhere, but I'll expand the topic here. What is the collective wisdom for printing threads in general for workshop items? I'm about to experiment & just wondering beforehand. Nothing onerous, not a 3DP trailer hitch to be sold on Ebay LOL. Mostly prototyping what will ultimately be metal. OTOH if printed threads work for the application why not use it.

- I could generate a true thread but extra work in my particular CAD app. No drag & drop vee/helix profiling like Fusion. This would theoretically make the part ready to go, but now all the other factors - accuracy of print vs class of thread, orientation of threads relative to print action, print goobers etc.

- I could spec a pilot hole only, print & tap no different than metal. But (my limited understanding) this could be bad news if the threads cut into the hole ID skin into the mushy / low density infill. So spend time in the print software to somehow increase the local hole density/thickness? is this even a thing?

- partial thread form intending to be finish tapped? (even more work)

- skip the whole thread printing thing & integrate provisions for metal thread inserts from onset?

 

[DavidR8]

I think a lot depends on the size of the hole and thread pitch.
A small thread like 10-32 is not really a viable thread to 3D print with any kind of accuracy. It can be tapped though.
Larger threads like 1/2-10 might work due to the size of the thread.
That said considering that the larger thread is likely to see more load the ultimate strength is a consideration.

And as you note hole orientation is a factor. I try to design such that all holes are axially oriented to the Z axis. I've never found a support style that works well for holes with axial orientation in the X or Y axis.

Personally I use brass inserts for anything that needs accurate, and durable threads.

 

[TorontoBuilder]

This got touched on elsewhere, but I'll expand the topic here. What is the collective wisdom for printing threads in general for workshop items? I'm about to experiment & just wondering beforehand. Nothing onerous, not a 3DP trailer hitch to be sold on Ebay LOL. Mostly prototyping what will ultimately be metal. OTOH if printed threads work for the application why not use it.

- I could generate a true thread but extra work in my particular CAD app. No drag & drop vee/helix profiling like Fusion. This would theoretically make the part ready to go, but now all the other factors - accuracy of print vs class of thread, orientation of threads relative to print action, print goobers etc.

- I could spec a pilot hole only, print & tap no different than metal. But (my limited understanding) this could be bad news if the threads cut into the hole ID skin into the mushy / low density infill. So spend time in the print software to somehow increase the local hole density/thickness? is this even a thing?

- partial thread form intending to be finish tapped? (even more work)

- skip the whole thread printing thing & integrate provisions for metal thread inserts from onset?

I tried a fair number of threads in PET and PLA and while standard large size threads can work, I had to design special profiles to have any decent holding power on my pneumatic chisel. It took tweaking on the internal grub clearance to get a good fit

I prefer heat stake insert for smaller threads, and even used threaded insert for wood

 

[pdentrem]

In the astronomy area, printing .75 and 1.0 mm threads have been done many times. Mind you that attachments are large in diameter like 42 mm X .75. Most success has been using .1 mm layer height. Here is a link to an area I found out of 133 pages discussing threads. Check post # 793. Hope this helps.
Pierre

https://www.cloudynights.com/topic/704315-3d-printed-astronomy/page-32#entry11339267

 

[djberta]

I found using thread inserts was simple and effective.

 

[PeterT]

I'm sure I even have some of these heat set inserts to experiment with. I'll have to research how to increase fill density around the hole location if that's a prerequisite

Threading 3D Printed Parts: How To Use Heat-Set Inserts

We can make our 3D-printed parts even more capable when we start mixing them with some essential “mechanical vitamins.” By combining prints with screws, nuts, fasteners, and pins, we ge…

hackaday.com

@djberta when you say thread inserts do you mean a particular style? I'm also familiar with the ones with aggressive external threads like for wood etc. but assume that would be too coarse for 3DP application even if heated?