Thread design for 3d printing issue

[Anonymous]

Hi,

I am having an issue with the female part of the thread. The thread couldn't be printed near the end/edge of the thread as it transitions into a smaller hole (shown in the picture). I was wondering how to design it to prevent it from happening.

[LeonardoBN]

Hi @Anonymous. Were you able to print well the remaining of the thread?

If you want to avoid supports, you could add a angled transition between the two diameters, like a Chamfer.

 

[Anonymous]

so I have printed couple of models. the one on left has no chamfer, the right one has, but it is still not turning out correctly.

I also did a pure thread print and it was ok. so i guess it is purely a design issue?

[LeonardoBN]

What filament and layer height are you using? You printed both full and thread-only part with same configurations, right?

I 3D printed some threads in the past. If I remember well, I went up to a M16 thread using a 0.15 mm layer height without support, as I didn't want to give post-processing.

[Anonymous]

i am using 0.2mm as layer height. is that too high?

for the prints, they are all in the same config.

[artemSIV · Accepted solution]

Hello. This problem is associated with the selection of layer height for the diameter of the printer nozzle. In the picture I gave an example for a nozzle with a diameter of 0.5 mm and a layer height of 0.2 mm and 0.12 mm. Also, high speed can spoil such an angle. I wish you success.

[GRSnyder]

I believe @LeonardoBN has identified the problem correctly, but you'll need more than a simple chamfer to address the issue. At some locations, the unsupported overhang is so large that a 45 degree chamfer would disconnect the thread from the barrel. I think this is why you're seeing some improvement with a chamfer but still having some trouble spots.

There are various ways to address this, but the easiest and most robust is probably to adjust the outside envelope to remove the 90 degree inset if you can, replacing it with a 45 degree ramp. Then you can print the part upside down (with the thread portion upwards) without support.

 

 

[Anonymous]

Thanks very much for the help

[LeonardoBN]

I have to rectify my previous anwser. As pointed out by @GRSnyder, the chamfer by itself will not eliminate all overhand areas. If the original design could be printed upside down, you would need supports only outside, whicj is far better than support touching near thread. 

A 0.2 mm layer height should work well for the thread.