Threads and strings

I am printing a large threaded cap, and am having problems with what looks like strings on the threads. I had read the thread with a similar problem and increased the nozzle temp and tried supports. The nozzle temp from 200 - 215 had no effect at all. The sports and I tried lines, grid and tree were impossible to get off they fused to the threads.

I had enclosed a picture to show problem. Any help would be greatly appreciated.


Threads need to be designed to make them FDM printable. Basically, the thread is creating an unsupported overhang and as these overhangs are printed, the plastic is drooping to stick to the supports or the angle is so sharp that the line of plastic doesn’t have enough area to stick to the layer below (“strings on threads”). You might be able to print the part with a smaller layer height – or try Cura’s Adaptive Layers. And/or, try lowering the print temperature, up the cooling (if possible), or slowing the print speed down.

When testing different settings, lower the part into the bed until only 3-4 threads are showing to save on filament.

Hope this helps!


Thanks. That makes sense. I will give it a try.

Let us know what works for you!


I have other projects going wright now, and I am going to be out of town for a week, so it will be in two weeks

thanks for the advice again.

The main issue IMHO is layer adhesion. Since the print is not continuously there is a retract and move, before the next layer is printed and if the layer is not bonding, due to e.g. under extrusion after retract, it looks like this. The layer bond is not there and it drags the lines. Once a line missed its spot the next layer one has no change to bind to the previous, because it is not there, so the issue gets worse. It basically prints in “mid air”, cause by the prior layer simply missing.

I use dynamic layer height for parts like this, so the thread gets more “detailed”, but the main issue is that wrong retract settings are causing layer adhesion issues.