Hello,
I got some issue printing the top of a skull. On the very top the inner wall and outer wall appear in a stange way which is not consistent with the other part of the print.
Any idea how or what I should change so that this part looks the same as the other ?
thank you
Welcome to the community.
What you’re seeing is a “stair-stepping” effect, a byproduct of layered Fused Deposition Modeling (FDM) – filament printing. Although we call it 3D printing, it’s really more like 2.5D printing since the slicer builds a stack of 2D layers.
As a side note, there is research into non-planar nozzles that can tilt around curves, but that’s still experimental. Check out this video from Teaching Tech for a great demonstration that explains what’s happening in your prints:
https://www.youtube.com/watch?v=gmePlcU0TRw
Non-Planar 3D Printing
Here’s an exaggerated illustration of what’s happening in the slicer and how to improve it. The fix is imperfect but will noticeably reduce the effect.
Two ellipse models: one is short with shallow slopes (similar to your issue), while the taller one has steeper sides and less visible stepping.
You could set the entire model to print at 0.08 mm layer height for the finest resolution, but that greatly increases print time.
A better approach is to use the Variable Layer Height tool to print only the top areas at 0.08 mm, leaving the rest at standard height.
This will smooth the surface, but you’re still limited by the nozzle size. Switching to a 0.2 mm nozzle helps even more but can make prints take 6× longer and reduces strength. That tradeoff is fine for artistic prints but not recommended for functional or structural parts.
