Ultimaker Cura slicing bug

When I slice a model of a graph (like a truss with spheres at the vertices), Cura is filling the central triangles of the model, rather than leaving the model open. Any idea why? I have attached the model file. If you select S5 as your printer with PLA in one extruder and PVA for support in the other, and slice the model, you will see what I mean carmaSpikey1.STL (463.0 KB)

Hi Matto,

This often means there’s a pin-hole gap somewhere in the geometry of the design. There are many ways to repair the STL, surprisingly Microsoft 3D Tools does a decent job.

For those wondering what we’re talking about, top image is the design, bottom is the sliced object at a specific layer where the filled-in area occurs.

I accept that a fault in the model is possible, I have a simple workaround, which is to tilt my model slightly so none of the triangles is parallel to the build plate, then the model slices just fine. I don’t know if this discounts the pinhole gap theory?

Nice find. It could be that the pin-holes in the STL are not seen at the new layer increments when rotated.

If it works, then it’s perfect!

As it turns out, the model (produced by Mathematica) has closure issues where the cylinders meet the spheres. What I find truly remarkable is that the Ultimaker S5 is so precise that it faithfully reproduced these defects in the printed model: