Rhino bug when exporting to STL (mesh tolerance exceeded)

I designed and 3D printed this part and was suprised to see that one of the features was malformed. After examining the STL file, I saw that the mesh was incorrect. I had been using standard STL export settings for other parts with no issues (simple controls, 0.01mm max deviation). The geometry is a closed polysurface in the model and all surfaces seem clean. The only setting I found that affects the STL is the maximum edge length. If I set it to 5 mm, the hole feature is now well defined in the STL. I have uploaded the model and bad STL.

Is there something I am doing incorrectly or is this a bug with the export module?

model.stp (171.6 KB) export.stl (436.4 KB)

It looks like the MaxAspect ratio setting is bunging this up - please open the detailed controls and set the Aspect Ratio setting to zero. This does look like a bug…


1 Like

Hi wind, the mesh gets “corrupt” because one of the extruded surfaces is made up from linear segments and multiple fillets. (The left rectangular cutout in your image). This requires much denser settings compared to single surfaces for every fillet. If you run _DivideAlongCreases _SplitAtTangents=_Yes on the whole polysurface the meshing should work as expected.


Indeed clement, that solved the issue. I believe I used “wirecut” to create that cutout. I’m surprised to see that the tangent surfaces are without edges.
Thanks pascal for creating a bug report. I wish you a speedy recovery!