I have three small objects, scaled down to mm from an original in metres for 3D printing.
Whenever I export the mm sized ones to STL, two of the three objects have all their faces reversed.
Here’s what the original SKP file shows:
And the STL imported back into SU:
Notice the extra line introduced in the rear part, top right. If I delete that line, the face disappears, and drawing a rectangle corner to corner normal to the green axis won’t recreate it.
The Mac Preview viewer shows the same face reversal.
Here’s the original SU file.
Trammel parts.skp (878.7 KB)
I can fix it for printing by reversing the faces in the two outer parts before STL Export, but why is it happening in the first place? The original parts are all solid according to Solid Inspector 2, and their component axes are parallel to the overall model axes.
(BTW, the file is purged, but not shown in the images are other parts which won’t be 3D printed.)
Is this a bug in the STL exporter, or some quirky feature of the way I drew the parts or scaled them?