Simplify3D User Forum

Most of my model doesn't get past the slicer. It looks fine and the normals are good. However it tests as mostly non-manifold and self-intersecting. I selected the heal and checked the box (forget the name) in the FFF advanced tab to have it repair. Still the result is just a few floating bits, but most of the model is missing. The support generated as if the entire model is present.
Are there more 'fix' options..... Should I expect the slicer to be able to repair this? Screen shot is from my Onshape document. I tried several STL export resolutions. Really no other adjustments available for exporting.

Your best choice is to repair the errors automatically. Have you tried running the 3D file through a repair service? I would recommend you try https://makeprintable.com/ It fixes nonmanifold surfaces, intersections and flipped faces and wall thickness issues.