Preform filling in hollow lattice STL objects

Trying to play around with lattice structures using 3Dexpert for Solidworks. Exporting a basic sphere with lattice to STL and then bringing it into preform, it’s solid. Opening in meshmixer shows that it contains two objects, the lattice and the shell. Even after merging the two objects, exporting as STL again, Preform still fills in the middle. Just to make sure I’m not crazy here I’ve imported the STL back into Solidworks and it sees it as a hollow.

I believe it is filling it in because it would create a suction when trying to lift the build platform. If it were to keep the lattice the print would most definety fail.


the object is a solid.

parametric apps like solidworks do not necessarily export the things they show as hollow as hollow… because you have two object… one qualified as a solid the other may be nothing but a lattice pattern that the app is treating as a rendered emptiness.

You should have only ONE object on the export… the lattice, and the sphere should have been SUBTRACTED from the lattice to ensure its interior area was hollow.
If the sphere is hollow, and the lattice is also hollow, then having both objects in a single STL can result in a boolean reversal- 2 negatives making a positive.

Or - its also possible the lattice is a surface that has ZERO thickness. this will not show up as a solid. This might Display as a lattice in your software of origin.- but without a thickness its can’t be rendered in the slicer.

either way preform is not changing the model… the model you are exporting is not properly configured or modeled as a correct solid.

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