Problem slicing STL exported from FreeCAD

[JanErik]

I have initially created an enclosure, intended for 3D printing, using an OpenSCAD model. Then imported it to FreeCAD and somehow made a Part from a Mesh.
Cut some holes in it using Boolean Cut and now I have tried to export it as STL again.
But it does now slice correctly neither with PrusaSlicer nor Curaengine;

Looks OK when opened in RepetierHost even though it complains it is not manifold;

Screenshot_20210407_175814.png (19.32 KiB) Viewed 638 times

But sliced, it looks like this.

Screenshot_20210407_175208.png (147.4 KiB) Viewed 638 times

I have tried to run the Analyze and repaired inconsistencies but that did not help. What could I be doing wrong here?

[chennes]

Can you post your FCStd (and possible SCAD) files here?

[JanErik]

http://users.abo.fi/jskata/equalizer.zip
customizable_enclosure_equalizer.stl is the original output from the SCAD file with the same name.
equalizer_meshed.stl is exported from FreeCAD.

Tried both Standard and Mefisto mesher, as well as just taking File->Export on the Cut16 object.

[JanErik]

So, any ideas on this?

[jmaustpc]

So, any ideas on this?

Can you [post the FCstd (FreeCAD) file?

You can see in your second image that the holes in your object are showing as cylinder walls rather than a hole. That could explain why your other program says that the STL is non-manifold. I have often seen STL files from other applications that actually contain several STL components with in it, for example a hole may have a separate cylinder, there are some tools that you can edit those with varying degrees of success. I wonder if you had the wrong thing selected when you ran the FreeCAD Export? FreeCAD does not export at the "complete file" level, you select just the object required from within your file and export that.

That may be you problem if you selected both the cylinders that you used for the Boolean cut and the result of the cut and then exported, for example.

[JanErik]

Uploaded it here;
http://users.abo.fi/jskata/equalizer.zip
customizable_enclosure_equalizer.stl is the original output from the SCAD file with the same name.
equalizer_meshed.stl is exported from FreeCAD.

Tried both Standard and Mefisto mesher, as well as just taking File->Export on the Cut16 object.

[jeno]

So, any ideas on this?

If I take a closer look at your model I see the follwing

JanErik.png (55.68 KiB) Viewed 443 times

Your Model is a compound constisting of two shells. They are hollow. Booleans make it worse. Then the shells are open.

JanErikopenshell.png (18.89 KiB) Viewed 443 times

Of course then slicers are throwing "non-manifold" errrors. Probably you forgot to make the Part->Convert to solid step.
I would suggest to start with the orignal mesh and split box and lid. Save the lid as it is, it is fine for the slicer. Then delete the lid. Convert the box to a solid Part-> Shape from Mesh followed by a refine Shape and Convert to Solid afterwards. Then apply your Booleans. In your case Draft Array would be a time saver

Regards

[JanErik]

Great, thanks! I am making progress now.