STEP import excludes big chunk of part. STL import of same part slices as intended.

[henriksundeodegard]

Description of the bug

I've tried lately to use the new STEP import feature because it made the arrangement of this WIP print-in-place model a lot easier. However, the slicer seems to be struggling on this hinge.

Unsliced, PrusaSlicer warns that the STEP-file model has 127 open edges, while the same part imported as STL does not have any such warning. Also, when trying the option "Fix through the Netfabb" on the faulty part, it seems to fix the issue. But upon further inspection the hinge is not sliced correctly and would not work as a hinge..

Also asked this on Reddit: https://www.reddit.com/r/prusa3d/comments/xusdyq/prusaslicer_25_step_import_excludes_big_chunk_of/

Project file & How to reproduce

Relevant project files.zip (includes faulty STEP file and working STL file)

---

Screenshots

1. Unsliced - PS 2.5 warns that the STEP file has 127 open edges:

---

2. Slicing as is makes this huge horizontal gap in this one part:

---

3. Tried the option "Fix through the Netfabb", but then the model is missing an indentation-feature on the hinge:

Checklist of files included above

• Project file
• Screenshot

Version of PrusaSlicer

2.5.0

Operating system

Windows 11

Printer model

Prusa i3 MK3S

[n8bot]

Just curious, where did you export the STEP file? From what software? STEP files are not consistent. Even though there are standards for STEP files, there are many different standards they can follow and they all have errors sometimes lol.

[henriksundeodegard]

I'm using Fusion 360 for designing.

[n8bot]

Would you be willing/able to attach the fusion .f3d file? It could help in discovering what might be leading to the issue on import.

[henriksundeodegard]

Towel Paper Holder v65.zip - containing .f3d file

At this point I'll take all the help I can get. I made sure the hinge-features are the latest features on the history line.

[n8bot]

I just had a chance to confirm that the fusion file doesn't have any problems with it. The export to step from fusion can be reimported into fusion and there are no errors.

When the step is brought into PrusaSlicer, the conical features and maybe others do not get imported. The importing of the step or the conversion to mesh seems to be the problem.

[n8bot]

To resolve your issue short-term, you can right-click the top-level component in Fusion 360, and select save as mesh. Save it as one file. Then, when you import the .3mf (or stl, whatever you choose) into prusaslicer, select YES when it asks you if you want to import as one object with parts.

Ensure that you choose high-enough refinement options in Fusion 360 to get smooth curves. You might have to to custom, as "High" can still be a bit faceted for my liking.

[henriksundeodegard]

That's great, thank you for finding a workaround.
Also didn't know about the multi-part import feature to keep the parts arranged as in the design in PrusaSlicer - will be useful for other projects as well. Thanks again!

By the way, is this a bug that might be long-term fixed in the future?

[DragonFinlay]

I'd hope so! The STEP import is still very new to PrusaSlicer and bugs are to be expected.
This issue will be kept open along others of the same kind until we can get to fixing them.

[bubnikv]

The STEP import quality depends on the OpenCASCADE CAD kernel implementation quality. We cannot do much here at PrusaSlicer side, we will have to wait for OpenCASCADE to improve. It would be great if you guys could try to import into FreeCAD and if you get the same issue, report it to OpenCASCADE folks. They may be thankful for more input. st 5. 10. 2022 v 15:41 odesílatel Dominik ***@***.***> napsal:

…

I'd hope so! The STEP import is still very new to PrusaSlicer and bugs are to be expected. This issue will be kept open along others of the same kind until we can get to fixing them. — Reply to this email directly, view it on GitHub <#8998 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/ABMPSI7GMFVZCBFMMA7GG4DWBWAQTANCNFSM6AAAAAAQ4ACOOY> . You are receiving this because you are subscribed to this thread.Message ID: ***@***.***>

[henriksundeodegard]

Seems to be only the inward conical features that's failing. I tried inverting the hinge "polarities" and this happened:

[n8bot]

Somewhat surprisingly, the step files exported from Fusion 360 import fine into FreeCAD (the old version I had installed).

I do wonder if I remember seeing some commits to FC that were aimed at fixing step import. OCCT is a failed cad package from the 90s, at its core... as much as I love it... heh...

[allesblinkt]

Same issue here with PrusaSlicer 2.5.0+win64.
STEP file is exported from Fusion 360. It opens fine and is not broken in FreeCAD (0.20.1) and Rhinoceros (7.21). Currently my workaround is opening the STEP in Rhino and exporting it again.

Thank you very much though for implementing the STEP support. It is a major change in our printing workflow.
I have added one example STEP file which imports with missing faces in PrusaSlicer.

C_DrivenPlate_Free_print_broken.zip

[jepler]

This printable has a step file that looks fine but slices wrong: https://www.printables.com/model/348322-odette-the-owl/files -- the stl file is fine. I think their workflow is fusion 360-based.