Export: STEP...: Export Zones: bugs

Layout 3D Models
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When exporting a PCB as a STEP file:

  • First I want to say it works. Thank you. This is a big deal. It simplifies a lot of CAD work later.
  • Second, it has a bug.

Having exported the same PCB 3x times I have gotten 3x slightly different results when importing the STEP into Fusion 360. Actually I have conducted more than 9 exports between 2 PCs and two versions of KiCAD. Also including making changes to the file in hopes of altering the results.

  1. In most cases the result is that the copper layer becomes a Bspline, and I am sure there is a way to make the spline into a cookie cutter in fusion 360, I am not sure how just yet.
  2. Some of the time the Through hole or VIA is cut out fully, bu then the cut out is not erased. So holes are plugged.
  3. Some of the time a Through hole or VIA are not cut out at all.
  4. The zone around any through hole that is part of the separation and thermal relief is also sometimes left in place as an object to be removed.

Basic export is carried out without error. Though they have been stripped of material data, only reference to colors are carried. The resulting imported has no issues. PCB, and individual STEP files exported as part of this process seem in perfect working order after import to Fusion360.

Export Zones option, generates error: failed to ad edge to wire. But succeeds.
The resulting imported file exhibits issues, 1, 2, 3, and 4.
Deduction is that the Export Zones option is the sole cause of export issues at this time.

Export Tracks pads and vias option, does not generate any errors. The resulting imported has no issues. PCB, and individual STEP files exported as part of this process seem in perfect working order after import to Fusion360. VIA, Through Hole and Traces are in good working order.

Tested in KiCAD verion 8.0.1 and 8.0.2.
Windows 10 Pro 64bit

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Basically the cutting algorithm in OCCT (the 3D geometry library that KiCad uses) has bugs, even for simpler shapes:

0033536: BRepAlgoAPI_Cut produces broken shapes - MantisBT (opencascade.org)

It might be possible to cut the holes in the 2D polygon, then approximate it with arcs and construct OCCT geometry from that to avoid bugs in OCCT’s cutting algorithm.

I recommend reporting this on GitLab so that it’s not forgotten.

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On the upside, even with the bugs. It works good enough. To be worth a thumbs up.
It’s a feature thats bugged. So I am not freaking out.

On the downside I really hate that there are so many sites.
Gitlab now makes 4, I’d have preferred that one remain reserved for the devs.
Open Cascade Issue Tracker makes 5. I am totally lost.

With that said I have never used Gitlab, and do not know my way around the repository. I do not know where I should create a post for this issue. Another topic has a link to the parts builder section and there is a Issues repository for that section. However I see no way to access the issues, unless you already have a link to it.

So I imagine the same is true for other folders.
But I still don’t know what folder the export system is associated with.

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