[Feature Request] STEP export compound merge

[NewJoker]

Hi,

whenever I export a model which consists of multiple faces/volumes that are fused with Part boolean operations (like Part Fuse) to STEP, I still get multiple entities after importing to another software (I tried with various programs). It would be great to have an option that could truly merge entities for export to STEP so that they would be recognized as individual object after importing to other software.

I attached an exemplary file. Even though it's fused, exporting it to STEP and importing to other CAD or CAE programs results in separate face objects. The same happens with solid models.

Step export compound.FCStd

(8.72 KiB) Downloaded 12 times

[easyw-fc]

Hi,

whenever I export a model which consists of multiple faces/volumes that are fused with Part boolean operations (like Part Fuse) to STEP, I still get multiple entities after importing to another software (I tried with various programs). It would be great to have an option that could truly merge entities for export to STEP so that they would be recognized as individual object after importing to other software.

I attached an exemplary file. Even though it's fused, exporting it to STEP and importing to other CAD or CAE programs results in separate face objects. The same happens with solid models.


Step export compound.FCStd

simply convert your fusion to solid (with Part https://wiki.freecadweb.org/Part_MakeSolid )
then your step file would be a single merged object

Step export compound-solid.FCStd

(10.42 KiB) Downloaded 9 times

Step export compound-Fusion (Solid).step

(7.29 KiB) Downloaded 8 times

[NewJoker]

simply convert your fusion to solid (with Part https://wiki.freecadweb.org/Part_MakeSolid )
then your step file would be a single merged object

Thank you very much, I didn't realize that this tool can do it. However, this works with surfaces but doesn't work with solids. Sometimes I want to merge assemblies into a single part, like in the attached example where Part Fuse still results in multiple parts after exporting to STEP.

Step merging solid 2.FCStd

(152.26 KiB) Downloaded 9 times

[easyw-fc]

only when an object is a watertight solid the union can result in a single object... Otherways you will get a compound of detached objects
EDIT:
see here in 3d printing

https://danieltal.com/is-your-3d-print- ... ht-part-1/

search also for "manifold"

[NewJoker]

only when an object is a watertight solid the union can result in a single object... Otherways you will get a compound of detached objects

In my case, the geometry should be watertight since I'm creating compounds out of valid solid parts placed on each other. Unless there's some issue with the accuracy of adherence of curved surfaces.

[easyw-fc]

In my case, the geometry should be watertight since I'm creating compounds out of valid solid parts placed on each other. Unless there's some issue with the accuracy of adherence of curved surfaces.

in your case the issue is because of co-planar surfaces (an issue on OCC)
https://wiki.freecadweb.org/Part_Boolean (look for 'Coplanar problems')
you may workaround it with a small co-penetration between objects
(probably the best option because you generate your parts with code)
or using fuzzy fusion
https://dev.opencascade.org/content/fuz ... operations

you can use it (or get some code tips) with Defeaturing WB 'fuzzy union' command (and play with fuzzy tolerance)

Step merging solid fuzzy.FCStd

(222.47 KiB) Downloaded 7 times

Step merging solid fuzzy-UnionFuzzy.step

(117.66 KiB) Downloaded 4 times

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union-fuzzy.png (98.13 KiB) Viewed 545 times

[adrianinsaval]

or using fuzzy fusion
https://dev.opencascade.org/content/fuz ... operations

That's very interesting, would be nice if it was possible to control this property on regular BOP in FreeCAD.

[easyw-fc]

there is an old thread
https://forum.freecadweb.org/viewtopic. ... b&start=10
and a detailed surwey
https://github.com/realthunder/FreeCAD_ ... issues/235
Fuzzy union/common can be used only through python code ATM
there is also an open issue
https://github.com/FreeCAD/FreeCAD/issues/5612

[NewJoker]

@easyw-fc Thank you for the information, I didn't know that there are such fuzzy boolean operations available in one of the add-on modules. It would be great to have them implemented in Part workbench.

[drmacro]

@easyw-fc Thank you for the information, I didn't know that there are such fuzzy boolean operations available in one of the add-on modules. It would be great to have them implemented in Part workbench.

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