Fundamental problem with switching position of shapebinder!

[anatolli]

Hello!

Freecad 0.17 Rev.Nr: 13522.
Drawing in PDWB.
In the attached File i am using a shapebinder called "SBUntgFuss". If i change the value "AbFussY" in the spreadsheet, at times the shapebinder "SBuntgFuss" switches his position. A recompute doesn't change anything. After changing the "AbFussY" value one more time, the shapebinder moves to his correct position.

I think the geometry of the File is realy simple, if it gets more complicated,than the shapebinders are totaly useless and so parametric drawing is impossible.

Does anyone have some workaround, can fix this problem or have an explanation for the issue.

thanks greetings
anatolli

[DeepSOIC]

Hi!
I can confirm.

To me, it looks like topological-naming related problem. It is fundamental. It is because FC remembers face's ordinal number, and that number is not a stable thing.
In particular, it looks to be a manifestation of issue #2721.

There are a few things you can do:
* use Realthunder's Assembly3/LinkStage2 experimental builds, where proper toponaming is implemented, along with an assembly workbench.
OR
* do not use faces of solids. Link to sketches instead.
OR
* for this particular example, making one hole a few nanometers wider than another might help
OR
* for this particular example, make two independent pockets, one for each hole.

[anatolli]

Hello DeepSOIC!

Thanks for explanation and for the aproaches. Two independent pockets work fine. Thanks for the clear instruction.

greetings
anatolli

[chrisb]

I have seen the equivalent topic in the german forum and thought it was a recompute issue. In fact it is a topological naming issue. In the german forum we have already given the advice to avoid referencing faces. Use sketches instead, they are more stable.

[triplus]

Hi anatolli.

I took a quick look and something doesn't add up. Did you model everything and after deleted some features. Before uploading the file?

P.S. If yes please attach the sample file with all features included.

[anatolli]

@triplus
If i understand your question, there is no feature which was deleted. The model is drawed from zero to the point it was uploaded. So nothing was deleted or added or substracted.
thanks
anatolli

[anatolli]

@"Use sketches instead"; The problem is, i didnt now how to do this.Im willing to do so. Please can anyone explain me on my simple example how i can make a reference to a sketch. Is it the "use external Geometry" button in sketch mode? Is this reference parametric.
Why is there a shapebinder in the programm, if it shouldnt be used?

I guess the solution "Use sketches instead" is realy simple, albeit i didnt know how to do. So please can anyone explain it to a newbie.

thanks greetings
anatolli

[DeepSOIC]

Please can anyone explain me on my simple example how i can make a reference to a sketch. Is it the "use external Geometry" button in sketch mode? Is this reference parametric.

Yes, yes. But first, you need to bring a ghost of the sketch from one body to another. That's what Shapebinder is for. It can bring anything across, not just faces.

[chrisb]

Before creating the ShapeBinder select the Sketch parts of it. If you want to select only parts of it it is easy if you make everything invisible except the sketch.

[anatolli]

@DeepSOIC; So i made a Shapebinder with Edges instead of faces. But after that, i can't figure out how to bring the xz plane (from "Fuss") of the sketch in order to the shapebinder Edges in Y orientation. If i made a face shapebinder, i can simple switch on the face to put the sketch on it, with the Edges i didnt know how to place the sketch on it. I hope you understand where my problem is.

thanks
anatolli