3D constraints: How to prevent the disapparance of faces?

One of the issues I have when working with 3D constraints is that faces, even faces with a dimensional constraint, can disappear. I have meanwhile found out that applying 'Rigid Set' constraints to combinations of faces or edges can help prevent this. But finding out where to apply this constraint can be quite a puzzle as it will obviously interfere with the parametric behavior of the model.

Attached is an under-constrained example to demonstrate the problem.
Test:
1.
Change Distance_1 to 100, then to 300 and finally to 150.
2.
The last change results in the loss of a constrained face.
3.
In this case the problem can be solved by applying a 'Fix' constraint to the faces that are in the YZ and the XZ plane in the original drawing. I don't understand the logic that is at work here.

My question:
What is the most appropriate way to deal with this issue?

Comments

  •  Hello Roy,
    We know about this issue and already working on it. As a workaround for your model you can change value smoothly 300 -> 200 -> 150
  • Aren't they wonderful - everything's 'can do' - and happens fast! How long can they keep it up, as the s/ware gets fatter, till it's almost unmanageably complex and interconnected, like Bentley?
  • @ Ilya: Thank you.

    @ Tom: I am unsure how your comment is intended.
  • Masively appreciative, but aware how difficulties may accumulate.
This discussion has been closed.