Before when using freecad I created some sketches/solids intensively using sketches attached to face. It was very convenient to attach sketches to faces but it was a nightmare when I had to do some modifications leading to face renaming.
I found this very interesting article https://wiki.freecadweb.org/Topological_naming_problem
Recommended solution are :
But it's not very convenient to create some datum planes attached for example to xy planes and find needed offset to place it on a given face.Avoid attaching sketches and datums to generated geometry of the model. (Generated geometry is any face or edge created as a result of a pad, pocket, etc..)
Place your sketches on standard planes, or on custom datum planes.
Sketches with attachment offests or attached to datum planes with attachment offsets, are less at risk of being unexpectedly reattached to a different reference.
When creating datum geometry, do not attach it to generated geometry
Attach it to standard planes/axes and/or sketches and use attachment offsets to position it as needed
How can I do to quickly place a datum plane on a face without using it as attachment? Maybe it's a stupid question, but, Is it a good practice to attach a datum plan to a sketch and when created removing this attachment? Or still quicker, create a sketch attach on a face and removing this attachment? Doing that, sketch does not depend on any face. What are the drawbacks of this approach compared to clean solution : creating a datum plan and manually setting offsets?
Thanks for your help