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Dependencies (Plain-English Explanation)

This page explains dependencies in FreeCAD using everyday language. You do not need to understand FreeCAD’s internal dependency system to work safely and predictably.

The key idea

Dependencies describe what an object uses, not what it contains.

This distinction removes most confusion.

“Uses” vs “Contains”

In FreeCAD:

  • Contains means physically holds something in the model tree
  • Uses means relies on as a reference

Most dependencies are uses, not contains.

Examples

Example 1: A sketch on a plane

  • The Body contains the sketch
  • The sketch uses the plane
  • The plane is not part of the sketch

Deleting the plane does not delete the sketch, but it may break its references.

Example 2: Geometry using the Origin

  • Geometry uses the Origin’s planes and axes
  • The Origin does not contain the geometry
  • Geometry does not belong to the Origin

The Origin is a reference framework, not a parent part.

Why the model tree can be misleading

The model tree shows structure, not ownership.

Just because something appears “under” another item does not mean: - it will export together - it will duplicate together - it will be deleted together

Tree position ≠ dependency direction.

What the Object Selection dialog is telling you

When copying or exporting, FreeCAD may say:

“The selected objects contain other dependencies.”

What it really means:

“Other objects rely on this one, or this one relies on others.”

The dialog exists to keep those relationships intact.

Safe mental model

When working in FreeCAD, think in these terms:

  • Bodies contain geometry
  • Geometry uses references
  • References support, but do not own
  • Dependencies describe support relationships, not hierarchy

Practical rules of thumb

  • Don’t delete reference geometry casually
  • Accept default dependency selections when copying
  • Hide objects to control export, not dependencies
  • If something breaks, a reference was removed — not the geometry

One-sentence takeaway

Dependencies explain support relationships, not ownership or containment.