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FreeCAD: How to edit shape parametrically?

Update: April 12, 2021
FreeCAD 0.19

In FreeCAD, Shapes are expressed as a "history of shape operation". Hence you can change parameters of shape operation and re-calculate the shape easily.

  • At first, create a shape with Part Design workbenchPartDesign workbench.

    1. Draw sketch and extrude it to create 3D shape.

      Sketch
      Sketch
      Extruding result
      Extruding result
    2. Select a top face of 3D shape and create a new sketch plane. Cut out the 3D shape with the sketch to create a hole.

      New sketch
      New sketch
      Cutting out result
      Cutting out result
  • Model tree will be as follow.

    Model tree
    Model tree

    Model tree represents the history of the operation. Upper of the tree and nearer leaf item is older operation.

    In this example, we will see that the operations were performed in the order of "Sketch" → "Pad" → "Sketch001" → "Pocket" by model tree.

  • Then we will change 3D shapes by editing first created "Sketch".

    1. Double click "Sketch" in a model tree to show and edit the sketch.

      Sketch before editing
      Sketch before editing
    2. Change a value of a radius constraint at upper-right of sketch. Change the value from 30 mm to 40 mm. So FreeCAD will re-compute the 3D shape automatically.

      Sketch after editing
      Sketch after editing

    FreeCAD may not be able to re-calculation of shape depending on the operation.

    For example, if you change the value of the radius constraint from 30 mm to 60 mm, the sketch become invalid and extruding operation will fail in re-computing.

    In this case, you should re-edit the sketch to be valid and recompute the 3D shape.

    Model tree that has be invalid edited.
    A operation that can not be recomputed marked with a red icon.
    3D view in invalid editing
    3D view in invalid editing
  • You can also edit other operations. Double click "Pad", "Pocket" or other operation item in tree and change parameters like extruding size or cutout depth.

    Before changing
    Before changing
    Changing extruding size
    Changing extruding size
    Changing extruding size and cutout depth
    Changing extruding size and cutout depth
  • If newest shape and older shape overlaped and you can not confirm newest shape, select item in model tree and push space key to show/hide the shape.

    モデルツリー
    Shows only "Pad" and "Sketch001" - Model tree
    3Dビュー
    Shows only "Pad" and "Sketch001" - 3D view