FreeCAD: How to edit shape parametrically?

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 workbench.

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

     

     

  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.

     

     

• Model tree will be as follow.

  

  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.

     

  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.

     

  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.

  

  

• 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.

  

  

  

• 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.