FreeCAD: ShapeBinder

[last updated: 2023-05-08]
FreeCAD home page
FC Operation notes
-----

In process ...
---------------------------------------------------------------------------------

• If you are building a model that contains more than one Body,
  and you want to reference/align them to each other,
  that is, you want to constrain some feature of one body,
  based on some reference point on a feature of another body,
  you can do that using PartDesign - ShapeBinder
  ---------------------------------------------

• Here's one way that worked for me:
  • Build a model that contains two bodies.
  • One of them will be the bodyWithRef.
    This will contain a feature that you want to use as a reference point for some constraint in the other body.
  • The other body will be the bodyNeedsRef.
    This will contain a feature that you want to constrain,
    based on the reference point in the bodyWithRef body.

  • bodyNeedsRef must be active (highlighted - else double-click to activate)
    The shapeBinder will be created in whichever body is active.
    But in order to reference it, you need the shapeBinder to be IN the bodyNeedsRef.
    So the bodyNeedsRef must be active when you create the shapeBinder.
  • Click on a face (or whatever feature desired) in bodyWithRef that you want to reference.
    Select create shape binder:
    datum shape binder dialogue opens
    with the element name of bodyWithRef in object field
        (perhaps the name of the sketch that contains the feature you selected)
    and the ID of the face or whatever feature you selected will be listed in the geometry block

    click OK
    You will see the shapeBinder you created in the model tree under bodyNeedsRef

  • Click bodyWithRef in model tree,
    then click spaceBar to hide it.
        (notice the face or whatever feature you selected as a reference will still be visible)
  • Open sketch in bodyNeedsRef,
    select external geometry,
    and you can now select whatever feature in your shape binder body
    that you want to use to constrain whichever feature in the sketch.

  ----------------------------------------------

• Notes from Reddit:
  If I need to do this, I would make the second body active, select the face on the first body, make a binder for the face, go to the data tab for the binder, and set its synchronization setting to disconnected. This will import the face without the TNI, or dual origins. You may or may not be able to attach sketches to this binder directly at this point depending on how well constrained it was. If you can't attach to it directly, you will be able to attach a datum plane to it by various means. This is not the very best way of doing things but it will work in most cases.