Datum
Introduction
In FreeCAD the word "Datum" is normally used to refer to auxiliary geometry in the PartDesign Workbench. These geometrical elements will not form part of the final Shape of the Body, but can be used as references and supports for sketches and other types of features.
The following correspond to elements derived from the Part::Datum
class, itself derived from Part Feature:
The following are derived directly from Part Feature:
Usage
- Switch to the PartDesign Workbench.
- Press
PartDesign Body.
- Select the Origin of the Body, and make it visible by pressing the Space bar in your keyboard.
- Press
PartDesign Plane to open the plane task panel.
- In the 3D view, click on one of the standard planes, for example, the XY plane. Then press OK to close the task panel.
- Now in the tree view, select the newly created DatumPlane, and then press
PartDesign NewSketch.
- Create a closed wire, and then use
PartDesign Pad to extrude the sketch, and create an initial solid.
Now you can move and rotate the DatumPlane as you wish, by changing its properties in the property editor, and the Sketch and Pad will follow its new Placement.
You can add other types of datums to be used with other sketches and features.
Notes
Since they appeared in v0.17, datum objects were intended to be used inside PartDesign Bodies. However, since they are useful "reference" objects with different attachment methods, it has been proposed that they should be available outside of the PartDesign Workbench. In this way, they will be usable in all workbenches as supporting geometry, particularly in the context of creating assemblies.
- Create and display local coordinate system
- Datum objects in App::Part
- Structure toolbar and datums
- Local CS cannot be used in Part Wb?
- Structure tools: Std Part, Std Group
- Helper tools: Body, New sketch, Edit sketch, Map sketch
- Modeling tools
- Datum tools: Create a datum point, Create a datum line, Create a datum plane, Create a local coordinate system, Create a shape binder, Create a clone
- Additive tools: Pad, Revolution, Additive loft, Additive pipe, Additive box, Additive cone, Additive cylinder, Additive ellipsoid, Additive prism, Additive sphere, Additive torus, Additive wedge
- Subtractive tools: Pocket, Hole, Groove, Subtractive loft, Subtractive pipe, Subtractive box, Subtractive cone, Subtractive cylinder, Subtractive ellipsoid, Subtractive prism, Subtractive sphere, Subtractive torus, Subtractive wedge
- Transformation tools: Mirrored, Linear Pattern, Polar Pattern, Create MultiTransform
- Dress-up tools: Fillet, Chamfer, Draft, Thickness
- Boolean: Boolean operation
- Extras: Migrate, Shaft design wizard, Involute gear
- Contextual Menu tools: Set tip, Move object to other body, Move object after other object
- Core: App DocumentObject
- Basic: App FeaturePython, App GeoFeature, Part Feature, Mesh Feature, Fem FemMeshObject
- Internal shapes: Part TopoShape, Mesh MeshObject, Fem FemMesh
- Structure: App DocumentObjectGroup (Std Group), App Part (Std Part), App Link (Std LinkMake)
- Derived: Part Part2DObject, Sketcher SketchObject, PartDesign Body, PartDesign Feature

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