Part Module: Difference between revisions

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the CAD capabilities of FreeCAD are based on the [http://en.wikipedia.org/wiki/Open_CASCADE OpenCasCade] kernel. The Part module allows FreeCAD to access and use the OpenCasCade objects and functions. OpenCascade is a professional-level CAD kernel, that features advanced 3D geometry manipulation and objects. The Part objects, unlike [[Mesh Module]] objects, are much more complex, and therefore permit much more advanced operations, like coheent booleans operations, modifications history and parametric behaviour.
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{{Docnav
|[[OpenSCAD Module|OpenSCAD Module]]
|[[PartDesign Workbench|PartDesign Workbench]]
|IconL=Workbench_OpenSCAD.svg
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[[Image:Part example.jpg]]
[[Image:Workbench_Part.svg|thumb|128px|Part workbench icon]]
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{{TOCright}}
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== Introduction == <!--T:1-->
The solid modelling capabilities of FreeCAD are based on the [[OpenCASCADE|OpenCASCADE Technology]] (OCCT) kernel, a professional-grade CAD system that features advanced 3D geometry creation and manipulation. The [[Image:Workbench_Part.svg|24px]] [[Part Workbench|Part Workbench]] is a layer sitting on top of the OCCT libraries, that gives the user access to OCCT geometric primitives and functions. Essentially all 2D and 3D drawing functions in every workbench ([[Image:Workbench_Draft.svg|24px]] [[Draft Workbench|Draft]], [[Image:Workbench_Sketcher.svg|24px]] [[Sketcher Workbench|Sketcher]], [[Image:Workbench_PartDesign.svg|24px]] [[PartDesign Workbench|PartDesign]], etc.), are based on these functions exposed by the Part Workbench. Therefore, the Part Workbench is considered the core component of the modelling capabilities of FreeCAD.


<!--T:35-->
Example of Part shapes in FreeCAD
The objects created with the Part Workbench are relatively simple; they are intended to be used with boolean operations (unions and cuts) in order to build more complex shapes. '''This modeling paradigm is known as the [[constructive solid geometry]] (CSG) workflow, and it was the traditional methodology used in early CAD systems.''' On the other hand, the [[PartDesign Workbench|PartDesign Workbench]] provides a more modern workflow to constructing shapes: it uses a parametrically defined sketch, that is extruded to form a basic solid body, which is then modified by parametric transformations ([[feature editing|feature editing]]), until the final object is obtained.


<!--T:54-->
=== The tools ===
Part objects are more complex than mesh objects created with the [[Mesh Workbench|Mesh Workbench]], as they permit more advanced operations like coherent boolean operations, modifications history, and parametric behaviour.


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The Part module tools are all located in the '''Part''' menu that appears when you load the Part module.
[[Image:Part_Workbench_relationships.svg|600px]]
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<!--T:55-->
{{Part Tools}}
{{Caption|The Part Workbench is the basic layer that exposes the OCCT drawing functions to all workbenches in FreeCAD.}}


== Tools == <!--T:4-->
=== Boolean Operations ===


<!--T:5-->
[[Image:Part_BooleanOperations.png|500px|left|An example of union (Fuse), intersection (Common) and difference (Cut)]]
The tools are all located in the {{MenuCommand|Part}} menu.


===Primitives=== <!--T:6-->
{{clear}}


<!--T:36-->
An example of union (Fuse), intersection (Common) and difference (Cut)
These are tools for creating primitive objects.


<!--T:37-->
=== Explaining the concepts ===
* [[Image:Part_Box.svg|32px]] [[Part_Box|Box]]: Draws a box by specifying its dimensions
* [[Image:Part_Cylinder.svg|32px]] [[Part_Cylinder|Cylinder]]: Draws a cylinder by specifying its dimensions
* [[Image:Part_Sphere.svg|32px]] [[Part_Sphere|Sphere]]: Draws a sphere by specifying its dimensions
* [[Image:Part_Cone.svg|32px]] [[Part_Cone|Cone]]: Draws a cone by specifying its dimensions
* [[Image:Part_Torus.svg|32px]] [[Part_Torus|Torus]]: Draws a torus (ring) by specifying its dimensions
* [[File:Part_Tube.svg|32px]] [[Part_Tube|Tube]]: draws a tube by specifying its internal radius and external radius. {{Version|0.19}}
* [[Image:Part_Primitives.svg|32px]] [[Part_Primitives|Primitives]]: A tool to add any of the defined geometric primitives.
* [[Image:Part_Shapebuilder.svg|32px]] [[Part_Builder|Shapebuilder]]: A tool to create more complex shapes from various parametric geometric primitives


===Modifying objects=== <!--T:38-->
In OpenCasCade terminology, we distinguish between geometric primitives and (topological) shapes. A geometric primitive can be a point, a line, a circle, a plane, etc. or even some more complex types like a B-Spline curve or surface. A shape can be a vertex, an edge, a wire, a face, a solid or a compound of other shapes. The geometric primitive are not made to be directly displayed on the 3D scene, but rather to be used as building geometry for shapes. For example, an edge can be constructed from a line or from a portion of a circle.


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We could say, to resume, that geometry primitive are "shapeless" building blocks, and shapes are the real spatial geometry built on it.
These are tools for modifying existing objects. They will allow you to choose which object to modify.


<!--T:40-->
To get a complete list of all of them refer to the [http://www.opencascade.org/org/doc/ OCC documentation] and search for Geom_Geometry and TopoDS_Shape. There you can also read more about the differences between geometric objects and shapes. Please note that unfortunately the OCC documentation is not available online (you must download an archive) and is mostly aimed at programmers, not at end-users. But hopefully you'll find enough information to get started here.
* [[Image:Part_Extrude.svg|32px]] [[Part_Extrude|Extrude]]: Extrudes planar faces of an object
* [[Image:Part_Revolve.svg|32px]] [[Part_Revolve|Revolve]]: Creates a solid by revolving another object (not solid) around an axis
* [[Image:Part_Mirror.svg|32px]] [[Part_Mirror|Mirror]]: Mirrors the selected object on a given mirror plane
* [[Image:Part_Fillet.svg|32px]] [[Part_Fillet|Fillet]]: Fillets (rounds) edges of an object
* [[Image:Part_Chamfer.svg|32px]] [[Part_Chamfer|Chamfer]]: Chamfers edges of an object
* [[Image:Part_RuledSurface.svg|32px]] [[Part_RuledSurface|Ruled Surface]]:
* [[Image:Part_Loft.svg|32px]] [[Part_Loft|Loft]]: Lofts from one profile to another
* [[Image:Part_Sweep.svg|32px]] [[Part_Sweep|Sweep]]: Sweeps one or more profiles along a path


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The geometric types actually can be divided into two major groups: curves and surfaces. Out of the curves (line, circle, ...) you can directly build an edge, out of the surfaces (plane, cylinder, ...) a face can be built. For example, the geometric primitive line is unlimited, i.e. it is defined by a base vector and a direction vector while its shape representation must be something limited by a start and end point. And a box -- a solid -- can be created by six limited planes.
* [[Image:Part_CompOffsetTools.png|48px]] [[Part_CompOffsetTools|Offset tools]]:
** [[Image:Part_Offset.svg|32px]] [[Part_Offset|3D Offset]]: Constructs a parallel shape at a certain distance from original.
** [[Image:Part_Offset2D.svg|32px]] [[Part_Offset2D|2D Offset]]: Constructs a parallel wire at certain distance from original, or enlarges/shrinks a planar face. {{Version|0.17}}


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From an edge or face you can also go back to its geometric primitive counter part.
* [[Image:Part_Thickness.svg|32px]] [[Part_Thickness|Thickness]]: Hollows out a solid, leaving openings next to select faces.


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Thus, out of shapes you can build very complex parts or, the other way round, extract all sub-shape a more complex shape is made of.
* [[File:Part_ProjectionOnSurface.svg|32px]] [[Part_ProjectionOnSurface|Projection on surface]]: Project a logo, text or any face,wire,edge to a surface. With the projection part it is possible to create a solid or wire. {{Version|0.19}}


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=== Scripting ===
* [[Image:Part_Compound.svg|48px]] [[Part_CompCompoundTools|Compound Tools]]:
** [[Image:Part_Compound.svg|32px]] [[Part_Compound|Make compound]]: Creates a compound from the selected objects.
** [[Image:Part_ExplodeCompound.svg|32px]] [[Part_ExplodeCompound|Explode Compound]]: Tool to split up compounds of shapes
** [[Image:Part Compound‏‎Filter.svg|32px]] [[Part Compound‏‎Filter|Compound Filter]]: The CompoundFilter can be used to extract the individual pieces.


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The main data structure used in the Part module is the [http://en.wikipedia.org/wiki/Boundary_representation BRep] data type from OpenCascade.
* [[Image:Part_Booleans.svg|32px]] [[Part_Boolean|Boolean]]: Performs boolean operations on objects
About all contents and object types of the Part module are now available to python scripting. This includes geometric primitives, such as Line and Circle (or Arc), and the whole range of TopoShapes, like Vertexes, Edges, Wires, Faces, Solids and Compounds. For each of those objects, several creations methods exist, and for some of them, especially the TopoShapes, advanced operations like booleans union/difference/intersection are also available. Explore the contents of the Part module, as described in the [[FreeCAD Scripting Basics]] page, to know more.
* [[Image:Part_Fuse.svg|32px]] [[Part_Union|Union]]: Fuses (unions) two objects
* [[Image:Part_Common.svg|32px]] [[Part_Common|Common]]: Extracts the common (intersection) part of two objects
* [[Image:Part_Cut.svg|32px]] [[Part_Cut|Cut]]: Cuts (subtracts) one object from another


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=== Examples ===
* [[Image:Part_CompJoinFeatures.png|48px]] [[Part CompJoinFeatures|Join features]]: smart booleans for walled objects (e.g., pipes) {{Version|0.16}}
** [[Image:Part_JoinConnect.svg|32px]] [[Part_JoinConnect|Connect]]: Connects interiors of objects {{Version|0.16}}
** [[Image:Part_JoinEmbed.svg|32px]] [[Part_JoinEmbed|Embed]]: Embeds a walled object into another walled object {{Version|0.16}}
** [[Image:Part_JoinCutout.svg|32px]] [[Part_JoinCutout|Cutout]]: Creates a cutout in a wall of an object for another walled object {{Version|0.16}}


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To create a line element switch to the Python console and type in:
* [[Image:Part_CompSplittingTools.png|48px]] [[Part CompSplittingTools|Splitting tools]]: {{Version|0.17}}
import Part,PartGui
** [[Image:Part_BooleanFragments.svg|32px]] [[Part_BooleanFragments|Boolean fragments]]: makes all the pieces that can be obtained by Boolean operations between objects {{Version|0.17}}
doc=App.newDocument()
** [[Image:Part SliceApart.svg|32px]] [[Part_SliceApart|Slice a part]]: tool to split shapes by intersection with other shapes
l=Part.Line()
** [[Image:Part_Slice.svg|32px]] [[Part_Slice|Slice]]: Splits an object into pieces by intersections with another object {{Version|0.17}}
l.StartPoint=(0.0,0.0,0.0)
** [[Image:Part_XOR.svg|32px]] [[Part_XOR|XOR]]: removes space shared by even number of objects (symmetric version of [[Part_Cut|Cut]]) {{Version|0.17}}
l.EndPoint=(1.0,1.0,1.0)
doc.addObject("Part::Feature","Line").Shape=l.toShape()
doc.recompute()


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Let's go through the above python example step by step:
* [[Image:Part Defeaturing.svg|32px]] [[Part_Defeaturing|Defeaturing]]: {{Version|0.18}}
import Part,PartGui
* [[Image:Part_Section.svg|32px]] [[Part_Section|Section]]: Creates a section by intersecting an object with a section plane
doc=App.newDocument()
* [[Image:Part_CrossSections.svg|32px]] [[Part_SectionCross|Cross sections...]]: Creates one or more cross-sections through a selected shape
loads the Part module and creates a new document
* [[Image:Part Attachment.svg|32px]] [[Part Attachment|Attachment]]: attachment is a utility to attach an object to another one.
l=Part.Line()
l.StartPoint=(0.0,0.0,0.0)
l.EndPoint=(1.0,1.0,1.0)
Line is actually a line segment, hence the start and endpoint.
doc.addObject("Part::Feature","Line").Shape=l.toShape()
This adds a Part object type to the document and assigns the shape representation of the line segment to the 'Shape' property of the added object. It is important to understand here that we used a geometric primitive (the Part.line) to create a TopoShape out of it (the toShape() method). Only Shapes can be added to the document. In FreeCAD, geometry primitives are used as "building structures" for Shapes.
doc.recompute()
Updates the document. This also prepare the visual representation of the new part object.


=== Measure === <!--T:58-->
Note that a Line can be created by specifiying its start and endpoint directly in the constructor, for ex. Part.Line(point1,point2) or we can create a default line and set its properties afterwards, like we did here.


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A circle can be created in a similar way:
[[File:Part Measure Menu.png|64px]] [[Part Measure Menu|Measure]]: Allows linear and angular measurement between points, edges, and faces.
import Part
doc = App.activeDocument()
c = Part.Circle()
c.Radius=10.0
f = doc.addObject("Part::Feature", "Circle")
f.Shape = c.toShape()
doc.recompute()
Note again, we used the circle (geometry primitive) to construct a shape out of it. We can of course still access our construction geometry afterwards, by doing:
s = f.Shape
e = s.Edges[0]
c = e.Curve
Here we take the shape of our object f, then we take its list of edges, in this case there will be only one because we made the whole shape out of a single circle, so we take only the first item of the Edges list, and we takes its curve. Every Edge has a Curve, which is the geometry primitive it is based on.


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Head to the [[Topological data scripting]] page if you would like to know more.
* [[Image:Part_Measure_Linear.svg|32px]] [[Part_Measure_Linear|Measure Linear]] allows you to make linear measurements.
* [[Image:Part_Measure_Angular.svg|32px]] [[Part_Measure_Angular|Measure Angular]] allows you to make angular measurements.
* [[Image:Part_Measure_Refresh.svg|32px]] [[Part_Measure_Refresh|Measure Refresh]] updates the measurements on screen.
* [[Image:Part_Measure_Clear_All.svg|32px]] [[Part_Measure_Clear_All|Clear All]] Clears all measurements.
* [[Image:Part_Measure_Toggle_All.svg|32px]] [[Part_Measure_Toggle_All|Toggle All]] shows or hides all measurements.
* [[Image:Part_Measure_Toggle_3d.svg|32px]] [[Part_Measure_Toggle_3d|Toggle 3D]] shows or hides 3D measurements.
* [[Image:Part_Measure_Toggle_Delta.svg|32px]] [[Part_Measure_Toggle_Delta|Toggle Delta]] shows or hides delta measurements.


===Other tools=== <!--T:41-->
{{docnav|Mesh Module|Drawing Module}}


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{{languages | {{de|Part Module/de}} {{es|Part Module/es}} {{fr|Part Module/fr}} {{pl|Part Module/pl}} {{ru|Part Module/ru}} {{se|Part Module/se}} }}
* [[Image:Part_Import.svg|32px]] [[Part Import|Import]]: This tool allows you to add a file *.IGES, *.STEP, *.BREP to the current document.
* [[Image:Part_Export.svg|32px]] [[Part Export|Export]]: This tool allows you to export a part object in a *.IGES, *.STEP, *.BREP file.
* [[File:Part_BoxSelection.svg|32px]] [[Part_BoxSelection|BoxSelection]]: add to the selection the faces of the shapes that are touches by the rectangular selection. {{Version|0.19}}
* [[Image:Part_ShapeFromMesh.svg|32px]] [[Part ShapeFromMesh|Shape from Mesh]]: Creates a shape object from a mesh object.
* [[File:Part_PointsFromMesh.svg|32px]] [[Part PointsFromMesh|Points from mesh]]: creates a shape object made of points from the mesh. {{Version|0.19}}
* [[Part_MakeSolid|Convert to solid]]: Converts a shape object to a solid object.
* [[File:Part_ReverseShapes.svg|32px]] [[Part_ReverseShapes|Reverse shapes]]: Flips the normals of all faces of the selected object.


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[[Category:User Documentation]]
* Create a copy:
** [[Image:Part_SimpleCopy‎.svg|32px]] [[Part_SimpleCopy|Create simple copy]]: Creates a simple copy of the selected object.
** [[File:Part_TransformedCopy.svg|32px]] [[Part_TransformedCopy|Create transformed copy]]: creates a transformed copy of the selected object. {{Version|0.19}}
** [[File:Part_ElementCopy.svg|32px]] [[Part_ElementCopy|Create shape element copy]]: creates a copy from an element (vertex, edge, face) of the selected object. {{Version|0.19}}
** [[Image:Part_RefineShape.svg|32px]] [[Part_RefineShape|Refine shape]]: Cleans faces by removing unnecessary lines.

<!--T:62-->
* [[Image:Part_CheckGeometry.svg|32px]] [[Part CheckGeometry|Check geometry]]: Checks the geometry of selected objects for errors.

=== Context menu items === <!--T:80-->

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*[[Std_SetAppearance|Appearance]]: determines appearance of the whole part (color transparency etc.).
* [[File:Part_ColorFace.svg|32px]] [[Part_FaceColors|Set colors]]: assigns colors to part faces.

== Preferences == <!--T:43-->

<!--T:44-->
<!--The PartDesign preferences are defined in the Part workbench and both the PartDesign workbench and the Part workbench use them-->
* [[Image:Preferences-part_design.svg|32px]] [[PartDesign_Preferences|Preferences]]: preferences available for Part Tools (the Part workbench also uses the PartDesign Preferences).
* [[Image:Preferences-import-export.svg|32px]] [[Import_Export_Preferences|Import Export Preferences]]: preferences available for importing from and exporting to different file formats.
* [[Fine-tuning]]: some extra parameters to fine-tune Part behavior.

== Scripting == <!--T:18-->

<!--T:56-->
See [[Part scripting|Part scripting]].

== Tutorials == <!--T:34-->

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* [[Import_from_STL_or_OBJ|Import from STL or OBJ]] : How to import STL/OBJ files in FreeCAD
* [[Export_to_STL_or_OBJ|Export to STL or OBJ]] : How to export STL/OBJ files from FreeCAD
* [[Whiffle_Ball_tutorial|Whiffle Ball tutorial]] : How to use the Part Module


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{{Docnav
|[[OpenSCAD Module|OpenSCAD Module]]
|[[PartDesign Workbench|PartDesign Workbench]]
|IconL=Workbench_OpenSCAD.svg
|IconR=Workbench_PartDesign.svg
}}

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Revision as of 00:21, 12 October 2020

Part workbench icon

Introduction

The solid modelling capabilities of FreeCAD are based on the OpenCASCADE Technology (OCCT) kernel, a professional-grade CAD system that features advanced 3D geometry creation and manipulation. The Part Workbench is a layer sitting on top of the OCCT libraries, that gives the user access to OCCT geometric primitives and functions. Essentially all 2D and 3D drawing functions in every workbench ( Draft, Sketcher, PartDesign, etc.), are based on these functions exposed by the Part Workbench. Therefore, the Part Workbench is considered the core component of the modelling capabilities of FreeCAD.

The objects created with the Part Workbench are relatively simple; they are intended to be used with boolean operations (unions and cuts) in order to build more complex shapes. This modeling paradigm is known as the constructive solid geometry (CSG) workflow, and it was the traditional methodology used in early CAD systems. On the other hand, the PartDesign Workbench provides a more modern workflow to constructing shapes: it uses a parametrically defined sketch, that is extruded to form a basic solid body, which is then modified by parametric transformations (feature editing), until the final object is obtained.

Part objects are more complex than mesh objects created with the Mesh Workbench, as they permit more advanced operations like coherent boolean operations, modifications history, and parametric behaviour.

The Part Workbench is the basic layer that exposes the OCCT drawing functions to all workbenches in FreeCAD.

Tools

The tools are all located in the Part menu.

Primitives

These are tools for creating primitive objects.

  • Box: Draws a box by specifying its dimensions
  • Cylinder: Draws a cylinder by specifying its dimensions
  • Sphere: Draws a sphere by specifying its dimensions
  • Cone: Draws a cone by specifying its dimensions
  • Torus: Draws a torus (ring) by specifying its dimensions
  • Tube: draws a tube by specifying its internal radius and external radius. introduced in version 0.19
  • Primitives: A tool to add any of the defined geometric primitives.
  • Shapebuilder: A tool to create more complex shapes from various parametric geometric primitives

Modifying objects

These are tools for modifying existing objects. They will allow you to choose which object to modify.

  • Extrude: Extrudes planar faces of an object
  • Revolve: Creates a solid by revolving another object (not solid) around an axis
  • Mirror: Mirrors the selected object on a given mirror plane
  • Fillet: Fillets (rounds) edges of an object
  • Chamfer: Chamfers edges of an object
  • Ruled Surface:
  • Loft: Lofts from one profile to another
  • Sweep: Sweeps one or more profiles along a path
  • Thickness: Hollows out a solid, leaving openings next to select faces.
  • Boolean: Performs boolean operations on objects
  • Union: Fuses (unions) two objects
  • Common: Extracts the common (intersection) part of two objects
  • Cut: Cuts (subtracts) one object from another

Measure

File:Part Measure Menu.png Measure: Allows linear and angular measurement between points, edges, and faces.

Other tools

Context menu items

  • Appearance: determines appearance of the whole part (color transparency etc.).
  • Set colors: assigns colors to part faces.

Preferences

  • Preferences: preferences available for Part Tools (the Part workbench also uses the PartDesign Preferences).
  • Import Export Preferences: preferences available for importing from and exporting to different file formats.
  • Fine-tuning: some extra parameters to fine-tune Part behavior.

Scripting

See Part scripting.

Tutorials