Std Part

Description
Std Part (internally called App Part) is a general purpose container that keeps together a group of objects so that they can be moved together as a unit in the 3D view.

The Std Part element was developed to be the basic building block to create mechanical assemblies. In particular, it is meant to arrange objects that have a Part TopoShape, like Part Primitives, PartDesign Bodies, and other Part Features. The Std Part provides an Origin object with local X, Y, and Z axes, and standard planes, that can be used as reference to position the contained objects. In addition, Std Parts may be nested inside other Std Parts to create a big assembly from smaller sub-assemblies.

Although it is primarily intended for solid bodies, the Std Part can be used to manage any object that has a Placement property, so it can also contain Mesh Features, sketches, and other objects derived from the App GeoFeature class.

Do not confuse the PartDesign Body with the  Std Part. The first one is a specific object used in the PartDesign Workbench, intended to model a single contiguous solid by means of PartDesign Features. On the other hand, the Std Part is not used for modelling, just to arrange different objects in space, with the intention to create assemblies.

The Std Part tool is not defined by a particular workbench, but by the base system, thus it is found in the  that is available in all workbenches. To group objects arbitrarily without considering their position, use Std Group; this object does not affect the placements of the elements that it contains, it is essentially just a folder that is used to keep the tree view organized.



Usage

 * 1) Press the  button. An empty Part is created and automatically becomes active.
 * 2) To add objects to a Part, select them in tree view, and then drag and drop them over the Part.
 * 3) To remove objects from a Part, drag them out of the Part, and onto the document label at the top of the tree view.

Limitations

 * At this time, Draft Snap methods do not work on selected Part containers nor on the objects inside of them.
 * A Part has no topological shape, therefore 3D operations like Part Boolean cannot be used on a Part itself. For example, you cannot select two Parts, and perform a Part Union or Part Cut with them.
 * These boolean operations only work on the contained objects as long as these are derived from Part Feature and have a topological shape.

Properties
A Std Part is internally called App Part ( class), and is derived from an App GeoFeature ( class), therefore it shares most of the latter's properties.

In addition to the properties described in App GeoFeature, the App Part class has some properties that help it manage information in the context of an assembly, for example,, , , , , and.

These are the properties available in the property editor. Hidden properties can be shown by using the command in the context menu of the property editor.

Data

 * : a description for this object. By default, it is an empty string.
 * : an identification or part number for this object. By default, it is an empty string.
 * : a field to specify the license for this object. By default, it is an empty string.
 * : a field to specify the web address to the license or contract for this object. By default, it is an empty string.
 * : a tuple of four floating point RGBA values to define the color of the object; by default it is, which is displayed as  on base 255, white color.
 * : the position of the object in the 3D view. The placement is defined by a point (vector), and a  (axis and angle). See Placement.
 * : the angle of rotation around the . By default, it is (zero degrees).
 * : the unit vector that defines the axis of rotation for the placement. Each component is a floating point value between and . If any value is above, the vector is normalized so that the magnitude of the vector is . By default, it is the positive Z axis,.
 * : a vector with the 3D coordinates of the base point. By default, it is the origin.
 * : the user editable name of this object, it is an arbitrary UTF8 string.
 * : a list of referenced objects. By default, it is empty.

Hidden properties Data

 * : map with material properties. By default, it is empty.
 * : map with additional meta information. By default, it is empty.
 * : the universally unique identifier (UUID) (128-bit number) of the object. This is assigned at creation time.
 * : a longer, user editable description of this object, it is an arbitrary UTF8 string that may include newlines. By default, it is an empty string.
 * : a list of expressions. By default, it is empty.
 * : whether to display the object or not.
 * : the App Origin object that is the positional reference for all elements listed in.
 * : whether the group is touched or not.

View
The App Part only has the five properties of the basic App FeaturePython, and it does not have hidden properties.


 * : (default),, ,.
 * : (default), . If the option is, the entire shape (vertices, edges, and faces) will be highlighted in the 3D view; if it is  only the bounding box will be highlighted.
 * : if it is, the object appears in the tree view. Otherwise, it is set as invisible.
 * : if it is, the object appears in the 3D view; otherwise it is invisible. By default this property can be toggled on and off by pressing the bar in the keyboard.
 * : if it is, the object appears in the 3D view; otherwise it is invisible. By default this property can be toggled on and off by pressing the bar in the keyboard.

Assembly concept
The Std Part is intended to be the basic building block to create assemblies. Unlike a PartDesign Body, an assembly is meant to be a collection of separate, distinguishable elements which are connected in some way in the physical world, for example, through pressure, screws, or glue.

Examples that could be Parts:
 * A wooden table that consists of individual wooden pieces (legs, top), which are put together by glue or metal screws.
 * A ball bearing that is composed of multiple steel balls, an inner ring, a retainer, a seal, and an outer ring.
 * An assembly of a screw with a washer, and a matching nut.



In general terms, when importing a STEP file into the program, the main assembly and its sub-assemblies will be imported as Part containers, each of them containing a simple Part Feature.

Active status
An open document can contain multiple Parts. An active Part will be displayed in the tree view with the background color specified by the value in the preferences editor (by default, light blue). An active part will also be shown in bold text.

To activate or de-activate a Part:
 * Double click on it on the tree view, or
 * Open the context menu (right click) and select.


 * The of Parts was developed in v0.17 in parallel with the  of PartDesign Bodies; however, as of v0.19 this status does not serve a real purpose for Parts.
 * Even when a Part is active, newly created objects are not placed inside of it automatically. In this case, simply drag these new objects, and drop them onto the desired Part.
 * Only a single Part can be active at a time.



Origin
The Origin consists of the three standard axes (X, Y, Z) and three standard planes (XY, XZ and YZ). Sketches and other objects can be attached to these elements when creating them.



the Origin is an App Origin object ( class), while the axes and planes are objects of type and  respectively. Each of these elements can be hidden and unhidden individually with the bar; this is useful to choose the correct reference when creating other objects.

all elements inside the Part are referenced to the Part's Origin which means that the Part can be moved and rotated in reference to the global coordinate system without affecting the placement of the elements inside.

Visibility Management
The Part's visibility supersedes the visibility of any object it contains. If the Part is hidden, the objects it contains will be hidden as well, even if their individual property is set to. If the Part is visible, then each object's determines whether the object is shown or not.



Inheritance
A Std Part is formally an instance of the class, whose parent is the basic App GeoFeature ( class), and is augmented with an Origin extension.



Scripting
FreeCAD Scripting Basics, and scripted objects.

See Part Feature for the general information on adding objects to the document.

A Std Part (App Part) is created with the method of the document. Once a Part exists, other objects can be added to it with the or  methods of this Part.

A Part is a container for other objects, so it doesn't have its own Shape (Part TopoShape). However, in expressions or in the Spreadsheet Workbench, it is useful to get the compound shape of all objects contained inside the Part. This can be accomplished by using the pseudo-property, which can then be used to extract other attributes.