PartDesign project

Here the project plan for the PartDesign as part of the Development roadmap.

Purpose and principles
This is a software development project aimed to implement a Part Design capabilities. Its about implementing some core features into the CAD modules of FreeCAD, Part, PartDesign and Assembly.

The development steps are planed here and tracked in the Issue tracking system to get a well formed change log: Issue tracker

Outcome
Aim of the project is to enable FreeCAD accomplish a design task like the one at the right.



This will be achived by using the Sketcher and the PartDesign to design special part and Part to load standard part as STEP (like the linear bearing). The Assembly puts it all together with constrains.

Also an important outcome is the Feature editing methodology. Which gives the user an intuitive approach to instantiating and editing Features. This is importand for all other Modules and Workbenches to be come, to comply to a consistent user interface!





Sketcher
A parametric sketcher with a geometrical constraints solver, for more details see the Sketcher project.

Body feature
Since a history based modeling can have a lot of steps leading to the final shape a bracket is needed. Thats the Body, which holds the final outcome of the modeling and acts as a group to all the features of the history tree.

Pad feature
A Pad feature extrude a Sketch (or any Part2DObject) in its normal direction. Always guaranty a solid, or fail.

Pocket feature
Imprint a sketch in a base solid either defined by depth or "Up to last | Up to first). Also guaranty a solid.

Bore feature
Very good bore parameter definition from the NaroCad specification:

Pattern
Replicate one of the above features

RectangularPattern
Replicate one of the above features along an x,y pattern

CircularPattern
Replicate one of the above features along a pattern in polar coordinates

ScriptedPattern
Replicate one of the above features according to a general rule provided in form of a script.

What others do

 * SolidWorks examples

Pattern Implementation
The Pattern feature class can be implemented as a tabular pattern and serve as a base class for the Rectangular, Circular and Scripted Pattern features. These derived classes will only have to fill in the repetitions table of the base class.

Each line of the repetitions table of the base Pattern class has to hold at least a transformation matrix to applied to the Placement of the original feature to be replicated. Additionally we could have optional transformation rules like for example manipulating some parameter value the feature to be replicated (e.g. in order to create a pattern of holes with varying radius).

Modeling objects hierarchy
This UML chart shows the planed object hierarchy and its relationships. Yellow is a abstract base class, blue implemented and grey is planed.



Next actions
Next actions are defined in the Mantis roadmap entry for PartDesign:

Roadmap

Body
Since the parametric/associative nature of the PartDesign we need finally a "Body" which groups and organizes a construction history. The Body itself holds the end result as a shape and has grouped as children the PartDesign features. It also defines the actual head of the modeling history. Its also related to the Assembly project since its the building block for products and compounds.

Additional features
The Pad and Pocket features are the first teaser for the PartDesign. There is still work to do especially the visibility control and the visual manipulators. But then additional features are needed.

Pattern
Pattern feature which repeatingly apply a Pad or Pocket feature according to a circular or rectangular patter. An Example in IronCAD.

BoreHole
Classical bore hole with all parameters for threading and counter bore....

Sweep
Sweeps a Sketch along a curve and create a Solid.

Revolve
Rotate a Sketch along one of its Axis and a certain angle.

TODO List
1. Fillet/Chamfer Part

1a. Apply fillet/chamfer operation to different selection types (face/faces pair/whole body)

2. Pad Tool

2a. Create 'up to next' mode DONE [mrlukeparry]

2b. Create 'up to surface/face' mode [mrlukeparry]

2c. Create draft property for pad DONE [mrlukeparry]

2d. If pad is selected on face automatically create a sketch?

3. Pocket Tool

3a. Create 'up to next', 'through all', 'up to surface/face' modes

3b. If pocket is selected on face automatically create a sketch?

4. Revolution Part

4a. Allow a generic line segment/axis to be used for reference

5. Hole Feature

6. Pattern Feature

7. Sweep Feature

8. Body Feature

9. Reference Geometry

9a. Plane