Here are some changes or additions that I propose :
Part Workbench Concepts
Part Workbench is a Constructive Solid Geometry (CSG) style modeling. The operator combines various primitives to end up with a representation of the desired shape. (In fact, Part Workbench goes one step further than just primitives and allows the operator to use a sketch+extrude operation to create its own primitives.)
When each primitive or shape is created, it has no relationship to other objects created, it is a single solitary solid.
This condition ...
PartDesign Workbench Concepts
In the PartDesign Workbench, the Body object is constructed directly as a single cumulative solid.
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The lowest/last operation (the current Tip of the Body) is the current state. Any other feature under the Body but above the Tip, does not represent a complete/stand alone solid. Only the Body (basically a proxy for the tip) or the Tip represent a complete solid.
(question : what do you mean about « proxy »?)
Note :
At each time of construction, the last function used is the "Tip", which can be defined as "active stage in the construction of the object" or "stage preceding the next action in the construction of the object".
When the object's drawing is complete, Tip is naturally the last stage or feature of the construction.
But if desired, in case of forgetting, any feature of the construction can be provisionally declared as Tip: it then becomes the step preceding the next action in the construction of the object, which means that new feature(s) can be inserted anywhere in the construction, ON CONDITION NOT TO CREATE ANY INCOMPATIBLE WITH THE SUITE.
When everything is finished, you have to redeclare the last feature as Tip, which corresponds to the finished object.
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This image shows a Body. It is a cumulative solid that consists of a padded sketch and a cone primitive. This is a single solid. The pad can exist separately (Tip on pad) but the cone cannot exist separately (Tip on cone = pad + cone).
The Ramifications
Although not recommended, it is possible to combine tools from Part WB and PartDesign WB, provided you know what you are doing. For example :
People get caught when they attempt to use some feature under the Body (rather than the Body itself) as one selection of a Part Workbench Boolean operation. This is a problem, because the selected feature does not represent THE complete solid.
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The Caveats
… the Mirror is operating on the underlying feature …
I disagree here : the Mirror does not necessarily apply to the last step or even to a single step. You must select the feature(s) on which you want to apply the Mirror. The same goes for the other transformation features of PartDesign (Linear or Polar pattern).
Comparison
I think that a comparison in pictures on the same example can facilitate the understanding of the differences. So I therefore propose below the same example built with each of the two workbenches. Of course, there are always several possible construction timelines with each workbench.
Note : The starting stages could have been the same.
- PartWBvsPartDesignWB01.jpg (102.91 KiB) Viewed 1044 times
- PartWBvsPartDesignWB02.jpg (90.86 KiB) Viewed 1044 times
- PartWBvsPartDesignWB03.jpg (101.19 KiB) Viewed 1044 times
- PartWBvsPartDesignWB04.jpg (63.11 KiB) Viewed 1044 times
- PartWBvsPartDesignWB05.jpg (98.13 KiB) Viewed 1011 times
Info:
If you think my remarks and example are useful, I will provide all the pictures needed, or try (1st time!) To complete the wiki myself.