When we model an object in FreeCAD we model it's outer shape. The "Contour" tool is aware of a projection and creates a path around it.
The raw material we start with encloses this object, it can be bigger in any dimension. Usually it is a block or a cylinder as these are readily available at the steel traders. Since standard sizes are much cheaper then custom sizes it is usually somewhat bigger than the bounding box. In fact it can even have an arbitrary shape as it can be a leftover from some other piece.
If the raw material is too big to be milled in one step with the desired step over the Contour tool should respect this and create a more complicated path.
I have the strong feeling that everything is ready to achieve this but I am not yet sure how I would like to define it:
- We can model the raw material separately in FreeCAD. This would give maximum flexibility. Questions: Is this too complicated? How do we distinguish it from other objects modelled?
- We could have a special path object. I think it would be sufficient to have boxes and cylinders. A possibility to place the object in the raw material would be necessary, e.g. when we have one (or two rectangular) plane sides on the object it could well be placed at the plane sides of the raw material. This can e.g. ease the placement of the holding tags.