The central tenant of OpenCAD is Intent Driven Design. The geometry of the parts and assemblies is driven by intent.
So for instance, the driving features of a bracket are the mating surfaces and the hole patterns. Edge distance and part thickness would be secondary considerations, as would be any webs or other structural elements.
There should be relationships between the bracket and the parts that it connects. The software should either maintain the relationships automagically or it should notify the user that the part's intended design is not fulfilled.
These relationships are defined at the project level. In this way, the designer can maintain relationships on a project-by-project basis. Parts shared between projects can be stored in a library. The project is responsible for maintaining the link between the project and the library.
- Design intent doesn't always translate into real world terms
- For example, a design may be symmetrical around an overall length of 5.375 inches, so each half is 2.6875 inches. Using standard aerospace practices, dimensions are taken out to 3 decimal places, so the halfway dimension would be 2.688 inches.
- Tolerance analysis needs to take these type of rounding errors into consideration to ensure proper fit.