For the built-in component types, we enter the dimensions and tolerances of the component terminals, and Library Expert automatically calculates the pad shape and size based on various preferences. For example, I usually select the rounded-rectangle shape, and the pad size is usually somewhat larger than the terminal size.

However, it appears that with custom components (FP Designer), there is no way to specify the terminal size/shape. Instead, we must directly specify the pad stack geometry – even though the terminal size/shape is the thing that is truly constant for a part, while the pad stack geometry could conceivably change with different preferences.

Given the goals of the FPX library architecture, it seems like there ought to be a way to define custom parts in the same way built-in parts are defined: Instead of directly entering pad-stack details, enter the truly constant physical aspects of the part – Lead type, size, and shape, location, and tolerances – and let the software calculate the pad-stack geometry from that information combined with the preferences.

• Is there a way to do that that I am overlooking?
• Short of that, how do I calculate the dimensions of, say, a rounded-rectangle pad stack, given the dimensions and tolerances of a component terminal, using the same rules Library Expert uses for built-in components?