As you can see up there with Aquila it's confusing and not straight forward for noobs
Hm.. have you had a chance to look at the footprint I attached up there for a 100x100 board?
I find it very easy to follow the outline on the drawings layer with segments/arcs on the edge cut layer.
This then also can be pulled in an existing project where much of the layout has been done already (for conversions for example).. and messing up the mounting holes/cutouts is pretty hard that way also, as they're fixed on the footprint and dimensional fit of the board edges can always be checked visually by just looking at the lines ( no need for measuring anything)
On the other hand, if somebody likes different outlines better (chamfered edges, some other cutout, etc..) he can easily incorporate them without loosing the reference outline for the 'standard' hat, nor does he need to do calcs or measurements while modifying.
I whipped up the RPi-hat footprint just for demonstrating the concept for the PTH version...z_RPi_Hat_PTH.kicad_mod (7.3 KB)
Would probably need to be centered on the connector though for the 3d model placement without offset, but that is details..
The end of the story is, you can treat the shields/capes/hats as you treat any other connector footprint (like a uSD card slot for example) and you won't be able to mess up mounting holes if they've been done right first time.
Looked at it from this angle your customized symbols for the SMT and PTH 2x20 pinhead connector would make more sense too, as those would be really symbolizing footprints of those hats (SMT and PTH).
That's a pro and you won't get edge cuts out of the footprint in the first place anyway - have you actually tried to get edge cuts into a footprint file? Text-editor only.. and even then, don't load that footprint with the footprint editor as he will complain and move them to some other layer.
Already hard enough that the footprint editor doesn't allow direct drawing on Dwgs.User and Cmts.User layers..
Admitted you can put edge cuts into a footprint (did a Nokia 5110 display backward and had the cutout in the footprint) but after a while I decided against it and just kept the cutout info on the dwgs layer and redid the cutout on the board the display got onto:
So the edge cuts wont be in the footprint, everybody would have to 'redraw' them according to the footprint outline/cutout lines. And as I said, that's a plus.
- it's fully customizable (sharp corners, chamfered corners, different cuts, etc pp)
- people learn to do edge cuts/cut outs properly (show a man how to fish
- people don't lose the reference dimensions/forms by manipulating the edge cut drawings as they will always be there with the footprint (no need for those dimension sizers also)
- if really needed the footprint on that board can be manipulated (pads changed, etc..) either in-situ just for that board or for all in the FPeditor
- can be loaded into existing projects/boards to save on layout time
- less clutter/easier to manage (just 1 symbol and 1 footprint per version), no need for a project template that you have to use from the beginning and with all that is contained
- no chance of accidentally altering any of the sub-components positions without noticing (mount holes, pin header, edge cuts, etc..)