Unconnected tabs when putting PCBs of different sizes side by side

[GioMusto]

Prerequisites

• I have read FAQ
• I have searched existing issues (including closed ones)
• I use KiKit at least version 1.7.1 (older version are not supported)

KiKit version

1.7.1

KiCAD version (only KiCAD 8 and 9 are supported)

9

Operating system

Windows 10

Description

I modified the script found here to include just the bare minimum to put two different boards side by side. One of the two is shorter than the other, but both are simple rectangles.

When I use the railstb framing type, the tabs on the shorter board don't extend all the way to the rails, and when I use the frame type, the rails are not generated at all on the smaller board.

Steps to Reproduce

Simply run the attached script.

Unfortunately, I can't share the actual boards, but the issue should appear with any rectangular board.

custom_panel.zip

[GioMusto]

The problem is that the partition line is always mid-way between two substrates. In case of two boards it's not a problem, because both will create their half of the tabs, but we don't create tabs for the framing substrates.
This is not an issue for the longer board because the frame is always created so that the partition line falls on its edge. The shorter board, however, will always have the partition line detatched from the frame.

[GioMusto]

I managed to make railstb work for my use case, albeit with a hack. I added the framing substrates to the panel substrates, so that tabs were generated also for them.

There are just two minor issues in my use case:

1. The frame width is 1mm more than specified
2. The space between the board and the frame is double the specified amount

Both issues can be fixed by modifiying the underlining code handling the frame.

Furthermore, if I move the small board up instead of keeping it centered, a dangling tab is added to the frame, because it encounters the backbone. This can already happen in other circumstances and could be solved by adding another step to the code, where all unconnected tabs are removed.

Below you can find the result and the modified script.

Is there any chance a similar approach can be used in the code instead of requiring this hack? Maybe making it work in more cases.

custom_panel-2025-03-08.zip