Circular Board Panelization Tip

[thestumbler]

I was trying to panelize a circular board, but the mouse bites on the tabs were missing. I was puzzled because I read from a 3 year previous closed issue that this feature was available and working.

Then I remembered reading about an issue with "parts" located off the board causing issues, and suddenly I had a theory. In KiCad, one common method when making zones on circular, or any non-rectangular, board is to just draw the zone outside the edge of the board. For example a ground plane would be drawn as a large square containing the circle, but KiCad clips it at board's edge.

I suspected this was related to my problem, so I went through all the zones on my board and replaced them with new ones that hugged the board edge (turned down the grid to 0.01 mm and manually created a whole bunch of vertices approximating a curved edge). It took a bit of work, and was a gamble since I didn't really know that was the problem.

Fortunately, I guessed right. The board, now with revised zones, was panelized as-expected with mouse bitten tabs.

A related note: since drawing all those vertices is painful, you can do it in sections. I did a quarter of the circle, then copied / rotated three times to complete the circle. As I was just finishing, I realized you could do any number of wedges, say 1/8 or even 1/16 pie slices. At some point there's a trade off between being able to draw shorter and shorter linear approximations of curves and the annoyance of the replication process. If I did it again I might consider 1/8 wedges, but 1/16 would probably be overkill. Also you can copy zones from one copper later to another, but I don't think it's possible to copy from a copper layer to a non-copper layer (like copying a ground plane zone to become a solder mask zone).

[yaqwsx]

I am not sure if I follow: mouse bites were missing because your zone was not included? If so, please open issue; this is a bug.

For selecting zones that are larger the board, please use the tolerance option: https://yaqwsx.github.io/KiKit/v1.3/panelization/cli/#source

[thestumbler]

I don't know why it happened, but trimming the zones down so they didn't leave the board solved the issue.

If the zones were simply excluded, then it seems that the panelization would have succeeded, but just the boards would be wrong.

I will collect some details and images and file a big report as you say.