Rounded inside custom pad

I am working on a board design which has a large custom pad and standard filled copper ground planes. The custom pad has two merged pads plus a triangular polygon to create a 45 degree angle where the two merged pads meet and the copper fill zone approaches the custom pad with spacing set by a zone rule area. I would prefer the 45 degree angle to be curved if possible but there doesn’t appear to be a way to use the arc line since it is just a line and not a filled area. There is no issue with the outside corners of the pads since I’m using pads with rounded corners already but I’m stumped at how to create this inside rounded corner. If there’s no easy way to do this I’ll just leave the 45 degree polygon in there but I thought I’d ask just in case there is a simple way to achieve this in v8.0.5 footprint editor.

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After selecting arc you should have in context menu something like convert selection into tracks (I’m not at PC with KiCad to check exactly).

It can be done. It’s a bit messy and will need a little arithmetic.
Note: the arc has been drawn on a different layer in “A” only for clarity.

  • Draw your arc then open its properties and increase the width of the line to large. This example shows 40mil.
  • Draw your polygon so its edge is on the centre line of the arc at the beginning and end of the arc, BUT less than the centreline of the arc as the short straight lines continue around the arc.
  • Go to polygon properties and edit the line width to match the arc line width.
  • Place a pad on the finished graphic shape and use “Edit Pad as Graphic Shape” (Ctrl + E).

Comments:
If you cross over the centreline of the arc with any part of the polygon, you will have bumps showing on the outer edge of the arc when you increase the width if the polygon line to match the arc line width.

Arithmetic is needed to work out the overall dimensions of the shape because you need to increase the width of the arc and polygon edge lines after they have been drawn.

Happy drawing. :slightly_smiling_face:

You can first draw a continuous closed shape with line tools: arc and straight lines. Then select them and use the context menu → Create from Selection → Polygon. This can be made to one custom pad.

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Thanks for the responses, I think eelik’s suggestion sounds the easiest and I will try that the next time I want something like this. But I’ve already created my pcb panel with 6 different prototype versions (experimenting with a capacitance sensor sizes) so I’d have to rework 6 different versions. It’s more for aesthetics anyway (although I prefer not to have sharp corners when possible either).

Had a little spare time this morning so I tried eelik’s solution and it works great (thanks again!). I created a few construction lines first to help determine the arc’s center point:

Next I created two straight lines to connect the arc ends using the space bar to make sure dx and dy were 0 for orthogonal (I don’t know another way to draw orthogonal lines). You also have to launch footprint editor from pcb editor to be able to see dx and dy because if you launch from Kicad manager you run into the bug I have outlined previously where the bottom status line is not viewable cleanly when you launch any of the KiCad tools not using stand-alone mode. This shows all the lines selected and ready to convert:

Finally the finished product with the filled polygon selected with the points on the arc portion:

While I was constructing this I thought I might have to slide the curved polygon a bit to avoid a hump where it intersects the two pads to make this custom pad but when I zoomed in it’s smooth so that step was unnecessary.

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