How to Create High Voltage Routed Isolation Gaps in Board?

Seems like there is a need to support an easy method of specifying and laying out routed (milled out) areas on a PCB for high voltage isolation.

My KiCad specific questions are at the end of this post. I am looking for how to address this common high voltage board design task. My thoughts on this are as follows:

When searching for information on how to accomplish this I found two concepts mentioned.
1-Create an outline of the routed area on the cutout layer. Difficult for track type (non-straight) slots. Can’t use newPCB track tools to tweek design.
2-Create a tool path (gerber or G-Code) on a separate layer. My preferred option for air gap isolation slots. Very easy to design using a track the width of a router bit.

With respect to the board houses: Most have available a 100 mil router bit, with a 78 mil router bit being the next most common. Smaller router bits can add more cost as they potentially require routing only one board at a time due to tool breakage issues.

I’ve designed my routed air gaps on a copper layer. Visualization and design is easy. Gerber output should be easy to turn into g-code tool path for milling operation. I am planning on renaming the gerber copper layer to a cutout/milling layer. On viewing the gerber file produced I see the through hole pads showing up. I’d rather not have to manually edit this layer’s gerber file to remove the pads.

Is there any way to suppress the pads from showing up on the gerber output for a layer? Is there another type of layer I can use that is better suited to this need?

I don’t get this part… any screenshot available of what the problem is?
Why are there through holes? Where do they come from?

Layer wise I would take Eco1.User or Eco2.User as the Edge.Cuts layer doesn’t really work for this (KiCAD 3D view freaks out if there are ‘free floating’ lines in a closed contour, without a contour defined they work like a milled cutout though).

It’s pretty straight forward to get the Eco layer plotted and renamed afterwards to fit the naming expectations of your boardhouse. Graphic lines can be thickness modified and also restricted to 45 deg in the preferences…

You might also want to have a read here:

Guess I wasn’t clear about my board being a through hole board with no SMT parts. The through hole pads show up since I did the gap routing tracks on a copper layer (In1.Cu). Might be nice to have a more general purpose layer definition setup where one can pick what layout features are shown/plotted. Also using an inner layer type means I have to manually edit the xxxdrl.rpt output file to remove all references to the inner 2 layers of my, in reality, a two layer board.

Using the program Gerbv (gEDA project) I was able to delete the through hole pads manually to get the gerber output I wanted.

I did read the “Making a PCB gap / slot / milling / routing” post. Couldn’t find any other references to making slots with KiCad. Their approach appears much more difficult to me (closed outline track for slot).

As a new user it doesn’t look like I can upload any images.

I noticed that when using a graphic line, on the Eco1.User layer, under a footprint, I was unable to modify the graphic line’s width.

Do you have any drawings showing the sort of slots you’re creating? I can’t imagine what your problem is from the description.

I really wouldn’t use a copper layer for slot or cutouts… this just begs for trouble.

You didn’t read closely enough then… the OP in that thread did use the Eco1 layer for drawing the router tracks like you want to. Here is a screenshot of me just doing that:

The graphic lines width can be adjusted any time to any dimension afaik, would need more detail on that ‘under a footprint’ problem…

It then depends on your ability to tell the boardhouse what this layer means and what they should do with it.
My ‘track record’ for cutouts is with two chinese boardhouses only so far and I’ve been using edge.cuts with closed outlines. But that’s just one option that’s possible.

As for picture posting… just depends on how long you leave your browser open really and going through a couple of threads: