Best way to trace existing PCB (not for piracy!)

[daxliniere]

Apols if you already do or knew that. Originally I tried small bits, shallow V-cutters, etc., so ISTM you may be at in the first leg of your PCB making journey.

No, no, this is all great to hear. Thank you for sharing your experience. I'm sure it's saved me from a few mistakes.

Dust is not such a problem for me as I have my CNC in a cabinet, but that's interesting about the blunting. Is that a big concern when making such little cuts in FR4?

[PlainName]

FR4 seems to be pretty hard on sharp edges - try cutting or shaving it with a knife a few times. A better indication is the copper tracks which, without oil, I find start nice and well defined but quickly get rough and require a tool change to get a good edge again.

[nctnico]

FR4 is glass and epoxy resin. HSS tools are useless for FR4. Really go for tungsten (or other very hard metal) bits if you want to have some lifespan.

[SiliconWizard]

KiCad allows importing on any layer from vector graphics (SVG and DXF currently.)
Not directly bitmap images, but there's a separate tool for converting bitmap images to footprints, that you could then just add on the copper layer.
Alternatively you can use Inkscape or some other tool to convert your bitmap to SVG (vectorization will be better using Inkscape I think) and then import that in KiCad directly. That's pretty straightforward.

Do not expect not to have to do manual touch-ups though. And of course you need to finely adjust the dimensions.

[PlainName]

Really go for tungsten (or other very hard metal) bits if you want to have some lifespan

Indeed - I use carbide for drills and they last an age. But hard metal is very brittle and snaps easily when not going in dead straight. Not so hot for tiny milling bits.