CNC milling / carving copper PCB

I’ve got best results milling the PCB with this kind of tools:

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You can find them on ebay with words “Carbide PCB Engraving Bits CNC Router Tool 90 Degree 0.1mm”.

My settings for PCB-GCODE are:

Depth 0.1mm
Tool size 0.25mm

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In eagle’s DRC / DRU I usually set the “sizes” tab “minimum width” to 0.8mm, but with carefull positioning of the clad I have achieved 0.4mm minimum widths.