I have had reasonable results using V bits (60° 0.2mm) but I’m still experimenting. I’ve tried end mills from 0.5mm and 1mm but I keep snapping them.

STEP4 – In Pronterface load the files produced in Cambam (.nc files) for etch/trace and hole files you can recombine these files to one in Cambam if that is easier. When happy you can produce gcode for edited board. If you want to edit the tap file in Cambam, open file, Right click on machining tab and select “Toolpaths to geometry” this converts the traces to polylines which can be edited as you like. You can set machining properties within PCB-GCODE but I didn’t. You then select the machining parameters and produce toolpaths and gcode. If you open the bottom etch file, for example, it will show the tracks to be cut. tap files which I couldn’t get to open in Pronterface, so I used Cambam. STEP 3 – The files produced in Step 3 are. I think it produces top and possibly other layers also but I haven’t tried. For a single sided board it will create a file for bottom etch and file for holes.

When board is finished you run PCB-CODE from within Eagle it produces the Gcode files. If you go on Youtube there is an excellent tutorial by a guy called Matt Westwick which explains how to get, install and use the PCB-GCODE software. If you, or anybody else, wants to try yourself I will explain how I did it, but I will say now I’m no expert, this worked for me but there are probably much easier ways.

Cambam forum