Main consideration is that the one FreePCB project is placed into stand-alone directory with no other projects. Then we can copy the fpccovert.conf.default file in fpcconvert directory to fpcconvert.conf in our project directory or create a new file called fpcconvert.conf and write following lines:

N_VERT_CIRCLE_APPROX   = 28
ADDED_CONN_WIDTH_HALF  = 75UM
ADDED_PAD_RADIUS       = 75UM
ADDED_VIA_RADIUS       = 75UM
Z_START_POSITION       = 10MM
Z_MOVING_POSITION      = 2MM
Z_MILL_DEPTH           = -0.25MM
X_TOOL_CHANGE_POSITION = 90MM
Z_DRILL_DEPTH          = -4.3MM
FEED_RATE_DRILLING     = 40
WORKING_AREA_LEFT_BOTTOM_POINT = 0,0

                            

N_VERT_CIRCLE_APPROX is increased to 28 due to smoother board outline, which has circle shape. Pads, connections and vias are increased by 75 micrometers. Z_MILL_DEPTH is most important parameter and should be always negative. X_TOOL_CHANGE_POSITION is set to 90 millimeters to allow drill bit change, because it could not be possible when spindle is above on the clamp. The PCB board is held directly by clamp without aluminum table, so there is a lot of space to drill. This is the reason why Z_DRILL_DEPTH is set more than twice of board thickness. FEED_RATE_DRILLING is slowed to 40 millimeters per minute. WORKING_AREA_LEFT_BOTTOM_POINT is set to 0,0. This is necessary to match top and mirrored bottom layers, when the board is centered using FreePCB.