I intend to document the procedure I use for manufacturing printed circuit boards using my milling machine controlled by LinuxCNC's Enhanced Machine Controller. Until then, here is a photo of a board I recently made.
The IC pads are on a .05" spacing, the connector on the left is .1", and the connector on the right is 4mm. The traces are about .01" wide. The holes range from .029" to .040"
The outlines around the traces are cut with a 60 degree carbide V tool rotating at 20,000 rotations/min and traveling at 20 inches/min. Since the tool has two "teeth", this means that each tooth cuts only .0005 (half of a thousandth) of an inch! This is the usage suggested by the tool manufacturer, and it gives great results and long tool life.
The board is then drilled with various sizes of carbide drills, and finally cut out with a 1/16" carbide end mill.
The FR-4 (fiberglass) circuit board material will quickly destroy any HSS tool, so using only solid carbide is a must.This board is the Pminmo design and was produced on the mill to be used as an A axis driver.