You simply set the 'Milling Tool Depth' for the tool as per the instructions. When you select a tool from the magazine you should see an option. It's a case of using a small area of the board to define a line, the width is then measured by the camera and the user adjusts until the desired value is obtained. However, always check after making the adjustment ans sometimes it is more robust to perform at two opposite corners on the board. I should also mention that we found that it is best to half the suggestion by the LPKF software.