There is "Milling Machine Simulator" on Steam Store. I thought that you have to use a special bit for X and Y touch-off and set X and Y coordinates to zero. The game told me to turn on the spindle with a regular bit and move the table until the bit touches the workpiece. Is this wrong?
It depends. If your stock is oversized and are going to mill that sides away anyway, you can just kiss the edge with a turning bit. Then you just factor in 1/2 the diameter of the bit when you establish zero. If its a surface you cant mill, then use an edge finder.