Setting the X and Y Axis Square

Changing the home sensors on my CNC Router requires to set the X and Y axis square again. For this process I am using a known standard a calibration square. First I align one side of the square with the Y-Axis of my machine using a dial indicator. Next I check the X-Axis against the other side of the square and change the home position on one side of the gantry until I get a minimal acceptable deviation.
Re-homing the machine again and making a new measurement shows me that the new Panasonic optical sensors are a great improvement for my machine.