You’ll want to plug the cnc into a computer and connect to is via candle (or other gcode sender) and read the grbl settings. and provide the value for $100
James made a great video using the 3018, but the process is the same for your FA4040.
Another quick question, is this your first carve on the CNC or have you made prior successful carves that were not dimensionally skewed?
Also, here is a video showing the calibration process, BUT you will want to VERIFY that the movement is actually inaccurate BEFORE bothering with the calibration process.
