Skew Compensation corrects for misalignment in the XY, XZ, and ZY axes. This can help with hardware inconsistencies on your 3D printer. First, you need to print 3 calibration squares called YACS (Yet Another Calibration Square). You can download them from Thingiverse.
The first square is flat on the bed (X and Y axis). Print it and measure AC, BD and AD, then enter the values:
The second square is standing on the bed in the X axis direction (X and Z axis). Again, print it and measure AC, BD and AD, then enter the values:
The second square is standing on the bed in the Y axis direction (Y and Z axis). Print it and measure AC, BD and AD, then enter the values:
Tap on the Checkmark button to save these settings. The firmware will compute, apply the Skew correction factors ans save save in the EEPROM memory of the printer.