Super Simple Bed Levelling Ender 3 (or any 225*225 bed size printer)

When levelling your bed, straight lines are pretty useless, to ensure the bed is level you need to print curved lines as only when the bed is level can you print a line that is changing direction.

The in the four corners and the middle are different shapes, you can check to see if these are nice and smooth (bed level), if they are a bit rough like sandpaper you are to close, if they are stringy or do not form a single piece when printed you are to far away.

Slicer Settings: (Cura).

Disable Ironing,
Enable: Print Sequence - One At a time under special mode