Originally Posted by
Roxy
To fully realize the benefits of UBL, you need to have a mesh that is tuned to your print bed. It's not a big deal, but it will take an hour to go up the learning curve and get things right. (If you print on multiple pieces of glass... You can do the second piece of glass in 15 minutes of machine time and 5 minutes of your time)
But the EEPROM is required because with a 10 x 10 mesh, or a 15 x 15 mesh... It ends up being a lot of data. You don't want to generate that every print.
There is a UBL Guide in the Documentation folder of MarlinFirmware. (It is in the 'Features' area) You can do the Quick Start list of instructions and probably get your mesh very nicely turned with no hair pulling. But please make sure you can print a small calibration cube in the center of the bed with bed leveling turned off first. If you can't do a print, trying to bring up UBL is going make your brain explode.