Huh! For some reason I can't post this - something squirrelly going on here:
Z-Offsets are nothing more than extremely small adjustments to the
Starting Height of the bed before your print starts.
The reason that previous users had to use
Z-Offsets, was that it was just about physically impossible to turn the screw that contacted the
Z-Stop with enough accuracy to get the
Starting Height correct. So we went in and adjusted the starting point for the plate from inside the software with
Z-Offsets, which physically moved the bed a little closer or farther away from the
Starting Height that was coded into the firmware.
Rev. E machines do not have to set a
Z-Offset. They set a much more accurate
Starting Height in the beginning, using the
QuickStart Application, and then the machine keeps that much more accurate setting, and you don't have to worry about it anymore.
Now say that you want to change the surface that you are printing on. The machine thinks that the Starting Height is still at the same place that it was the first time you set it, and it moves the plate up into position, but since now the top of the plate is higher because of the new surface on it, you whack into the nozzle and it causes the hot nozzle to either gouge the material or drop the bed down because it hit something.
Unfortunately, you cannot just use the just the
QuickStart Application again to set the
Starting Height unless you re-perform the
Leveling function as well. That is because the
Starting Height information is not saved to the firmware unless the whole process is performed. (This throws off a lot of resets for people who do not re-run the leveling process and save the
Starting Height too early in the process.)
You CAN use the
Z-Adjust Application, which does the same thing as the
QuickStart app, but without having to go through leveling again. It just sets the
Starting Height and saves the information to the firmware. It is just as accurate at setting that initial
Starting Height as the
Quickstart app. Once you use the
Z-Adjust app, your
Starting Height is set correctly, and there is no need for further
Z-Offset adjusments.
Now when you become an expert, and want to start making
minuscule adjustments to the
Starting Height to start impacting how the bed is placed for a certain filament,
(PETG comes to mind), then you can go in and use either the Z-Adjust application or the G-Code adjustments to really, really,
really fine tune the placement through coding. But it's really not necessary for this purpose, you are just trying to reset your
Starting Height.