After watching every possible YouTube video on the subject and reading any source available, and although I'm a PhD and quite computer savvy, I still can't make my Anet A6 (no probe) behave in terms of Z offset. I upgraded to silicone bed buffers instead of the stock springs; now my bed is ~5 mm raised, and I don't know how to proceed. Some observations:
G28 makes the nozzle go to the center of the bed. Display says X 111 and Y 111. Is it preferable to set the home to the bottom-left corner, or is the center just fine?
G28 makes the nozzle squish the bed ~5 mm deep.
I've tried the G92 approach and the M428 approach. I can't quite understand what's the difference between them. Can anyone explain why sometimes the former is used and sometimes the latter?
I had high hopes for M428. What could be simpler? You physically guide the nozzle to where you want it to be, send the command, and that's your new 0,0,0. But I guess not. Since my "home" is at 111,111 and apparently M428 can only be used at a maximum of 20 mm from 0, I get a "too far from reference" error message.
At any rate, both approaches (also M206) haven't helped. When I G28, the nozzle still squishes the bed. The display either says Z 5 or Z -5 or whatever I've played with, but the nozzle still squishes the poor bed.
In my LCD menu (Marlin 1.1.9), I don't have Control -> Motion -> Z offset. Since many videos recommend using this, this is quite sad. Can anyone tell me why this option is absent?
On a very conceptual level, I can't quite understand why in all the video guides the bed screws are completely ignored when discussing Z offset. One guy showed how he's correcting his Z offset 0.3 mm using G-code. But he could've easily done it by adjusting his screws... They all say "Z offset means the distance between your nozzle and bed, and here is how to adjust it". Now comes G-code, or LCD menu, etc. But why is everyone forgetting that you can adjust the distance between your bed and nozzle using the screws?! I can't seem to wrap my head around this. In my case, of course, I can't use the screws -- they've reached their limit, so I need to add extra using G-code. But nobody seems to really explain this nicely...
Summary: I urgently need a walkthrough for 6-year-olds. Make that 4-year-olds.