Please do not tell me what I did and did not do. it has no gain and it wastes both of our time if I were to lie, never mind that it would bs (excuse me if that is perhaps a bit inappropriate) me and send me on a wild goose chase when I have stuff to do 😕 . I'm saying it as it is, straight up, at least for my pc and machine, considering that every one of our machines and pc's are different (and also considering Cura 4.2.1 is still.... very buggy... some flow settings, despite active for example, are completely invisible unless I search for them .... no they are not greyed out and their values do affect my prints.)
Regardless, I DID change the settings, BOTH of them in fact (extruder 1 in machine settings and custom materials in preferences), and tried a few different combinations of them too. I did not change to 2.85 as that would be unreasonable to test for the extremes for 1.75mm filament to see if the setting actually worked for fine tuning (my filament is 1.70, that's what setting SHOULD have an effect, but it doesn't have any affect on my print at all), and as such, only between 1.45 and 2 mm were used to test far extremes for 1.75 filament, so that might be why it didn't do anything at all... perhaps my pc would just switch directly between 1.75 and larger filaments instead of fine tuning? But again, it showed me that fine tuning filament diameter is impossible, save for flow settings (I should really have said I changed to those diameters to those values... oh how this topic has derailed, lol.)
There was no difference in filament length used, weight or time... and the actual finished print reflected that as well when I measured time and weight. the print was under extruded when set to 1.45 and under extruded when set to 2mm's (flow at 100 percent, and the nozzle was not clogged)
I downloaded the "printer settings" plugin and changed the filament diameter to 1.70mm and the difference in weight and filament used was huge. I changed flow, and the difference was huge (started over-extruding). I uninstalled the plugin (as I really do not like or use them and it was only for testing) and then changed the diameter again, in extruder settings and materials... and absolutely nothing happened (back to under extruding). Flow is what I just ended up using because it's all that worked and actually did anything (107 percent flow was the equivalent of the 1.70 diameter setting in the plugin.), but it is impossible to tune filament diameter finely it seems in stock Cura if you don't see flow as diameter adjustments.
The plugin's diameter settings seem to work... entirely different than the stock Cura's printer settings. it behaves like flow does... sort of. but again, the Cura on my pc may be bugged, as it has been bugged and acting weird ever since the first 4.0 update 😕
Edit: Indeed it is my pc acting up... ah well. at least I know what the problem is now.