I am just trying to deeply understand relations between those parameters. I am not a noobie, but just trying to be more smart with a printer, instead of changing parameters randomly to see effects on the print.

So Let's Assume Bed is leveled perfectly and all Motor steps are calibrated correctly (X,Y,Z,E)

I do understand some of the correlations e.g.:

  1. When Flow is too low, on first layer you have to lower Z-Offset to get nice squish, but next layer will be under extruded, because Z-Offset does not apply on any layer except 1st.

  2. When your flow is too high, you have to bring Z-Offset higher, to get first layer perfect, but then next layers will be over extruded and looks squished too much.

Now, I have calibrated flow, with method of printing shallow cube with 2 walls (perimeters). I've set all line widths to be 0.4 (like my nozzle), so on the measurements I expect wall to be 0.8 (2x0.4), some tutorials says I should aim for 0.82, but for now I left it at 0.8 which was pretty much spot on.

Leaving line width's set to 0.4 for all lines and layers, and line height to 0.2 on all layers, I started printing, on the fly I adjusted Z-Offset to get that first layer right. But on every other layer, I had too much squish (over extrusion). And that does not fit the things I though I understand. Because now if I lower flow, flow calibration will come wrong. I also know that by default in most slicers, layer height and line width are not set to same values for all layers.

Of Course I could just fiddle around, keep changing those settings and probably I would finally get what I want, but I want to understand what to change and why, so rather than telling me what I am doing wrong, I would like to know how it should work, I am guessing there is How it should work in ideal world, and how it works with budget printers. But I really really want to understand that part of the printing, and maybe there is other complications I am missing in here.

  • $\begingroup$ Level to 0.0mm, set extrusion width to 110-120% of your nozzle diameter. Calibrate flow like you did (2x walls, aim for exactly that) and compensate the rest with first layer flow or Z offset. $\endgroup$
    – towe
    Dec 3 '20 at 13:11
  • $\begingroup$ why extrusion width should be set to 110-120% of the nozzle ? I've seen that before but why is that ? $\endgroup$
    – uneasy
    Dec 3 '20 at 14:07
  • $\begingroup$ You're pushing hot plastic through a hole with a 0.4 mm diameter. It's going to expand a bit upon leaving it - you'll never know exactly where. Extrusion width is usually set a bit larger than the nozzle diameter to catch that uncertainty. It's also why you can't reeeaally print with extrusion widths < nozzle diameter: How do you tell where it's going to go? $\endgroup$
    – towe
    Dec 3 '20 at 14:33
  • $\begingroup$ I get you, makes sense. I think I need to understand where are those imperfections in the printer, so it can be all 1:1. So, following what you said, I should set width to 110 of my nozzle, and when doing calibration should I still aim to 0.8mm (2x0.4 of the nozzle) or aim for that extra 110% on the width ? $\endgroup$
    – uneasy
    Dec 3 '20 at 14:56
  • $\begingroup$ You'd set your extrusion width to e.g. 0.44, and calibrate so that your two walls are 0.88 thick. $\endgroup$
    – towe
    Dec 3 '20 at 14:57

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