<p>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.</p>
<p><strong>So Let's Assume Bed is leveled perfectly and all Motor steps are calibrated correctly (X,Y,Z,E)</strong></p>
<p>I do understand some of the correlations e.g.:</p>
<ol>
<li><p>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.</p>
</li>
<li><p>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.</p>
</li>
</ol>
<p>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.</p>
<p>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.</p>
<p>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.</p>

CC BY-SA 4.0
2020-12-03T13:11:42.297Z
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.
towe
CC BY-SA 4.0
2020-12-03T14:07:05.837Z
why extrusion width should be set to 110-120% of the nozzle ? I've seen that before but why is that ?
uneasy
CC BY-SA 4.0
2020-12-03T14:33:23.013Z
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?
towe
CC BY-SA 4.0
2020-12-03T14:56:18.993Z
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 ?
uneasy
CC BY-SA 4.0
2020-12-03T14:57:28.193Z
You'd set your extrusion width to e.g. 0.44, and calibrate so that your two walls are 0.88 thick.
towe
CC BY-SA 4.0
2020-12-03T15:22:55.997Z
Cool, after that, should line width (extrusion width) should be same for all layers, or maybe there is some pattern to follow, similar to layer height where first layer should be thicker for adhesion etc? Currently I have it set up same for everything. 
Or like you said previously, change flow for first layer and leave it default for the rest ?
uneasy
CC BY-SA 4.0
2020-12-03T15:31:19.563Z
Thicker extrusions on the bottom layer might be beneficial, but I never bothered with that.
Yes, I leave it at the same width for all feature types and layers.
One interesting venue might be thicker extrusion width for infill, saving a bit of time as long as you're under the volumetric limit of your hot end.
towe
CC BY-SA 4.0
2020-12-04T06:01:00.613Z
The idea that you can't print smaller than the nozzle is a myth. https://3dprinting.stackexchange.com/a/14676/11157
R.. GitHub STOP HELPING ICE
<ultimaker-cura><bed-leveling><layer-height><prusaslicer>
Flow + Line Width = over / under extrusion, how does that work?
uneasy
# Flow + Line Width = over / under extrusion, how does that work?

(Asked by: username_0 on 2020-12-03)

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.

**Tags:** ultimaker-cura, bed-leveling, layer-height, prusaslicer
> **Comments:**
> **username_1**: 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.  
> **username_0**: why extrusion width should be set to 110-120% of the nozzle ? I've seen that before but why is that ?  
> **username_1**: 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?  
> **username_0**: 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 ?  
> **username_1**: You'd set your extrusion width to e.g. 0.44, and calibrate so that your two walls are 0.88 thick.  
> **username_0**: Cool, after that, should line width (extrusion width) should be same for all layers, or maybe there is some pattern to follow, similar to layer height where first layer should be thicker for adhesion etc? Currently I have it set up same for everything.  Or like you said previously, change flow for first layer and leave it default for the rest ?  
> **username_1**: Thicker extrusions on the bottom layer might be beneficial, but I never bothered with that. Yes, I leave it at the same width for all feature types and layers. One interesting venue might be thicker extrusion width for infill, saving a bit of time as long as you're under the volumetric limit of your hot end.  
> **username_2**: The idea that you can't print smaller than the nozzle is a myth. https://3dprinting.stackexchange.com/a/14676/11157  

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## 0 answers

