<p>As pointed at by @Horitsu, the Nozzle was the problem. Its outflowing hole was not perfectly round anymore, leading to a higher extrusion rate in one direction than others.</p>

<p>I exchanged it, and now everything works great again!</p>

CC BY-SA 4.0
2018-07-04T06:08:39.093Z
2018-08-04T15:14:57.597Z
2018-08-04T15:14:57.597Z
iFreilicht
<p>Due to the advice from @0scar i formulate my answer in the comments as a proper answer ;)</p>

<p>Check the nozzle, if it is in shape and good condition.
I scratched my nozzle over the metal heat bed by accident...it becomes nasty... and produced inconsistent line widths. Since the metal of most nozzles is brass it is easy to machine...and easy to deform. And since you will need several nozzles over time get some new ones and try with them.</p>

<p>Also not every new nozzle will be perfect, so defect products happen, especially if they are cheap and have really tight measurements.  </p>

CC BY-SA 4.0
2018-08-04T09:06:46.163Z
2018-08-04T15:14:38.887Z
2018-08-04T15:14:38.887Z
Horitsu
<p>I just re-ran all basic calibration steps from the Original Prusa i3 MK2 Manual.</p>

<p>Now, when doing the first layer calibration, lines that are running in positive X direction are ok, while those running in negative X direction are severely squished.</p>

<p><a href="https://i.sstatic.net/5zzEl.jpg" rel="noreferrer"><img src="https://i.sstatic.net/5zzEl.jpg" alt="Print of the default V2Calibration.gcode file on my Prusa i3 MK2"></a>
<em>(The "waviness" of my print bed is an artifact of the camera lens distortion of my smartphone)</em></p>

<p>I already did Bed level correction, so each line is exactly the same width over its entire distance and tried to raise the live-adjust Z, but that leads to the thin lines not adhering at all. My printer is 100% stock, I modified nothing about it. </p>

<p>What can I do to troubleshoot this further?</p>

CC BY-SA 4.0
2018-06-29T12:51:20.527Z
do you have any play on the head?
profesor79
CC BY-SA 4.0
2018-06-29T13:49:26.673Z
Can you check the g-code to be sure the head speed remains the same for movement in both directions?
Carl Witthoft
CC BY-SA 4.0
2018-06-30T20:57:11.737Z
@profesor79 I tried to wiggle it, but it stays put. My current assumption is a damaged or partly clogged nozzle.
iFreilicht
CC BY-SA 4.0
2018-06-30T21:01:30.600Z
@CarlWitthoft I don't think that can be the case. I did this calibration step successfully when assembling the printer for the first time and didn't change the gcode in the meantime. It was supplied with the printer. I'll have a look though.
iFreilicht
CC BY-SA 4.0
2018-07-02T04:58:15.607Z
Check the nozzle. I scrached my nozzle over the metal heat bed by accident...it becomes nasty... and produced inconsistent line widths. Since the metal of most nozzles is brass it is easy to machine...and easy to deform. And since you will need several nozzles over time get some new ones and try with them.
Horitsu
<prusa-i3><print-quality><fdm><calibration><troubleshooting>
Line width changes depending on the direction the print head moves
iFreilicht
# Line width changes depending on the direction the print head moves

(Asked by: username_0 on 2018-06-29)

I just re-ran all basic calibration steps from the Original Prusa i3 MK2 Manual.

Now, when doing the first layer calibration, lines that are running in positive X direction are ok, while those running in negative X direction are severely squished.

[![Print of the default V2Calibration.gcode file on my Prusa i3 MK2](https://i.sstatic.net/5zzEl.jpg)](https://i.sstatic.net/5zzEl.jpg)
*(The "waviness" of my print bed is an artifact of the camera lens distortion of my smartphone)*

I already did Bed level correction, so each line is exactly the same width over its entire distance and tried to raise the live-adjust Z, but that leads to the thin lines not adhering at all. My printer is 100% stock, I modified nothing about it.

What can I do to troubleshoot this further?

**Tags:** prusa-i3, print-quality, fdm, calibration, troubleshooting

> **Comments:**
> **username_1**: do you have any play on the head?  
> **username_2**: Can you check the g-code to be sure the head speed remains the same for movement in both directions?  
> **username_0**: @username_1 I tried to wiggle it, but it stays put. My current assumption is a damaged or partly clogged nozzle.  
> **username_0**: @username_2 I don't think that can be the case. I did this calibration step successfully when assembling the printer for the first time and didn't change the gcode in the meantime. It was supplied with the printer. I'll have a look though.  
> **username_3**: Check the nozzle. I scrached my nozzle over the metal heat bed by accident...it becomes nasty... and produced inconsistent line widths. Since the metal of most nozzles is brass it is easy to machine...and easy to deform. And since you will need several nozzles over time get some new ones and try with them.  

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## 2 answers

### Answer by username_3 on 2018-08-04. Score: 3 | Accepted answer

Due to the advice from @0scar i formulate my answer in the comments as a proper answer ;)

Check the nozzle, if it is in shape and good condition.
I scratched my nozzle over the metal heat bed by accident...it becomes nasty... and produced inconsistent line widths. Since the metal of most nozzles is brass it is easy to machine...and easy to deform. And since you will need several nozzles over time get some new ones and try with them.

Also not every new nozzle will be perfect, so defect products happen, especially if they are cheap and have really tight measurements.


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### Answer by username_0 on 2018-07-04. Score: 3

As pointed at by @username_3, the Nozzle was the problem. Its outflowing hole was not perfectly round anymore, leading to a higher extrusion rate in one direction than others.

I exchanged it, and now everything works great again!


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