<h3>What is it?</h3>
<p>This reversal of the gear direction is perfectly normal, and is called <strong>retraction</strong>. It is basically a <em>recoil movement</em> of the filament.</p>
<p>Retraction (generally) occurs when the extruder effects movement and displacement from one part of a print to another. It is to prevent the molten filament from dripping unnecessarily all over the print and the print bed - otherwise known as <em>stringing</em>.</p>
<p>In short, it is perfectly normal behaviour and nothing to worry about.</p>
<hr />
<h3>Additional information</h3>
<h4>Retraction towers</h4>
<p>Note that you can check that your retraction is fine by printing <em>retraction towers</em>, such as this:</p>
<p><a href="https://i.sstatic.net/e6qAz.jpg" rel="nofollow noreferrer" title="Retraction towers"><img src="https://i.sstatic.net/e6qAz.jpg" alt="Retraction towers" title="Retraction towers" /></a></p>
<p><sub>Image source: <a href="https://www.reddit.com/r/FixMyPrint/comments/rcptu0/persistent_stringing_with_retraction_tower/" rel="nofollow noreferrer">Persistent Stringing with Retraction Tower</a></sub></p>
<h4>Parameters</h4>
<p>There are a number of parameters that can affect retraction, and these include:</p>
<ul>
<li>Retraction distance</li>
<li>Retraction speed</li>
<li>Minimum displacement</li>
<li>Enable combining</li>
<li>Z-axis elevation when retracted (Lift z)</li>
</ul>
<p>You can adjust some, or all, of these parameters should your retraction not be &quot;up to scratch&quot;.</p>
<p>However, this is going beyond the scope of your question, so I won't cover them here. Moreover, as haven't mentioned that your prints are failing, then it is probably best if you don't change these settings - unless you have to.</p>
<h4>Further reading</h4>
<p>There are many online resources about retraction. Some suggested reading:</p>
<ul>
<li><a href="https://reprap.org/wiki/Retraction_Tuning_With_Slic3r" rel="nofollow noreferrer">Retraction Tuning With Slic3r</a></li>
<li><a href="https://blog.prusa3d.com/slic3r-and-marlin-configuration-for-reprap-firmware-retraction-2_3686/" rel="nofollow noreferrer">Slic3r and Marlin configuration for RepRap FW retraction</a></li>
<li><a href="https://filament2print.com/gb/blog/34_retraction-in-3d-printing.html" rel="nofollow noreferrer">What is retraction in 3D printing? Definition and adjustments</a></li>
</ul>

CC BY-SA 4.0
2024-03-15T22:40:52.763Z
2024-03-16T17:14:45.040Z
2024-03-16T17:14:45.040Z
Greenonline
<p>The extruder gears on my Ender 3D printer v.4.1 occasionally reverse direction when feeding the PLA filament, as if testing it by trying to pull it out, then resume the correct direction and continue proper feeding. So far there is no effect on the quality of the prints.</p>
<p>What is the purpose of this occasional momentary reverse action, and is it to be expected?</p>

<extruder>
Extruder occasionally reverses direction
Eddie
# Extruder occasionally reverses direction

(Asked by: username_0 on 2024-03-15)

The extruder gears on my Ender 3D printer v.4.1 occasionally reverse direction when feeding the PLA filament, as if testing it by trying to pull it out, then resume the correct direction and continue proper feeding. So far there is no effect on the quality of the prints.

What is the purpose of this occasional momentary reverse action, and is it to be expected?

**Tags:** extruder


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## 1 answers

### Answer by username_1 on 2024-03-15. Score: 3

### What is it?

This reversal of the gear direction is perfectly normal, and is called **retraction**. It is basically a *recoil movement* of the filament.

Retraction (generally) occurs when the extruder effects movement and displacement from one part of a print to another. It is to prevent the molten filament from dripping unnecessarily all over the print and the print bed - otherwise known as *stringing*.

In short, it is perfectly normal behaviour and nothing to worry about.

---

### Additional information

#### Retraction towers

Note that you can check that your retraction is fine by printing *retraction towers*, such as this:

[![Retraction towers](https://i.sstatic.net/e6qAz.jpg "Retraction towers")](https://i.sstatic.net/e6qAz.jpg "Retraction towers")

Image source: [Persistent Stringing with Retraction Tower](https://www.reddit.com/r/FixMyPrint/comments/rcptu0/persistent_stringing_with_retraction_tower/)

#### Parameters

There are a number of parameters that can affect retraction, and these include:

* Retraction distance
* Retraction speed
* Minimum displacement
* Enable combining
* Z-axis elevation when retracted (Lift z)

You can adjust some, or all, of these parameters should your retraction not be "up to scratch".

However, this is going beyond the scope of your question, so I won't cover them here. Moreover, as haven't mentioned that your prints are failing, then it is probably best if you don't change these settings - unless you have to.

#### Further reading

There are many online resources about retraction. Some suggested reading:

* [Retraction Tuning With Slic3r](https://reprap.org/wiki/Retraction_Tuning_With_Slic3r)
* [Slic3r and Marlin configuration for RepRap FW retraction](https://blog.prusa3d.com/slic3r-and-marlin-configuration-for-reprap-firmware-retraction-2_3686/)
* [What is retraction in 3D printing? Definition and adjustments](https://filament2print.com/gb/blog/34_retraction-in-3d-printing.html)


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