<p>As pointed out by <a href="https://www.matterhackers.com/articles/retraction-just-say-no-to-oozing" rel="noreferrer">this article</a>, you can try to:</p>

<ol>
<li>Increase your speed for travel moves</li>
<li>Increase retraction length</li>
<li>Place objects strategically during print</li>
</ol>

<p><strong>1. Calibrating travel speed</strong></p>

<p>When calibrating travel speed, you can work with:</p>

<ul>
<li>Maximum travel speed</li>
<li>Acceleration</li>
<li>Jerk</li>
<li>Z-hop/lift *</li>
</ul>

<p>I found this <a href="http://prusaprinters.org/calculator/" rel="noreferrer">acceleration calculator</a> (by RepRap Central) and <a href="https://www.youtube.com/watch?v=7HsIZuj9vOs" rel="noreferrer">video</a> (by Thomas Sanladerer) very useful.</p>

<p>*' <em>when moving at high speed, your stepper motors are more susceptible to getting de-tracked by nozzle collision from imperfections during print. If this becomes an issue, consider increasing your z-lift setting.</em></p>

<p><strong>2. Adjusting retraction</strong></p>

<p>You can be fairly certain that your filament will clog if it actually retracts past those 2mm recommended by E3D at the hot end. However - as pointed out about by Ryan - bowden retraction is based on <a href="https://en.wikipedia.org/wiki/Hysteresis" rel="noreferrer">hysteresis</a>, meaning that that the actual retraction distance at the hot end is <em>lagging behind</em> the distance retracted at the cold end.</p>

<p>I have been battling this exact issue on my 30cm bowden tube E3D V6 setup recently, and currently use a fairly conservative ~2mm retraction. I am still getting occasional clogs while printing PETG.</p>

<p><strong>3. Distance between objects</strong></p>

<p>From the <a href="https://www.matterhackers.com/articles/retraction-just-say-no-to-oozing" rel="noreferrer">article</a> linked at the top: </p>

<blockquote>
  <p>The faster you’re able to move to the next print position, the less time there is for filament to ooze from the hot end</p>
</blockquote>

<p>As such, the distance between the printed objects will change the characteristics of the stringing:</p>

<p><a href="https://i.sstatic.net/xsmW1.jpg" rel="noreferrer"><img src="https://i.sstatic.net/xsmW1.jpg" alt="Effect of object distance"></a></p>

<hr>

CC BY-SA 3.0
2016-03-30T06:10:05.103Z
2016-03-30T06:10:05.103Z
Tormod Haugene
<p>To my experience, there is absolutely no problem in increasing retraction in E3D assemblies up to at least 5&nbsp;mm. Typical retraction distance for my Bowden system is 3.5&nbsp;mm (ABS). Clogging may occur after a series of retracts when thermal break doesn't have enough time to cool itself down.
To avoid clogging when there is a real need in long retracts (printing with filaments like PLA or PETG) you need to:</p>

<ul>
<li>keep amount of retracts at possible minimum</li>
<li>make sure that thermal break is properly cooled. You may want to use thermal grease and extra cooling for that</li>
</ul>

CC BY-SA 4.0
2018-03-06T22:08:49.933Z
2019-05-01T09:09:23.347Z
2019-05-01T09:09:23.347Z
Mikhail Z
<p>In addition to the already excellent answers above, I want to mention that maybe a change in hotend temperature (lower) can also help reducing ooze/stringing. That is, if not other parameters prevent that.</p>

CC BY-SA 3.0
2016-03-30T14:36:42.193Z
That is very true!
Tormod Haugene
CC BY-SA 3.0
2016-03-30T13:28:47.177Z
2016-03-30T13:28:47.177Z
kamuro
<p>Yes, you can increase retraction past E3D's max 2&nbsp;mm recommendation to compensate for Bowden tube stretch and slop. The reason for the recommendation is that jams will occur with most all-metal hot ends if you pull molten filament up into the cold zone. Any molten filament that enters the cold zone rapidly cools and hardens and sticks to the walls, very often forming a jam. </p>

<p>So, the requirement is to keep your retraction distance <em>at the extruder</em> less than 2&nbsp;mm. Additional retraction travel that is absorbed by the Bowden tube and not seen at the extruder is fine. I personally run 2.5&nbsp;mm retraction on an E3Dv6 Bowden system without any issues. </p>

CC BY-SA 3.0
2016-03-30T05:48:42.437Z
For direct extrusion systems they recommend 0.5-1mm retraction, so the "at the extruder" value should be about that, I guess.
Tom van der Zanden
CC BY-SA 3.0
2016-03-31T17:44:05.307Z
I think there may be a 3mm vs 1.75mm filament difference here. Larger diameter filament will require less filament travel to produce enough volume displacement to clear the nozzle orifice.  I've never had success with direct drive retraction of less than 1mm. I usually use 1.3-1.5mm DD retraction or around 2.5mm Bowden retraction.
Ryan Carlyle
CC BY-SA 4.0
2016-03-30T00:15:10.073Z
2019-05-01T09:07:18.267Z
2019-05-01T09:07:18.267Z
Ryan Carlyle
<p>E3D mentions on their <a href="http://wiki.e3d-online.com/wiki/E3D-v6_Assembly#Usage_Guidance" rel="nofollow noreferrer">own wiki</a>:</p>

<blockquote>
  <p>Excessively long retractions will cause issues by dragging soft filament into cold areas. [...] for bowden systems you might want to go up to 2&nbsp;mm. Retraction beyond 2&nbsp;mm is likely to cause issues.</p>
</blockquote>

<p>I have retraction set to the recommended maximum of 2&nbsp;mm, but I still get a lot of stringing and blobs. My printer is set up with a relatively long Bowden tube (500-600&nbsp;mm). I wonder if I need to push my retraction setting slightly beyond 2&nbsp;mm to take up some of the slack. Is the 2&nbsp;mm a conservative rating (I guess they don't want dissatisfied customers with clogging problems) or is it really the maximum? Is there anything else I can do to improve retraction performance? (I already have a small coasting distance of 0.1&nbsp;mm set.)</p>

<bowden><e3d-v6>
Can I increase retraction length on an E3D v6 beyond 2 mm if I have a really long Bowden tube?
Tom van der Zanden
# Can I increase retraction length on an E3D v6 beyond 2 mm if I have a really long Bowden tube?

(Asked by: username_0 on 2016-03-29)

E3D mentions on their [own wiki](http://wiki.e3d-online.com/wiki/E3D-v6_Assembly#Usage_Guidance):

> Excessively long retractions will cause issues by dragging soft filament into cold areas. [...] for bowden systems you might want to go up to 2 mm. Retraction beyond 2 mm is likely to cause issues.

I have retraction set to the recommended maximum of 2 mm, but I still get a lot of stringing and blobs. My printer is set up with a relatively long Bowden tube (500-600 mm). I wonder if I need to push my retraction setting slightly beyond 2 mm to take up some of the slack. Is the 2 mm a conservative rating (I guess they don't want dissatisfied customers with clogging problems) or is it really the maximum? Is there anything else I can do to improve retraction performance? (I already have a small coasting distance of 0.1 mm set.)

**Tags:** bowden, e3d-v6

---

## 4 answers

### Answer by username_4 on 2016-03-30. Score: 9 | Accepted answer

Yes, you can increase retraction past E3D's max 2 mm recommendation to compensate for Bowden tube stretch and slop. The reason for the recommendation is that jams will occur with most all-metal hot ends if you pull molten filament up into the cold zone. Any molten filament that enters the cold zone rapidly cools and hardens and sticks to the walls, very often forming a jam.

So, the requirement is to keep your retraction distance *at the extruder* less than 2 mm. Additional retraction travel that is absorbed by the Bowden tube and not seen at the extruder is fine. I personally run 2.5 mm retraction on an E3Dv6 Bowden system without any issues.

> **Comments:**
> **username_0**: For direct extrusion systems they recommend 0.5-1mm retraction, so the "at the extruder" value should be about that, I guess.  
> **username_4**: I think there may be a 3mm vs 1.75mm filament difference here. Larger diameter filament will require less filament travel to produce enough volume displacement to clear the nozzle orifice.  I've never had success with direct drive retraction of less than 1mm. I usually use 1.3-1.5mm DD retraction or around 2.5mm Bowden retraction.  

---

### Answer by username_1 on 2016-03-30. Score: 7

As pointed out by [this article](https://www.matterhackers.com/articles/retraction-just-say-no-to-oozing), you can try to:

1. Increase your speed for travel moves
2. Increase retraction length
3. Place objects strategically during print

**1. Calibrating travel speed**

When calibrating travel speed, you can work with:

* Maximum travel speed
* Acceleration
* Jerk
* Z-hop/lift \*

I found this [acceleration calculator](http://prusaprinters.org/calculator/) (by RepRap Central) and [video](https://www.youtube.com/watch?v=7HsIZuj9vOs) (by Thomas Sanladerer) very useful.

\*' *when moving at high speed, your stepper motors are more susceptible to getting de-tracked by nozzle collision from imperfections during print. If this becomes an issue, consider increasing your z-lift setting.*

**2. Adjusting retraction**

You can be fairly certain that your filament will clog if it actually retracts past those 2mm recommended by E3D at the hot end. However - as pointed out about by Ryan - bowden retraction is based on [hysteresis](https://en.wikipedia.org/wiki/Hysteresis), meaning that that the actual retraction distance at the hot end is *lagging behind* the distance retracted at the cold end.

I have been battling this exact issue on my 30cm bowden tube E3D V6 setup recently, and currently use a fairly conservative ~2mm retraction. I am still getting occasional clogs while printing PETG.

**3. Distance between objects**

From the [article](https://www.matterhackers.com/articles/retraction-just-say-no-to-oozing) linked at the top:

> The faster you’re able to move to the next print position, the less time there is for filament to ooze from the hot end

As such, the distance between the printed objects will change the characteristics of the stringing:

[![Effect of object distance](https://i.sstatic.net/xsmW1.jpg)](https://i.sstatic.net/xsmW1.jpg)

---


---

### Answer by username_2 on 2018-03-06. Score: 4

To my experience, there is absolutely no problem in increasing retraction in E3D assemblies up to at least 5 mm. Typical retraction distance for my Bowden system is 3.5 mm (ABS). Clogging may occur after a series of retracts when thermal break doesn't have enough time to cool itself down.
To avoid clogging when there is a real need in long retracts (printing with filaments like PLA or PETG) you need to:

* keep amount of retracts at possible minimum
* make sure that thermal break is properly cooled. You may want to use thermal grease and extra cooling for that


---

### Answer by username_3 on 2016-03-30. Score: 4

In addition to the already excellent answers above, I want to mention that maybe a change in hotend temperature (lower) can also help reducing ooze/stringing. That is, if not other parameters prevent that.

> **Comments:**
> **username_1**: That is very true!  

---

