Can I increase retraction length on an E3Dv6 beyond 2 mm if I have a really long Bowden tube?
Channel: Roel Van de Paar
Date: 2019-06-27

3D Printing: Can I increase retraction length on an E3Dv6 beyond 2 mm if I have a really long Bowden tube?


The Question: E3D mentions on their 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 2mm, 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 2mm 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.)

Solutions: Please watch the whole video to see all solutions, in order of how many people found them helpful

== This solution helped 9 people ==
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.

== This solution helped 7 people ==
As pointed out by 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 prusaprinters.org/calculator/ (by RepRap Central) and video
(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 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 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]
----

== This solution helped 4 people ==
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.

With thanks & praise to God, and with thanks to the many people who have made this project possible! | Content (except music & images) licensed under cc by-sa 3.0 | Music: www.bensound.com/royalty-free-music | Images: stocksnap.io/license & others | With thanks to user Tormod Haugene (askubuntu.com/users/115), user Tom van der Zanden (askubuntu.com/users/26), user Ryan Carlyle (askubuntu.com/users/298), user Mikhail Z (askubuntu.com/users/3839), user kamuro (askubuntu.com/users/168), user 0scar (askubuntu.com/users/5740), and the Stack Exchange Network (3dprinting.stackexchange.com/questions/894). Trademarks are property of their respective owners. Disclaimer: All information is provided "AS IS" without warranty of any kind. You are responsible for your own actions. Please contact me if anything is amiss at Roel D.OT VandePaar A.T gmail.com.