Cura Stringing/Retraction issues

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KennyAdams
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Cura Stringing/Retraction issues

Post by KennyAdams » Thu Jun 15, 2017 3:05 am

When I change the retraction distance to up to 10mm in my cura settings for my prusa i3 mk2 clone, I am still getting lots of stringing. I also made my minimum retraction distance .01mm just to make sure thats not it. Thanks!

ronka
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Re: Cura Stringing/Retraction issues

Post by ronka » Thu Jun 15, 2017 5:22 am

Sounds like temperature too high..

oakdesign
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Re: Cura Stringing/Retraction issues

Post by oakdesign » Thu Jun 15, 2017 12:16 pm

I'll hook in here as I'm facing a similar issue and still trying to learn about retraction.
I have a Anet A8 and have been printing with the stock direct drive for 3 weeks now. I didn't touch the retraction settings in Cura 2.5
So 6,5mm retraction and 20mm/s speed. All my prints in PLA and PETG came out quite fine, at least comparing with pictures of similar prints from others.
I just changed to a E3D all Metal Bowden setup mainly because I want to print Nylon and need a complete enclosed filament travel from spool to nozzle.

So my first Bowden prints are still ok, but quality dropped a bit. I'm getting some blobs, sometimes in the middle of a long outer wall but mainly on the edges.
From my readings and knowledge I would have to adjust retraction while changing to Bowden. On the other hand the suggestions found so far I found differ quite. There are suggestions referring to max retraction of 2mm others suggest to set higher values up to 10mm to avoid stringing and blobing.
As being a learning by doing guy I will just start a series of prints starting with no retraction and then going my way up.

Just would be interested what you guys have set your retraction to.

Regards Richard
Opa's bester Rat: Probieren geht über Studieren, Grandpas best advice: the proof of the pudding is in the eating

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ThomasMüller
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Re: Cura Stringing/Retraction issues

Post by ThomasMüller » Thu Jun 15, 2017 6:44 pm

I use 2.5 mm but 50mm/s retraction speed.
Delta with bowden extruder and original E3D hot end.

oakdesign
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Re: Cura Stringing/Retraction issues

Post by oakdesign » Thu Jun 15, 2017 9:40 pm

As I'm a complete noob with just 4 weeks of practical experience to 3d printing I might explain my understanding of how retraction works and how I think it is affected by a Bowden setup. And maybe someone experienced can proof or disapprove my thinking
While extruding pressure is put on the filament towards the nozzle. While retraction should take away this pressure

This my main question;
As in a Bowden the distance from the extruder stepper to the hotend is much longer as in a direct drive wouldn,t there be some kind of additional flex to the filament in a Bowden setup and therefore more retraction distance is needed?

On the other hand if I set the retraction to high the filament might be completely pulled out of the hot zone.
Opa's bester Rat: Probieren geht über Studieren, Grandpas best advice: the proof of the pudding is in the eating

ronka
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Re: Cura Stringing/Retraction issues

Post by ronka » Fri Jun 16, 2017 7:13 am

thats just it, if you retract it will retrieve only the not molten filament, the already molten filament can stil ooze out..
lower temperature so the plastic 'sticks' longer in the nozzle.. (not too low or you get slippage of the hobbed bolt)

LKM
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Re: Cura Stringing/Retraction issues

Post by LKM » Fri Jun 16, 2017 7:38 am

So my first Bowden prints are still ok, but quality dropped a bit. I'm getting some blobs, sometimes in the middle of a long outer wall but mainly on the edges.
If the problem is getting worse over time, it might not be a retraction or temperature issue. Maybe your hotend is leaking. Make sure that your hotend is properly assembled, and that filament is only coming out of the tip of your nozzle.

oakdesign
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Re: Cura Stringing/Retraction issues

Post by oakdesign » Fri Jun 16, 2017 9:52 am

@LKM thanks for your suggestions, but it's not a leaking issue. The hotend is assembled correctly. My main passion is repairing engines so assembling metal parts I think I know what I'm doing.
I started a series of strigning test prints yesterday evening, first with retraction turned of completly, and then retraction speed set fixed to 50mm/s and retraction set to 2mm, 3mm, 4mm even so the stringing was noticable reduced still there, so in my last test I went up to 10mm retraction and no differnce to the test with 4mm. Will go on with further tests in changing retraction speed and print temperature. I'm trying to limit th changes in parameters to max 2 at a time in order to get a better understanding which settings are causing different print outcomes.
Will post pictures tonight once I have at least a 10 print series.

Btw this leads me to the idea of setting myself up a print database but might start a own thread on this.

Regards Richard
Opa's bester Rat: Probieren geht über Studieren, Grandpas best advice: the proof of the pudding is in the eating

ronka
Posts: 41
Joined: Thu Jun 15, 2017 4:00 am
Location: Holland

Re: Cura Stringing/Retraction issues

Post by ronka » Sat Jun 17, 2017 3:49 am

google --3d stringing issue---, 1st suggestion:
https://ultimaker.com/en/resources/1950 ... -stringing
enjoy

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