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Stringing is a printer-specific issue?  

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theologos.m
(@theologos-m)
Eminent Member
Stringing is a printer-specific issue?

Using the latest Slic3r 1.36... with its default settings (Retraction: 4) on my Mk2S MMU produces a lot of stringing.

Raising the Retraction at 7 cures the problem.

It is a problem with my printer only or, perhaps, we should change the default settings in Slic3r?

I use(d) the following filaments: ColorFabb PLA / GlowFill / nGen, Extrudr PETG and two 0.4 nozzles: the stock one (brass) and Olsson Ruby.

Posted : 15/08/2017 12:11 pm
PJR
 PJR
(@pjr)
Moderator
Re: Stringing is a printer-specific issue?

A retraction of 7mm is rather looking for trouble.

You may find reducing temps more effective than increasing retraction.

I am currently printing with 2.5mm retraction setting + Preload (aka "Pressure/Linear Advance"), and I retract a further 2mm when moving to/from the waste tower.

Peter

Please note: I do not have any affiliation with Prusa Research. Any advices given are offered in good faith. It is your responsibility to ensure that by following my advice you do not suffer or cause injury, damage…

Posted : 15/08/2017 2:34 pm
theologos.m
(@theologos-m)
Eminent Member
Topic starter answered:
Re: Stringing is a printer-specific issue?


A retraction of 7mm is rather looking for trouble.

You may find reducing temps more effective than increasing retraction.

I am currently printing with 2.5mm retraction setting + Preload (aka "Pressure/Linear Advance"), and I retract a further 2mm when moving to/from the waste tower.

Peter

And how can I use Preload? Is the same with "Use firmware retraction" from Slic3r?

I read that there is some sort of calibration for this. How can I do it?

TIA for your support

Posted : 15/08/2017 6:23 pm
theologos.m
(@theologos-m)
Eminent Member
Topic starter answered:
Re: Stringing is a printer-specific issue?

...and another question:

Why 7 mm retraction isn't good? I read that for a bowden setup (like my Mk2S MM) the values can be till 15mm.

Posted : 15/08/2017 7:25 pm
theologos.m
(@theologos-m)
Eminent Member
Topic starter answered:
Re: Stringing is a printer-specific issue?



A retraction of 7mm is rather looking for trouble.

You may find reducing temps more effective than increasing retraction.

I am currently printing with 2.5mm retraction setting + Preload (aka "Pressure/Linear Advance"), and I retract a further 2mm when moving to/from the waste tower.

Peter

And how can I use Preload? Is the same with "Use firmware retraction" from Slic3r?

I read that there is some sort of calibration for this. How can I do it?

TIA for your support

According to http://marlinfw.org/docs/features/lin_advance.html it seems that it is "Extra length on restart" but still no clue on what value(s) should I put there. Also, it seems that there are problems with Bowden setups...

Posted : 15/08/2017 7:33 pm
PJR
 PJR
(@pjr)
Moderator
Re: Stringing is a printer-specific issue?


And how can I use Preload? Is the same with "Use firmware retraction" from Slic3r?

I read that there is some sort of calibration for this. How can I do it?

TIA for your support

KISS 😉

Peter

Please note: I do not have any affiliation with Prusa Research. Any advices given are offered in good faith. It is your responsibility to ensure that by following my advice you do not suffer or cause injury, damage…

Posted : 15/08/2017 10:44 pm
PJR
 PJR
(@pjr)
Moderator
Re: Stringing is a printer-specific issue?


...and another question:

Why 7 mm retraction isn't good? I read that for a bowden setup (like my Mk2S MM) the values can be till 15mm.

Because you are taking hot filament into the cold end. This will cause blockages.

From the E3D wiki: https://wiki.e3d-online.com/wiki/E3D-v6_Assembly

Excessively long retractions will cause issues by dragging soft filament into cold areas. E3D-v6 hotends need less retraction than most hotends. For direct extrusion systems you should use anywhere from 0.5mm-1.0mm, for bowden systems you might want to go up to 2mm. Retraction beyond 2mm is likely to cause issues.

Note that the MMU heat break is slightly modified and slightly larger retractions (up to 4 or maybe 5mm) can be used without issue.

Peter

Please note: I do not have any affiliation with Prusa Research. Any advices given are offered in good faith. It is your responsibility to ensure that by following my advice you do not suffer or cause injury, damage…

Posted : 15/08/2017 10:49 pm
theologos.m
(@theologos-m)
Eminent Member
Topic starter answered:
Re: Stringing is a printer-specific issue?



And how can I use Preload? Is the same with "Use firmware retraction" from Slic3r?

I read that there is some sort of calibration for this. How can I do it?

TIA for your support

KISS 😉

Peter

No kisses. Only slic3rs. 🙂

Can you help??

(Thnx btw)

Posted : 16/08/2017 10:38 am
PJR
 PJR
(@pjr)
Moderator
Re: Stringing is a printer-specific issue?


No kisses. Only slic3rs. 🙂

😥

https://github.com/Sebastianv650/Prusa-Firmware/tree/MK2-LIN_ADV-PR

And lower temp...

Peter

Please note: I do not have any affiliation with Prusa Research. Any advices given are offered in good faith. It is your responsibility to ensure that by following my advice you do not suffer or cause injury, damage…

Posted : 16/08/2017 10:59 am
mavu
 mavu
(@mavu)
Estimable Member
Re: Stringing is a printer-specific issue?



No kisses. Only slic3rs. 🙂

😥

https://github.com/Sebastianv650/Prusa-Firmware/tree/MK2-LIN_ADV-PR

And lower temp...

Peter

I can understand that you are proud of your efforts to write your own post processor for MMU and kiss slicer.
I salute your efforts, and I really think its a great idea to create something that does things better, but its really not helping people, if you give them answers they cannot possibly follow.

As far as I know you have not yet released your post processor for public use, so currently everyone is "stuck" with using Slic3r Prusa edition. Which I think is currently the best option, baring selfmade solutions.

Using a basically undocumented fork of the MK2 firmware is also not something you should suggest to anyone you don't know, because you cannot be certain they understand exactly what they are about to do.

On to the stringing problem, I have reduced my retraction to 3mm and this seemed to provide slightly less stringing.
On my current PLA I also get better prints when I reduce the flow to 0.96. but in general, yes, MMU prints are much more stringy for me too.

Posted : 16/08/2017 11:40 am
PJR
 PJR
(@pjr)
Moderator
Re: Stringing is a printer-specific issue?


I can understand that you are proud of your efforts to write your own post processor for MMU and kiss slicer.
I salute your efforts, and I really think its a great idea to create something that does things better, but its really not helping people, if you give them answers they cannot possibly follow.

As far as I know you have not yet released your post processor for public use, so currently everyone is "stuck" with using Slic3r Prusa edition. Which I think is currently the best option, baring selfmade solutions.

Using a basically undocumented fork of the MK2 firmware is also not something you should suggest to anyone you don't know, because you cannot be certain they understand exactly what they are about to do.

On to the stringing problem, I have reduced my retraction to 3mm and this seemed to provide slightly less stringing.
On my current PLA I also get better prints when I reduce the flow to 0.96. but in general, yes, MMU prints are much more stringy for me too.

OK, in the second post of this topic, I answered the question regarding stringing (lower temps) and again in a later post.

Follow-on questions were then asked which I answered.

Regarding my post processor, see this post: http://shop.prusa3d.com/forum/original-prusa-i3-mk2-multimaterial-f26/variable-layer-height-mm-printing-t5361.html#p38698

I would not say I am proud of it, just trying to help. Josef and staff have copies and are welcome to the source.

It is available to anyone wanting to try it - but I will not publish the links on these forums.

As for the undocumented fork, that link was given to me by a PR staff member; I have posted the same link on these forums before.

And FWIW, I don't get stringing, except for the occasional wispy strings I also had on certain models with the single-filament printer. so the solution must lie in one or more of the things I mentioned.

Peter

Please note: I do not have any affiliation with Prusa Research. Any advices given are offered in good faith. It is your responsibility to ensure that by following my advice you do not suffer or cause injury, damage…

Posted : 16/08/2017 12:19 pm
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