Still massive stringing problems with my A20m

[BR365]

Hello all,
I have still massive problems with stringing:

59553749_2192196167555015_6136238016521306112_o.jpg (238.15 KiB) Viewed 23831 times

58698479_2192196147555017_945432931617210368_o.jpg (189 KiB) Viewed 23831 times

I reduced / increased retraction, no success. I modified temperature, E-Steps/mm, Filament, ...

Now, the next I will try is to increase the print speed and to use Cura to enable Coasting, which isn't supported by Slic3r.

Any ideas?
Or, can somebody provide an gcode of the Benchy or any other sample which works well on his A20m?

Thanks,
Moritz

[BR365]

Hello Vert,
very interesting, you mean these small balls?

It looks like a kind of back pressure valve to prevent, that the filament is pressed from one filament feed to the other one. But, then it is very clear, why retracting doesn't work so effectively like with single hot ends.

That means, that there is a technical reason, why a color mixing hot end will create more stringing then a single hot end.

Where is the picture from? Is there a discussion about this issue anywhere?

Thanks,
Moritz

[BR365]

I increased the print speed, activated wipe and reduced the E-Steps/mm. Now, it is a bit better but still not comparable to what I get with my i3 Pro C.

IMG_20190502_224817_01.jpg (232.49 KiB) Viewed 23790 times

IMG_20190502_224844_01.jpg (295.86 KiB) Viewed 23790 times

I will now test Cura which supports Coasting, it may be a good alternative to retractiong, which doesn't work so good with the color mixing hot end.

Moritz

[dtouton]

Hi,

I have removed the two balls and still have big stringing problems.

I have tried all distance and speed of retraction.

Have someone found the good settings ?

Thanks

[DzzD]

That is what I call massive stringing !

Here is a picture of a benchy printed with A20m stock with valve probably, dont know(only stepper drivers of X,Y,Z have been replaced by TMC2208 but I am sure that can not modify stringing), I try to join the gcode but I can only attach picture to the post..., I will try by PM.

Settings I remember : (but that shouldn't help a lot, you probably have a mechanical issue)
- layer height : 0.2
- print width : 0.4
- perimeters : 3
- main speed 50mm/s
- outline speed 37.5mm/s
- retractation 5mm at 30mm/s

Some ideas :
- wet filament ? https://www.youtube.com/watch?v=FAXUjZZER5E
- too fast retraction or extruder untight , that could make the filament slip when retracting
- temperature too hot
- cooling fan breaked

NB: stringing is not the only problem you have, some of your surfaces show a lot of rugosity

[3DAngel]

may I know what slicer are you using?
and what travel speed you have set.
what was your Max acceleration set in the FW.....

I have the back flow disc removed, but still fighting the stringing.
are you using linear advance, traditional Jerk....

too many variant to play with..

I have set 200mm/s travel speed
8.5mm retraction
30mm/s retraction speed
1.75mm coasting
linear advance disabled.
using S3D V3.11 or Slic3r Prusa results are similar
PLA temp @185C bed 60C

appreciate any feedback

thanks

[dtouton]

Hi,

I removed the balls, tried all i can do on Cura. Single color prints are really nice, better than my ED3 Pro, but Dual Color look like tihs

IMG_2484.jpg (274.21 KiB) Viewed 22870 times

[William]

Hi,You can refer to:
Retraction speed: 40-50mm/s;
retraction distance: 3-4

[dtouton]

This print :

distance : 4
Speed : 40

I think i will try to re-install the balls

[DzzD]

may I know what slicer are you using?
and what travel speed you have set.
what was your Max acceleration set in the FW.....

I have the back flow disc removed, but still fighting the stringing.
are you using linear advance, traditional Jerk....

too many variant to play with..

I have set 200mm/s travel speed
8.5mm retraction
30mm/s retraction speed
1.75mm coasting
linear advance disabled.
using S3D V3.11 or Slic3r Prusa results are similar
PLA temp @185C bed 60C

appreciate any feedback

thanks

I use simplify 3D with the default A20M profile for PLA
Linear advance 0.2 but with 0 it is also ok
Travel speed 80mm/s
No coasting
PLA temp 200 or 210
Bed 45
Main speed 50mm/s
Outline 37.5mm/s
3 perimeters

But once again I am pretty sure that is not a settings problem, I never have to fight the stringing on the A20m even with default A20m profile with simplify 3D.

I've updated to Marlin 2.0 but it was printing nice before.