@Konrad_Mueller You can play with higher extrusion speeds, PETG does not necessarily have to be printed slow - only retraction should be slow
@Daniel_Seiler thats true but printing it faster does build up more pressure in the nozzle which does leak more when the head slows down or retraction happens. quite big effect with pet, no so much with petg and even less with abs.
@VolksTrieb I’m away from my computer right now, so I’ll grace you with one of my terrible hand drawings.
So with the hotend, there’s a clear spot above the hot zone that is below melting point (temps used are common for PLA). This area is not air tight, as if it were, it’d take more torque to move the filament through here. For this reason, air seeps through, causing little to no negative pressure on the melted plastic. The inner diameter of this track is usually around 1.8mm for the sake of filament tolerances (so your cheaper no-name Chinese filaments work almost just as well as your Polymaker filament). You just can’t get enough suction, not would you want to, to suck molten plastic up. If it did, it would cause jams because the sucked up filament would have air bubbles and would be severely deformed.
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Yeah! The stringing vanished completely. Like I said, I increased the retraction distance to 2mm and extra lenth on restard to -0.1mm. I also decreased the temperature to 218°C.
I am really surprised that a lower retraction speed helps also.
Thanks everyone!
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Speeds:
Perimeters/Infill: 15mm/s
Travel: 25mm/s
Retraction: 10mm/s
Extrudion width:
Perimeters: 250%
External perimeters: 200%
Infill: 200%
Solid Infill: 150%
Extrusion multipler: 0.93 @ 1.76mm filament
Temperature: 218°C
Nozzle: 0.4mm
Retraction length: 2mm
Extra length on restart: -0.1mm
Minimum travel after retraction: 1mm
Wipe while retracting: on
Interesting results. I have a couple filament spools that are leaving those little branches as well lately. My retraction is typically at 2.0 - 2.5 mm and 25 - 30 mm/sec on a direct drive. I’ll have to try the lower speed and see what that does for me.
@Jeff_Parish Konrads settings are fairly simmilar to mine but using only 0.5-1mm retraction.
@VolksTrieb That is why I find this interesting. For oozing the procedure I have been using is to first lower the temp as much as possible and still have it extrude smoothly, then increase the retraction speed, and lastly the distance. Never more than 2.5 and 30. A large majority of the time my prints come out perfectly clean. Now with the branches forming when using some recent new filament the trick seems to be to lower the speed and possibly the distance but still with a lower temp. Pretty much opposite of what I’ve done before.
@Konrad_Muller Congratulations to your settings! Start with that. Then,after printing PETG for some time, you might want to play with higher temperatures and see whether that has effects on a) inter-layer adhesion and b) finish of the extruded filament. I vaguely recall that I had non-optimal inter-layer adhesion at too low temperatures with PETG - might not even matter for what you are doing.
it’s gravity so if you are not printing upside down you can add a high z-lift and the z-seam allignment need to be random so the head is lowererd within the print and could not strip off at the edge (which will build up to the diagonal remains). Further Nozzle diameter and temp /cooling has an influence too, also different PETG show different behaviour.
@_Spice you could pull a closed syringe - a vaccum is formed, but doesn’t mean you cant pull it apart. But what happened here is not suction it is cohesion so if you retract, the molten plastic shear that will also pull a bit.
You’re welcome 
Increase retract to 5mm and lower its retract speed to 60mm/s (3600mm/min) and see what that does.