Hi, i am currently fine tuning PETG settings.
I have it almost done, but can’t get rid of those little things building up (marked on photo). Any ideas?
My settings:
230°C
0.2mm layer
1.5mm retraction
100mm/s retraction speed
-0.05mm on restart
0.92 extrusion multiplier
0mm z-lift
Bowden or direct? For my bowden set up it takes 3mm to keep from stringing, which this looks like (filament strings, but instead of bridging between two parts, it just builds up like this.
well on direct extruder 1mm should work, but with slow retraction (try 10-30mm/s retraction speed). Even works with flexible filament and nylon for me
@VolksTrieb remember, retraction doesn’t suck melted plastic back in, it just keeps more plastic from being melted and leaked. The higher the retraction distance and speed, the less likely it’ll string, since it’s vacating the hot zone before it melts any further. It also just depends on if your printer is prone to leaking a lot. If it does, then a higher retraction distance may be needed.
Another thing I’d like to know is if OP has wiping enabled or not. That might fix this problem if not.
My apologies, I just realized you said for direct, not bowden. For direct 1mm is ample distance.
@_Spice i didnt post something about theory iwas telling him my experience with retraction on those softy material. I print even ninjaflex stringless with this settings.
I am using a direct extruder.
Wipe while retracting is also enabled. As a side note, I am working with slic3r. I will set the retraction speed lower to 20mm/s and try a test print. Thanks for the advice so far :).
@VolksTrieb yeah, for some reason I thought bowden and didn’t even read direct, and immediately thought you were implying retraction causes suction. Sorry about that.
@Konrad_Muller what speed are you printing at? If your printing slow, then you may want a faster retraction and possibly a slightly lower temperature (I’ve not worked with PETG yet, so I don’t know the correct temp for it off hand).
@_Spice even though, you might consider thinking over this again. Why should retraction not suck back molten plastic? The molten plastic very well seals itself to the wall of the nozzle and pulling back on the filament just does pull it back, yeah on the very first moment air gets into the nozzle the sucktion more or less stops, letting the plastic run down the nozzle again, but dont tell people that it does not suck in or back plastic because that simply is not true. should make a demonstration about that.
Give @VolksTrieb 's advice a try - slow retraction speed is improving stringing with PETG - I have the same experience. Also, your print already looks awesome, those artefacts are not even real stringing 
I keep the speed low at about 15mm/s to 20mm/s.
The roll says (230 ± 10) °C.
@VolksTrieb I do believe @Thomas_Sanladerer covered that in a video, or maybe it was just a comment here in this community. But here’s a problem with that idea: if that were true, then a jammed hot end wouldn’t allow you to pull out the filament, because there would be no airflow through the nozzle. Also if that were the case you wouldn’t be able to feed your filament in at a certain point without heat. There’s also the fact that you could have air bubbles trapped in the nozzle, which would cause areas to just not extrude without priming again. But also, the parts aren’t machined precisely enough to allow for complete suction. In a system where a PTFE tube is in the hot zone, the tube isn’t pressed up against the end of the (forgot the name) threaded tube that would block air from flowing from the top that would, in turn, reduce suction.
That isn’t to say there isn’t a little bit of suction, it’s just not enough to suck it all out of the nozzle and hot zone.
@VolksTrieb my mistake, it wasn’t Thomas, it was on Matter Hacker’s website:
Myth - Retraction “sucks” filament back up through the hot end. So, the more retraction you use, the less oozing you’ll get.
Fact – Once filament has melted in the “melt zone” of your hot end, it cannot be retracted. Retraction does not create negative pressure. Hot ends are not sealed/airtight. If they were, then the negative pressure would “suck” molten filament back up through the hot end. This would likely lead to lots of jams and other extrusion issues, but this is not the case.
@_Spice cant feed in filament or get out without airflow? So you are telling me, that vacuum has infinite force without destroying your universe? You only need to overcome one atmosphere and the force is only given by that and the area which seals this vacuum. No that idea is highly theoretical. You know that nothing has to be 100% airtight to use sucktion. The smaller the gap the more effective moving air or liquids is. And fluids are very good at sealing stuff like oil in your cars engine or hydraulic cylinders. Also i didnt say it would suck the whole plastic out of the nozzle. Quite the reverse.
So I did another test print.
I reduced the temperature to 220°C and retraction speed to 10mm/s.
It already looks way better. Those strings are way thinner. I will increase retraction from 1.5mm to 2mm and extra length on restart from -0.05 to -0.1
missing/deleted image from Google+
@VolksTrieb but it does not have enough of a suction to pull all the melted plastic back uniformly, as mentioned in the article I posted above.
missing/deleted image from Google+
Oh man matterhackers. Yeah. Its not airtight i know. But even ig it were it would not cause jams. E3d themselfs recommend not to use over 5mm retraction. You know why? Because it would get into the cold zone an clogg up. Aslong as you stay in the HOTEND nothing will clogg even if it were airtight
@Konrad_Muller that negativ extra length on start didnt help me but give it a try. The thing is not even the retraction here, its plastic which just runs or thermally expands out of the the nozzle while your printhead moves. Trx cranking up the move speed there
