Any hints on how to improve here:
This is “ecoPLA” for which I have empirically settled at 215°C, already at lower speed, filament had been dried for a few hours, first layer is “so so, ok” and machine has been Z calibrated. I’m running out of ideas. I guess I could fiddle around more with the temperature?
This is only an issue with concave movements, whereas the convex outer path, straight lines etc. pose no problem.
@sciss I would try reducing the wall line width and perhaps also the layer height. Wall ordering should be inside to outside wich i think it is by default. Make sure that the resolution of the .stl is not too low.
If that doesnt work you could also try increasing the flow and nozzle temp while reducing the print speed…
These are some thick strings. You first layer seems to be a bit high, but it’s nothing to do with stringing.
It’s a circle, I don’t see why would it do these jumps across.
Can you check the simulated tool path?
The simulation toolpath is good. Also I did multiple copies, and the lines appear in different locations, so it’s not a GCode problem. I already tried thicker and thinner layers, doesn’t change much. Wall ordering is inside-to-outside as suggested. Flow is already at 100%. Here are the settings, perhaps there is something obvious (is based on default Snapmaker PLA):
What about reducing the line width. Did you try that? Also if the resolution of the .stl is too low, it will be hard to get it to work no matter what settings you adjust…
What slicing software are you using?
Luban 4.8.2 ; machine is still on the firmware from January, though, don’t know if I should risk updating it?
Reduce outer wall line width and increase outer wall flow is probably the solution… 
There is no “outer wall flow” parameter in Luban? There is a “wall flow” parameter in the “unclassified” section without documentation - is that perhaps a no longer used parameter? It stands at 100%
You need to change parameter display to “all” and dont forget to set the outer wall line width to less than nozzle size and use appropriate layer height.
could you share stl (maybe in PM) so I could slice it in luban and prusa to see difference in the toolpath?
Circle really shouldn’t leave the stringing like this, at least I have yet to see such behavior.
It’s really just a cylinder exported from OpenSCAD:
$fn = 180;// Quality
ringDiaOutside = 212.0;
ringThick = 4.0;
ringHeight = 10.0;
module all(){
difference() {
cylinder(h = ringHeight, r = ringDiaOutside/2);
translate([0, 0, -1]) {
cylinder(h = ringHeight + 2, r = ringDiaOutside/2 - ringThick);
}
}
}
all();
gordite_vertebra_ring.stl (70.4 KB)
The outer wall extrusion is not consistently adhering to the inner wall wich causes the extrusion to bridge from latest adhering point to the next adhering point of the circle, so it’s not reallly stringing but rather bridging…
@Rwide - it actually makes sense, I get this issue when pushing too fast. But in my case, it would stick to the layer below, and I only would get a small gap between perimeters, but no bridging like sciss does.
I would run a smaller test print to test your theory if I’d be in sciss’s shoes.
Then again, I only use Luban for console.
I tried to slice…
in luban 4.8.0 I get weird line at first, but then reapplied “Normal Profile” and it went alright.
I would assume Luban/Cura has similar option to Prusa, but Luban’s “Avoid printed parts” was on when I sliced. I gues it did avoid the printed parts, limiting itself to travel withing inner circle =)
Follow up question to @sciss - if you squeeze the printed circle (that failed) - do you hear light crackling? Like layers separation?
Yes, when squeezing the stringy/bridging parts, you get slight crackling sound, like there is “too much air” in those parts. The idea that outer walls don’t stick to the inner walls sounds like a reasonable explanation. I think there are a few parameters to try making the inner walls a bit “overshooting”, or trying inner walls before outer walls. I will have a go soon trying some of these.
Thanks for all the suggestions so far, also the link to ‘Dallas Makerspace Talk’, looks very similar (even the last photo with small circles not printing properly the first layer, I see this too in other models).
This crackling sound could is another sign of bad layer adhesion. This would explain bridging, since the filament is not sticking to layer below and to side perimeter. Like in the Dallas Marketplace Talk.
The part should delaminate in layers if you push it beyond the breaking point.
Collective brain 
I did fresh profiles based on standard PLA and normal print, adjusted temperature and now use 105% overall flow value, inner-walls before outer-walls and more overhang for inner walls, and this improves the stability, and there is definitely less bridging, although it’s not entirely gone.
That skirt doesn’t look so good… You should probably clean the bed surface and lower your z-offset. Regarding the bridging issue, I have already suggested what I think you should do. If you will not follow those instructions there’s nothing more I can do…
