Constant Extrusion + Stringing
I've been having issues for a few months now with constant filament extrusion while preheating/calibrating. I suspect it's constant during the printing too, since I've been having stringing problems as well. I included some images to show what I'm talking about. These were taken during heating up and the first part of the "1st Layer Calibration" test, so it's not a g-code issue. The exact same thing has been happening with our Prusa Mini+ as well, and it's only 2 months old.
My best guess so far is that it's a problem with the filament. We were storing our filament in the same room as the 3D printers, and it doesn't have good air circulation. I suspect that it's caused the filament to absorb some moisture. We've moved the filament back to the room it used to be in, which has much better air control. I never had this issue before, so I feel confident about that room's ability to store filament safely.
However, the brown filament shown in the pics is only a few weeks old and has been stored in the safe room the entire time, so it shouldn't be having these problems. I'm at my wit's end here. I've seen recommendations for changing retraction settings and reducing temperature, which I do, but this is also happening during calibrations and other things that don't include any g-code. Anyone have suggestions/experienced this themself?
RE: Constant Extrusion + Stringing
Moisture is a potential cause. Do you hear popping or sounds of hissing when it is extruding?
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Chuck H
3D Printer Review Blog
RE:
In all honesty, this doesn't look excessive to me. Some filament will ooze more than other when hearing up. I use tweezers/needle nosed pliers to pick up any hanging filament when the nozzle is heating up.
RE: Constant Extrusion + Stringing
hearing
* heating
RE: Constant Extrusion + Stringing
If you have filament loaded and you heat up your hot end the filament will melt and even without expanding moisture in the filament gravity will do it's thing, nothing you can do about it... If that annoys you so much leave the nozzle heated a few minutes after unloading so the residual filament can drip out and do your calibration and preheating without filament loaded. Or just grab the filament as fuchsr said and everybody else does and forget about it.
During printing the retraction should prevent the dripping from happening - if you really have stringing problems during print (pictures?) you might need to adjust your retraction settings but I'd recommend to check other issues first (moisture, nozzle temperature by heat tower) before messing with the retraction settings, the default settings are pretty good in the predefined profiles.
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