Stringing or oozing, also known as "hairy prints", is the name given for when small strings of filament are left on a printed model. This usually happens when the filament keeps flowing from the nozzle while the extruder is moving to another object. You can see this as a marginal line of filament left between the objects.
This issue is caused by very high printing temperatures and/or using incorrect retraction settings. This can be solved by changing a couple of settings in PrusaSlicer and checking your hardware.
If you print for a long time from a single type of filament, such as PET-G, the filament can create a thin layer in the nozzle. This can cause stringing as the strands of the filament stick to the surface of the print. Therefore, thoroughly clean the nozzle before printing and make sure that any dirt or remnants of previous filaments are removed from the nozzle.
You should start by checking a parameter known as Retraction. What does retraction do? When the extruder has finished printing one section/object of your g-code, the filament is pulled back into the nozzle. Once the extruder moves to the next location the printing process continues – the filament is pushed back out and it starts extruding from the nozzle again. Retraction settings can be found in PrusaSlicer in Printer Settings -> Extruder 1.
Flexible filaments usually need longer retractions, because the material stretches while being pulled back to the nozzle. Flexible materials are a special case and can need a lot of tweaking and tuning.
The retraction settings are:
Other settings that affect retraction:
Try using a different spool than the one that is causing the stringing. The filament might have gathered moisture, which will cause a lot of stringing.
Stringing in the nozzle might be caused by a heat dissipation issue in the nozzle. Try re-applying thermal paste on the threads between the heatbreak and the heatsink.
If you have recently changed any component in the hotend, it is also possible that some individual parts are not in place. Go over the assembly of the hotend and check for any parts that may be different from the instructions.
If you don’t feel like tweaking any of the settings, well, then there is an alternative. You can get rid of the strings with a heat gun (or often with a lighter – but be very careful). Set your heat-gun to around 200 °C and aim at the strings for one or two seconds. This will melt the strings, and the printed object should remain undamaged. Do not leave the heat source on the printed model for longer than one or two seconds, as this may deform the part.
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