Stringing and Ozzing

Hairy print? If there are hairy strings of plastic on your print, which typically occur between two parts, this is called stringing. Other terms for this problem are oozing, hairy prints or whiskers. When the nozzle is moving to another location, it could happen that the fluent filament oozes/leaks out of the nozzle and produces the strings. In this case, check if the retraction is enabled, because in many cases you can solve this problem by optimizing the retraction settings. You may use a fine positive Features performance model, like the one from the make magazine. Download link: http://www.thingiverse.com/thing:533472/#files

Adjust the nozzle temperature
Adjust the retraction
Avoid crossing parameters
Adjust the nozzle temperature

As often it is a combination between retraction and nozzle temperature settings to get the best results to reduce stringing. If the nozzle temperature is too high, the molten filament is so liquid (has a low viscosity) that the nozzle will leak during moving to the next location. If the nozzle temperature is too low, you may have problems with extruding your filament. For the best results, try to minimize the temperature by 5-10 degrees so that the plastic doesn´t ooze anymore.

Adjust the retraction

Retraction is the pulling backwards of your filament during the printing process. When the hotend of your 3D printer is moving to a new location (extruder moves without extruding) strings may occur, because the melted filament is oozing out of the nozzle. This can be improved by pulling back the filament in the moment your hotend stops extruding.
First, make sure that you have enabled retraction. Second step will be to optimize retraction settings, like retraction – distance and speed.

Retraction distance

The distance defines how much the filament is pulled back of the nozzle. It depends on your printer what the best distance will be. Try it out by printing two cubes which are 40mm away from each other and increase retraction distance by 0,5mm and monitor the best performance. For most printers, the retraction distance should be between 1 and 5mm.

Retraction speed

The retraction speed is also an important setting that influences your print. If you retract the filament too fast, the filament may separate from the melted part. Otherwise, if you retract too slow, the nozzle may leak before starts printing at the new position. For most printers, the retraction speed should be between 20-100 mm/s or 1200-6000 mm/min.
Try it out by printing two cubes which are 40mm away from each other and increase retraction speed by 20mm/s or 1200mm/min steps and monitor the best performance.

Avoid crossing parameters

There are some slicers on the market, which have special to avoid that your hotend crosses gaps when moving from one place to another.

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