3D prints sometimes show small strands of plastic on places where the Ultimaker shouldn’t print and the print head must only travel from one place to another. These unwanted strands of plastic is called stringing. Stringing can be material dependent, but here we describe some general things you could do when dealing with stringing.
Moisture in the filament can evaporate in the nozzle and push material out of the nozzle opening. Therefore, it is important that the filament is in good condition. The best ways to dry your Ultimaker filament are described in this guide.
At the places in a print where the printer has to do a travel move between two printed parts and you don’t want it to leave plastic in between the use of retraction is important. This means that the filament is pulled back a little bit by the feeder, so that it doesn’t leak from the nozzle during the travel moves.
Retraction is a setting that can be found in Cura and is enabled by default. If you doubt about the retraction setting being on, it’s always wise to check it. You should also be able to see this in the Layers view in Cura. Small dark blue vertical lines represent the retractions in the print. Retractions can be improved by either adapting the retraction length or the retraction speed. Although retraction may be turned on, there’s still a chance that small strands of plastic show up on places where you don’t want it. Read on to find out what else you could do to decrease the amount of stringing.
The blue lines are retraction and travel moves
To reduce the amount of stringing temperature is key. A high temperature means that the material will be more liquid, through which it can easily drip from the nozzle (even though retracted). By using a lower temperature the material is less liquid and thus less likely to string.
It’s hard to say which temperature to use exactly, because this depends on the material (even colors can differ) and other print settings being used. But if you notice stringing on your print we would recommend lowering the temperature in steps of approximately 10 degrees to find out what the best setting for your material is. We figured out that for some prints in PLA we were even able to lower the temperature to 180 degrees.
With a higher temperature the material will string more
While lowering the temperature is one thing, the print speed also plays role. If you lowered the temperature there’s a chance that your material starts under extruding when still printing at a (too) high speed. Therefore it’s recommended to reduce the print speed accordingly. This way you should for example be able to reach the low temperature of 180 degrees for PLA with a print speed of approximately 20 mm/s.
Furthermore it could help to increase the travel speed. This way the print head will travel a bit faster, so that the material has less time to drip from the nozzle while traveling. A travel speed of 150 mm/s should be fine for most prints.
Advanced Cura settings
There are also some advanced Cura settings that can minimize stringing for 3D models or materials that are susceptible for this, such as thin walled models using PETG.
- The setting “Max Comb Distance With No Retract" can be decreased and will greatly reduce stringing. Downside is that printtime will increase, and top surface quality may also degrade in some situations. As a compromise, a max comb distance of 8 mm is set for Ultimaker PETG.
- Disable the "Fill small gaps" setting will also decrease the amount of travel moves and therefore decrease the amount of stringing. However, carefully look at your preview, since this may also remove important features in the top surface and may decrease the mechanical properties of the object.
With the right settings you can minimize the amount of stringing