No Stings Attached - How To Beat 3D Printing Stringing
Strings Attached? Not Anymore.
Here are a couple of ways you can reduce or prevent retraction
As a FDM printer nozzle travels across an open space to get to the next point; it may sometimes ooze melted plastic, which then solidifies and sticks to the printed parts. This is referred to widely as 3D printer filament stringing, and it leaves your 3D printed parts with thin strands of plastic that resemble cobwebs or strands of hair.
The leading causes of stringing in FDM printers are using incorrect retraction settings and setting the hot end temperature too high. PETG, for example, requires relatively high temperatures for melting and is notorious for stringing. PLA and ABS, however, are also known to have this issue.
Luckily, there are some ways of preventing 3D printer stringing. Let’s take a look!
Enabling retraction is the most common method used to combat 3D printer stringing. Enabling retraction means that, where the extruder has to cross an empty space, the filament will be pulled back – just a little bit – by the feeder. This prevents the molten plastic from trailing behind as the printer head moves because the “pulling back” action serves as a countermeasure against oozing. Once the extruder has arrived at the next location, the filament is pushed back out, and printing resumes from the nozzle again.
In most slicing applications, like Cura, retraction is usually enabled by default. However, it’s always a good idea to confirm that this is true, especially when you start experiencing stringing. If the retraction setting is turned on and you’re still experiencing 3D printer stringing, you may then need to go into the nitty gritty of the retraction settings.
Retraction distance is probably the most critical retraction setting, as it determines how far the filament travels. Generally, if your nozzle can retract further, it means you’re less likely to encounter 3D printer stringing. But again, if you retract too far, the filament may be unavailable in the hot end when you need to resume printing.
To determine the correct retraction distance, you may have to perform test prints. Try this retraction test print: It prints quickly and does not require too much filament.
The retraction speed determines how quickly the filament is retracted. A faster retraction speed suggests that 3D printer stringing is less likely to occur because the filament is pulled back fast enough before it starts oozing. However, when the retraction speed is too fast, it may cause the filament to disconnect with the other portion inside the nozzle. Worse, a quick movement of the drive gear may grind the molten plastic and jam the nozzle or create areas where the filament is not deposited.
As the temperature increases, the printing material becomes more liquefied and is more likely to drip from the nozzle, even after adjusting the retraction settings. A lower temperature reduces this likelihood. However, you must be careful to not set the temperature too low. Very low temperatures could make the filament not melt enough, which could create issues with extrusion.
An ideal temperature depends on the printing material and other printing settings. However, it’s generally recommended to lower the temperature once you notice stringing. You can try reducing the nozzle temperature by 5 to 10 °C increments, but never reduce the temperature below the manufacturer’s minimum specifications. These are the commonly recommended temperatures for some of the most common filaments:
- PLA: 180-220 °C
- ABS: 200-250 °C (90-100 °C print bed)
- PET: 215-235 °C
- TPE: 210-240 °C (20-70 °C print bed)
- PVA: 160-190 °C (60 °C print bed)
- TPU: 230-250 °C (60 °C print bed)
Using a temperature calibration tower test print is a great way to identify the ideal temperature for each printing material.
For further guidance, our article on the best printing temperatures for different filaments has covered the most common filaments and is a great place to start if you’re looking for the ideal printing temperature for your filament.
The print speed can also affect 3D printer stringing. If, for example, your nozzle takes too long to move between two points, stringing is likely to occur because molten plastic has more time to ooze out of the nozzle. But if the extruder can travel faster, the short moves may be quick enough that the filament will not have enough time to ooze.
Increasing the travel speed of the nozzle when it’s not trying to print can reduce 3D printer stringing, but if the temperature is low and the print speed is too high, you may end up with under extrusion because the plastic will lack enough time to drip.
Generally, a speed of 190 to 200 mm/s will work fine with most printing materials, but MatterHackers has found 150 mm/s to be the ideal travel speed for most printers.