Purchasing a 3D printer is not just a simple plug and play exercise. There are many issues that may crop up ranging from under or over extrusion to stringing related issues. Let’s look at one of the most common issues facing the Ender 3: stringing in your prints.
Ender 3 Stringing or Oozing Problems
Stringing is also known as oozing, hairy prints, or whiskers. This problem typically occurs when very small strings of filament plastic have been left behind in a 3D printed model.
This is a more common issue with old machines rather than new ones. This is typically due to the filament plastic slowly oozing out of the main nozzle of the unit, even as the extruder is in the act of moving to a new location.
Not only can it leave an ungainly string protruding out of your printer, but it can also jam the nozzle if left unattended. Apart from that, it also gives a tacky and unseemly look to both the printer as well as the 3D object. Luckily there is plenty of information regarding this topic both online and offline. Let us take a quick look at the more common remedies to this problem.
3D printing stringing is not the end of the world, even if it starts occurring in your new Ender 3. You can eliminate this problem, once and for all by following these few simple steps.
However, it is incumbent to understand the issue of stringing 3D printing before you can try to resolve it. Of course, running a stringing test can help, but until you get to know the solution, it won’t be of much use.
What Causes Stringing On 3D Prints?
As an FDM printer’s nozzle goes from point A to point B, it may sometimes start oozing or dripping melted plastic. Once this string solidifies it will stick to the printed parts.
This, in a nutshell, is 3D print stringing. Once you are done with your print you will observe thin strands of plastic that might resemble strands of hair.
The nozzle of your machine should never deposit filament strands while 3D printing as it travels over the print bed. However, in practice, it often happens that molten plastic starts leaking onto parts where it has no right to be and thereby leave your prints with a distinctive “whiskery” look. This does a hatchet job on your 3D printing job.
PLA filament strands are prone to oozing. Often more than most other filament types out there. However, there exist plenty of solutions to this problem.
Common Solutions to Stringing While Using the Ender 3
There are several solutions to this issue and some of them include the following:
When your Ender 3 Pro pulls the filament back during traveling, it will automatically take off most of the pressure from the nozzle. This is precisely why many if not most 3D slicer software tends to have advanced retraction settings. They will aid you in finding your “no stringing” zone for your Ender 3.
Retraction distance is widely considered by most experts to be the single most critical retraction setting available in the Ender 3 series. It is possible to access it via Ender 3 Cura settings.
It will determine how far the filament will travel over the print surface. As a general rule, the further the nozzle can retract, the less likely will you be able to encounter 3D printer oozing. But then again, if you were to retract a bit too far, the filament just might turn out to be unavailable at the hot end whenever you decide to resume printing.
The retraction distance typically varies as per the type of extruder that you use on your Ender. However, a Bowden extruder will almost always need a higher retraction distance. This is thanks to the considerably longer distance in-between the nozzle and the machine’s drive gear.
If you were to search online, you will see that the retraction speed will determine precisely how quickly the machine retracts the filament. Generally speaking, faster retraction speeds mean that it is easy to follow through, and stringing is markedly less likely to occur.
This is because the filament will be pulled back very fast. Too fast for it to start oozing. However, here, it is pertinent to note that whenever the retraction speed becomes a bit too fast, it just might cause the filament to disconnect entirely from the nozzle
Therefore, it is very important for you to search for and find the sweet spot between the fast and slow speeds of the nozzle, where retracting levels would be optimal.
This precise speed will vary due to the printing material used. You should ideally perform a few test prints in order to determine the perfect retracting speed. You should commence with 50 mm/s and then proceed to slow down if you see any filament damage.
Retraction Extra Prime Amount (REPA)
Next comes REPA. This setting will allow you to safely compensate for any material that might have been lost through oozing and get the maximum output. When the Ender 3 printer primes itself after retracting, it will automatically push whatever amount is still available in this setting.
You should work on the retraction setting until the amount being pushed is 0. Once it is at zero your retraction distance will be correct and you won’t have this problem anymore.
Minimum Extrusion Distance Window
This will help you to specify the precise length of filament that the Maximum Retraction Count will be enforced on so that you get the desired prints.
For instance, if the Maximum Retraction Count is set to 5 while the Minimum Extrusion Distance Window (MEDW) is set at 10mm, the machine’s extruder will only retract five times over a piece of filament 100 mm in length. The printer will ignore all retracting related commands after that.
It is recommended to keep this number as close to the ideal ‘Retraction Distance,’ as possible. You should work with your Maximum Retraction Count (MRC) to make sure you don’t inadvertently damage the filament.
MEDW: Set the desired Retracting Distance
Limit Support Retractions
This is a checkbox setting. (If it is not available in your system, you should get it checked.) Once enabled, it will stop retracting when the extruder is moving within the supports. Yes, there will be a bit of stringing, but only within the support structure.
Retracting is a fine balance. Too much of it increases the print time and it can even damage your filament. However, many experts suggest using this option since it will help protect the filament and even increase print speed. There will be a slight stringing effect on the build, but it would be negligible.
These settings are instrumental in setting total retracting distance as well as speed whenever the nozzle is in standby mode. However, they are more useful for multi-nozzle printers. The Ender 3 comes equipped with only one nozzle so you should simply leave them at the default settings and tweak if necessary. They are as follows:
Nozzle Switch Retraction total distance: 16 mm
Nozzle Switch Retraction Speed: 20 mm/s
The combing mode instructs the slicer software to keep the nozzle well within the printed areas while moving from point A to point B. The four settings for this mode include Off, All, Within Infill, and not in Skin.
The best option here would be Within Infill. It will substantially reduce total retractions by keeping the machine’s nozzle well within the infill areas. Yes, it will increase the print time but it will also serve to protect your filament.
Combing Mode: Enable, Within Infill
Set the Right Temperature
As the temperature will increase, so too will the printing material become more liquefied. This leads to dripping issues from the nozzle. They will happen even if you carefully adjust the retracting settings.
However, a lower temperature setting will inevitably reduce this likelihood. This is why it is important to refrain from setting the temperature a bit too low. This is because very low temperatures would lead to solidified filament material which will jam the nozzle.
An ideal temperature will always depend on the printing filaments as well as various other print settings. You can of course lower the temperature whenever you notice stringing.
However, it is generally recommended to lower the temperature once you see any oozing. Decreasing nozzle temperatures by 5-10 °C increments will usually do the job. Some of the highly recommended temperature settings for most commonly used filaments include the following:
- TPU: 230-250 °C (60 °C print bed)
- PLA: 180-200 °C
- PVA: 160-190 °C (60 °C print bed)
- TPE: 210-240 °C (20-70 °C print bed)
- ABS: 200-250 °C (90-100 °C print bed)
- PET: 215-235 °C
Let us go through the list one again for your Ender 3 retraction settings:
- Enable Retraction: Yes
- Retracting Distance: You should commence with a setting of 5 mm then proceed to adjust it up/down by 1 mm until all stringing has vanished.
- Retracting Speed: Begin with 50 mm/s and start slowing down in case there is any residual filament damage
- Retracting Extra Prime Amount: Leave at zero and then proceed to focus on Retraction Distance
- Maximum Retraction Count: Set to 10 and then only adjust it in case you see filament damage
- Minimum Extrusion Distance Window: Set this option as per your Retraction Distance
- Combing Mode: Yes, Within Infill
- Limit Support Retractions: Yes
- Nozzle Switch Retraction Distance: 16 mm
- Nozzle Switch Retraction Speed: 20 mm/s