If you’re in the field of 3D printing, you might have come across an issue of strings of melted plastic or plastic oozing from your 3D prints. This is called stringing and oozing, which fits perfectly.
Fixing stringing and oozing is best done by having good retraction settings, where a good retraction length is 3mm and a good retraction speed is 50mm/s. You can also decrease your printing temperature to help filament be less runny, which reduces the instance of stringing and oozing.
It’s a fairly common problem that people experience which leads to poor quality prints, so you definitely want to get this fixed.
There are more details to know about so keep on reading the article to find out why this happens in the first place, and how to fix it once and for all.
Here’s an example of stringing in a 3D print.
What Causes 3D Prints to Have Stringing & Oozing?
Sometimes users try to print an object in which the nozzle has to move through an open area to reach the next point.
Stringing and oozing is the problem in which the nozzle extrudes the melted plastic while moving from an open space.
The melted plastic sticks between two points and look like attached strings or threads. To prevent or solve the problem, the first step is to find out the actual cause of the issue.
Some of the major causes behind the stringing and oozing problem include:
- Retraction settings not being used
- Retraction speed or distance too low
- Printing with a temperature too high
- Using filament which has absorbed too much moisture
- Using a clogged or jammed nozzle without cleaning
Knowing the causes is a good way to start before getting into the solutions. The section below will take you through a number of ways how to fix stringing & oozing in your 3D prints.
Once you’ve gone through the list and tried them out, your problem should hopefully be solved.
How to Fix Stringing and Oozing in 3D Prints
Just like there are various reasons that cause stringing and oozing problems, there are also plenty of solutions that can help you fix and avoid it.
Most of the time this type of problem can be fixed just by changing some settings in the 3D printer such as extruder speed, temperature, distance, etc. It’s not ideal when your 3D prints are stringy so you want to get this sorted out quickly.
Below are some of the simplest and easiest solutions that can be implemented without requiring any major tools or techniques.
The methods that will help you to get rid of the problem for once and for all includes:
1. Print at a Lower Temperature
The chances of stringing and oozing increase if you are printing at a high temperature. The very first thing that you should do is to reduce the temperature and check for the results.
Reducing the temperature will help you because it will extrude less liquid material reducing the chances of stinging and oozing.
Those higher temperature materials are more prone to stringing because of the effects of higher heat on the viscosity or liquidity of filament.
Although PLA is a relatively low temperature material, it doesn’t mean it’s safe from stringing and oozing.
- Reduce the temperature step by step and check if there are any improvements.
- Make sure that the temperature is within the range required for the type of filament being used (should be on the filament packaging)
- Try to use a filament that melts at lower temperatures efficiently like PLA
- While reducing the printing temperature, you may have to lower down the extrusion speed because the filament material will take time to melt at low temperatures.
- Do test prints of little objects to get an idea about the perfect temperature because different materials print well on different temperatures.
- Some people will print their first layer 10°C hotter for good adhesion, then lower the printing temperature for the rest of the print.
2. Activate or Increase Retraction Settings
3D printers include a mechanism that works as a pullback gear called retraction, as explained in the video above. Enable retraction settings to pull back the semi-solid filament that is pushing the liquid to extrude from the nozzle.
According to experts, activating the retraction settings usually work to fix the stringing problems. What it does is relieve the pressure of the melted filament so it will not drip while moving from one point to another.
- Retraction settings are activated by default but check for the settings if you are experiencing stringing or oozing.
- Enable the retraction settings so that the filament can be pulled back every time the nozzle reaches an open space where printing is not designed or required.
- A good retraction setting start-point is a retraction speed of 50mm/s (adjust in 5-10mm/s adjustments until good) and retraction distance of 3mm (1mm adjustments until good).
- You can also implement a setting called ‘Combing Mode’ so it only travels where you have already printed, rather than in the middle of your 3D print.
I’d advise you to download and use this Retraction Test on Thingiverse, created by deltapenguin. It’s a great way to quickly test out how well in-tune your retraction settings are dialed in.
It really is hit or miss, high retraction settings of 70mm/s retraction speed and 7mm retraction distance works well, while others get good results with much lower.
One user who was experiencing some pretty bad stringing said that he fixed it by using a retraction distance of 8mm and retraction speed of 55mm. He also shortened his Bowden tube by 6 inches since he replaced the stock one with some Capricorn PTFE Tubing.
The results does depend on what 3D printer you have, your hotend, and other factors, so it’s good to test out some values with a test.
3. Adjust Print Speed
Adjusting the print speed is a common factor to fix stringing, especially if you have reduced the printing temperature.
Reducing speed is necessary because with the reduced temperature the nozzle can start under extruding. After all, the filament will take more time to melt and become ready to extrude since it’s less runny.
If the nozzle is moving at a high speed, with a high temperature, and no retraction settings, you can bet you’ll experience stringing and oozing at the end of your 3D print.
- Reduce the printing speed because this will mitigate the chances of leaking filament and causing stringing.
- A good starting speed ranges from 40-60mm/s
- A good travel speed setting is anywhere from 150-200mm/s
- As different filaments take different time periods to melt, you should test the material by reducing the speed before starting your printing process.
- Make sure that the printing speed is optimal because both too fast and too slow speed can cause problems.
4. Protect Your Filament from Moisture
Most 3D printer users knows that moisture affects the filament badly. Filaments absorb moisture in the open air and this moisture turns into bubbles when heated.
The bubbles usually keep on bursting and this process forces the dripping of the filament from the nozzle causing stringing and oozing problems.
The moisture can also become steam and will increase the chances of the stringing problems when mixed with the plastic material.
Some filaments are worse than others such as Nylon and HIPS.
- Keep your filament stored and protected in a box or something that is totally airtight, with desiccant and has the ability to stop moisture from reaching the filament.
- If suitable, try to use a filament which absorbs less moisture like PLA
I’d recommend going for something like the SUNLU Upgraded Filament Dryer from Amazon. You can even dry filament while you’re 3D printing since it has a hole that can feed through. It has an adjustable temperature range of 35-55°C and a timer that goes up to 24 hours.
5. Clean the Printing Nozzle
Whenever you print an object some particles of the plastic are left behind in the nozzle and with time get stuck in it.
This happens more so when you print with a high temperature material, then switch to a lower temperature material like from ABS to PLA.
You don’t want any kind of blockage in the way of your nozzle, since this is a very significant area for creating successful prints without imperfections.
- Clean your nozzle thoroughly before printing to make it free from the residues and dirt particles.
- Use a brush with metal wires to clean the nozzle, sometimes the common brush can also work well.
- It will be better if you clean the nozzle every time you complete a print because it becomes easier to remove the heated liquid residues.
- Clean your nozzle using acetone if you are printing after a long time.
- Keep in mind that cleaning the nozzle is considered essential whenever you switch from one material to another.
After going through the above solutions, you should be in the clear for getting rid of that stringing and oozing problem that you have been experiencing.
It may be a quick fix, or it can require some trial and testing, but at the end of it, you know you’ll come out with some print quality you can be proud of.
For people struggling with various 3D printing issues, you might want have wanted more guidance towards getting ideal 3D printing results. I created a full course that's available to purchase called Filament Printing 101: Beginner's Guide to Filament Printing that takes you through some of the best 3D printing practices early on, so you can avoid those beginner mistakes.