If you want flawless prints then you need to adjust properly your retraction settings.
This is because the most common aesthetic issues originate from oozing, this effect occurs when the hotend shifts from one place to another letting behind strings on our printed design.
3D Printing Stringing
Why does oozing occur? And how to avoid it?
Normally, problems of this sort derive from 3 parameters:
- Retraction Speed
- Retraction Distance
First of all, an excessive hotend temperature will make the material very thin and it will be easier to stretch a longer distance.
So the first step is finding the right temperature.
After that, we will need to determine the best values for retraction speed and retraction distance.
Some of you probably already tried putting high values into these settings but be aware, exaggerating with these settings can lead to other problems as described below:
Using a very low temperature could lead to lower viscosity of the melted plastic, therefore a greater effort for the stepper motor which at a certain point will start to lose steps. This can lead to under extrusion or worse, not printing entire layers.
An extreme retraction speed leads to a gradual consumption of the filament. Turning very fast can damage the filament instead of pushing it, this way, lots of material will accumulate on the gear and progressively worsen the grip.
Each printer has a suggested retraction distance which is based on the type of hotend. A greater distance could bring the filament to a colder point of the extruder channel, where it will cool quickly, becoming solid and taking up all the free space. It is a very common reason why hot end blockages are formed. It can happen immediately or even after a certain amount of time. This is because retraction doesn’t need to pull the loose plastic material, but just to remove the pressure from the nozzle. This means that it is not necessary to exaggerate with this value.
How to get the right settings
Aiming to test a wide range of temperature settings, I will be using a model that has a range of temperature from 220 °C to 180 °C, on the side, there are 5 temperature zones, divided by a small step.
You can Download the STL here
Temperature Test Result
Looking very carefully and analyzing every step I can say that the temperature that satisfies me the most is 200 degrees.
So this is the temperature I will be using.
In this guide, I will be showing how retraction speed affects print quality in relationship to retraction distance.
We will see that these 2 settings change different aspects when we want to reduce stringing.
We will use as a comparison the first image in the article where we don’t have retraction enabled.
With these settings I’ve reached the sweet spot already, it would be useless going for higher values. Rember that we want to get them balanced.
feel free to download the Gcodes I’ve prepared so you don’t have to bother slicing every single setup, just put the Gcode files on your 3D printer and you are ready to go.
I’ve made them for my Ender 3
ENDER 3 RETRACTION SETTINGS TEST
Download page and settings description here.
I have a glass on my printer and the bed temperature might be to high ,even my test got some warping. Be aware!
But if you want You can find the STL on Thingiverse at this address: Thingiverse
Retraction Test Result
We can see that there isn’t that much of a difference using these 3 different speeds but at a second analysis, we see that that the bulkiest parts are still there but those thinner strings that are very similar to spider webs have vanished.
Also increasing the speed we have a better result on the top layers of the print.
The higher part is the most tricky one when it reaches this point the extruder will move very fast from one end to another. Retraction speed-compensates these movements and reduces oozing.
We saw that retraction speed isn’t going to resolve our problems and looking better at our tests it obvious that we need to get this parameter right.
Adjusting the retraction distance will eliminate all our ugly artifacts and will definitely improve the quality.
Looking at the picture we see that even with low value as 1 mm we have obtained a result. But we want to eliminate all stringing.
Using 3 mm in my case it completely resolves the problem, the print is clean, no sign of stringing and the last layers are perfectly done. If your distance is to high the tip of the cones will not come perfectly, the extruder motor will not have time to compensate for the fast movements.
No cheap filaments
I had to use some cheap quality filament because with my quality ones it was almost impossible to achieve this kind of result.
This makes me take into consideration another factor: Quality of the filament.
Even if all 3D printers are different this test should give you an insight on how retraction works but most important how you can test for yourself and eliminate this problem once and for all.
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