The phenomenon of underextrusion and overextrusion arises from the fact that current printers have no way of verifying the amount of plastic coming out of the nozzle. At least the desktop printers that we are used to seeing and using
Obviously we speak of under-extrusion when we are in the presence of insufficient material to properly compose the model. We are instead in the case of over-extrusion when the extruder of matter emits too much of it. We begin to see unintended drippings and protrusions. In essence, however, we are facing the same problem, an incorrect amount of material extruded on the plate.
The phenomenon of underextrusion is more “famous” because statistically more frequent, simply because it has more causes than its twin brother over extrusion.
In fact, the partial clogging of the nozzle can cause underextrusion and, at the same time, the abrasion of the filament in the wire pusher. In this article you’ll find the methods of cleaning the extruder (since it is a partial clogging we can use the fast method). While, in this other article we have treated in more detail the phenomenon of abrasion of the filament.
However, we must bear in mind that when we are in these 2 cases we must examine the whole handling group, both at software and hardware level.
Underextrusion / Overextrusion: Software e programming
Obviously this problem does not come out on its own, it normally occurs after replacing the firmware, or having changed some data from the keypad on the eeprom of the control board of our printer. So, if in presence of these problems we have to go back with the old version, or at least return to indicate the extrusion values of the factory.
If the printer is custom, maybe because a new extruder has been installed or you can not go back to the previous settings then you must follow a special procedure made of tests and adjustments indicated in the guide. Through this very short guide you can adjust the spillage of the filament. This will permanently eliminate the problems of under-extrusion.
Extruder that requires less power:
Underextrusion / Overextrusion: Meccanics
Mechanically all the part that deals with the traction of the wire, until its extrusion must be examined, now I make a list of all this. Some things have happened to me personally, others are more rare but not to be excluded.
- Poorly imbobed thread. Poorly imbobed filaments can, in extreme cases, interrupt extrusion, but commonly become more difficult to pull, so they can give problems of underextrusion.
BUY QUALITY FILAMENTS:
- Adjust the preload spring. Each extruder has a preload, some fixed (a simple spring) and others variable (by means of pulling or loosening a screw). An exhausted spring or a preload that is not sufficiently tensioned can cause undue extrusion.
- Toothed pulley worn. Well, yes, it may happen that a fury to extrude the filament, if the pulley is not of excellent quality consume, until you no longer have the teeth sharp enough to make grip. Yes, this mki happened personally!
- Slow motor: This depends on the Vref, you can see HERE how to adjust it.
- Damaged PTFE tube. Your ptfe tube, in the case of the Bowden extruder, may have damage, crushing or imperfections in general that do not allow comfortable passage of the filament, if above a certain level it may lead to underextrusion.
Hot End Unit
- PTFE tube not correctly positioned in the Hot End. One of the most common causes of underextrusion. Sometimes we forget that the tube has to beat against the arrival. The arrival can be directly the nozzle, if we are in the case of a 3mm throat completely crossed, or against the housing of the throat in other cases. However, the failure to couple forms a small room where the loose wire is deposited and remains plasma. Not too solid to clog completely but not too liquid to allow a regular print. All you have to do is add up the hot end and reassemble it with the utmost care.
- Nozzle partially blocked by residues of previous prints. This happens with some frequency if you use plates loaded with solid substances such as wood, marble, terracotta and others. Or maybe even just remnants of a previous print that solidified a little too much inside. In this case a good cleaning of the nozzle and the throat can solve everything.
If you have find other problems write in the comments. Your personal experience can help someone else!
Underextrusion / Overextrusion: To Err is Human
Let’s remember that to err is human! Check everything! And maybe again until the problem is solved, now I’ll give you some examples of stupid mistakes we might run into.
One of the reasons why underextrusion and overextrusion can occur may be that you have incorrectly indicated the filament in use on the slicer.
It happens very often that those who use printers with 1.75 filament use Care and do not realize at first that the program is pre-set for products Ultimaker (being part of the universe Ultimaker), which use the 2.85 filament. You will then find yourself with a result like the one in the picture without knowing the reason.
The same could happen to Ultimaker users who want to use Slic3r, and find themselves with serious problems of overextrusion.
In any case, you can check the diameter in use at each printer on the market through our page of reviews that you can find here.
Print Flow settings
If we exclude the causes mentioned above and we still have a problem of incorrect flow during printing, we can, through the settings of the slicer, increase the extrusion multiplier.
Each extruder has its own optimal extrusion parameter. In the majority of cases this is 1.00 so 100%, others are different. In this case we will have to find it independently by trial and error. Trying to verify the improvements / deteriorations of the print.
We will have to vary the settings by 5%, maximum 10% at a time (1.05 maximum 1.1). We will increase or decrease and reprint our test cube, many times until we are satisfied.
Unfortunately, the theory can come to our aid on many issues related to 3D printing, but not this time.
We can see in these examples the multipliers of 2 of the most famous slicers. Cura on the left, and Slic3r above.
As we can see Cura expresses the flow rate in percentage, so to increase the flow of 5% we will have to set 105. Slic3r instead expresses it with integers, to always increase of the usual 5% we will have to write 1.05.