We notice the inconsistent extrusion already from the first layer. We can certainly say that the first layer would undoubtedly be the most observed. Sometimes looking at it to determine if the print has been set correctly, we can see that the plastic does not come out uniformly. It does not create a precise and well-defined line as it should, but it extrudes a very jagged line.
This can cause a lot of trouble during printing, and if it doesn’t resolve, it won’t allow us to complete the printing properly.
The causes of discontinuous extrusion are many, but here we will try to identify and “cure” them all. As usual we will have to proceed with many checks and tests on time.
Ready? Let’s start, as usual, to examine the most trivial and fastest causes to solve, up to the most rare causes or for which there will be more work to be done.
Inconsistent extrusion: Incorrect setting of the thread-pusher motor
Incorrect setting of the wire feeder motor (commonly E) can lead to over/underextrusion. A right calibration of extruder motor must me done
We can verify the correctness of the settings through this very fast guide.
Inconsistent extrusion: Problems
First of all, you must check that the wire can be pulled by the extruder, that there are no impediments of any kind. For example, you must check that the filament roll rotates freely in the filament holder, in the case of bowden extruders you must make sure that the tube is unobstructed and eventually clean and lubricate the tube and other checks of the kind that will depend on your set-up. If you tighten it manually, check that the screws, knobs or anything else tighten the filament against the toothed pulley of the extruder motor are not loose. On the contrary, tighten well! You must check that the teeth grip on the intact filament, and not in the abrasion conditions described in this article.
Inconsistent extrusion: Small Mistakes
It can happen to print, especially at the beginning of our practice with the 3D printer, an object with the characteristics of the cube in the picture, which shows obvious signs of underextrusion and we will have to look among the settings that led us to have a discontinuous extrusion of this magnitude, in this case is the result of incorrect indication of the diameter of the filament used (2.85 mm instead of 1.75 mm), but can also give the same result the wrong indication of the diameter of the nozzle.
Obviously it must be verified that the plate is well levelled, or we can find ourselves in the case in which in some points we will see the molten plastic very flattened. It will seem transparent and inconsistent and in others we will see a beautiful line marked. It may seem like an extrusion problem while a leveled platter will solve all problems. This guide explains how to level the platter step by step.
Inconsistent extrusion: Nozzle partially clogged
If you still have a problem at this point, you may have the nozzle partially clogged. Small debris may be present inside the extruder, preventing the molten filament from flowing evenly. You can try to open the wire pusher and try to push manually, if the filament will not come out with the appropriate diameter and constant you must devote yourself to cleaning the nozzle by following the advice of the guide provided for this purpose.
My advice is to change nozzle every month, even with no apparent problems. Nozzle are so cheap do no worth it to let us have problems related to this!
Inconsistent extrusion: Old/wrinkled filament
Sometimes, however, we can be misled and the symptoms we attribute to the blocked extruder can be due to problems with the filament. A very old filament or one that has been stored in damp rooms can give this kind of problem.
In general, filaments tend to degrade over time and become difficult to extrude. Then some particularly hygroscopic filaments such as PLA and Nylon can over time absorb moisture from the air degrading the print quality. In the most serious cases we will hear small crackles coming from the extruder, when it will heat more humid points. To verify that you are not using a filament with problems we will have to try to replace it with a newer one or one that has been less exposed to moisture.
If we find that the filament has taken too much moisture, do not worry, we can still recover it through a dryer or a simple oven at home.
Just follow our simple guide
Inconsistent extrusion: Meccanics
The last causes we’re going to look at are mechanics.
It can happen for several reasons to have problems with the wire pusher. Typically the most common problem is the loss of tightening by the pulley on the shaft. You must check these screws and tighten them monthly.
It may also be the case that the motor does not have enough copy to push the filament and there is a real loss of the motor pitch. This problem is characterized by the typical ticking in correspondence of the failure. Here the situation gets a little more complicated, but our guide on the Vref adjustment runs to your rescue, follow it and you’ll be back on the road in no time!