Learn to distinguish the good filament from the bad, and the consequences of printing with a filament of poor quality.

Home / Uncategorized / Learn to distinguish the good filament from the bad, and the consequences of printing with a filament of poor quality.

3D Printing has its tricks, you do not learn to print well overnight. In fact, there are certain mistakes that everyone makes at the beginning, and that the experience leaves to commit.

One of them is to spend thousand euros in a 3D printer and yet find the cheapest filament market. It is a common mistake, which usually results in not only poor quality prints but can even lead to breakdowns and obstructions that ultimately involve buying parts that make expensive filament choice come out.

But why does that happen? that is, what it is really the difference between a good and a bad filament ?. That is why in this article we explain what is necessary so that you do not take your hair:

What consider when choosing filament ?.

What difference a good filament from a bad ?.

What are the consequences of poor print quality filament?


If you already have a 3d printer, you are not in time to choose. But if you do not have your printer, you will have to choose between 3 mm and 1.75 mm.

Personally, I think the filament of 1.75 mm is better. Firstly, it is more common in the market, and therefore, when you sell more, you are less likely to be sold a reel that takes a long time in storage and has lost its properties.

Furthermore, the filament of 1.75mm seems to have a better extrusion and retraction and generally better flow of plastic. This is because the stepper motor of the extruder requires more revolutions to extrude the same amount of plastic using 1.75 mm extruder than if we used 3 mm. As more revolutions are required for the same amount, the extrusion will be more accurate and the flow control will be better.

Filament Tolerance

Regardless of the diameter you choose, if there is a factor that marks the difference between a good filament and a bad one, it is the tolerance.

The good filament is not only good for the composition of the plastic, but also for the quality of its manufacturing process. Good filament occurs on a production line that has laser diameter control wire is extruded as. In this way, the margin of error in the filament gauge is always within reasonable parameters.

When printing with any FDM type 3d printer, it is important to understand that the software that controls the printer calculates the extrusion volume based on the filament diameter (theoretical), the diameter of its extrusion die and the extrusion speed (commonly referred to as As flow rate – in mm / s). In essence, the printer controls the volume of plastic being pushed out of the nozzle by turning the extruder wheel and pushing a certain length of filament downward toward the hot tip.

If the diameter of the coil is irregular to be of poor quality, the volume of extruded plastic software varies and can not set this parameter to compensate for the variation.

That will make the extruded plastic not really match the theoretically extruded, and this variation generates defects appreciable impression. It is what is called inconsistent extrusion,  as shown in the following figure:

A bad filament has probably been extruded and rewound without controlling the wire gauge well since that control requires economic investment, so there are differences in diameter that the 3d printer

sometimes fails to tolerate:

If the filament suddenly becomes too thin for tensioning mechanism and not enough pressure to grip the filament, this will leave, interrupting the printing and blocking the extruder to build up inside.

At the other extreme, when the diameter is suddenly too wide and extruder motor is not strong enough to push it . This will, again, cause the extruder jam.

When shopping for a new strand, it is not a bad idea before use use a micrometer to measure the diameter in several places and make sure it meets tolerance announcing the label.

Usually it is sufficient with a tolerance of at most  0.05 mm. The problem is that virtually any filament you buy, on the label will say that the tolerance is 0.05 or even lower, whether or not true.

Filament roundness

When making contact with the wheel of the extruder, the filament will always suffer a little compression due to the grip to which it is subjected. This flattening reduces the roundness of the filament, so if the filament does not have a good roundness, being caught in the extruder print quality could be compromised.

The correct roundness of the filament, as you can imagine, is achieved using the right machinery during its manufacture, so again, the cheaper filament will usually be more susceptible to poor roundness. A bad filament that loses in certain sections of the reel its roundness, becoming oval, can cause an incorrect grip of the extruder.


Another important factor is the humidity. Usually, the plastic will absorb moisture and the longer it is exposed, the more it will absorb.

Know if your filament has absorbed too much moisture if splashes or small evaporations extruder tip produced by the effect of moisture evaporating on contact with heat to reach the temperature of 100C. Ultimately, this will produce poor impressions and poor adhesion of the layer .

As you might imagine, the quality filament absorbs much less moisture than the bad, so that a filament of poor quality, once opened, will be worse with each passing day, unless we take many precautions to save the filament.

There are those who removed the coil of the printer and keep the filament in a box with rice after each print. With a good filament, this should not be necessary unless you are going to be without printing a lot of time.

A perfectly good Filament Shop come vacuum packed , and silica bags absorb moisture. After opening, the good filament will be much less sensitive to moisture than a bad one.

At this point it is worth noting the initiative of the Spanish manufacturer of filament Smart Materials , based in Jaen, presenting their coils in a zip bags protected against ultraviolet rays, designed to keep the coils after use .


Impurities in plastic are one of the major problems: chemical impurities produce a poor viscosity of molten plastic, and also these impurities end up clogging the extruder die , which is a big headache: besides losing what you were printing , You will have to remove the tip, and clean it with care.

Sometimes, the tip can not be cleaned and after many attempts, there is no choice but to throw it and buy another. Logically, the quality of the filament is inversely proportional to the amount of impurities it contains.

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