Working with 3D Printing filament – [F]requently [A]sked [Q]uestions

Getting started with a 3D printer often raises a lot of questions that are not always answered correctly. If you have already found the right 3D printer, tailored to your requirements and expectations, another tough decision comes: which filament to choose for 3D printing? A number of issues should be taken into account here – the level of skills, the purpose of the project, the possibilities of the selected 3D printer and the material.

Which filament to choose for 3D printing? What to do when a problem occurs during the 3D printing process? In the article below, we will answer the most frequently asked questions.

WHAT SHOULD YOU TAKE CARE OF WHEN CHOOSING A FILAMENT FOR 3D PRINTING?

Check the label

The label contains all key information about the material, such as color, thickness of the line, or the amount of material on the spool. The packaging should also include the temperature of the extruder at which the material should be printed and the heatbed.

Correct filament diameter

Information for beginners – filament diameters vary. The vast majority of 3D printers use a filament with a diameter of 1.75 mm, however, there are many models on the market that use materials with a higher diameter: 2.85 mm. It is related to the type of extruder pressing the filament to the head – if it is mounted directly above the head, it will most likely use a diameter of 1.75 mm, while in Bowden type extruders mounted on the housing of the device, a higher diameter is required. There are exceptions to this, so you should always check it – be it before buying a 3D printer or when buying the filament itself.

If we buy a filament with a different diameter than the one used by our 3D printer, we won’t do much about it. Theoretically, you could modify selected extruder components, but it would be much easier to just try to replace the filament with the appropriate diameter at the vendor.

From the consumer’s point of view, it is also worth remembering that due to the fact that 3D printers using filaments with a diameter of 1.75 mm are much more popular than those using materials with a diameter of 2.85 mm, some manufacturers give up the production of the latter – applies to it is both species and colors.

Material shrinkage

Some plastics are materials that undergo significant shrinkage on cooling. ABS is considered a highly shrink filament – the effect of this phenomenon is especially visible on larger prints. It should be remembered that although PLA is much less susceptible to shrinkage, with large elements this phenomenon also begins to affect the 3D print. The shrinkage of the material may result in the deformation of the printout, its cracking or curling. How to prevent it? One of the solutions is a closed working chamber, as it allows you to maintain a constant and high temperature. As a result, the element does not cool down quickly in an uncontrolled manner.

Heated work table

When choosing a filament, you should pay attention to whether our 3D printer has a heated work table? If not, the choice of materials for 3D printing will be limited to PLA and selected composites based on this material. ABS and many other materials require the use of heating the heatbed, otherwise the printout will peel off.

Price

It is not worth succumbing to the temptation to buy a very cheap filament (e.g. at PLN 50.00 per 1 kg spool). Such filaments may not be as durable, sometimes they are heterogeneous, which affects the quality of the printout. The problem may also be the low adhesion of the element layers. In addition, dubious quality filament can clog the 3D printer head.

Amount of material needed

Manufacturers have different sizes of filament spools, ranging from 0.5 kg, through 0.75 or 0.85 kg, ending with rolls of one or several kilograms. The amount of material needed can be estimated using special model cutting software. It will also help to determine the duration of the printout as well as the number of supporting elements and their location.

Irritating vapors

Some filaments (eg ABS or polyamides – nylons) emit a very irritating smell when melted in the head. When 3D printing, some materials release toxic compounds that are released into the room air. In order to prevent the negative impact of emitted vapors, prints should be made in properly air-conditioned rooms, especially if we print from materials such as ABS or PA6.

Drying the filament before printing

Not everyone remembers that some filaments require drying before printing. The first thing is proper filament storage. The materials used in 3D printing are hygroscopic, which means that they easily absorb moisture from the environment, which results in the destruction of the filament. Plastics containing nylon, polycarbonate and copolyester fibers are very susceptible to the damaging effects of moisture. They then become brittle and more prone to cracking, require a higher extrusion temperature, and lose their tensile strength. In order for the material not to get wet, it should be properly stored, e.g. in vacuum bags or ordinary zip bags with silica gel beads.

Nevertheless, some filaments, e.g. nylon (PA6), require additional drying before printing. This can be done using home methods (using a mushroom dryer or in an oven – which we do not recommend, because the temperature control in the oven is not very accurate) or by using professional filament dryers. For this purpose, you can also use a 3D printer with a heated work table. Set its temperature to 40 ℃, put a cardboard or cardboard box on the work table and put the spool on it. Nevertheless, moderation and care should be taken in any case so as not to damage the material.

HOW TO FIT THE FILAMENT TO THE 3D PRINTER?

In addition to adapting the filament to our skills, it is important to choose the right material for our 3D printer. If it is an amateur device, without a heated workbench and closed chamber, I advise against choosing ABS material, which is a demanding filament. For such printers, PLA is best suited, which is easy to print, both in terms of user skills and the capabilities of the printer. Below I present a list of important parameters for the most popular plastics used in additive technology.

WHAT PROBLEMS CAN I HAVE WHEN 3D PRINTING?

Shrinkage of the printout

The phenomenon of curling the printout usually concerns materials with high shrinkage (eg ABS). It can be caused by too low temperature of the heatbed, therefore increasing its temperature by 5-15 ℃ should solve the problem. Another solution is to enable the Brim or Raft option in the software before starting the 3D printing process. Brim allows you to make a few or a dozen additional material loops around the base of the model, usually on the first layer. This action increases the adhesion of the material to the heatbed. Raft consists in making a special base on which the model will be printed.

Moreover, high-shrink materials tend to delaminate, crack, and curl. If, during printing, additional air is used, which results in the material cooling down quickly, the printout may curl or break. To minimize this phenomenon, enclose the working chamber or purchase a 3D printer with a closed working chamber, so that the printout is not exposed to changing external conditions.

No filament extrusion – nozzle in the print head clogged

When the filament stops flowing during printing, it may be because of a clogged nozzle in the print head. You can prevent clogging of the nozzles by keeping the 3D printer and the material used clean, or by using high-quality filaments. However, if it is after the fact and the head is clogged, you can try to “save” this element. In the case of PLA, the matter is relatively simple: heat the head to a temperature of about 10 ℃ higher than the temperature of 3D printing. Then try to force the material out with a needle smaller than the diameter of the nozzle. If the head has been clogged with ABS material, you can try to dissolve it chemically with acetone. Dismantle the clogged head and place it in acetone for several hours. Contrary to PLA, in the case of PET-G the matter is much more difficult, as the material is very resistant to chemicals. You can try to thermally stuff the head, but this is very problematic.

Please note that filaments that glow in the dark, with glass and carbon fibers require a larger nozzle size (approx. 5 mm). Failure to adjust the capabilities of the 3D printer to the material may result in the accumulation of plastic filler (e.g. fibers) and therefore clogging of the nozzle in the print head. Moreover, repeated clogging of this element may result in a deformation of the inner surface of the nozzle, affecting its efficiency and the tendency to more frequent problems with the lack of extrusion of the material.

No material extrusion – filament is tangled or missing

Improper storage of the material may result in its tangling on the roll. We can only see the seriousness of the situation when, during printing, after unwinding a few meters of material, it turns out that we cannot complete our project until the end. To properly store the material, insert the end of the filament into the holes on the roll. Then we will be sure that the material will not get tangled and that our printing will be carried out from the beginning to the end.

Another thing is the lack of filament. We will estimate the amount of material needed to make the printout using a special slicer. We will then receive a lot of important information about the printing process; duration or amount of material needed.

Supports

It is worth remembering that the support material will have to be removed from the printout. In the case of uncomplicated structures it is quite simple, so when we print elements with complex geometry, the matter becomes more complicated. It is worth considering here whether we will be able to remove the supports. Should this prove impossible, a soluble support material such as HIPS can be considered. We will remove the supports from this filament using limonene, a special chemical solvent. After placing the print in a limonene-filled vessel, the HIPS changes consistency and becomes easy to remove. In the topic of supports, it is also worth mentioning to do it delicately, because removing the supports can damage the printout.

SO WHICH FILAMENT TO CHOOSE IN THE FIRST?

PLA will be the best choice for people starting their adventure with 3D printing. Polylactide is one of the most popular materials used in FDM technology. It is undemanding, has a low printing temperature, does not shrink significantly (especially for small prints), which makes it ideal for simple prints, such as toys or packaging. Another choice may be PET-G, thanks to which we will be able to start learning to print from materials that require a heated workbench. Therefore, it will be an excellent introduction to working with ABS, which is much more difficult to print than the above-mentioned filaments. It is characterized by high shrinkage, requires a heated work table and a closed chamber. Moreover, it often cracks, deforms and tears off the workbench. Additionally, during 3D printing with ABS, harmful fumes are released, so we should work with this material in well-air-conditioned rooms. For beginners, PA6, TPU and ASA materials, which require special 3D printers and experience, will not work.