When starting with 3D printing with an FFF/FDM printer, which is a printer using filament (plastic thread), it can be a bit overwhelming. We've made a summary of the most frequenty asked questions, to help you get off to a flying start.
1. Filament diameter
Filament, the plastic thread used by the printer, is available in two thicknesses: 1,75 and 2,85 mm diameter. A 3D printer is made for one of these diameters, which one can be found in the specifications. In general, 1,75 mm is used most of the time, but some professional brands like Ultimaker use 2,85 mm.
2. Material type
Materials differ a lot from each other. Some types are very strong but difficult to print, whereas others like PLA are less strong but give very few printing problems. For beginning users we recommend to start with PLA or a strengthened type of PLA like PLA-HT or Tough PLA. When the printer and printing process has become more familiar, one can always transfer to harder to print materials.
3. Fiber reinforced materials
Some materials are reinforced with carbon or glass fiber to create an extremely strong material. These fibers however are that hard, that they become abrasive to normal print nozzles (opening through which filament is extruded). Therefore, these materials need to be printed with special, reinforced nozzles (or CC Red print core for Ultimakers). With these material, the advice is as well to stick to PLA or PLA variants until more experience has been gained with the printer.
4. STL slicing
Do you have an 3D model? This model cannot be printed directly. First it needs to be exported as STL file (for most types of software), and the STL file then needs to be made print ready. This process is named ‘slicing’, as the model will be sliced into layers for printing. The software used for this is called slicing software, or a ‘slicer’ for short. The software will translate the STL into instructions, based on settings chosen by the user. To create fast print, the layers can be thicker; to create a very fine print, the layers should be thinner, but this will also increase the print time (exponentionally). Usually it is best to start with relatively high layer thickness: often the required smoothness is overestimated, causing the prints to take way more time than needed.
5. Thin walls
FF printers work with a nozzle through which molten material is extruded. The diameter of this nozzle decides how thin or fine details can be. The standard size nozzle opening usually has a diameter of around 0,4 mm. This will then also be the minimum details size of the print: a wall of 0,2 mm cannot be printed (accurately at least)! And, even if it were possible, details or walls with such thickness would be way too vulnerable to survive the printing and removal process. When a life size model is scaled to be printed as a scale model, the walls also scale down; this aspect is often overlooked.
6. Orientation and support placement
FFF/FDM printers work with molten plastic, extruded layer by layer on a build plate (also called print bed) or on the printed layers below. It cannot print in mid-air, as the extruded materials would just fall down. In this case ‘Support’ is needed, consisting of scaffold structures created by the printer from the same material or a second material (like water soluble PVA) during the printing process. These support structures need to be removed after printing, which unfortunately affects the vulnerability and/or smoothness of the print.
Support does not have to be drawn in the 3D model, the slicer calculates whether a part needs support and places it during slicing. Support can also be disabled, but this means the printer will print the model regardless of whether or not is actually printable without support! The printer does not check whether the part is printed correctly during the printing process, so for beginners we strongly recommend to always enable support.
By orienting the model in such a way that each layer can be build on top of the previous layer, you can avoid needing support. Luckily, printers are able to print layers diagonally on top of each other, a 45 degree angle is usually safe to print. The orientation of the print will also affect the appearance or strength of the print because of the layer-based construction. The adhesion between the layers is often weaker than throughout the layer, affecting the dimensional strength.
7. Bed adhesion
During printing it is crucial that the print sticks to the build plate. Because of this the build plate is heated during printing so the material will remain somewhat softer, shrinks less and thus sticks better to the build plate. In addition to this we recommend to use a good print glue like Dimafix or Magigoo. The print glue will not only help with adhesion during printing, it will also release the print more easily after cooling and protects the build plate against damage during detaching. Several difficult to print materials have specific print glues like Magigoo PA for Nylon and Magigoo PP for Polypropylene.
Watch out when using a glue spray, as the build plate always need to be taken OUT of the printer to prevent glue getting into moving parts of the printer.
8. Bed leveling
To adhere the print to the build plate during printing, the print bed needs to be level and have the right distance to the nozzle. The process of adjusting this is called ‘Bed Leveling’ and is of extreme importance. Incorrectly leveled print beds can and often will cause print failures. Some printers (like the Ultimaker S3 and Ultimaker S5) have and Auto Bed Leveling procedure, to ensure this can’t go wrong. In case a printer does not have this procedure, please ask us for instructions or check the manufacturer, as this is a very important procedure.
Filaments can absorb moisture from the air, which can cause problems when heated. Some filaments are more sensitive to this than others, PVA and Nylon being the most notorious. Even naturally hydrofobe (moisture repelling) materials such as PET can still become hygroscopic (moisture absorbing) due to additives to improve printability of the material.
Storing filaments in a closed bag with silica gel is good, but often not enough to sufficiently dry the material. For this, filament dryers and vacuum filament containers are available, but filaments can also be dried in a slightly opened oven for several hours. For the Ultimaker S5, the Material Station works as a climatic cabinet.
The printing process can emit particles that are less than healty, like (Ultra) Fine Dust Particles (UFDP’s) and Volatile Organic Compounds (VOC’s). How many and which particles are emitted depends on the material and printing temperature. PLA will emit fairly little particles, while ABS emit much more UFP’s and VOC’s. And when ABS is printed on a higher temperature, like in ABS-Carbon fiber composite materials, even more particles are emitted. Because of this, 3D printers need to be placed in well ventilated rooms. Even when only printing in PLA, we still advise against spending much time in a closed space next to a working printer.
Please do avoid large temperature fluctuations due to ventilation, which can cause the print to warp or get loose from the build plate.
Do you have other questions? We can help you. With our training offer (both online and in-house) we can train you in various 3D printing related topics, and our Support department can answer a wide range of technical questions. Also regarding material choice we will be happy to think along with you. Please contact your closest MakerPoint location by phone or email.