In this article, I have summarised the most important points on how I maintain my FDM 3D printer. It is important to maintain the printer regularly to ensure that it works properly, as this is the only way to achieve optimal results and enjoy your device for a long time. Regular maintenance can significantly increase the service life of the individual components, and reliability is probably the most important aspect.

The filament

In most cases, it will not be necessary to clean the filament, but I would like to point out that any dust that sticks to the filament due to static electricity is drawn into the nozzle and can accumulate there. With smaller nozzle diameters, this can very quickly lead to clogging of the nozzle.

Where does the dust come from?

From the manufacturer

I have received filament rolls that were dusty and left clear black residue on a handkerchief when I pulled just a few centimetres of the filament through the cloth. However, this was some time ago and should not happen with reputable filament manufacturers. I suspect that the filament was stored openly before it was packaged. I wasn't the only one with this problem at the time, as there were several hacks for cleaning the filament with a kitchen sponge before feeding it into the extruder.

From the ambient air

This brings me to my second point: anyone who displays their filament attractively, as many YouTubers like to do, or anyone who hangs their filament openly next to the printer, is exposing their filament to dust. As the plastic rubs against the extruder or Teflon tube when it is fed in, it can become electrostatically charged, which magically attracts dirt.

From the drying box

Anyone who stores their filament in drying boxes with silica gel and has not packed the silica gel in bags has probably already noticed that the granules produce dust when they rub against each other. That's why I put my silica gel bags in a fabric bag with as tight a weave as possible, which doesn't prevent drying but keeps the dust in the bag as well as possible.

Quickly put away

If you like to put your filament away between uses rather than putting it straight from the storage box into the printer, you run the risk of getting dirt on the roll due to the static charge mentioned above. I have had filament chips from another filament stick to the roll.

I don't want to exaggerate and say that there is dust everywhere and that filament rolls must be guarded like treasure, because in most cases you print with a nozzle with a diameter of at least 0.4 mm and problems are rare, but if, like me, you often print with smaller nozzles, you should think about it, because a 0.1 mm nozzle clogs extremely quickly.

What can you do about it?

If you want to be on the safe side, wipe the filament with a soft sponge before feeding it into the printer. I will shortly be posting links to print templates and the sponge I use.

The nozzle

The nozzle is the component that needs to be cleaned most often, because before each print, you should make sure that no filament residue is stuck to it, which could cause the print to fail.

Exterior

The nozzle should be wiped clean before each print to prevent the plastic from burning and producing unnecessary toxic fumes, which could cause the new print to fail. If plastic residue sticks to the nozzle, the extruded filament may stick to the nozzle instead of the print bed!

To reduce this problem, I have changed the G-code for the initial sequence so that a large amount of filament is extruded, which adheres well to the print bed and rubs off any contamination from the nozzle.

The nozzle is best cleaned with a brass brush, as this removes plastic residue very easily without scratching the nozzle.

You can also mount the nozzle on the printer and write a start procedure so that the printer automatically moves over the brush before each print, cleaning the nozzle independently.

Filament feed

PLA in particular can crystallise, so the nozzle/heat brake should be cleaned regularly. It is very important to clean it after printing a composite material, i.e. a filament to which particles such as carbon, glass fibres, luminescent particles, wood or stone particles have been added.

The easiest way is to use the ‘cold pull’ method

This involves heating the nozzle to a slightly higher temperature than the filament you last used and feeding the filament into the nozzle. Then allow the nozzle to cool to around 80 °C and pull the filament out again. Please note that you will need to bend the printer slightly, as you may need to pull quite hard. Ideally, you should remove the hot end and clamp it securely.

Ideally, this method should be used every time you change to a different material, as this ensures that no filament residue remains in the hot end. If PLA gets too hot for too long, it crystallises or even burns, which can lead to a clogged nozzle.

Cold pull with PA

For heavily soiled hot ends, I recommend heating the nozzle to 270 °C, inserting nylon filament, allowing it to cool back down to 80 °C, and then pulling out the filament.

Drilling

However, if you already have a heavily clogged nozzle, you can also drill it out. Be careful, as it is essential to ensure that you do not drill into the nozzle tip, but only into the plastic, otherwise you run the risk of drilling through. Ideally, use a drill bit that is slightly smaller than the rear nozzle inlet:

Drilling

If you erase the print bed or print with dusty/dirty filament, this can change the nozzle diameter.

Cleaning with a needle

To remove the dirt or burr, there are nozzle needles that can be used to carefully push the contaminants through from behind. To do this, warm up the removed nozzle with a hot air gun to soften the filament residues.

With a suitable drill bit

I do not recommend drilling out the nozzle bore with a suitable micro drill bit, as you will never achieve a precise hole with normal ‘household remedies’ and new brass nozzles only cost a few quid.

If you still want to try this, I warn you that it is not easy, because the thin drill bits break very easily, especially if the drill/hand grinder/mini lathe does not run perfectly round. Due to the imbalance or tilting, the nozzle diameter becomes uneven and larger, which can lead to even worse printing results.

We don't even need to discuss reworking rod nozzles, because this is not possible without the right equipment.

Chemical dissolution

Many plastics can be dissolved chemically without attacking the nozzle itself. With ABS, for example, you can place the nozzle in an acetone bath and hope that the blockage dissolves. In the article Chemically smoothing FDM prints, I have listed exactly which plastics can be dissolved with which solution.

Flatness of the tip

When printing rough filaments such as carbon, the small flat area of the nozzle tip can wear unevenly. To make it smooth again, you can level the tip with a very fine whetstone. This requires a great deal of skill, but if the nozzle is already damaged, you can give it a try, because you can't really do any more damage, and if you do, you'll have to replace the nozzle, but you'll have had some practice and maybe it will work next time. My tip is to save up several old nozzles and then try to improve them all in quick succession. If you can refurbish several nozzles in succession, the amount of work involved is somewhat less and you can use the time in one go for longer, which increases your learning success.

I recommend wiping the print bed mainly with a damp cloth (preferably microfibre), ideally before each time you switch on the device, because the workpiece only adheres well to a clean printing surface. This even makes it possible to print ABS without brim or similar. For heavy soiling, I recommend washing-up liquid (a tiny drop on a cloth is sufficient), as it is very effective at removing grease and does not attack the surface, unlike acetone or alcohol. You should rinse the cloth at least once, or use a second one to wipe the print bed again with a damp cloth to remove any residue from the washing-up liquid.

If you clean with alcohol, make sure you add enough water. I have found that a ratio of 10% isopropanol to 90% water works best. The addition of water is important because, although alcohol is a very powerful degreaser, it does not dissolve everything, such as salts and sugars that may come from touching the printing plate with your hands. I achieve very good results with pure water and recommend everyone to try this.

The ball bearings

The original oil used in most printers is very thin and, in my opinion, is not suitable for the bearings because it is too thin. In my view, all bearings should be lubricated with grease, but it must be the right kind. After filling the bearings with grease using a syringe and needle, the printer became significantly quieter and vibrations were greatly reduced.

If the printer is not going to be used for a long time, it is a good idea to clean the guide rods with a cloth to remove any dust, because if the bearings run over them, the dirt will get into the bearings and you will eventually have to replace all the grease, which would mean completely dismantling the printer.

If you wipe the guides regularly with a dry cloth, you don't need to do anything else unless you notice that the printer is getting louder again, because then the grease has spread in the bearings. In this case, simply press some grease into the bearings again with the syringe. If you repeat this process for a few prints, you can fill the bearings completely with grease, thereby reducing noise, and the bearings will not require any further maintenance for a long time. It is advisable to clean the guide rods regularly with a dry, clean cloth, especially if the printer has been standing for a long time.

The belts

The printer's belts stretch slightly over time, so you should make sure that they are not too loose, as this can greatly affect the print image. To protect the belts, you can keep the print acceleration and jerk (speed when changing direction) as low as possible. This only slightly increases the printing time, but the print image will be significantly better.

If you want to get the best performance out of your printer, you can also replace the belts with reinforced ones. These are made of PU (high tensile strength) and reinforced with fine steel cables, resulting in minimal stretching and making them very durable and maintenance-free. Then you only have to install them once and can enjoy your printer for a long time.