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It is recommended to regularly take some time to maintain your printer. This should be done even if the printer is working perfectly. The inspection and maintenance of its various components should be done every couple of hundred hours of print-time. This guide is valid for the Original Prusa MK3.5 and MK3.5S.
Besides the usual tools, such as Allen keys, needle-nose pliers, and IPA + paper towels, you might need:
What to check on your printer:
The Original Prusa MK3.5 can spot if any of the fans stop spinning. However, that does not mean you should not check them during maintenance. Dust or plastic build-up can decrease their efficiency or even damage them.
A cotton swab can also be used to clean off dust and debris from the propeller or canned air will clear the dust. Tweezers can be used to take out any plastic strands. Hold the propeller of the fan to prevent it from spinning while cleaning it with canned air. Otherwise, it can get damaged. Clear away any debris that may be stuck and check that it can rotate freely.
The MK3.5 is equipped with two Bondtech gears, made of hardened carbon steel. One is the pulley gear, secured on the extruder's motor shaft by a set screw. The other is the idler gear, which spins freely mounted on the idler door. If you have had a clog, they can also have collected residue grinding the filament which will, in turn, reduce their grabbing force on the filament.
Regular cleaning and lubrication will:
If you're cleaning the gear inside the extruder without removing the extruder motor first, be sure to cover the PTFE tube to avoid any debris falling in. You can use a cotton swab - it will reliably cover the tube without damaging it). After you're done cleaning, give it a good puff of air to clear any remains, while the PTFE tube is still covered.
Open the extruder idler door by releasing the screw on the left side of your extruder.
Both hobbed gears can have a build-up of filament shavings stuck in the grooves. Using a brass brush, clean what you can, then rotate the gear a few degrees and repeat until you do a full turn. They can also be cleaned one at a time using the acupuncture needle that comes with the printer.
The gears can be covered by rust. There is no need to worry. The gears themselves should not be damaged. Remove any problematic bits of filament and clean them with a brush.
Make sure the Bondtech pulley gear is aligned with the path of the filament and secured on the flat side of the motor shaft. Also, check that the shaft of the idler gear goes through both "ears" of the Extruder-Idler-door plastic part and spins freely. You can find a more detailed guide in Comprobación/realineación del engranaje Bondtech (MK3.5/S, MK3S/+, MK2.5S).
Apply a tiny amount of the grease only to the teeth protruding outwards from the gear. Make sure that the lubricant never gets in contact with the filament teeth. Do not use oil-based lubricant as it may spread to unwanted sections, like where the filament is fed into the hotend.
It is a good practice to check and optionally reconnect the electrical connectors on the xBuddy board every 600-800 hours of printing.
To access the xBuddy board, loosen four M3x6 screws to remove the metal box cover. To access the lower part of the xBuddy board, loosen two M3x10 screws from the bottom cover, and remove the cover.
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Putting an exact number on how long a nozzle will last is very difficult, as it depends on how much you print, what types of filament you use, and how often you change between filament types. It is not the first thing you should look to if you are experiencing extrusion issues, but if the printer has been in use for more than 3-6 months and you are getting poor print quality, even after doing the mentioned maintenance, you may want to consider replacing the nozzle.
You should always be using the latest stable firmware version that we have published for your specific printer model. You can check the firmware version you have in the LCD menu - Info - Version info.
See this article to flash the fimware on your MK3.5/S.
We also recommend using the latest version of our PrusaSlicer, as it enables you to enjoy all the features of your printer. It even saves information about the printer model, nozzle diameter, and firmware version directly into the g-code file so that the printer can warn you if anything is out of date or incompatible.