Regular maintenance: Bearings, Fans, Extruder driver gear, Electronics & PEI.
In order to prevent any possible print failures, we highly recommend taking regular care of the following parts (as suggested also in the 3D Printing Handbook you have received with your printer).
After a few hundreds of print time hours, or in case the printer stands idle for several days in a dusty room, the smooth rods should be cleaned with a paper towel. Then apply a little bit of lubricant on the smooth rods and move the heatbed/extruder back and forth a couple of times. If you feel the axis is not moving smoothly when moving it by hand from one side to another, you can take the bearings out and lubricate them on the inside (they need to be removed from the smooth rod in this case).
As for the type of lubricant, there are various options. Using oils such as the WD-40 is not optimal, as the thin substance may not bring as much lubrication as needed. On the other hand, denser greases may accumulate dust over time, which may cause even more damage to the bearings at the end of the day. In general, Super-lube or any other multi-purpose grease will do just fine, as well as White Lithium Soap.
Both fans should be checked and cleaned every couple hundred hours; dust or plastic build-up can decrease their efficiency or even damage them. Computer cleaner spray will get the dust away and tweezers can be used for little plastic strands.
Additional information for Noctua fans used on the Original Prusa i3 MK3 and MK2.5
Both extruder and part cooling fans measure current RPM (Revolutions Per Minute). Because of that, they can detect any problem that will cause the fan to slow down, like a piece of filament getting stuck in it. If you get a fan error, check that it can rotate freely; clear any debris that may be stuck in it.
The nozzle cooling fan is made by Noctua. These premium fans are known for their superb quietness and exceptional performance.
You can turn off the monitoring in the LCD menu - Settings - Check fans for example if you replaced one of the fans with a replacement not supporting RPM sensing.
Extruder driver gear
The hobbed drive gear on the extruder motor shaft can have a build-up of filament shavings in the grooves and cause under-extrusion. A small brass brush is an ideal tool to clean the grooves, but a regular toothpick will do the job as well. Check and clean from the access window on both sides of the extruder assembly. Clean what you can, then rotate the gear and repeat. Nothing needs to be disassembled. Clean when you see signs of missing plastic in the objects, e.g. missing lines of extrusion.
PEI print surface preparation
PEI can lose its adhesive powers after a couple hundred hours. Wipe it thoroughly with acetone when you see models getting loose to restore the adhesion. You can find more information on how to take care of the PEI surface in PEI print surface preparation.
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