Extruder Maintenance

The MK3/S/+ printers are 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.

Open the Extruder idler door by releasing the screw(s) on the left side of your extruder.

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.

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.

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.

The idler screw should be about flush to protruding 0.5 -1 mm with the plastic part when the filament is not loaded

Use tweezers to pull any debris or plastic strands in the hotend fan and part cooling fan.

Compressed air can be used to clean off any small debris or dust.

Hold the propeller of the fan to prevent it from spinning while cleaning it with canned air. Otherwise, it can get damaged.

Unload any filament from the printer.

At the printing temperature of the previously loaded filament, load cleaning filament until the printer extrudes it cleanly.

Unload the cleaning filament.

New filament can now be loaded.

Cooldown the printer if not in use.