Prusa Research MMU3 Manual Del Usuario página 112

PASO 6 INFO Tubo PTFE hotend
VERY IMPORTANT INFO! READ CAREFULLY!!
There is a short PTFE tube inside the extruder's hotend. It plays a major role in the
MMU operation. This tube cools down a molten filament tip to form a narrow sharp
end on it, while the MMU does a material change.
The tube is considered a consumable as it wears down over time during the
regular use. Therefore, it
went over certain amount of material changes. We strongly recommend
replacing it now, since the extruder is partly disassembled already.
A new hotend PTFE tube has a 1.85mm internal diameter. If your printer is new
or very lightly used, you can skip the PTFE replacement in the upcoming steps
and proceed to " New chimney: parts preparation. "
The specimen on the right, however, was taken off a printer after approx.
20000 material changes, using a high-temperature abrasive filament that wore
down the tube's bore up to 2.4mm. This caused increased stringing and
malformed filament tips, leading to frequent MMU filament loading problems
on that machine. The worn PTFE tube needed replacement.
PASO 7 Extracción del ventilador
Release and remove all screws holding the Hotend fan on the side.
Remove the fan. We need to split the extruder in order to replace the hotend PTFE
tube.
Look at the back of the extruder. Remove the M3x40 screw in the top right corner.
112
9C. Extrusor MK3S+ (UPG)
should be replaced
Ensamblaje Original Prusa MMU3
once in a while, after the printer