Can´t load filament
Just got the preassembled MK4S + MMU3 combo and have BIG problems loading filament.
I have put the MMU3 aside since I only want to do single color prints right now (in other words, I have not used it once).
When I try to load filament it doesn´t go down at all into the extruder but if I press the idler (see picture) all the way to the left it will load and I can let go of the idler and everything works. This is a workaround that works for now but how will this work with the MMU3 when I decide to start to use it?
What is wrong in the idler/extruder? I have cut the filament to a pointy end to better go into the small hole in the extruder but nothing works (except for the idler-trick I just described).
ANY help would be greatly appreciated!
Best Answer by JoanTabb:
Hi Robert,
the filament sensor for the stand alone Mk4 and the MMU3 version of the mk4 are different.
on the standard Mk4, the filament, moves a spring loaded ball bearing and Magnet which signals the printer to start loading filament.
on the MMU3 version of the Mk4, the filament sensor is activated by displacement of the extruder idler assembly. As you have found, if You manually displace the idler assembly it will trigger a filament load action,
However in normal MMU3 use, the printer will read Gcode and when it sees a filament load instruction, it will pass the instruction to the MMU3, the for a first load instance MMU3 will select the appropriate filament and begin advancing the filament towards the Finda, in the MMU, once the finda triggers, the MMU will fast feed the filament towards the extruder, along the reverse bowden tube, the MMU Knows when to expect the filament to arrive at the Extruder filament sensor, and triggers the nextruder to begin feeding the filament, as the filament enters the nextruder, the nextruder is already running which causes it to enter between the planetary gear and the nextruder idler, causing the idler to move aside a certain distance, this triggers the mk4 printer to acknowledge that the filament has entered the nextruder, the printer instructs the MMU to release the filament and the nextruder feeds the filament to the nozzle. and the print starts, usually with a purge line...
If the printer is already printing, a change filament command, causes the printer to stop printing, engage purging and ramming, on the purge tower, then it feeds the filament back into the MMU3, as the nextruder releases the filament, the filament sensor instructs the MMUto take over handling of the filament, and the MMU continues to backfeed the filament towards the filament buffer (Which prevents the filament back feeding to the filament reel, and potentially derailing).
as the end of the filament passes the Finda sensor under retraction, the MMU Knows to feed the filament a short distance further, to clear the back of the filament selector and then the selector is moves to select the new filament, and the process reverses with the MMU feeding the new filament towards the extruder...
A filament feed action, is only considered successful, if both Finda and Filament sensor sense presence of filament at the correct times, and the nextruder motor does not identify lost steps if the motors identify lost steps, a stuck filament situation is signalled and the printer / MMU will endeavour to resolve this by retrys to feed, and cutting filament, as appropriate.
I Hope this makes sense to you,
these activities are based on My observations I Have no insight into the firmware.
regards Joan
RE: Can´t load filament
Hi Robert,
the filament sensor for the stand alone Mk4 and the MMU3 version of the mk4 are different.
on the standard Mk4, the filament, moves a spring loaded ball bearing and Magnet which signals the printer to start loading filament.
on the MMU3 version of the Mk4, the filament sensor is activated by displacement of the extruder idler assembly. As you have found, if You manually displace the idler assembly it will trigger a filament load action,
However in normal MMU3 use, the printer will read Gcode and when it sees a filament load instruction, it will pass the instruction to the MMU3, the for a first load instance MMU3 will select the appropriate filament and begin advancing the filament towards the Finda, in the MMU, once the finda triggers, the MMU will fast feed the filament towards the extruder, along the reverse bowden tube, the MMU Knows when to expect the filament to arrive at the Extruder filament sensor, and triggers the nextruder to begin feeding the filament, as the filament enters the nextruder, the nextruder is already running which causes it to enter between the planetary gear and the nextruder idler, causing the idler to move aside a certain distance, this triggers the mk4 printer to acknowledge that the filament has entered the nextruder, the printer instructs the MMU to release the filament and the nextruder feeds the filament to the nozzle. and the print starts, usually with a purge line...
If the printer is already printing, a change filament command, causes the printer to stop printing, engage purging and ramming, on the purge tower, then it feeds the filament back into the MMU3, as the nextruder releases the filament, the filament sensor instructs the MMUto take over handling of the filament, and the MMU continues to backfeed the filament towards the filament buffer (Which prevents the filament back feeding to the filament reel, and potentially derailing).
as the end of the filament passes the Finda sensor under retraction, the MMU Knows to feed the filament a short distance further, to clear the back of the filament selector and then the selector is moves to select the new filament, and the process reverses with the MMU feeding the new filament towards the extruder...
A filament feed action, is only considered successful, if both Finda and Filament sensor sense presence of filament at the correct times, and the nextruder motor does not identify lost steps if the motors identify lost steps, a stuck filament situation is signalled and the printer / MMU will endeavour to resolve this by retrys to feed, and cutting filament, as appropriate.
I Hope this makes sense to you,
these activities are based on My observations I Have no insight into the firmware.
regards Joan
I try to make safe suggestions,You should understand the context and ensure you are happy that they are safe before attempting to apply my suggestions, what you do, is YOUR responsibility. Location Halifax UK