Remove old filament and press the knob to start loading new filament.
 
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[Solved] Remove old filament and press the knob to start loading new filament.  

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rhjpires
(@rhjpires)
Active Member
Remove old filament and press the knob to start loading new filament.

After completing the upgrade from MK3 to MK3s + MMU2S my printer does not want to print a multi-material object. 

It initiates the bed leveling without issue, but when it goes to begin extruding it does not. I see the idler screw moving and some noises come out of the extruder, but nothing happens. After a few seconds, it raises by a few cm and goes to the right corner of the printing bed where it issues the request:

Remove old filament and press the knob to start loading new filament.

I have removed the old filament and the problem continued.

I have attempted to print a GCode sample and tried to slice my own object, but that didn't change a thing.

I have changed the filament and get the same problem.

I have restarted the printer, the problem persisted.

Although I am yet to print an entire object using just one single filament, when printing the first layer calibration, material is extruded without a problem. Also, If I press the knob (as indicated on the LCD warning) a good amount of material is extruded - after which it asks me to check if the color is correct, etc. So there is no indication that there is blockage anywhere in the system.

Does anyone have a clue what might be happening? Why does it want to change the filament, and why that is all it does?

Thanks in advance!!

Best Answer by rhjpires:

Well after some digging around different fora the issued appeared to be potentiated by a sensor conflict of some kind. People seem to mention problems with the IR sensor, but that was not my case. IR sensor was reading 1 with the filament inserted. The problem I found was related with the PINDA, which was slightly above the threshold to detect the presence of the filament. So, while the IR sensor was detecting the presence of filament at the sensor, the MMU was not detecting anything via PINDA. Thus, the printer was taking the activation of only the end-point sensor as an indication that a bit of OLD filament was inserted and needed to be removed. But because PINDA was never getting activated, despite changing the filament the problem appeared over and over again.

Hope this helps someone.

Posted : 22/09/2020 12:09 am
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rhjpires
(@rhjpires)
Active Member
Topic starter answered:
RE: Remove old filament and press the knob to start loading new filament.

One more detail I forgot to mention: If I press the knob as indicated in the LCD panel (followed by  confirmation that the color is OK and it is good to proceed), the extruder moves back to the left and lowers to the bed to begin printing, but it extrudes only a very tiny amount of material into the purging line after which it raises again, goes to the right, issues the same warning, etc etc etc..

So the printer is stuck in this loop, of constantly asking to remove old filament and replace it with new one, after which it attempts to print and then returns back with the same request - over and over and over. So far I have not been able to pass/break this loop.

Please help!

Best

R-

Posted : 22/09/2020 6:56 am
rhjpires
(@rhjpires)
Active Member
Topic starter answered:
RE: Remove old filament and press the knob to start loading new filament.

Well after some digging around different fora the issued appeared to be potentiated by a sensor conflict of some kind. People seem to mention problems with the IR sensor, but that was not my case. IR sensor was reading 1 with the filament inserted. The problem I found was related with the PINDA, which was slightly above the threshold to detect the presence of the filament. So, while the IR sensor was detecting the presence of filament at the sensor, the MMU was not detecting anything via PINDA. Thus, the printer was taking the activation of only the end-point sensor as an indication that a bit of OLD filament was inserted and needed to be removed. But because PINDA was never getting activated, despite changing the filament the problem appeared over and over again.

Hope this helps someone.

Posted : 22/09/2020 1:26 pm
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