Need Help, First Layer Cal creates large oozes?  

RE: Need Help, First Layer Cal creates large oozes?

To be honest, I have never seen this.  What size nozzle is that?

RE: Need Help, First Layer Cal creates large oozes?

That really looks like something is amiss in your startup gcode. Save your PrusaSlicer part & settings off in a 3MF project file, zip it up, and attach it to a reply here so we can look at everything together. 

RE: Need Help, First Layer Cal creates large oozes?

@cwbullet

It's just the 0.6mm Nozzle

RE: Need Help, First Layer Cal creates large oozes?

@bobstro

I'm not actually trying to print anything so there is no Gcode, this is literally me just going to the calibration menu on the printer and hitting "First Layer Calibration"

RE: Need Help, First Layer Cal creates large oozes?

I don't have an MMU to compare against, but it looks like the actual extrusion is fine, but the nozzle is never moved to print the prime lines. It just stays put. Your pics show damage to the filament that often occurs when there's a jam and the extruder can't move any more filament, but that is usually accompanied by skipping sounds out of the extruder.

RE: Need Help, First Layer Cal creates large oozes?

@kuulbots

Wow, I have never seen a 0.6 extude so fast.  

RE: Need Help, First Layer Cal creates large oozes?

@bobstro

So as far as I can tell, I think when it's creating the oozes, it does it in little pulses, like it'll pull through the filament then stop, then pull through more, then stop, then pull through more and stop, and so on. Perhaps that's what is happening to cause the bites? any idea why?

RE: Need Help, First Layer Cal creates large oozes?

@kuulbots

It's hard to tell from that video, but you mention 'little pulses'. That's the behaviour of the MMU when it's failed to load, and trying to get the extruder to grab the filament. Usually after three attempts at loading though, and usually starting at the MMU end and pushing maybe an inch, pausing, pushing another inch, etc. That clearly didn't happen here, and it looked like it went straight to the nozzle. In full MMU mode the extruder gear would then pull it back and push it down once more before starting the print.

So, the question is; is the *filament sensor on the print head adjusted correctly*? (I'm thinking that it wasn't detected and somehow kept getting fed in.)

RE: Need Help, First Layer Cal creates large oozes?

Like stewartr said: looks like the IR sensor never reports the filament reaching the extruder. As a consequence the loading sequence is never terminated correctly and when the MMU tries to abort and retracts the filament the extuder gears eat the marking into the filament. 
Recalibrate the IR Sensor. 

RE: Need Help, First Layer Cal creates large oozes?

@robin

@stewartr

How would I go about checking if the filament sensor is adjusted correctly? Or as Stwartr suggests, re-calibrating the sensor?

RE: Need Help, First Layer Cal creates large oozes?

IR filament sensor calibration (MMU2S) - Prusa Knowledge Basehelp.prusa3d.com › article › ir-fila...

RE: Need Help, First Layer Cal creates large oozes?

@robin

thank you

RE: Need Help, First Layer Cal creates large oozes?

@kuulbots

I've been having the same problem, but I have calibrated the IR sensor a few times, don't see anything funny  but it doesn't make a difference.. have you figured anything out?

RE: Need Help, First Layer Cal creates large oozes?

@anniefish

Yeah, just fixed the IR sensor now and its appears to have solved the problem, however I'm starting to notice issues with consistency so now for trying to troubleshoot some other issues for me haha

RE: Need Help, First Layer Cal creates large oozes?

@anniefish

The manual says to use the Allen key for calibrating the filament sensor, but I've found using some actual filament is better. If nothing else, it's what the sensor's designed to detect after all. It's also worth remembering that the 'chimney' will move around a bit as you tighten up the screws. It'll also creep over time. So it's always worth unhooking the coupler at the extruder end and sticking a bit of filament in a few times as you check the sensor info. (I got for 10 / 10 on that check.)

RE: Need Help, First Layer Cal creates large oozes?

@stewartr

The sensor is made to detect the bed and not filament.  

RE: Need Help, First Layer Cal creates large oozes?

@cwbullet

Indeed. The PINDA is designed to detect the bed. The filament sensor, on the other hand, is designed to detect filament.

The manual says to roughly align the PINDA with a tie-wrap, and the filament sensor with an Allen key. I'd suggest that's all good, but for a final check of the filament sensor; use actual filament.

RE: Need Help, First Layer Cal creates large oozes?

@stewartr

I am not sure that the filament sensor has to do with the first layer success.  

RE: Need Help, First Layer Cal creates large oozes?

@cwbullet

If it's just oozing out and not printing the priming line, then it's likely the filament sensor's not triggered... The MMU and extruder are both feeding it through.

Pure speculation, of course, as I've not had that problem. But it fits the observed facts.