Need Help, First Layer Cal creates large oozes?  

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Kuulbots
(@kuulbots)
Active Member

Hey guys,

So I have a strange issue where when I go to do a first layer Cal, it ends up checking the points and then just starts endlessly extruding filament into a big ooze. You can see what I mean in the video provided.

An extra notes is that I've noticed on the filament when ejected from the machine, shows signs of intermittent bites coming out of the filament.

So if anyone can help then that'd be most appreciated!

 

Help video 1

Posted : 08/02/2021 4:24 am
cwbullet
(@cwbullet)
Illustrious Member

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

--------------------
Chuck H
3D Printer Review Blog...
Posted : 08/02/2021 4:27 am
bobstro
(@bobstro)
Illustrious Member

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. 

My notes and disclaimers on 3D printing and miscellaneous other tech projects
He is intelligent, but not experienced. His pattern indicates two dimensional thinking. -- Spock in Star Trek: The Wrath of Khan...
Posted : 08/02/2021 5:57 am
Kuulbots
(@kuulbots)
Active Member

@cwbullet

It's just the 0.6mm Nozzle

Posted : 08/02/2021 6:04 am
Kuulbots
(@kuulbots)
Active Member

@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"

Posted : 08/02/2021 6:06 am
bobstro
(@bobstro)
Illustrious Member

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.

My notes and disclaimers on 3D printing and miscellaneous other tech projects
He is intelligent, but not experienced. His pattern indicates two dimensional thinking. -- Spock in Star Trek: The Wrath of Khan...
Posted : 08/02/2021 6:14 am
cwbullet
(@cwbullet)
Illustrious Member

@kuulbots

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

--------------------
Chuck H
3D Printer Review Blog...
Posted : 08/02/2021 10:37 am
Kuulbots
(@kuulbots)
Active Member

@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?

Posted : 09/02/2021 12:55 am
stewartr
(@stewartr)
Eminent Member

@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.)

Posted : 09/02/2021 4:22 pm
Robin
(@robin)
Trusted Member

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. 

This post was modified 2 months ago 2 times by Robin
If at first you don't succeed, skydiving is not for you....
Posted : 10/02/2021 6:59 pm
Kuulbots
(@kuulbots)
Active Member

@robin

@stewartr

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

Posted : 11/02/2021 3:39 am
Robin
(@robin)
Trusted Member

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

If at first you don't succeed, skydiving is not for you....
Posted : 11/02/2021 3:40 pm
Kuulbots
(@kuulbots)
Active Member

@robin

thank you

Posted : 14/02/2021 11:03 pm
anniefish
(@anniefish)
New Member

@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?

Posted : 20/02/2021 8:31 pm
Kuulbots
(@kuulbots)
Active Member

@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

Posted : 21/03/2021 5:03 am
stewartr
(@stewartr)
Eminent Member

@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.)

Posted : 21/03/2021 12:14 pm
cwbullet
(@cwbullet)
Illustrious Member

@stewartr

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

--------------------
Chuck H
3D Printer Review Blog...
Posted : 21/03/2021 5:54 pm
stewartr
(@stewartr)
Eminent Member

@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.

Posted : 21/03/2021 11:28 pm
cwbullet
(@cwbullet)
Illustrious Member

@stewartr

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

--------------------
Chuck H
3D Printer Review Blog...
Posted : 21/03/2021 11:32 pm
stewartr
(@stewartr)
Eminent Member

@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. 

Posted : 21/03/2021 11:47 pm
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