Weird zebra patterns of non-extruded filament  

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WpA09
(@wpa09)
New Member

First post. I am a beginner when it comes to Prusa printers but use other printers daily at my workplace. 

 

TL:DR, see images at the bottom of the weird zebra pattern I am getting recently.

 

So, this problem started a few days ago (well, more like weeks because I didn't have the time to fix it right away) and I've gotten strange behaviour from my printer. My prints went along fine and I've had several small prints and one "big" 24+ hour print. Recently all my prints have failed due to under extrusion. I've been going at it for 3 days now and I am starting to give up. I've tried a lot of different tips and even got an unopened fresh filament spool from work to see if I can solve the problem. Seemingly nothing works and I am starting to lose hope and patience. There has been no changes to the print settings in the slicer, in fact the Prusa logo print is the stock file bundled with the printer.

 

What I know:

- Zebra patterns and extrusion failure.

 

What I've tried to do to solve it:

- Removed the PTFE tube from the hot end AND the extruder housing to see if there were any filament leftovers, without finding any.

- Tightened and loosened the tension screw on the side of the extruder housing. Tightening it too much proved to help with the pattern, BUT;

- Disassembled the entire extruder housing multiple times to clean out the filament that got stuck when I tightened the screw too much.

- Tried to unwind a bit of filament from the spool to see if that would help the extruder, if the problem was that the extruder was too weak to pull the filament. Did not help.

- Tried both a glossy/smooth filament and a textured/matte filament. Matte worked a bit better but eventually ran into the same problem.

- Done about 50 filament purges and a couple of filament changes (glossy->matte and glossy->another spool of glossy).

- Tightened/loosened the extruder assembly screws. Tightening the assembly worked for a while.

I've tried to do each of these things separately and not all at once, to no avail. I might have done other things but I honestly can't remember anymore.

 

Thanks in advance! I'll gladly post more information if needed! I need all the help I can get, before I go mad.

 

Pictures:

Picture 1: A previous print from a couple of weeks ago. Glossy filament.

Picture 2: Latest attempt. Glossy filament.

Posted : 05/02/2021 8:35 pm
cwbullet
(@cwbullet)
Illustrious Member

The image quality makes it tough.  It almost looks like you Live Z is off.  It could also be a dirty bed.  

--------------------
Chuck H
3D Printer Review Blog...
Posted : 05/02/2021 8:41 pm
cwbullet
(@cwbullet)
Illustrious Member

I would defintely check the live Z with a first layer calibration.  Post a close up of the small rectangle when complete.  

--------------------
Chuck H
3D Printer Review Blog...
Posted : 05/02/2021 8:42 pm
WpA09
(@wpa09)
New Member

Thank you for the quick reply. TBH I kind of overlooked this as I did the setup once and got it good. I have done the setup and noticed that it was way off. I tuned it to a better offset and tried to do a print. Here is the result: 

Now the print clears the first layer of the print, I can see the pattern still but the filament gets extruded fine. When it comes to the second layer, the extruder just stops grabbing the filament and prints nothing (see the top right of the print). I had to push the filament manually to get it to extrude. The same goes for the third layer (see top left of the print). Had to push the filament there too. 

Posted : 05/02/2021 9:28 pm
cwbullet
(@cwbullet)
Illustrious Member

You might need to redo it periodically but especially with new filaments or nozzle hotend changes.  

--------------------
Chuck H
3D Printer Review Blog...
Posted : 05/02/2021 9:40 pm
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