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Uneven Print Extrusion  

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lshadrick
(@lshadrick)
Active Member
Uneven Print Extrusion

Hello Everyone,

I have had a Prusa MK3s+ for over a year, and have ~600 hrs of print time on the printer.  An issue has developed recently, and I can't determine anything that triggered it.  When I start my print, the first layer calibration is set correctly.  However, the filament comes out unevenly and produces small ridges.  The second layer compounds on the uneven surface until the print crashes.  See the attached picture, and notice the uneven edge around the print and throughout the surface.

I have checked the belt tension, re-calibrated the Z-axis, performed maintenance including lubricating the bearings, and performed a cold pull to clean the nozzle.  I have also tried the same print with PETG and a couple different brands of PLA.  I have also re-sliced the print to ensure that the G-code wasn't corrupted.  At this point, I am out of ideas. 

Any suggestions would be much appreciated.  Thank you!

Posted : 26/07/2022 11:35 pm
fuchsr
(@fuchsr)
Famed Member
RE: Uneven Print Extrusion

Looking at this picture, the first layer looks everything but correct. The wavy pattern is a tell tale sign of a live z set too low. This creates the ridges you're seeing. 

Posted : 27/07/2022 12:00 am
Jimbo70
(@jimbo70)
Estimable Member
RE: Uneven Print Extrusion

I have used Prusa printers for several years and am not an expert but to my eye it looks like too much filament extruded at the end of each line.  

Consider: 1. adjusting your linear advance, 2. decreasing your filament printing temperature, 3. increasing retraction or z lift.

 

Posted : 27/07/2022 12:54 pm
Diem
 Diem
(@diem)
Famed Member

I agree with @fuchsr, your first layer Z is set too low.

Cheerio,

Posted : 27/07/2022 4:21 pm
lshadrick
(@lshadrick)
Active Member
Topic starter answered:
RE: Uneven Print Extrusion

@fuchsr,  Thanks for your idea.  I adjusted my z-calibration for a higher first layer.  That did reduce the waviness in the first layer, but the second layer still looked basically the same as the picture in my first post.  Here's a picture of my print when it failed on the third layer.  

@Jimbo70, Thanks for your comments.  I have tried decreasing the nozzle temp, and that didn't seem to make a difference.  I'll dig into your other suggestions and see if that makes a difference.  It would be surprising to me if those settings were incorrect, however.  I have completed many prints with PLA without an issue until recently.  Since I haven't adjusted any of those settings, I'm not sure why they would be incorrect now.

Thanks for all of your help, guys!

Posted : 27/07/2022 7:12 pm
cwbullet
(@cwbullet)
RE: Uneven Print Extrusion

 

Posted by: @diem

I agree with @fuchsr, your first layer Z is set too low.

Cheerio,

 

Posted by: @fuchsr

Looking at this picture, the first layer looks everything but correct. The wavy pattern is a tell tale sign of a live z set too low. This creates the ridges you're seeing. 

I agree with these two posters.  I think this is more being too low and not an extrusion issue.  

--------------------
Chuck H
3D Printer Review Blog

Posted : 28/07/2022 8:29 am
Diem
 Diem
(@diem)
Famed Member

Probably still too low.  Please run a first layer Z calibration and show us the result *on the print sheet.*

Cheerio,

Posted : 28/07/2022 10:54 am
lshadrick
(@lshadrick)
Active Member
Topic starter answered:
RE: Uneven Print Extrusion

Here's a picture of my first layer Z calibration.  Thoughts?  It's difficult to see clearly from a picture.  

Posted : 29/07/2022 12:56 am
cwbullet
(@cwbullet)
RE: Uneven Print Extrusion

Show the back of the rectangle.  

--------------------
Chuck H
3D Printer Review Blog

Posted : 29/07/2022 1:00 am
lshadrick
(@lshadrick)
Active Member
Topic starter answered:
RE: Uneven Print Extrusion

Here's a couple other pictures of the z-layer calibration.  

Posted : 30/07/2022 5:18 pm
lshadrick
(@lshadrick)
Active Member
Topic starter answered:
RE: Uneven Print Extrusion

Last night I tried re-printing an old print that I had saved from several months ago.  That print completed without issues.  

Based on that, I'm thinking that my problem is related to the slicer settings for this print and is not a mechanical issue with my printer.  I re-sliced the model using a concentric base layer instead of monolithic.  I'll reprint today and see if that makes a difference.

Thanks.

Posted : 30/07/2022 5:20 pm
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