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Weird under extrusion?


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Posted · Weird under extrusion?

 I am noticing this weird under extrusion of the outline in one corner (always a left corner). What could be causing this?

3D Printer Anycubic Kobra.


 I use these settings. (on pictures)



Posnetek zaslona (1).png

Posnetek zaslona (2).png

Posnetek zaslona (3).png

Posnetek zaslona (5).png

Posnetek zaslona (6).png

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    Posted · Weird under extrusion?

    Those settings look pretty normal.  Retraction/Prime speed is a bit fast.  You might try them at 35mm/sec.

    Do you have Coasting turned on?  If so, turn it off and see if it makes a difference.

    In the Walls section make sure you are printing "Inside to Outside".  It's not a fix but can hide the under-extrusion on the inside of the model rather than showing it on the outside walls.

    "...always the left corner." Is that where you have the Z-seam located?


    At 0.2 Layer Height and 0.4 Line Width - 1mm of filament will get you ~30mm of extrusion.  You can guesstimate how much filament you are short by measuring the length of those under extrusions.


    That's pretty bad though.  Load the model and set Cura up to slice and use the "File | Save Project" command to create a 3mf project file.  Post the 3mf file here.  Right now I'm assuming that the under-extrusion is occurring at the beginning of a run.

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    Posted · Weird under extrusion?

     Coasting is off.  Z-seam setup (picture).  I have added two more pictures of the just finished printing.
    With the previous settings, not the new ones. You can see that the under extrusion is only on the left at the bottom, but the wall is good. On the back side, the bottom is good and the wall is under extrusion. Left side only.

    Thanks for the help.

    Posnetek zaslona (7).png



    AK_Test file.3mf

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    Posted · Weird under extrusion?

    Take a look at the tooltip for "Max Comb Distance with No Retract".  When it is set to "0" there is never a retraction prior to a combing move.

    So your printer is traveling across the print to the outer wall to start a new layer and it's oozing all the way.  Because there was no retraction there is also no Prime either.  That may have something to do with this.  It's also dragging the ooze across the print.

    I sliced your project file and after pasting in my own StartUp and Ending gcodes I printed it. 




    I'm not sure what caused that line near the bottom.  Your travel Accel was 5000 so that might have been it.  My E3Pro hates going above 1000.



    You can try making those changes I described.  One more might be disabling "Print Infill First".  

    After printing this and looking at the differences between what your printer did and my print I think you may need to take a good look at what is going on between your extruder and nozzle.  It's possible there is a partial clog in there and it's impeding the startup flow at the beginning of the layer.


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    Posted · Weird under extrusion?

    "retract at layer change".  Make sure that is unchecked. 


    Also look at it in layer view where it underextrudes and use the *horizontal* scroll bar (the one at the bottom center of the screen) to see what order it is printing everything and what happens just before the underextrusion.

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    Posted · Weird under extrusion?

    I changed these settings and it is better. But it does result in a little rounder corners. (Picture).


    Retraction extra prime amount from 0.0 to 0.064mm

    Max Comb Distance with No Retract from All  0.0 to Within Infill  30.0mm

    Wall Thickness 1.6mm , if I change it to default, which is 1.2mm , under extrusion appears again.





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    Posted · Weird under extrusion?

    In the Walls section you have the Wall Ordering set to "Inside to Outside"?


    The "rounded" corners are often associated with the Accel and Jerk combination.  500 Accel and 8 Jerk are good starting points.  Going into a corner, slamming on the brakes and the accelerating out is OK for Lewis Hamilton and can be handled by some printers, mine isn't one of them.  I generally run the Accel at 1000 and Jerk at 10 for largish models and 500/8 for smaller models.  Your model has a lot of straight runs but when a model has a lot of direction changes in a small area (like printing small text) then my printer starts to dance around and all the vibration can end up in the print.


    The "Extra prime amount" is in "mm³".  The length of your under-extrusion x LayerHeight x LineWidth should give you a good base point for the setting.  Remember - that setting is going to happen on every prime, not just the one you are focusing on.


    I have to repeat here though - I think something is going on with the printer.  I printed the model and it came out fine so I don't think we are looking at some sort of bug here.  I think you may need to send a M503 query to the printer but you need something to read the response.  You can use PronterFace/PrintRun or I have a little app I wrote that you can have.

    I see that your printer definition uses the default Cura setting of 299 billion mm/sec.  It is safe to assume that your printer is actually less than that.  If the Maximum E speed in M203 is low at "15mm/sec" or something, then it just isn't snapping the filament forward on prime in order to start the extrusion.

    This is the M503 response from my Ender.  The Maximum feedrates are in the highlighted "M203" line.



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