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What's causing these artifacts in my sliced model?


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Posted (edited) · What's causing these artifacts in my sliced model?

I'm trying to print a die model that I made in OpenSCAD, but slicing it in Cura creates ugly artifacts on the sides of the cube. I'm using the default profile for the ender 3. Is there something wrong with my model or is this a bug in Cura? How do I fix it? I've attached all relevant files, and the SCAD code is here.




CE3_die.gcode CE3_die.3mf die.stl

Edited by Rygno
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    Posted (edited) · What's causing these artifacts in my sliced model?

    I don't get things like that when I model things in Inventor.  I printed the die and the artifacts you show on the "5" side showed up very faintly.  It looks like an "X" crosswise and a square connecting the outside dots.  I think it might be something you did in OpenScad but I don't know that software.


    As I watched it print (this is how I use up the ends of rolls) I was thinking that the acceleration setting was either off or set very high.  When looking at the 3mf file you did have Accel and Jerk enabled at 500 and 8 which is very reasonable.  This is from the gcode file when I sliced the model

    M204 S500  Print and Travel Accel
    M205 X8 Y8  Jerk control

    G0 F7200 X102.903 Y102.37 Z0.2


    But the gcode file you posted (and that I printed) doesn't show any Accel or Jerk control.  In that case your printer (not being told anything different) would default to either the last Accel and Jerk settings used, or to the Max Accel setting in M201. 

    This is from the gcode file you supplied.  Something changed though between when you generated the gcode file and when you saved the project file.

    G0 F6000 X102.903 Y102.37 Z0.2


    My print showed a lot of ringing which I usually don't get at 50mm/sec.  I'm guessing that the printer went to 3000mm/sec² on Accel which is the maximum I have set in M201.  Also, the infill printed much faster than the 50mm/sec that your 3mf file showed.


    This is the wireframe view of the die in MS 3D Builder.  You can see how dense the triangles are that run around the dots on the 5 side.  I wonder if Cura is just getting a lot of short line segments there and that is causing the artifacts.  The pattern is exactly the same as I saw in the Cura preview and what showed up on the actual print.



    Here is the Cura preview a few layers below the center dot of the 5.  You can see the short line segments being generated by the density of triangles in the STL file.  There are your artifacts.



    To take this analysis to the point of ridiculous - here is layer 39 in AutoCad.  Instead of 4 red lines making up the 4 outside walls path there are 90 lines that jig jog back and forth. There are a lot of line segments on the inner wall as well.




    Edited by GregValiant
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    Posted · What's causing these artifacts in my sliced model?

    Thanks a lot for your analysis! I was able to reduce the resolution of some of the curves in OpenSCAD, which seems to have resolved the problem.

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