Simplify3D weirdness..

  • Hi,
    I got this very strange behavior when printing with Simplify3D (that I don't get with let's say Cura).
    Exactly ever other layer the perimiters bulges out, this only hapends when a retraction has been made.
    And it's not only a couple of millimeters, it's pretty much that whole layers perimiter.

    I've tried a bunch with coasting/retraction distance/extra retraction distance and so on.. nothing seems to remove the fat perimiter.

    Has anyone any idea of what could case this?

  • @Haggan90 Open up two "identical" gcode files and post the commands for a couple layers, this might make the difference apparent. A good place to start.


  • @timothyz
    This is the first line of code made with S3d:

    G1 E-1.8000 F3900
    ; feature skirt
    ; tool H0.320 W0.720
    G1 Z0.320 F1200
    G1 X214.920 Y212.896 F8400
    G1 E1.8000 F3900
    G1 X217.896 Y209.920 E0.4031 F2520
    G1 X232.104 Y209.920 E1.3610
    G1 X235.080 Y212.896 E0.4031
    G1 X235.080 Y227.104 E1.3610
    G1 X232.104 Y230.080 E0.4031
    G1 X217.896 Y230.080 E1.3610
    G1 X214.920 Y227.104 E0.4031
    G1 X214.920 Y212.896 E1.3610
    G1 E-1.8000 F3900
    G1 Z0.640 F1200
    G1 X215.640 Y213.194 F8400
    G1 Z0.320 F1200
    G1 E1.8000 F3900
    G1 X218.194 Y210.640 E0.3460 F2520
    G1 X231.806 Y210.640 E1.3039
    G1 X234.360 Y213.194 E0.3460
    G1 X234.360 Y226.806 E1.3039
    G1 X231.806 Y229.360 E0.3460
    G1 X218.194 Y229.360 E1.3039
    G1 X215.640 Y226.806 E0.3460
    G1 X215.640 Y213.194 E1.3039

    I can't really find anything strange here..

  • Moderator

    @Haggan90 Looking at that gcode, the only thing I can see is that you have Z hop enabled, so the nozzle is lifted up (or bed dropped) before a longer travel move, usually after a retraction. I don't use S3D, but in other slicers you can set the maximum travel distance move before it triggers a retraction and a Z hop. The slicer will usually try doing the Z hop at the highest speed possible.

    As you say this is only happening in layers with a retraction, what's probably happening is that the Z motors are missing steps on the Z hop, because the speed, acceleration and/or jerk is set too high for the Z axis motors to cope with moving the weight of the Z axis. This will happen in one direction, but probably be able to move in the other direction where the weight of the axis helps, so you end up with a squashed layer.

    Try sending G1 Z moves at F1200 (which is what is asked for in the gcode), and see if the Z axis is capable of moving that fast. Check both up and down movements. Post your config.g motor settings and description of your Z axis (printer layout/type, leadscrew type/steps per mm, motors, weight of axis) for recommendations about what would be good Z axis motor settings.


  • Something I have noticed, is that the S3D Coasting and Z-hop is not compatible with Duet's Pressure Advance feature (M572) - or at least this is what I think (disabled Z-hop and Coasting and the bulges disappeared).

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