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Solved Hot end pressing into print

Discussion in 'Troubleshooting' started by Jason Hough, Sep 4, 2017.

  1. Jason Hough

    Jason Hough New Member

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    Hey everyone,

    I've been trying to calibrate my printer since fixing an alignment issue last week (see my other post).

    So I'm printing Benchy today and I noticed that my hot end is literally pressing down into the filament as it goes around the layer.
    Any idea why this might be happening, and how to fix?

    Here's a quick video showing what I mean. Watch toward the end as the hot end goes around the perimeter, you can see it warping the filament as it goes.
     
    #1 Jason Hough, Sep 4, 2017
    Last edited: Sep 4, 2017
  2. WheresWaldo

    WheresWaldo Volunteer ( ͠° ͟ʖ ͡°)
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    Two possible issues from that short video, no way to make definitive statements, Over-extrusion and overly hot extruding.

    To fix the first follow the general procedures in this video:


    The second is adjust your extrusion temperature by lowing it a few degrees. Some slicers will allow you to set an arbitrary number of layers at one temperature (useful if you want to assure adhesion to the print surface) and then lower it a bit for subsequent layers. Please review the options in your slicer to see what can be accomplished.
     
    #2 WheresWaldo, Sep 4, 2017
  3. Jason Hough

    Jason Hough New Member

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    Thanks for the tips. I watched the video and tested my extruder - when I told it to extrude 100mm only 90mm went through, so oddly it seems to be under extruding? That seems counter to your theory, though.

    Is it possible I've got something wrong with my z offset?
     
    #3 Jason Hough, Sep 4, 2017
  4. WheresWaldo

    WheresWaldo Volunteer ( ͠° ͟ʖ ͡°)
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    Z offset only affects layer #1
     
    #4 WheresWaldo, Sep 4, 2017
  5. Jason Hough

    Jason Hough New Member

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    Whoa, really? So if the z-offset is the same as the layer height, then layer #2 is printed at the same z as layer #1?
     
    #5 Jason Hough, Sep 4, 2017
  6. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    No, the Z offset is added ONLY to layer one. From there all calculations are relative to the first layer height.

    Assume Z offset was 0.05:

    layer height = 0.2

    you first layer relative height is 0.25
    You second layer height is 0.2 (but starts at 0.25)
     
    #6 mark tomlinson, Sep 4, 2017
  7. Jason Hough

    Jason Hough New Member

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    Ahhh, I see what you mean now. So even if the z-offset was wrong, it would never print at one height and then later drop down below that. Okay.

    So, since it appears I'm actually under instead of over extruding, I'll try lowering the temperature.
     
    #7 Jason Hough, Sep 4, 2017
  8. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    Correct. if the Z offset is wrong your first layer will be too squished or not squished enough :)
    The other layers would be fine...

    If the Z steps/mm were wrong then every layer as the print increases in Z would be further and further off ... too low or too high.
    That is defined in the firmware though so unless you have the incorrect version for your printer that will not be an issue.
     
    #8 mark tomlinson, Sep 4, 2017
  9. Jason Hough

    Jason Hough New Member

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    Just wanted to thank everyone for the suggestions. This turned out to be due to insufficient cooling. I've printed/installed a fan shroud and now things are working well again.
     
    #9 Jason Hough, Sep 12, 2017

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