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Questions on infill and support structures

Discussion in 'General Questions' started by David Carter, Apr 30, 2017.

  1. David Carter

    David Carter Member

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    I'm trying to build a tower structure.

    TomerMacro1.png

    First, there's the question of infill. If I understand the concept correctly, infill will cause the internal structure to be something other than solid. In my case, I'm stinking solid is stronger, and that's what I want. To achieve this, I'd have to set the infill threshold to 100%. Is that correct?

    The second question is that of support structure. When I did a test print, it looked like this:

    IMG_1931.JPG

    That's a whole lot of plastic added to my print! I realize that support is necessary, but this is extremely difficult to remove. In the case of this print, I damaged it beyond repair. So my question is if there is a way to minimize this support structure in the printing phase?
     
    #1 David Carter, Apr 30, 2017
  2. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    Support structure is custom to the slicer.
    Some do it very well, others not so much. Most of the free slicers drop the ball in this area.

    Try other slicers...
    All of the free ones have strong areas and week ones. Sometimes one is better than another on a specific type of model.

    If you want perfect supports that are almost invisibly removable and full customization of them including manual additions/removals then investigate Simplify3D
     
    #2 mark tomlinson, Apr 30, 2017
  3. David Carter

    David Carter Member

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    Yup. Simplify3D looks good. My one question if you've used it: where the heck to I enter the Z Offset? There's a lot of option entries but I can't find anything that is clear to me as a Z offset setting. Do I have to add it directly to the GCode?
     
    #3 David Carter, Apr 30, 2017
  4. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    Open the process window, go to the scripts tab and enter it in the startup GCode block like this

    G28 ; home all axes
    M565 Z-1.0 ; set the offset for auto-leveling mechanism
    G29 ; run auto-level


    If -1 is too close to the bed then go more negative. If it is too high from the bed go less negative. Use 0.1 increments...
     
    #4 mark tomlinson, Apr 30, 2017
  5. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    That will cover it. Just remember to do that for any new processes you create for that printer.
     
    #5 mark tomlinson, Apr 30, 2017
    Geof likes this.
  6. daniel871

    daniel871 Well-Known Member

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    This might also be an option, depending on how good a job S3D does of handling it:

    [​IMG]
     
    #6 daniel871, May 1, 2017
  7. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    My only concern with that approach is that it is global.
    The M565 only applies to the autoleveling math when it is calculating the leveled plane.

    I am not sure that applying a global offset has the same net effect.
    I guess (were I motivated) I could dig into the code...
     
    #7 mark tomlinson, May 1, 2017
  8. daniel871

    daniel871 Well-Known Member

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    The end result should be the same, even if it is an offset on the slicer-side vs. an offset on the printer-side.

    Best way to test it would be to post a test cube using each method and looking at the first few lines to see what the differences are.

    I would, but I don't use any auto-leveling any more. I've started to feel like auto-leveling is a crutch for poor hardware, and that's from the perspective of a manually-leveled chinese knockoff i3 where the only leveling-modification I've made is to remove the springs, add some nuts and loc-nuts and call it done after leveling it once.

    EDIT: The last bit above is pretty similar to what Thomas Sanladerer did during his "Dolly" live build if anyone else watched that.
     
    #8 daniel871, May 1, 2017
  9. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    I agree that logically it could be the same, but the M565 is tied into the autoleveling code only.
    It does not (on its own) act like a global offset. It is applied during the calculation of the adjusted plane that is applied for autolveling.

    Having looked at the code that is my concern. It is not just a "global" Z offset.
     
    #9 mark tomlinson, May 1, 2017
  10. WheresWaldo

    WheresWaldo Volunteer ( ͠° ͟ʖ ͡°)
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    Here is exactly what S3D does when you put that offset in the Process >> G-Code tab.

    If it is zero no changes to the resulting g-code appears in the sliced model.

    Here is what happens when you put something in that field. For example, if you need a 1.00 mm offset and put 1.00 mm in that box the result is simply adding 1.0 to every Z dimension, so if your layer height is 0.25 mm then layer 1 starts at 1.25 mm, layer two starts at 1.50 mm and so one. If you have an LCD the display will show 1.25 mm for layer one and so on. If you use a real offset like M565 or M851 (depending on leveling mechanism used) the offset is applied before layer 1 or faded into as many layers as you need (Marlin 1.1.0 only feature), but all the while the printer will tell you and any host software that layer 1 is 0.25 mm and layer 2 is 0.50 mm, etc.

    The result may be the same but the mechanism is not, nor should they be equated with one another.
     
    #10 WheresWaldo, May 1, 2017
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