S3D Issue - First Layer Height - Second Layer hight

Discussion in 'Calibration, Help, and Troubleshooting' started by AndyVirus, Jun 6, 2017.

  1. AndyVirus

    AndyVirus Well-Known Member

    Joined:
    Apr 10, 2016
    Messages:
    221
    Likes Received:
    46
    Hello,

    I can never find what i want in the S3D forum and if i do, its something that does not work currently so i thought id ask here as someone may have hit this already...

    I am trying to perfect PETG. When i say perfect, stop being a pain in the ....

    In S3D you have the First layer hight option. Brilliant. use it all the time for various materials...
    The problem comes with the second layer and following layers...

    Lets say i am printing at 0.2mm layers and i have my first layer hight set to 90%
    The first layer is squished by 10%, great!
    The second layer starts 0.2mm above the last layer, so this is also squished by 10%. Not good.
    Am i going mad or should the second layer start at Z0.200 not Z0.180 as it does.

    So to re-iterate. 0.2mm layers.
    Layer 1 starts at Z0.180
    Layer 2 starts at Z0.380

    So First layer hight is not just first layer hight it is all layer hights starting with layer 1.

    Is there a way to have layer 1 90% of the later hight then layer 2 resume printing where layer 2 should be, in this case Z0.400?

    So what i want is for 0.2mm layers.
    Layer 1 starts at Z0.180
    Layer 2 starts at Z0.400
    Layer 3 starts at Z0.600 and so on.

    Is this possible? Is this is possible in S3D? Is this possible in any other slicer?

    I was wondering why all my PETG prints sucked and this would be why. Im sure other materials are more forgiving and i know they are to a point but this may explain why i always have had nozel rubbing my prints and often fail as S3D does not not what it says on the tin, instead it is implementing a Z offset for the entire print not just the first layer.
     
  2. Alex9779

    Alex9779 Moderator
    Staff Member

    Joined:
    Sep 4, 2015
    Messages:
    2,405
    Likes Received:
    731
    No it is not possible...
    As you said you first layer gets squished but what you forget is that its height is just 90%, 10% of the material gets squished to the sides of each line. That's why you get an "Elephant's Foot" if you reduce that number too much. That's why I always add a chamfer to my parts where they touch the build plate. Mostly 0.5mm * 45°, that works out pretty well. But you wnat it to squish to get better adhesion.
    Lowering the first layer height just lowers the height, it does not reduce the amount extruded. That's writte somewhere in the guides.
    If you increase the height above 100% then the extrusion amount is also increased.
     
  3. AndyVirus

    AndyVirus Well-Known Member

    Joined:
    Apr 10, 2016
    Messages:
    221
    Likes Received:
    46
    Ok. Makes sense. Thanks for clarifying.
    I guess i need to keep tweaking.

    One last question for tonight then. How does extrusion width on first layer work? Does that also afect hight or just push more material through?

    Trying to get a good first layer on a pei bed and on second layer have the nozel extrude with out touching the last layer with the nozel what so ever (as is recomended by a few for petg). Becuse you have to print so slow fir first layer for it to stick to pei, it seems that the extusion at the speed is also thinner thant at higher speeds. Windering if compensating with first layer width is the way to go?
     
  4. Alex9779

    Alex9779 Moderator
    Staff Member

    Joined:
    Sep 4, 2015
    Messages:
    2,405
    Likes Received:
    731
    Just pushes more (>100%) or less (<100%) material... WIth that number you can adjust the amount extruded so if you want to have 100% first layer height for best accurancy in Z direction (if you part height can be divided by your layer height for example) then you can still extrude more to get better adhesion by increasing the extrusion width. But you have to remember that everything is limited by physics, you can't push twice the material through your nozzle for exmaple at the same speed and you won't get a doubled extrusion amount...

    BTW I compiled the S3D Tips of the day from the S3D forums into my Wiki at https://confluence.alitecs.de/display/3DP/Simplify3D
    The tips were not updated for the 3.1.x version but most of the options are still there just the new ones are not described but there are not much new options yet...
     
    AndyVirus likes this.
  5. Jasons_BigBox

    Jasons_BigBox Well-Known Member

    Joined:
    Mar 25, 2016
    Messages:
    232
    Likes Received:
    69
    Errrmmmm...........

    Andy, just read your post and am a bit confused.

    "So to re-iterate. 0.2mm layers.
    Layer 1 starts at Z0.180
    Layer 2 starts at Z0.380"

    That means that layer 1 is 0.18mm - 0mm = 0.18mm thick
    Then layer 2 is 0.38-0.18=0.2mm thick

    If you made layer 2 begin at 0.4 then the layer height would be 0.40-0.18=0.22mm thick

    Is this what you mean?
     
  6. AndyVirus

    AndyVirus Well-Known Member

    Joined:
    Apr 10, 2016
    Messages:
    221
    Likes Received:
    46
    Yes Layer 2 would be 0.22mm thick (according to the printer).
    Then Layer 3 would be Z0.600 so 0.20mm thick and so on...

    Basically runny as hell PETG (cheap) likes not to be touched by a nozzle so ever so slightly air printed. My thought process was/is squish the first layer so that it sticks to the bed (though that has challenges not getting ripped back up with a rubbing nozzle occasionally) then second layer print as you say 0.22mm from the last so not to rub anything being extruded as fine infill is often higher on the first layer than the perimeters.

    I think im barking up the wrong tree anyway as Alex is correct, the relative movement should be sufficient, maybe im over extruding on very fine infill which is the cause. Ill focus on that a bit more. I was thinking i might be able to achieve what i want with 2 processes in S3D but i will fiddle with layer width, height etc a bit more first.

    To be fair its my own fault, I have gone down the Volcano route (0.4mm nozzles), just trying to tame it and it is not as simple as the v6 was. Wanted a challenge and that is what i got :)
     

Share This Page