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Answered Advice to Print Better Tops of Curved Surfaces or Spheres

Discussion in 'Troubleshooting' started by 3DMan, May 14, 2016.

  1. 3DMan

    3DMan New Member

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    Any advice to get a full curved surface without gaps? I have been able to get better results by increasing resolution (decreasing layer height) as the printer approaches the tops of curved surfaces or spheres.

    The same phenomenon occurs when printing spheres. The only thing that helps is to gradually decrease layer height down to 50 microns for the top of the sphere to successfully print. It was manageable (the top portion of the outside looked good but the top portion on the inside had imperfections.) Any other tips? How are you all printing cuved surfaces that have overhangs or spheres? For a while, to decrease time, I was just printing without the top portion included, but now I want to print the full curved surface or sphere with good quality.

    Also, for the pic shown, I am printing with full supports inside the circular shape and below it (note the bottom is actually shown on the top of this picture). It's also at a rather low 0.3 mm layer height. It's almost as if it is a layer height/resolution/slicng issue because you can only capture so much of a curved surface with a finite layer height. This may just be a problem with 3D FDM printing in general, though.

    Any helpful tips would greatly be appreciated. Also, my printing nozzle is 0.4mm in diameter. I could probably buy a smaller nozzle for more resolution, but I am wondering if anyone else is able to print high quality curved surfaces/spheres with their stock Robo 0.4mm diameter extruder.

    For this part, it has to be printed vertically, which is why I was using supports. I know there are multiple ways of printing this. I could just print this as a seperate feature and manually add it to my print later (rework). For the purposes of this post, I would just like tips on printing better curved surfaces/spheres.

    Thanks in advance.

    Curved Surface Overhang.JPG

    UPDATE: NEW QUESTION ADDED SO OTHERS CAN SEE IT MORE EASILY

    This next question relates to printing spheres in Simplify3D or S3D. I figured I would add it to this thread, though. I often see the slicer starting a layer in open space. I don't know why they don't have it set to just keep going around the edges. You would think it would make more sense, like how the spiral vase setting goes. Unfortunately, you can't have supports with that setting. I am trying to make a sphere that is several inches in diameter, and I would rather not have to print a support just for the very last tip of the sphere. How do you all handle this? Have you seen this occur?

    Simplify3D - Starts Layerin Open Space.JPG

    Simplify3D - Starts Layering Open Space2.JPG
     
    #1 3DMan, May 14, 2016
    Last edited: May 15, 2016
  2. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    What slicer?
     
  3. 3DMan

    3DMan New Member

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    Hey Mark, I'm using S3D.
     
  4. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    I'd start by calibrating the extruder then. You are likely under extruding.



    If that doesn't help we can review your other settings.
     
  5. 3DMan

    3DMan New Member

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    OK, thanks. I have calibrated the extruder before (thanks to the forums, referencing that very video! Great video btw!) and have gotten it calibrated very closely. The thing is that I usually see these "defects" present in the slice. Usually, decreased layer height helps, but it seems like others are able to make curved surfaces/spheres with a constant layer height. For example, here is a screen-shot of the slice, using 0.3 mm layer height.

    Curved Surface Overhang from S3D.JPG

    Here is the same with 0.05 mm layer height, but you can see that the issue is still present (bottom).

    Curved Surface Overhang from S3D 0.05 mm Layer Height.JPG

    I have also thought that perhaps my resolution on the .stl file is too low ("garbage in = garbage out").
     
    #5 3DMan, May 14, 2016
    Last edited: May 14, 2016
  6. 3DMan

    3DMan New Member

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    Watching that video again, around the 7:20 mark, he talks about extrusion multiplier. Maybe I should play around with that.
     
  7. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    How many layers thick is the top shell.
    From this angle it looks like it is only printing one layer.

    If the layers get too thin (or the model gets too thin for the layer height selected) then things will fall down.

    Hard to say from a single picture if this is a modelling flaw or the slicer dropping the ball.
     
  8. Robert Foreman

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    What do you have your top and bottom layers set at? I never go below 3.
     
    #8 Robert Foreman, May 14, 2016
    Last edited: May 14, 2016
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  9. 3DMan

    3DMan New Member

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    So the entire part is 2mm thick. I have 0.4mm diameter nozzle, and I was printing at an extrusion width of 1mm, so that I could save some time and only make two passes. I have been playing around with this setting in S3D, and it definitely makes a difference. Here is a picture using a 0.4mm extrusion width and a 0.05mm layer height. It looks worse to me.

    Curved Surface Overhang from S3D 0.4 Extrusion Width, 0.05 mm Layer Height.JPG

    Thanks for the reply, Robert. I was using 0 solid layers for top and bottom. I don't remember why I chose this setting. I think I was trying to avoid infill looking portions across the curved surface? Here is what it looks like with 0.3 layer height, 1mm extrusion width, and 3 layers solid top and bottom.

    Curved Surface Overhang from S3D 1 Extrusion Width, 0.3 mm Layer Height, 3 Solid Layers Top-Bot.JPG

    Here is what it looks like with 0.1 layer height, 1mm extrusion width, and 3 layers solid top and bottom.

    Curved Surface Overhang from S3D 1 Extrusion Width, 0.1 mm Layer Height, 3 Solid Layers Top-Bot.JPG
     
  10. 3DMan

    3DMan New Member

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    Here is a cross-section of the slice when I was using 0.3mm layer height, 1mm extrusion width, and 0 solid layers for top and bottom. I guess you have to have some solid layers or you will have gaps when the curved surface/sphere approaches the horizontal.

    Curved Surface Overhang from S3D 1 Extrusion Width, 0.3Layer Height,0 Solid Layers Top-Bot X.JPG

    Here is a cross-section using 3 solid layers top and bottom.

    Curved Surface Overhang from S3D 1 Extrusion Width, 0.3Layer Height,3 Solid Layers Top-Bot X.JPG
     
    Robert Foreman likes this.
  11. 3DMan

    3DMan New Member

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    I will give this a shot using solid layers this time. I can't remember why I had it set to 0. It may have been for time savings or that I thought it made other portions of the print unsightly. I will do a reprint, and see if it is improved. Thanks all. If you have any other suggestions, please do not hesitate to post them! I love this forum.
     
  12. 3DMan

    3DMan New Member

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    I think I may have been trying to duplicate the vase setting because of its speed? Do you all typically use solid top / bottom layers when printing curved surfaces and spheres?
     
  13. Robert Foreman

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    I do. Most of the time I will increase the top and bottom for curved to 4 or 5.
     
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  14. WheresWaldo

    WheresWaldo Volunteer ( ͠° ͟ʖ ͡°)
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    I am going to jump in here with one observation just based on the last couple of posts. @3DMan unless your multiplier is very large there is no way to have an extrusion width of 1 mm with a .4 nozzle. Your extrusion width using normal extrusion height and multiplier is probably somewhere between .45 mm and .6 mm. When you tell S3D your extrusion width it uses that number to calculate other print parameter and just how many passes it needs for your selected layer. By telling it your width is 1 mm you are nearly halving the number of passes required to fill in the space and leaving gaps in their place. Also you cannot do curves or spheres with no top layers unless you are using nearly 100% infill, which I assume you are not.

    This is a quote directly from Simplify3D's webpage
    Unfortunately they give you very little documentation on this parameter. I think they expect you to use their automatic setting rather than putting in a specific number. The default S3D seems to use is 120% of nozzle diameter.
     
    #14 WheresWaldo, May 15, 2016
    Last edited: May 15, 2016
  15. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    Agreed and the automatic setting works well.
     
  16. WheresWaldo

    WheresWaldo Volunteer ( ͠° ͟ʖ ͡°)
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    I did find this document which appears to be a compilation of tips that have been gathered from various Simplify3D forum posts. It is a rather nice guide, but I cannot verify 100% correctness. It has a much more in depth description of extrusion width and how it affects printing.
     

    Attached Files:

  17. 3DMan

    3DMan New Member

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    Interesting, thanks for attaching that .pdf. It seems like a great read, but I am confused about what you are saying. I visually can tell that by increasing the extrusion width setting, it is increasing the width of each "line" it puts down. It was my understanding that by increasing the extrusion width, it would extrude more filament to account for the increase, which would result in a larger width on the build plate. I can see a definite difference in width when I have the settings set to auto vs 1mm, etc. The reason I noticed this setting, in fact, was because I had noticed in the beginning that the Matter Control software had wider lines on the top and bottom surfaces of a cube I had printed vs the same cube printed via S3D. By increasing the extrusion width, it seemed to print wider lines, and I eventually got the same look I got with Matter Control.

    For this print, I had increased the extrusion width to decrease the amount of printing time. I thought that if the extrusion width was 1mm, for a 2mm thickness, it would halve the amount of passes, taking less time to print. This is verified by the time estimates given in S3D for various extrusion width values. When I measure my thickness, it's pretty close to being 2mm thick. It has two passes, and my nozzle diameter is 0.4mm. Perhaps, it prints more accurately if the nozzle diameter is larger as opposed to saying print 1mm with a 0.4mm nozzle diameter?

    Also, I have updated my initial question, with new one that is related to S3D. Sometimes, the S3D slicer will start a new line over open space (see 1st post again for picture). If anyone has any advice for this, I would greatly appreciate it. I have changed the extrusion width to "auto" to see if that makes a difference, but it still will show parts being extruded over open air. Thoughts? Thanks for all of the feedback! I am continuting to experiment with settings.
     
  18. WheresWaldo

    WheresWaldo Volunteer ( ͠° ͟ʖ ͡°)
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    I believe increasing line width only decreases the speed at which the head moves and it still extrudes the amount calculated, but extrusion multiplier determines how much it actually extrudes. Two key passages in that tips document should lead you to the same conclusion
    and the second
    I can only assume this reduction in speed happens automagically, since I rarely play with line width preferring to leave it at a specific value.
     
  19. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    It is not automagic (AFAICT) ... if you manually set/override one I think you have to do the other.
     
  20. WheresWaldo

    WheresWaldo Volunteer ( ͠° ͟ʖ ͡°)
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    I wasn't sure since the wording of the first passage is contradictory in two consecutive sentences, It can't AFFECT if you need to DO IT YOURSELF.
     
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