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I made a model for my 3D clock. Model has few vertical holes so I made one layer thick bridge for every hole. In Fusion 360 everything looks fine, but CURA (version 3.6.0) doesn't want to print those Bridges. Why?

The Full Wall is 1.68mm thick(in Fusion), infill is 20%, wall line count is 1, layer height is 0.28mm, the support-bridges are designed to be this thick too.

I'm not sure will be material stable above holes without Bridges.

Bridges in Fusion 360

Model in CURA 3.6.0

Hole at close

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  • $\begingroup$ what's the line width and the width of the wall that should be printed there? $\endgroup$
    – Trish
    Commented Feb 2, 2019 at 17:28
  • $\begingroup$ In Fusion walls are 1.68mm. Those Bridges are 0.28mm thick(same as layer height). $\endgroup$
    – Pararera
    Commented Feb 2, 2019 at 17:32
  • $\begingroup$ layer height is Z thickness, you need to check Line Width, which is XY thickness. $\endgroup$
    – Trish
    Commented Feb 2, 2019 at 17:33
  • $\begingroup$ While this isn't quite relevant to the question as asked, it looks like you are attempting to design supports for the top of the hole in your CAD program, which you will then remove after printing. I would not recommend this approach, but instead use your slicer (CURA) to generate the needed supports. These will be placed where they are needed, and should be easier to remove from the model. Alternatively, you can design so that you don't need supports (or as much). In the case of horizontal holes like these, you might make a "teardrop" shape that limits to overhang angle. $\endgroup$
    – mbmcavoy
    Commented Feb 4, 2019 at 19:35
  • $\begingroup$ @mbmcavoy This "custom made support" is one layer thick(0.4mm), can't be thicker than this. Hole is tear drop shape because slicer cuts end of the hole. Why I did those supports? They use less time and material to print. Also, wall is less than 2mm thick. $\endgroup$
    – Pararera
    Commented Feb 4, 2019 at 19:41

1 Answer 1

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Nomenclature help

  • A Layer is everything that is printed between the print head moving upwards.
    • Layer height is how tall each line is. It is in Quality.
  • A Wall is made up from lines put down next to each other.
    • line width is how thick a 1-perimeter-strong wall is in the XY-plane. It should never be smaller than the Nozzle Diameter. It is in Quality.
  • Nozzle Diameter is what is the physical diameter of your nozzle. It is located in the printer configuration.
  • A Bridge is printing horizontal layers that connect to walls at the sides but otherwise not connected to the printbed or print.

A simple bridge

Ultimaker Cura does ignore too thin walls

Your walls are 0.28 mm thick and your nozzle is most likely 0.4 mm thick. That can't be printed at all, in fact, you are way too thin to be printed: a printer should never print any object that is thinner than its nozzle as that is a perfect way to generate clogs.

Atop that, slicers ignore also what is thinner or exactly as thin as the line width. If the line width is 0.4 mm, and the wall is 0.4 mm, it gets ignored. If the wall is 0.45 mm, it is not. This can be remedied by setting the option print thin walls, but you still need to have one line nozzle-diameter as minimum line width - actually it is common to go about 10% larger for better extrusion.

Solution

Strengthen the walls to one line width (usually 0.4 mm) in your CAD-design and activate print thin walls under Shell.

A design with too thin walls

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  • $\begingroup$ Why? If is layer round(since noozle is round) and diameter of layer is 0.28 mm. Why it can't print 0.28mm wall? $\endgroup$
    – Pararera
    Commented Feb 2, 2019 at 17:35
  • $\begingroup$ @SilvioCro Layer Thickness is height in Z. $\endgroup$
    – Trish
    Commented Feb 2, 2019 at 17:39
  • $\begingroup$ Is 0.56mm too much for bridge? $\endgroup$
    – Pararera
    Commented Feb 2, 2019 at 17:46
  • $\begingroup$ @SilvioCro I added a nomenclature touchup. 0.56 mm is perfectly fine. $\endgroup$
    – Trish
    Commented Feb 2, 2019 at 18:16

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