Some shell lines (red) have some yellow in them and these differences also show up in the print

[TomKamphuys 1]

After slicing my model, some red shell lines have a yellow 'artifact'.

 

 

It's not just rendering as it shows up in the actual printed object:

 

 

It's hard to capture on camera, but the 'yellow-ish' lines actually stick out a bit.

 

What causes this and can I solve this?

 

I'm quite new to 3D printing, so please bear with me...

[Torgeir 280]

Hi @TomKamphuys,

 

Welcome in here.

 

Please tell us what printer you you're using as someone with the same printer may give additional info about this.

It's hard to give any advice here, but save your model as a "project" file. Use the "file pane" in upper left corner and share this file with us.  (This file will contain your model and the setting's in Cura.)

 

Then sure, someone will try to help you.

 

Thanks

Torgeir

 

[TomKamphuys 1]

I have an Elegoo Neptune 3 Pro. It's not dependent on the physical printer, as it is already present in the layer view.

 

I attached the file.

Petal.3mf

[TomKamphuys 1]

Maybe this is a clearer image. It is another model, but it exhibits the same problem.

 

 

N.B. This is a zoomed in image of the transition area, which can be seen in the center part of the part below:

 

 

The outside does not have these yellow lines in the Cura:

 

And the print in noticably cleaner on the outside:

[GregValiant 1,409]

Hello @TomKamphuys.  I've used your Petal model here.

It is the nature of FDM printing that when a surface is "nearly" horizontal there will be "steps" between the different layers.  The width of the steps is determined by the angle off the bed, and the layer height.

When your wall width is less than the step width then Cura fills in with top/bottom skin.  There is no way around that.

You can try increasing the wall count/wall width or enabling "Adaptive Layer Height".

There are going to be steps though because TAN(90-AngleOffTheBuildPlate) * Layer Height = Step Width.  If you want the step width to be "0" then you would need to print at "0.00" layer height and the print time becomes infinite.

This is sliced at 0.08 layer height.  Note the step width.

 

and this one is sliced at .35 layer height.  You can see how much "coarser" it looks.

 

You cannot slice a model with "Adaptive Layers" if the model is off the build plate.

[TomKamphuys 1]

Thanks for your answer. And although it is affected by the layer height, it is not the only element at play. In my case it happens also quite a bit higher up where the layers are much more directly on top of each other.

 

Here is a comparison of (slightly) other model, sliced in a different Cura version and with a different printer (so perfect for comparison...) :

 

 

I think I finally succeeded in capturing the transition clearly.

[GregValiant 1,409]

Load that model that printed poorly into Cura.  Set up your slice and use the "File | Save Project" command.  Post the 3mf file here and I'll take a look.

[TomKamphuys 1]

I already posted that 3mf file and you used it already 🙂

[GregValiant 1,409]

It opens for me as a 3mf model file.  There are no Cura settings or printer in it.

[TomKamphuys 1]

I think I did what you told me. Strange.

 

In the mean time I have found what triggers it:

 

Changing the ironing pattern between concentric and zigzag, turns the yellow artefacts on and off. So keeping the ironing at zigzag solves the problem. Selecting 'Iron only highest layer' also solves the problem (even with concentric ironing).

 

Is this expected behaviour?

Edited February 5, 2023 by TomKamphuys

[GregValiant 1,409]

"Is it Expected Behavior...."

If it's the way it works then yes, it's expected behavior.  Cura is a complicated program with a lot of options and a fairly steep learning curve.  When there are settings in place to mitigate a problem then my point of view is that it's up to the user to figure it out.  The tools are there, it's sometimes tough to tell which wrench to grab.

 

"There is no "Easy" button in Cura." - Me

 

Nice job figuring it out.

 

[TomKamphuys 1]

Thanks for your time and effort.