Strange infill layer before solid part begins in Cura 2.4

[purps 9]

Hello all, apologies if this has been covered elsewhere, I'm probably not searching with the right terms.

Why at the top of this internal feature, which should be the first solid layer that bridges the gap, does Cura do one solid layer, then a few infill layers, and then go back to what I believe to be the "proper" solid layers, then the main infill after that? Sorry if that doesn't make sense, hopefully the pictures make it clearer.

The strange infill is shown by the pink arrow, and the other two images show the model in CAD. It is a simple circular cutout, and the red part is just support structure.

The problem is that when I remove the support structure, I find it very hard to not damage the first single solid layer i.e. the uppermost inside face of the cutout.

Any and all help much appreciated.

Matt.

Edited April 3, 2017 by Guest

[DaHai8 74]

From your photos is looks like that first 'fake' solid layer is too wide for the top of the arch and really is not supposed to be there.

My guess is there is an error in the .stl file. If you look at in in x-ray view in Cura are there any Red areas? Those would be issues with the model.

You can test your STL file in some web-based STL repair tools, like MakePrintable, to see if there are any issues with it.

[purps 9]

Thanks for the reply. I think I have resolved the issue, or at least fixed it in this case.

I started by loading the STL back into my CAD program, and I couldn't see any obvious issues. I also checked the X-Ray view in Cura as per your suggestion, but couldn't see anything wrong.

It turns out that it was due to having a solid "roof" on my support structure. When I changed it to a rib design, this strange single initial layer went away, and Cura interpreted the area appropriately as per the settings.

The images show the 3 layers in question - no strange infill.

Cheers,

Matt.