Slicer Holes w/ Single "Wall Line Count"

[SefPinneyStudio 4]

Cura 4.4.1

 

I feel I'm missing some setting, and have read Cura may be limited somehow with single wall shells?  Therefore needing Spiralize?

 

I thought designing an .STL to Exact Nozzle thickness was recommended.   However I have two possibly related problems.

Problem #1:

Layer Height is disabled with .8mm UM nozzle and UM CPE+.  There is no ability to change the slider, but neither does it indicate WHAT the layer height will be.  It CAN be changed in Custom... but I'm trying to print only with UM recommended settings. See Greyed Out.

I have tried deleting Configuration Folder.

 

Problem #2:

1. 0.80mm for the Line Width causes the slicer to introduce major holes.
2. 0.78 is less bad
3. 0.75 Slices well.

 

The part has EXACTLY .8mm walls.  See Black 0.80 dims from Rhino.

 

This corresponds with .05 less Line Width than Nozzle Diam: 0.80 ---> .75 Line Width. 

But shouldn't Cura correctly slice a .8mm wall, with Recommended defaults?   This is such a PITA moving target!  I am willing to design / optimize a Solidworks part for the Nozzle width... but not if even THAT doesn't slice as Logically expected. 

I'm worried this a feature and not a bug.

 

Can the community help identify why .8mm walls won't slice with .8mm nozzle?  Pulling my hair out.

Edited February 4, 2020 by SefPinneyStudio
Added Cura Version

[burtoogle 501]

Cura does not cope well with walls that are not close to an even number of line widths wide. To be honest, it's a mess. You may get a reasonable print if you set the following. Line width to something less than the wall width (i.e. 0.6 in your example),  overlap compensation on and mimimum wall flow to at least 50%. YMMV.