I recently had a problem with a badly printed access hole for a camera lens when 3D printing a prototype case.  I mentioned the problem to fmilburn as he also has an AnyCubic Mega printer like mine.  I realize that these kinds of problems can be caused by many factors - printer configuration, printer mechanics, filament issues, and slicer configuration among others.

 

Printer: AnyCubic Mega-S

Filament:  white 1.75mm PLA (not sure of brand - supplied with printer)

Slicer: Cura 4.1.0

 

I've been using this printer for a few months and hadn't noticed this problem before and it is repeatable for this particular print so I suspected it might be an incorrect slicer setting.  I thought I'd play with the settings first before asking the community for help.

 

Here is a picture of the bad hole.  It has 4 perimeters (walls) and the inner 2 are badly attached.  The stippling that you see is the pattern on the printer's UltraBase heated bed.

Badly Printed Hole

 

I had been using Repetier and Slic3r with my previous printer and am new to using Cura.  I was having difficulty locating the settings that I was looking for until I realized that Cura has different visibility modes that can hide settings.  Modes are Basic, Advanced, Expert and Custom.  I decided that it was best to just "Show All".

 

I think I've figured out what was going on.  I made a couple of changes and the results are much improved.

Hole Problem Fixed

 

The primary problem is that in the Shell settings, Optimize Wall Printing Order was not set.  I selected it in the following menu.  The result was that the inner 2 hole walls would print then the outer perimeter of the part would print and then the next hole wall would print.  The hole problem is not so apparent on smaller prints but if the perimeter is far away the wall separation gets worse.

Setting for Wall Order Optimization

 

Here are 2 videos from the Cura simulator, the first without optimization and and the second with optimization:

 

 

The other setting that I changed was to over extrude by 5%.  This setting can help depending on the properties of the filament.  I had to Google where to find this setting in Cura.  It is located under the Material menu as one would expect, but the setting is called "Flow".  I set it to 105%.

Flow setting in Cura

 

3D printing really seems at times to be more art than science but I guess the fun is in the challenge