I’ve been using Simplify3D with my TAZ 4, and while I’ve been pretty happy with the software, I keep having this issue on my prints. I’ve attached a couple photos that show what I mean. I’m using the ABS - Medium presets with these changes:
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Increased extrusion width from 0.40mm to 0.42mm
Changed filament diameter from 3.0mm to 2.9mm
Increased infill outline overlap from 15% to 40%
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Any thoughts or solutions?
Have you tried increasing your infill?
Looks like your top layers might be ending in a gap in the infill.
Then curling a little when the ABS cools.
I just wonder if increasing your infill might close those gaps and prevent that shrinkage/curl. 
Haven’t tried that yet, though I have increased my infill overlap percentage from 15% to 40%.
Increasing infill by 20% helped, but now that puts me at 40% infill. Makes for a spendier print, that’s for sure.
have you tried to increase top solid layers?
I felt that simplify3d would in the default config put too little top solid layers. Default I think was 2 or 3. I usually do 5 and never had any problems with holes on the top layers any longer.
you specifically get the holes near the walls so it might be a different problem but it’s worth a shot.
