Gaps between perimeters on face mask print  

Gaps between perimeters on face mask print

Like others, I wanted to print some fast masks to help local medical people.  I printed one of the Prusa model, but then saw the one from 3DVerkstan here as shown by 3D Printing Nerd Joel Telling: https://3dverkstan.se/protective-visor/protective-visor-print-guide/.  Anyway, while the Prusa design is nice, I figured this one is very simple and can be printed on my Prusa Mk3 in just over 30 minutes.  Given I wanted to print faster, I decided to try larger nozzles.  I got one print done with 0.8mm, but decided I was extruder flow limited, so I might as well just use 0.6mm.   After getting it all re-calibrated, I managed to print several successfully.  Then I started having problems where gaps would be present between the perimeters.  The design is such that with a 0.6mm nozzle at around 0.65mm extrusion width, you will get 3 perimeters and then PrusaSlicer shows gap fill in the middle.  The problem is, it doesn't look like the printer is adding any actual gap fill.  So I started getting two pieces where I should have a single fused piece.   Here are some photos.

Here you see the result in PrusaSlicer where you have an outer perimeter and two more perimeters on each side.   In this case, I had widened my extrusion width until the gap fill line disappeared in the middle.  My initial prints were done using an extrusion width of 0.65mm same as the default config for a 0.6mm nozzle.   The third picture shows the whole thing on the build plate.  This is just after the first or second layer.  It's already showing gaps.  But one weird thing is that the part should be symmetric and yet one side will have a terrible gap while the other doesn't or at least it's a very small gap.  See the last picture where you can clearly see two pieces.  How do I fix this?

I've set the print to 4 perimeters, 0.65mm extrusion width with both 0% and 100% infill.  I've tried widening the extrusion width to 0.72 such that the gap fill disappears in the slicer.   When PrusaSlicer shows gap fill, is it supposed to actually make the printer include that fill?  If so, then it doesn't seem to be doing that.  I really want it to insert the fill.   

How do I fix this?  Any good suggestions?