Bad top surface & Gap between outer wall and infill

[tasopoulos 40]

Hey all. About a week ago I started getting really bad results with my prints: the top surface is always ugly (not flat and with some gaps) and in many cases the outer wall is not touching the infill. Take a look:

After reviewing 3Dverkstan's troubleshooting guide (plus a lot of posts here), I tried playing with bed levelling, material flow and/or speed, I checked my short belts (they are quite tight) but nothing worked. I've been using a 0.4 nozzle, printing 0.8 walls, bottom/top thickness is 1mm, infill is 20% and infill ovelap is 20 (let me know if any more settings are relevant for this type of issue and I'll post them here). Any help would be appreciated, because I didn't recall changing anything on my configuration and it really is driving me crazy! Thanks in advance, guys and gals.

[yellowshark 153]

Not easy to absolutely sure from the photo but looking at the walls you do not seem to be suffering any under-extrusion.

The first thing I would suggest is to try another filament. I once had a similar problem with a Faberdashery white - not Arctic white - with gaps between wall and infill. A different colour fixed it immediately.

I have no experience in printing letters but I would be inclined to try it real slow, 20mm/s max - maybe use 100% infill, I suspect impact on time and material used would be minimal with that geometry.