Wanhao i3, first good prints

After spending ~100 hours fixing and modding a used Wanhao i3 V2.1...

Finally something positive:

First good looking print

Settings: PLA, 60C bed, 215C extruder, CURA, 0.2mm layer height, 0.4mm nozzle, 0.4mm line width, 3mm brims, 2mm 60mm/s retraction, 40 mm/s print and infill speed, 0.4mm extrusion width, 0.8mm walls (2 perimeters), 100% infill, 15% infill overlap, 20% skin overlap, full fan after ~1mm. Excellent layer adhesion, great bridging, good corners, ok first layer adhesion. Still not getting amazing first layer adhesion to the bed with the PEI. Some initial underextrusion on brim (maybe needs more pre-print extrusion). Still has some blobs/strings, but not as bad. Not sure how to get rid of those without dropping temperature and getting poorer layer adhesion. Some ringing, but can't get rid of all of that with this printer...it's just not stiff enough. Overall pretty good though.

Next up, XYZ calibration cube:

This is by far the best one I've made. Similar settings to above, but 25% infill. No drooping on X or Y overhanding points, no overshoot on corners. The only major problem is the banding/lines. These match up with where the extruder rose up at the start of each layer. If I had aligned the Z axis moves, you wouldn't see the bands, but part of one side would be too wide. It looks like the printer is slightly over-extruding every time it starts a new layer, which is causing the first ~10-20mm of that line to be a little too wide. Not sure what's causing that. Maybe too hot, temperature fluctuations (I haven't retuned the extruder PID yet), or the cheapo filament I've been using. May also need to enable retraction at layer change, retract before outer wall, or Z seam alignment. There's also some (very) minor ringing, but I can't fix that without some major modifications. Excellent first layer and interlayer adhesion.

I repeated the above but extruder temperature lowered to 210 C for first ~13mm, then 205 C. The lower temperature helped slightly, but the bands were still there. No noticeable difference in interlayer adhesion strength at 205C, so 215C is likely too hot.

3DBenchy with same settings, but with retract before outer wall enabled and 200 C extruder temperature:

This is actually the second one. The first one failed about ~40% through when the extruder gear's grub screw backed out AGAIN. I put it back in with more loctite and as tight as I thought I could make it without stripping the socket. Anyways, this one worked pretty well. The horizontal banding is significantly less. Arches and bridges came out pretty well. Flag pole holder and smoke stack are intact. The super fine letters on the back of the tugboat mostly resolved. Dimensions are pretty close (height is dead on 48mm). There are a few layers where it looks like it was underextruding, particularly in the cabin, which is the only really concerning thing. This is probably either poor quality filament or the extruder gear again. I checked the extruder by extruding and retracting some...seems fine. There was a bit of stringing/blobbing. I like to run a little hot to get good layer adhesion, so some minor stringing is expected.