While this may work on lower layers, Im still fighting curling higher up in the print when doing overhangs. The outer edges of the overhang will bend upwards to the point where the extruder will hit them. After several layers when the PLA has cooled enough, the hitting becomes violent and will either knock off the model or make one of the axis “skip”.
What Ive tried so far:
- glass bed + blue painter tape = excellent adhesion
- I added a second fan on the other side with a duct, pointed at the extruder tip.
(yes Im using a printed shroud as support for that motherboard cooler 
The fan has a transparent duct that is doing the actual funneling though ).
I had high hopes for this, but it provided not much improvement
I then played around with slicer settings.
- Tried reducing speed, didnt help.
- Tried varying extruder temperature between 185 and 205. No help.
- changing layer thickness from default 0.25mm to 0.15mm, didnt help
- changing layer thickness from default 0.25mm to 0.4mm DID help. Of course, the entire print is much more coarse, to the point of being almost useless, but there is no curling now. In fact, its the opposite, overhangs bend down now.
I will try 0.3mm next and see what happens.
Anyway else have other tips?