PLA curling LATE in the print?

I have PLA prints that end up curling if they are taller than say 35mm (z axis, of course).

I am using clough's print cooler, but running a 12v fan at 5v. It's not a whole lot of air.

210 on the nozzle, 70 on the bed.

Anything jump out at you? I'm watching a print that is going right now. It's 56.75mm tall at the moment, and the corner closest to me has curled up off the bed by at least 7mm.

Thanks guys

what infill % are you using

Also post a pic of what your trying to print

I had it at 40% infill, but it actually made this last one solid. I guess there wasn't enough room. I'll take pics later. After looking at dunginhawk's layer fan thread, it looks identical. It's even the same corner. Front left (furthest from the board). Might be related.

the more infill the more curling you will get. because there is more heat trapped in the plastic, and as it cools it will curl.
if you need 40%, which is a LOT thats fine, but id try 15-20% just to test to see if it still happens.