On a hunch, try putting a box or something similar over the printer in order to enclose it.
I had a recent post wherein I was asking about a problem I was having with PolyCarbonate. The symptoms seem simlar: good bed adhesion but then the model starts to turn crappy further up with pieces of the fine detail (in my case infill) being broken off by the print head and scattered on the print bed.
I have not revisited it to confirm my suspicions, but it dawned on me that it could be temperature related:
On the bed surface, the filament cools more slowly because it’s on or near the heated bed, but further up it looses that advantage. Further, as you get into the intricate details, the segments being printed are smaller. In your case, the ironwork, in my case the infill. This results in small amounts of extruded filament (carrying heat) being almost completely surrounded by cooler air. The filament looses its heat much more quickly that way resulting in poor adhesion to previous layers. My theory (that I didn’t test), was that if I were to put the printer in a box or enclosure, the air temperature internally would be higher, and new filament would have a better chance of melting into the previous filament and not be flaked off.
I didn’t have anything handy to enclose the printer with, which is why I didn’t test it, but if you give that a try, please let us know the results.