One thing, however,
The forge cannot be totally open. One aspect of a traditional forge is that it was kept very dark. This makes it easier to read the metal to know its heat. So the forge was fully enclosed, with small shuttered windows and a small door. Any ventilation was done most likely through a hole in the roof. I don't know how chimney technology had progressed by the twelfth century, but I don't imagine your typical forge would have had much beyond this.

And this fits with the typical description, even up into fairly modern times forges were dark, smoky, dirty places.

DLB