So after extensive re-organisation of the studio, I spent a good chunk of yesterday figuring out how to weave Krokbragd on a rigid heddle loom, with two heddles:
My word, I think I've got it!!
Krokbragd is a weft-faced weave woven on three shafts. Just like with the 2-1 twill I experimented with a while ago, a rigid heddle loom with two heddles on it has three shafts. A 'regular' loom needs a harness for every shaft it uses; the rigid heddle gets an extra one for free, because the threads that pass through the holes in the heddle can be pushed down as well as pulled up, leaving the threads in the slots behind. With two heddles, a thread can pass through slots alone (let's call this shaft 1), through the front hole and the back slot (shaft 2), or through the front slot and the back hole (shaft 3).
Krokbragd is threaded on a four-thread repeat, over the three shafts, in a pattern that repeats 1-2-3-2. That looks like this on our rigid heddle threading:
Use a 1-2-3 lifting pattern, and you get something like this: