When we were making tempeh commercially we used a motorized Corona Mill for dehulling. We warmed up the soy beans first in a peanut roaster to make them softer. After cracking them we used a seed sorter to blow off the hulls.
I have always wondered whether a more dust free method could be designed and recently experimented with this basic idea. (It might also produce fewer small pieces)
A drum with a rough surface rotates and the beans are squeezed against an ever narrower opposing piece. A brush cleans out the pieces that adhere to the smooth surface.
To run a test I used an old bicycle wheel (of course you would want something wider eventually) and cemented the middle of the rim. As the opposing plate I just cut a piece of plywood to the same curvature with a slot at the top.
The beans were soaked for 24 hrs and then dropped in while the wheel rotated.
It worked just fine and I would pursue this design if I had to use whole beans.
A minimum of water could be used if the beans and skins were dropped into a bucket of water and were floated off, using a recirculating pump with a filter.