Yeah, the guy who did it successfully and posted videos (I posted his thread on here) designed it so that all of them had to be on the lever roost for the door to close. I think maybe plus/minus one or two birds, but by the time all but 1-2 are on the roost, likely all are already inside.
I think the way he designed his mechanism, it seems to be working just fine. If he put a tall lip in front of the chicken door, predators shouldn't be able to lift it up easily (unless they figure out to put flat palms on the door itself and use friction to slide it up...). One potential issue I see is that the mechanism is so tightly tied to the weight of the birds and their exact number. What happens if a few birds die or more are added? Seems like a lot of adjusting, but if your flock size is constant, that wouldn't be too much work.
I think the way he designed his mechanism, it seems to be working just fine. If he put a tall lip in front of the chicken door, predators shouldn't be able to lift it up easily (unless they figure out to put flat palms on the door itself and use friction to slide it up...). One potential issue I see is that the mechanism is so tightly tied to the weight of the birds and their exact number. What happens if a few birds die or more are added? Seems like a lot of adjusting, but if your flock size is constant, that wouldn't be too much work.
