2hotchicks
Songster
I agree. My commercially made automatic door closes VERY slowly, although it is a horizontal sliding door. It also senses resistance & will stop if it detects it. It has stopped closing midway because of litter in the track.Sorry about your problems, but it sounds like it is a matter primarily of design.
I only have experience with one commercial-made auto door (Chicken Guard Premium), but I can't see how it could kill a chicken. It uses a string to slowly raise/lower a relatively lightweight aluminum door (think cookie tray bottom) on a string. If a bird was somehow caught under it, they wouldn't be crushed. Some commercial designs (or home builds) force down the door which might result in crushing.
The thin aluminum door might not sound terribly secure, but it actually works well. It is strong enough to keep out predators and slides up/down in grooves in the frame and there is also a groove at the bottom of the frame so that the door goes down into the groove and a raccoon can't get his claws under it to lift it.
Also, the system can be set to raise/lower manually, based on timers or via lux (light) settings. There are other commercial devices that are very comparable and may have some different features you like. Here is a picture of my setup: