I'm trying to open a door. More precisely, I'm trying to design a mechanism to open and close a door mechanically which also allows me to open the door manually.
Now, I thought this would be fairly straightforward - just a simple servo, a rod, and an arduino then I'd be good to go. Easy Peasy.
But man, the more I try to think this I find I have to keep throwing out designs.
For instance, the problem with the basic servo idea is that I'd also like to be able to open and close the door on my own, without use of the mechanism. And, from my (admittedly very limited) experience with servos, I think this poses a problem. All the places I've read say that you shouldn't rotate a servo's arm manually - it can damage the gearing inside. If I'm trying to have a long-term installed mechanism, then the odds are pretty darn good I'll end up breaking things. (Plus, if it's just a direct attaching of the servo arm to the door then there's also be resistance from the arm against me pushing the door open).
So now I'm trying to find ways to design this thing. But my mechanical knowledge is every bit as limited as my servo knowledge... so I'm asking for help.
I have a few questions that hopefully the SE folks can answer:
- Does anyone know of a mechanism design that would allow for the door to be openable both mechanically and manually? I have found designs like this, but am not sure I'd have the ability to build something with that many moving parts. Is there any way to build this more simply?
- Are there any resources y'all could point me to to learn about designs for things like this? I've gone looking for a database or library of mechanisms, but don't know where to start.
- Dumb question: does anyone know of a servo model where the arm can freely be rotated manually? That'd.. actually be the easiest option.
- Anything obvious I'm missing in a plan like this?
I've looked at linear activators, too, but from everything I've seen they have the same problem as the servos. A simple solenoid could push the door open, but I'm not sure there's a way to make sure it can close it.
Note that this is a door that opens inward on a hinge (so your standard bedroom door).
Thanks for your input, and happy to answer any questions