I would like to open and close the door with the push of a button (and eventually cat + RFID tag). At first, I thought of a servo system, but I'm wondering if it is the right approach?
Could it be a magnet? When the door has to be opened, no power; when the door has to be closed, a lot of power then gradually less, only to keep it closed -- but it would have to be very strong to close the door when it is fully open.
What would be the best approach? The drywall is already done and I'd like something "external" if possible.
maybe a cogwheel connected to a continuous servo? place a grid on either the door or the wall and then mount the servo with the toothed-wheel accordingly so it can pull or push the door?
alternatly a pully system with a stepper motor or (again) continuous servo?
I think finding a magnetic solution might prove quite elaborate, and while it would be cool, its probably not worth the effort. (except you want to learn how to build magnetic doors, which I do find quite cool
I would like to open and close the door with the push of a button (and eventually cat + RFID tag). At first, I thought of a servo system, but I'm wondering if it is the right approach?
Could it be a magnet? When the door has to be opened, no power; when the door has to be closed, a lot of power then gradually less, only to keep it closed -- but it would have to be very strong to close the door when it is fully open.
What would be the best approach? The drywall is already done and I'd like something "external" if possible.
Thanks!
For a magnet, you can get electromagnets that are designed to hold doors open. You could use springs to make "open" the normal state for the door, and have the magnet hold it closed. You could also add some sort of hook on a servo, so that you could turn off the power to the magnet and still keep the door closed.
Your best bet would probably be an actuator, or some sort of string and pulley system, mounted to the top of the door. If you look around on instructibles.com and youtube, a few people have made automatic sliding doors that mimic the ones from Star Trek, you could probably get some ideas from those.
The below shows a setup for reversing a motor using relays with limit switches. It will be a challange to rig a motor to move the door (looks like a sliding door), especially if you still want an option to operate it manually.
Put a damper between the door and the wall, so that if you gently pull on the door it slowly opens/closes rather than slamming open/closed.
Put a linear actuator on the wall, with enough travel to fully open and close the door. Connect the actuator to the door using a spring that has enough travel for the actuator to be 'fully open' while the door is closed, and vice-versa. The actuator could be as simple as a motor/pulley and an end stop with a switch in it; no need for anything fancy, it just needs to go to the 'fully open' or 'fully closed' positions and then stop there.
If you get the spring and damper rates right, the door will smoothly accelerate across the opening and then slow to a halt as it reaches the end of its travel.
To control it, you need a proximity sensor. Perhaps you could use a PIR sensor? Open the door when it detects movement, and let the door close if there is no more movement after a while.
Put a linear actuator on the wall, with enough travel to fully open and close the door.
is there such a thing as a linear actuator that can open a human door which has a pricetag that allows it to be used in a DIY project? if so, can you post a link?
fkeel:
are we talking about a cat door, or a human door?
Put a linear actuator on the wall, with enough travel to fully open and close the door.
is there such a thing as a linear actuator that can open a human door which has a pricetag that allows it to be used in a DIY project? if so, can you post a link?
If it was my project, and given that the majority of the hardware would need to be custom made/adapted to fit. I'd use a small motor with gear reduction driving a pulley on one side of the doorway, with a cord looped around an idler pulley on the far side of the door. But I'm sure there are easier ways to do it (although more expensive) using automatic curtain opener components. It wouldn't be a huge job to make a worm drive a couple of feet long out of a piece of studding. It needn't be expensive, although of course it would also be possible to spend a lot of money on it.
A lot depends on how good your particular pocket door hardware is. With inexpensive or poorly installed hardware a project such as yours would be nearly impossible since the door will be hard to move. With good hardware, properly installed, it takes almost no effort to move the door. Your approach will also depend on how much destruction you are willing to do in order to get inside the pocket and what you will find once you get inside. If you didn't install the door yourself then you ought to consider how they mounted the picture and the towel bar in the photograph you linked to.
Somewhere on the net you might find info on the auto opening doors like in large stores to see how they work. Natures warning sign is that you don't see much in the way of working DIY sliding doors on the net (but I haven't really searched).
The KISS method would be a tooth rack on the door, a 25 RPM gear motor mounted to the frame, and a limit switch at each end.
A way to engage/disengage the gear (servo or solenoid) should also be included. Disengage the gear when not being moved by the motor so the door can be operated manually. I think servocity has gears and gear tracks at a reasonable price.
