closing a door?

Hi all,

Any suggestions to close a door that's been pushed/pulled open by a small animal (i.e. cat or dog)? I was thinking about a spool of thread attached to a servo with the thread's free end attached to the door - cat pushes the door open, pulling on the thread causing it to unspool, servo reels it back in.

However, the door cannot have any pressure making the cat unable to open the door from either side, so the servo idea won't work without something like a clutch which would allow the spool of thread to unspool freely, without resistance/drag. Then, with power applied to the clutch the servo would make the spool wind. I can't find any 3v clutches, only some small 12-24v ones on ebay.

Other approaches to this besides "get rid of the cat"?? :wink:

Thanks,

Bret

What is preventing to door from closing?

Perhaps posting a picture of the door, from both sides?

Use gravity for the major closing of the door. Maybe a solenoid pulling a spring could do the rest.

Our cat door is closed by gravity and it has a small magnet to hold it closed by pulling on a piece of steel embedded in the bottom of the door. Perhaps you need a different type of door.

Paul

To avoid resistance to opening, you use an arm separate from the door and a gearmotor. You will need limit switches - which you needed anyway to detect when the door was opened.

When you determine that the door needs to be closed - presumably once the cat clears it - you drive the arm against the door to push it closed, then drive it back to its resting position clear of the door.

@Paul__B. If the most interesting thing is excercising a controller, You are perfectly right. If the Project is solving a practical need, I wote for the proposiol from @Paul_KD7HB
Keep it simple.....

Railroader:
I vote for the proposal from @Paul_KD7HB

But that does not involve an Arduino!

bschuhma:
However, the door cannot have any pressure making the cat unable to open the door from either side,

The OP seems to have made it clear that "any pressure" includes gravity and magnets.

bschuhma:
Other approaches to this besides "get rid of the cat"?

Obviously the most practical. :grinning:

I repeat myself.
@Paul__B. If the most interesting thing is excercising a controller, You are perfectly right.

Who knows? Perhaps the OP will re-visit us? :astonished:

Have You heard about the Colombie egg? How to make an egg stand up? Thinking outside the box I Think we can say.

@OP Wellcome, exercising cats or Arduinos.

Use a weight , piece of string and a pulley to close the door .

bschuhma:
I can't find any 3v clutches, only some small 12-24v ones on ebay.

Why does it have to be a 3v clutch?

... because it’s a 3V cat ?

Our cat can write better code than most newbies* here.
(Don’t ask for proof

Idahowalker:
What is preventing to door from closing?

Perhaps posting a picture of the door, from both sides?

I should've mentioned this is a standard interior bedroom hollow-core door. Nothing's preventing the door from closing except that domestic interior doors don't have springs or hydraulics like commercial doors often do. And if it had springs or hydraulics to force the door closed that mechanism would be too strong for the animal to push or pull it open.

The goal is to not modify the door - I'm leasing. The door should operate without resistance, as normal. About 5-10 seconds after the door opens it should close. I envision it being pulled shut since the door won't always be pushed open the same distance for a push mechanism to reliably make contact. Plus, adding a push mechanism will require more holes in the wall (remember, I'm leasing).

I mentioned 3v clutch because I wanted to run it off the board and 3-5v is all we have. I don't want to run multiple power supplies. Ideally I'd be able to run it all off a lipo.

Is this a standard size people door, or a "cat flap" in a door? If it is a people door, put a cat flap in it.

Make sure that the closing mechanism is not strong enough to trap the cat in between the door and the frame. Or, worse, have you end up with two half cats instead of one whole.

zoomkat:
Is this a standard size people door, or a "cat flap" in a door? If it is a people door, put a cat flap in it.

Standard size people door... I can't modify it as I'm leasing. I also have a dog that uses the door and doesn't have the manners to shut it, so I'd have to install a large dog door. Again, can't modify the door.

wvmarle:
Make sure that the closing mechanism is not strong enough to trap the cat in between the door and the frame. Or, worse, have you end up with two half cats instead of one whole.

We'll, 2 half cats are better than one whole cat, right? I'm sure my wife would disagree, though!

bschuhma:
Standard size people door... I can't modify it as I'm leasing. I also have a dog that uses the door and doesn't have the manners to shut it, so I'd have to install a large dog door. Again, can't modify the door.

Why not?
You may have to give your landlord a new door when you move out but that isn't that expensive, really.

look at spring closer that attatch by hooking over the pin on the hinge.

a simple motor
rotate to close the door
retract and wait.
you could use a pot to sense the door position.
easy to install and remove and no marks or damage.