Automatic chicken coop door.

Do you guys think this design will work? I based it off the Z axis of RoBo using a threaded rod to raise and lower the door. A small Arduino board will control it using a light sensor to activate it at sun up and sun down. Li,it switches will stop it at the top and bottom.




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Would work in principle. Though a linear actuator would be faster acting and probably comparable in cost to the motor + accessories to turn circular motion into linear

 

Is there any risk of squishing chickens? In that case, you'll need a safety sensor. Also, is there any worry of chickens being trapped on the wrong side of the door?

 

I have thought of a sensor but I don't think it will be nessesory. The door will open and close slow and they all go back to the coop before dark because that is where they feel safe. I can just set the Arduino to close 15 min after dark.

Not sure about a linear actuator but I will look into it. The one thing I like about this design is that the threaded rod will hold the dorr closed to keep preditors out.

 

JDM, that is a interesting idea you have, you should consider marketing it? Maybe on Shark Tank. LOL
Could even be used for pet doors. Here in Florida every critter knows that a pet door is an open invitation to dinner.
Another possible solution to making the door safe would be attaching the threaded rod to a block that moves up and down in a slot in the door, allowing the door to hang on the block instead of being attached to it. This way the chicken would only have to contend with the weight of the door and not the pressure of the drive linkage pushing down on them. When closed the block will continue to move down to the end of the slot before hitting the limit switch thus holding the door down. At a slow rate I would think that a slot of a couple inches would be enough. Great project for a 3d printer.

 

Can anyone recommend a type motor for this project?
I don't know much about motors and I'd like to get one soon... It will only have to life a 1/2" thick piece of plywood.

 

You need to determine the max load the stepper motor will see, then select a motor that can handle that torque. Calculating max torque involves unwrapping the the screw thread to form a right triangle, accounting for friction and the weight of the door as the motor pushes the load up or down the hypotenuse. The equations for these calculations can be found at: "http://en.m.wikipedia.org/wiki/Leadscrew"
under the Mechanics section. The site explains things nicely but the math is intense.

However, I have found in designing control systems, calculations only get you in the ballpark. A simpler method to determine the torque, would be to build the door. Then use a good torque wrench to measure the maximum torque seen when raising the door. Rotate the screw smoothly and slower then you plan on running the stepper, so that the friction element can be measured. Do this several times, record the max torque measured, multiply by 1.3 or 1.4 and choose a stepper motor that will handle that torque. Since I am a retired EE, are there any mechanical engineers with additional insight? Please chime in.

Edit: Thinking about this, a DC motor with a pwm speed control would be a better choose, and with a little electrical know how could be controlled with a simple circuit. But a processor board would be more flexible.

 

Great idea, can easily handle the weight of a small piece of plywood and can be controlled by an Arduino board using a couple small relays or driver chips.

 

Agreed. A stepper motor would be overkill for this application, though I don't think you need to have a motor driver circuit for this application as it doesn't require speed control. A simple on-off is adequate.

I would recommend going through the calculations of torque to get you a ballpark estimate of the required torque.

So what it comes down to is speed vs cost.

http://www.mcmaster.com/#dc-gearmotors/=nocdk1

If it was me I'd go with the compact DC gearmotor. Good torque for the $. Granted the higher torque you need the slower it's going to run. The minature dc gearmotor is also great for this application if you're willing to pay the premium.

Chances are good you can lower the friction by using oils etc on the drive shaft. This will mean you can use a higher speed, lower torque option.

You'd have to calculate the number of threads per inch and determine if that closing speed is something you can live with. Then find a motor that has the speed and torque you need. If you don't want to go with a gearmotor you could gear a motor yourself if you're ok with exposed gearing or covering it.

 

Thanks mkelly.... I will build it the door and test the torque ASAP. My coop is far from my house. I was thinking about putting a small solar panel on it and run this off battery. To run it from battery i get a 12v motor right?

 

Yeah most solar cells charge 12v batteries.

 

Project update:

I've cut, sealed, and assembled all wood parts. The door moves smoothly up and down. Designed and printed the door mount with threaded nuts at top and bottom. My arduino boards should be in soon....
I'm still looking for a motor and need to order some limit switches. I might try to find a drill on Craigslist or at a garage sale.

 

Project update:

- Designed and printed limit switch mounts.
- found old cordless drill to use motor out of. Tested it and it will easily raise and lower the door.

Next step will be to figure out how to mount the motor.

 

Are you gonna take that drill apart or just use as is?

 

I am going to probably take it apart. Will be designing a mount for the motor this week.

 

has this men finished? how is it?

 

I'd be interested in your progress as well. I've been considering something similar for our chickens and ducks... but I'd need to open their pen door which is a 10'x20' dog kennel. It's heavy guage welded wire panels and large doors, so I'll probably need a spring or something. I'm still considering designs. I'm more interested in getting the door to open, and I'll be responsible for closing it up at night and making sure everybody is in and boxed up, as well as re-lowering their feed containers which I suspend from rope from the kennel roof. I keep it up during the day so they have to forage rather than just sit around eating kibble all day long. LOL

 

I want to buy a chicken coop and run, to house 3/4 hens. I like the raised coop design,mainly as vermin coundn't take up residence underneath, The nest box sits on the side, but will they get too cold in winter?
No option to get one DIY'd , so its a ready made.
If anyone has any experience of the shop bought kits and their robustness please share . The gimicky and expensive eglu is not for me.
Any thoughts?