Introduction: Mechanical Iris Door

Picture of Mechanical Iris Door

For a really long time now, my dad has wanted an automatic chicken door coop. A few weeks before fathers day I decided I would make one for him. But on the fathers day I knew I wouldn't have time to finish. I then decided I would continue to think about it but wait until summer to start it. It's a good thing I did. This project ended up taking way longer than I thought it would. However, I am really proud of what I have made. I think it was well worth the time I put into it. I certainly learned a lot.

If you want to learn how to make the bow tie featured read this Instructable.

Step 1: Materials/Tools


  • Formica
  • dc motor
  • Toggle Switch
  • 2x Limit Switch
  • plywood
  • Epoxy
  • Acrylic
  • Packing Tape
  • 25x Post Screws
  • 3x Bolts
  • 3x Nuts
  • 3x Washers
  • Primer
  • Paint
  • Arduino
  • Arduino Motor Shield
  • 12v Power supply


  • CNC Router
  • CNC Laser
  • Drill
  • Forstner Bits
  • Regular Drill bits
  • Roller Brush

Step 2: Laser Cut

Picture of Laser Cut

Scale the plans to whatever size you want. There are a couple things you will need to change. Pretty much all of the slots and holes are dependent on the hardware size. So buy the hardware, modify the design, and THEN cut it. At the time I was building this, my dad was putting together a CNC router. So I laser cut as much as possible, but on the last day, he finished building it and we cut out the final piece.

One key part of laser cutting the Formica was to keep it flat. We also found that if it is too much power/too slow the Formica will bend and mess up the cut.

Step 3: CNC Router

Picture of CNC Router

I don't have much to say about this step. I don't really know how to use a CNC router that well. My dad helped me a lot with this step, as we were both learning how to use it.

Step 4: Assemble the Iris

Picture of Assemble the Iris

Sand all the wood lightly

Follow the instructions in the pictures

Cut spacers, mine were about 1&1/2 inches thick

Drill holes in the edges of the spacers the size of your bolt

Step 5: Paint

Picture of Paint
  1. Prime
  2. 1st coat
  3. 2nd coat

I found some paint in my shed that I liked, but there wasn't too much. I decided that the inner side doesn't have to look good, so I used the nicest colour for the outside and then used some other paint to finish the 2nd coat of the inside. I am really happy how it turned out. The paint is "espresso" coloured. I just poured the paint on and used a roller brush to apply it more evenly.

Step 6: Mount the Iris Mechanism to the Bracket

Picture of Mount the Iris Mechanism to the Bracket
  1. Drill through holes for the bolts in the bracket.
  2. Push in the bolts from the outer side and flip over. It helps to secure them with some masking tape.
  3. Mount the iris with the spacers onto the bolts
  4. Add washers
  5. Add bolts and tighten slightly past hand tight.

Step 7: Electronics

Picture of Electronics

Start out by attaching the 12v power supply to the motor shield. It's really easy. Just strip the ends of the wire, use an ohmmeter to determine polarity, and then put the wire in the corresponding hole. Then just tighten it with a little flat head screwdriver.

The next step is to wire all the switches. Using the image above, wire in the limit switches and then the toggle switch.

Wire in the motor. The motor is the easiest thing to wire. Simply run a wire out of the motor shield "A" section to the terminals of the motor.

Tape the whole Arduino block to keep it from shorting out. Then take some sort of plastic container and cut a groove in the male threads, and a little bit more. Place the Arduino in it and screw on the lid. Then use hot glue on the lid to secure it to the backside of the iris.

Once you have completed all this, it's time to download the code and test it.

Step 8: Programming

This code enables a switch to open or close the door, and the limit switches stop it. If it does not work, switch the limit switches. It's easy to do by simply switching the inputs on the Arduino. It took me a couple of tries to get the code to work, but it works flawlessly now.

Once you upload the code to the Arduino, test the whole setup. You want to debug the system before you put it all together. It may seem like a pain, but it's worth it in the end.

Switch Code

const int forward = 2;
const int reverse = 4;
const int oc = 7;

int forwardState = 0;
int reverseState = 0;
int ocState = 0;

void setup() {

//Setup Channel A
pinMode(12, OUTPUT); //Initiates Motor Channel A pin
pinMode(9, OUTPUT); //Initiates Brake Channel A pin
pinMode(forward, INPUT);
pinMode(reverse, INPUT);
pinMode(oc, INPUT);


void loop(){

forwardState = digitalRead(forward);
reverseState = digitalRead(reverse);
ocState = digitalRead(oc);

if (forwardState == HIGH) {
digitalWrite(9, HIGH); //Engage the Brake for Channel A

if (reverseState == HIGH) {
digitalWrite(9, HIGH); //Engage the Brake for Channel A

if (forwardState == HIGH && ocState == HIGH) {
digitalWrite(12, HIGH); //Establishes forward direction of Channel A
digitalWrite(9, LOW); //Disengage the Brake for Channel A
analogWrite(3, 255); //Spins the motor on Channel A at full speed

if (reverseState == HIGH && ocState == LOW) {
digitalWrite(12, LOW); //Establishes backward direction of Channel A
digitalWrite(9, LOW); //Disengage the Brake for Channel A
analogWrite(3, 255); //Spins the motor on Channel A at full speed

Step 9: Switches

Picture of Switches

The limit switches are pretty easy to install. Just screw them down close to the main gear. Think about it to make sure it is facing the correct way.

Toggle switch. Take off the washers and bolts. Use the inner diameter of the washer to find a drill bit. Then use a forstner bit that is larger than the whole switch to make an indentation in the backside of the mounting bracket. This is only necessary to make sure the threads of the switch reach the other side. Then use the other drill bit to drill a through hole through the center of the large indent.

Step 10: Setting Up Limit Switches

Picture of Setting Up Limit Switches

Position the iris to either the open or closed position. Then glue up some scrap wood to trigger the switch. Repeat on the other position.

Step 11: It Works/Training

It now works, but the chickens are too dumb to use it. When I first made it, they wouldn't go out. But now they will. They have always gone in. To train them to leave I set each chicken on the threshold and encouraged them to jump off. After a couple times, they learned to do it automatically.

Step 12: THE END

I will be updating this instructables soon with a video of all the chickens walking out. I really hope you enjoyed this project. I worked really hard on it, and had a lot of fun.

I am finding more and more that on big projects, the two best parts are thinking of the idea and finishing the project. I had a lot of fun during this whole project. The key is to be relaxed and take a lot of breaks from it.

If you have anything to say, comment below. If you think this looks futuristic and awesome (it does) vote for me in the entered contests.


aliababua (author)2017-11-30

Great job! What is the thickness of Acrylic you used? Is it important to have hard Acrylic or I can use the soft and thin (about 0,020") Acrylic? Thank you and have a good inspiration!

EdL59 (author)2017-09-28

Ha. I was in the process of making the same thing when I came across this wonderful project. While a sliding door is ok - an iris door is so much clasier.

diy_bloke (author)2017-07-31

"No chickens were hurt in the making of this video"
Prize for originality and execution.
I will need to go through yr description a few times though coz not all very clear yet how you put things together, but I will probably be able to work it out

zposner (author)diy_bloke2017-07-31

Thanks, I added a video in the comments trying to explain how it works and how it goes together, maybe that will help?

diy_bloke (author)zposner2017-07-31

yes, has become much clearer

Sir Keefer (author)2017-07-15

I have two green thumbs, and one left hand, I can't even draw, can I buy this somewhere.

zposner (author) Sir Keefer2017-07-31

I am the only person I know who makes it, but I would only make and sell them for an incredibly high price.

dbess (author)2017-07-15

What happens if the power goes out?

zposner (author)dbess2017-07-31

If it is rotating, it will stop. If it isn't, nothing will happen. I think when it turns back on it won't move no matter what.

Udon (author)2017-07-28

This is awesome, while hilarious.

zposner (author)Udon2017-07-31


PogCarr (author)2017-07-13

Can you provide some more pics of how the parts go together/work? I am having trouble vizualizing the mechanism.

zposner (author)PogCarr2017-07-14

I also added the video to the instructables, I am adding it here so you can reach it fast. If you are still having trouble understanding it, just say the word and I will make another video.

diy_bloke (author)zposner2017-07-31

Very clear.
Just wondering if the screws in the slots will be capable of making that motion, just the sligthest pull may make them get stuck. But then again... you made it and it is working

zposner (author)diy_bloke2017-07-31

Yes, I had trouble with that at first. The key is to get the right spacer width so that the heads of the post screws are never tilted.

zposner (author)PogCarr2017-07-14

Yes. I'm on it! :)

diy_bloke (author)2017-07-31

Anybody want to make this for a different size....... you may find the gear generator come in handy:,200,100,6,1,0,0,4,1,...

zposner (author)diy_bloke2017-07-31

Very cool resource, thanks for sharing!

diy_bloke (author)2017-07-31

In one of your pictures there is an item that many electronics adepts will think is a crooked red cinch plug.
Chicken lovers know better, it is a water nipple

DDW_OR (author)2017-07-11

What CNC routers/lasers did you use?

zposner (author)DDW_OR2017-07-14

100 watt CO2 Boss laser

2.2kw spindle, mostly from CNC router parts

kz1 (author)2017-07-11

Screw the chickens! I want this for MY front door. No training to use required. :-}

zposner (author)kz12017-07-14

I do too! I would use a faster type of iris, but it would be so frickin cool!!!

phoe (author)2017-07-11

There's probably an inappropriate joke about cooking the chicken that could be made, half in jest, but could one get stuck in there as the iris closes ?

zposner (author)phoe2017-07-14

Yes. A chicken COULD POSSIBLY get stuck, but I would just call that natural selection ;)

holla2040 (author)2017-07-12

Well, how cool is that? I thought I took my chicken door seriously (search youtube for "150913 Warm Chicken". Your door makes me look like a kindergartner. Thanks, this is excellent work.

zposner (author)holla20402017-07-14

I skimmed through your video. It is really good. I wish I had enough time to make videos for all my projects. Glad you like it.

tedn187 (author)2017-07-12

This will be perfect for a hole I have to another dimension!

zposner (author)tedn1872017-07-14

Yes, yes it would be

deluges (author)2017-07-09

that's pretty cool, especially the training part ^^

zposner (author)deluges2017-07-09

I agree, the training is coming along slowly. They have very little capacity to think.

jibpsy (author)zposner2017-07-11

Yeah some chickens aren't to bright. I had friends that had two types of chickens, one for meat and one for eggs. The egg chickens weren't totally stupid but the meat chickens? One day I was helping my friends build an orchard where their meat chicken had free range and we needed to move the coop (it was just the box cover for a truck as it was just tall enough for them and they all fit in there). We moved it to the other side of the field. Later it started to rain. All the chickens huddled in a perfect rectangle where the box cover had been. A couple died from the rain because they looked up and drowned. We had to run out and get the box and bring it back to cover the chickens. It fit perfectly over their formation. They aren't great at learning, but they are good at keeping a routine.

zposner (author)jibpsy2017-07-14

Great story, thanks for being part of our comunity

deluges (author)jibpsy2017-07-11

This is the best story I've heard this month, thanks for the good laugh

charlessenf-gm (author)2017-07-11

Given the mess found in most coops I would think a simple drop door (sliding sheet of aluminum) would prove practical. So many moving parts. Could be my chickens are simply messier than your dad's.

Neat build. Envy your equipment.

zposner (author)charlessenf-gm2017-07-14

Yeah, ours are pretty clean. They roam around all day every day, so there isn't much poop in the coop. Also, we replace the straw every once and a while when it gets to dirty.

DeniseM122 (author)2017-07-11

Looks awesome. I would love to see a bow-tie on one of the chickens coming though it like James Bond. Super cute. Great job.

zposner (author)DeniseM1222017-07-14


booksmart (author)2017-07-10

Thanks for sharing the work and knowledge you gain in doing this. I think of try to make one myself. Thanks

God bless

zposner (author)booksmart2017-07-14

You're welcome

TURBOTECHNOLOGY (author)2017-07-09


What next you working on??

zposner (author)TURBOTECHNOLOGY2017-07-09

Thaks for the positive feedback. My next big project is a cement table with a river flowing through it. But I have a ton of little projects that I'm always working on

TURBOTECHNOLOGY (author)zposner2017-07-09

Yeah Nice
I hope you will get nice projects at the end...

cwarren205 (author)2017-07-09

This is a really neat father/son project! You guys make a great team. Hope to see more projects from you guys.

zposner (author)cwarren2052017-07-09

Thank you! I will tell my dad

About This Instructable



Bio: We're born, we make, and we die. So start making!
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