3D Design of a Mechanical Iris





So I've always wanted to build a mechanical iris, and this 3D design contest sounds like the perfect way to work the bugs out.

We'll call this step 0 (maybe? it is my first instructable...) - Research!  You need to figure out what you want to make and if its ever been made before.  What problems they have had, or success stories.  So hit up google images and search for mechanical iris.

the first image is what i actually ended up with!

Disclaimer:  I know the mechanical iris has been instructabled to death, but this is focusing on the CAD design of it, not the mechanism itself. 

Step 1: Draw It!

A 3D program is not a sketch book, make sure you have a plan before getting into it.  I generally use AutoCAD to do the first drawings.  I make a 2D drawing that gives the basics of the mechanism.  Each component of the mechanism gets its own layer so I can turn the others off and get a clear picture of what I'm working on.

Step 2: Check It

This is the point where you do the quick idiot check of the design, and make sure it does what you want.  Mine didn't, so I had to redesign it.  It would have sucked to have to build it in 3D before realizing this error my part...

After I made sure it would function the way I wanted, I took the time to focus on how i would make it.  Since I haven't wont the replicator yet, I would have to make this by hand.  look at all those complicated cuts?  So I made a 3rd version with less intricate cuts. 

Always remember that you can draw anything, model most things, but you're limited to what you can actually build.  That's why I want a 3D printer!

Step 3: Solid Works Setup

I know what you're saying.  This is supposed to be a 3D instructable.  well OK, here we go.  My weapon of choice is solid works, and its the 2007 flavor.  Each program is a little different, so I'm not going to bore you with details.  I'll focus on the main method of 3D'ing something.

Open solids works and make a part.  Immediately save it.  Now take the simplest component of the assembly and draw it very basically. In solid works you make a sketch, pick a plane, and draw it.  After that you extrude it.  This takes it from 2D to 3D.

I decided to use the outer ring as my template piece.

Once you have your template piece made, you can close the 3D program and copy and paste the file however many times you need it.  My assembly for the Iris has 5 distinct pieces:
Outer ring
Inner ring

Remember that most 3D programs are parametric.  That means you can draw it with any dimensions, then click on "smart dimension" and give it the size you need.

Step 4: Draw Your Parts

Now go into each part file one by one and change the shape.  Since all my parts are going to be cut out of the same thickness material i just need to go in and change the underlying sketch.

Step 5: Make Your Assembly

Now we have all these parts in different files, but we want them together.  Well we need to make a new file to combine all the old ones, but its not just the same type of file.  This new file will be an assembly file, which will basically link all the parts together and tell them how to move.  A simple concept and process, but so extremely important that it warrants its own step.

Step 6: Put Everything Together and Mate Them

So now that you have the assembly file, put the first piece in it.  I like to start with the piece of the mechanism that isn't going to move.  For this project, its the back plate.

Next you add another piece, I went with the outer ring.

As you add parts and mate them, you'll probably want to make some changes to them.  That's ok, just right click on the part in the tree to the left and click open part.  Make the changes and save the part.  when you go back to the assembly it will tell you that it was updated and make the changes.  Isn't technology wonderful?

Step 7: Paterns

Now that you have one of every part in the assembly, you can make a pattern out of the iris and linkage to add the other 4 instances of it.  If you do it right, all of the mates will duplicate as well and you'll basically be done in a few clicks.

The same trick works for parts if you want to pattern a feature, like the holes around outer ring and back plate.

Step 8: Go Make It

Well that was nice, but don't you want to actually build it?  Well i would just go press "Print" on my new replicator, but it hasn't gotten here yet ;0)

So built it the old fashioned way.  Redrew it on foam board and cut it out.  I used pins as hinges.

I'm not impressed with my construction skills (now you know why I changed the design from v2 to V3), but it mostly works.

Step 9: In Closing

This is my first instructable, and let me tell you, I have a new respect for you people that make these.  Between "where did i put my screen captures" and "well... that didn't turn out right" and "why the hell wont it upload?!?" the people in the room with me think i'm going to throw the pc across the room..

But it was fun, I'm glad i did it even if I don't win the contest.

3D Design Contest

Runner Up in the
3D Design Contest



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    11 Discussions


    4 years ago on Introduction

    I used this site to design an iris: www.iris-calculator.com

    It works it all out for you, and if you get the pro version you can even download the drawing and use it in whatever CAD program you use!


    6 years ago on Introduction

    I got all happy and ready to do this? Then i checked on this SolidWorks, its 100 bucks or more, any its not easy to just get you have to get a quote? Dude! This sucks. Is there a free version? I'm not going to make money with this?

    3 replies

    Reply 6 years ago on Introduction

    It's not a free program. I use it because I took a class on it and they gave me a free copy.

    Now that I know how to use it, I would probably buy a copy. It's worth it.


    Reply 4 years ago on Introduction

    I know I'm a little late to the party, but there are tons of open-source (Read: "free") alternatives out there that work just as well as solidworks.

    One of the best ones out there is called FreeCAD.



    6 years ago on Introduction

    Did you enter this in the digital fabrication contest that's running right now? I think that it's an excellent entry. Nice Instructable!

    3 replies

    Reply 6 years ago on Introduction

    I did, but it was rejected =o(

    I assume it's because I didn't actually fabricate it digitally, just designed it digitally and cut it out by hand.


    Reply 6 years ago on Introduction

    Ah yes, sorry, that is a requirement of the contest. In any case, good work.


    Reply 6 years ago on Introduction

    Thank you.

    I'll try again after i win the replicator and print it out!


    6 years ago on Introduction

    It finally says I'm in the contest, VOTE FOR ME! WOO HOO!


    Thank you so much, and this is a great post. They can be difficult to write, or organize, but each Instructable does so much good for our community of learners and makers!