How I Built a Giant Mechanical Iris Skylight with a CNC Router

Art & Sculpture CNC & Machining Craft & Design Digital Fabrication
How I Built a Giant Mechanical Iris Skylight with a CNC Router
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Over the years I’ve seen several implementations of cool mechanical irises used as architectural pieces.  There were the incredible front doors from Chris Schaie and the Nautilus art car’s iris that stand out in my mind. I knew I wanted to integrate a mechanical iris into the peculiar and unique house that I live in. I started off, intending to use one as a peephole. I designed it, 3d printed it, and revised it a few times.

The finished design is neat, and may still end up in place, but I felt I wanted more. I wanted people to stop in their tracks when they noticed it and say “WOW”.  In the back of my mind, I had been thinking that it would be neat to put a giant version at the top of my spiral stair case. This concept kept getting pushed back though, because I knew it would take me forever, and I’d get marginally cruddy results cutting everything by hand.

CNC Router Parts to the Rescue

CNC Router Parts had this cool booth at Maker Faire last year where they were making ukuleles. I was mesmerized watching the machines work.

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I kept returning to their booth to gawk at the machines and fantasize about what I’d do if I had access to one. Of course, this is where conversation ultimately turned as I chatted with Nathan Skalsky and his co-workers. I mentioned that there was a project I’d been kicking around for a while, but it had just simply been out of my grasp, and they pulled the idea out of me. They loved it. They got as excited as I was!

As you know, sponsors keep us going. We need these partnerships to keep making awesome content and throwing incredible events like Maker Faire. Companies like CNC Router Parts are looking for ways to show off their awesome machines that aren’t simply boring ads. When I explained what I wanted to do, they jumped on board, thinking this was a perfect opportunity to show off a bit, and boy were they right!

Nathan was so excited by the project, he got a jump start and completely designed a model from scratch. We ended up using his version instead of my half-baked ones that weren’t scaled up yet. You can download the complete iris model if you want to make your own, from the CNC Router Parts website!

The Tools 

To build the iris, I needed something that could cut the giant shapes for me, that I could count on for precision, and that would do it it all in a reasonable amount of time. The machine we landed on was their PRO 60120. It’s a 5 foot by 10 foot machine (yay I can fit 5 foot by 5 foot sheets of baltic birch!) with beefy nema 34 steppers and a 3 Hp spindle.

Nathan flew out to help me assemble it, show me how to use it, and help me cut the first few pieces of the design. You can follow along as We build it in this article.

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After getting it mostly built, Nathan had to go back home and I was left to figure a few things out on my own, such as how to surface the spoilboard. Of course they supplied all the files, so there really wasn’t a whole lot of “figuring out” to it, but rather just getting used to the machine.

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for this installation, I used mostly baltic birch, with a little MDF tossed in. Nathan cautioned that real woodworkers would scoff at my use of MDF, and I totally get that. However, this machine plows through it like butter and MDF happens to be a fantastic material for prototyping. That being said, I wouldn’t leave MDF in any project that needs to last more than a week or two. Any moisture or friction will quickly destroy it.

The bulk of what you see is baltic birch. This stuff comes in 5 x 5 or 5 x 10  sheets and the width of this machine means that I can easily cut that. I did have to experiment a little with which router bit to use to get good edges on my cuts. I still think there’s some room for personal improvement there.

The leaves, or parts that move to cover the hole, are made from aluminum. I found a local metal seller that had 4 x 10 sheets, so once again I was grateful for the size of the machine. It did take me a while to figure out how I was going to hold down that sheet for cutting, and you can see that whole project below.

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Assembling the Iris

Before beginning to assemble the whole unit, you’ve got to add the pivots to the aluminum leaves. I used “rivet nuts” and simply epoxied them in place. They hold very strong and they’re threaded for the 5/16th bolts I was using.

not shown: the aluminum leaves, which go below that large gear

Really, putting together this giant iris was easier than the tiny ones I had 3D printed. I just laid down the “face of it” then stacked the leaves in place, overlapping eachother, then laid down the “gear”. After carefully threading all my bolts into place, I could bolt on the final few pieces and simply lift it into place!

Since we cut it to fit exactly to the shape and size of my stairwell, all I needed were sturdy supports to place it on. I used 3 plain shelf mounts and simply plopped it on top.

What does it do?

In my house, it simply looks cool. If this were installed in a different location, it could be used for privacy, like a blind or even for temperature control. The room where I really need some heat blocking has a boring square skylight, so I haven’t messed with that one. So, right now the mechanical iris just looks awesome, and I’m happy with that.

In this case, I’m simply using a nema 23 stepper motor and the most basic arduino code. I’m running a switch case, basically, if the dial is in one position it closes, if it is in another it opens, if it is in the middle, it does nothing. That’s all.

Since this is hooked to an arduino, I could theoretically use the iris to regulate temperature based on the heat coming from the sky light. Or, I could have it do any number of other things, like open and close if I get an email or something. Who knows. Personally, just having the iris there is pretty cool and the automation part is less interesting. I’ve considered pulling the stepper motor and using it elsewhere, while simply using a hand crank instead.

However, I’m also drawn to the idea of having it open and close slightly somewhat randomly, or based on some kind of local weather data. The idea is that it would then feel more like the house was alive.

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I get ridiculously excited seeing people make things. I just want to revel in the creativity I see in makers. My favorite thing in the world is sharing a maker's story. find me at

View more articles by Caleb Kraft


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