Introduction: Mechanical Iris V2.0

Picture of Mechanical Iris V2.0

Before anything else, I would like to say that this Instructable is based on and inspired by carlbass and his Mechanical iris.


Inspired by his work I quickly put a piece of plywood in my desktop laser cutter and set it to work. Minutes later the promise appeared, and within moments I had pieced everything together in a fully functioning mechanical iris. Awesome!

However, after admiring the design I spotted few ways in which I felt it could be improved.

So here it is; my take on the Mechanical iris (v2.0).

Step 1: Improvements

Picture of Improvements

- In the original Mechanical iris there were three layers. I felt this was excessive and so this new design offers only two (plus 1mm for the optional Perspex cover).

- The points at which the 'arms' attached to the blades relied on a shared pin to partially rotate about. This aspect seemed over complicated when the same effect could be achieved with clever cutting. This means that post cutting assembly time is reduced.

- The holes have been changed to fit 6mm dowel instead of 5mm which, for some reason I found stupidly difficult to obtain.

- Drawing pins have been used to cap the wooden dowel pins ensuring that the blades and outer ring do not wonder or come off. This design does not however ensure the arms are kept in place when holding the finished product upside down. This is where the optional 1mm Perspex cover comes in should you feel you need it.

- Although this last part is very crude in its current design, I have included a use for the offcuts. Stuck together they form a raised grip for the back of the iris enabling you to hold and manipulate it more easily. This will prove its worth when you come to 'working' the outer ring in for a couple of minutes.

Step 2: Materials

Picture of Materials

Wood glue
Drawing pins
Your choice in wood
6mm dowel
Scalpel / hobby knife

1mm colourless Perspex (optional)

Step 3: Laser Cutting Files

Below are a choice of files for you to use. I couldn't think of any other file type you might need, so if I'm missing a major one please message me and I'll see if I can sort something out.

P.s. The .dxf and .svg files are a slightly updated version -- there are two turning handles so the iris can be used in one hand now.

Step 4: Assembly

Picture of Assembly

Assembly is very easy.

  1. Measure and cut a 6mm long length of your dowel.
  2. Use your knife to press down and cut as you roll the dowel back and forth.
  3. Repeat steps 1 and 2 a further nine times.
  4. Dab a small amount of glue in one of the base layer holes.
  5. Take one of the dowel 'lugs' and rotate/push into the glued hole.
  6. Ensure that the lug is flush with the back of your base layer.
  7. Wipe away any excess glue.
  8. Repeat steps 4-7 for the remaining 9 lugs.
  9. Glue the two semi circle off-cuts together and then glue to the back of the iris where you feel is most comfortable.
  10. Wait for the glue to dry.
  11. Place the outer ring over the glued lugs then spend a few minutes carefully working it in by repeatedly rotating it. You may need to shave minute amounts off the inside and outside of the lugs.
  12. Once the outer ring turns with minimal force add the blades and the arms linking everything up as you go.
  13. OPTIONAL - If you want to use a Perspex cover, this is where you would lay it over the top making sure that all holes align with the lugs underneath.
  14. Carefully push a drawing pin into the centre of each lug ensuring that the top of the drawing pin does not exert too much pressure on the piece reducing its mobility. Remember, these are merely a way of stopping the pieces falling off -- I left a fingernail's spacing under each one.

Step 5: Finished Product

Picture of Finished Product


HankH10 (author)2017-08-28


prank (author)2017-06-30

love it!

Evocatorum. (author)2017-06-25

How did you deal with the .dwg being drawn completely using splines? It seems like that would make it much more difficult to manipulate :-/

bburke37 made it! (author)2017-02-06

Thanks for the build. Has drawn lots of attention while sitting on my desk. Covered with .93 in. acrylic. Assembled with plastic push pins with the heads cut off. 3mm / .125 in balticbirch ply.

NTT (author)bburke372017-02-07

Really nice! Kudos ☺

Sockles (author)2016-10-08

what thickness wood are you using?

NTT (author)Sockles2016-10-09

Really doesn't matter that much. I used 3mm, but I suppose anything up to 6mm would work without looking too chunky.

AliZubair1 (author)2016-06-29

hi, can you please send me the files by email? i dont want to buy membership on email is i really need this for a school project

Sockles (author)AliZubair12016-10-08

No need to buy a membership, the files are there.

JohnA227 (author)2016-03-09

Clever design with the non-use of pins. Any chance you've made one with 8 blades? I've been scouring the web to find the calculations needed in designing this but have come up with none.Thanks!

AvivaF (author)2015-10-08

thanks a million.

Surferdude (author)2015-02-17

I don't see an SVG file listed here.

NTT (author)Surferdude2015-02-17

I'll stick one up this weekend. Of course if you can't wait that long you could always convert one of the existing formats to .svg

perpetualrabbit (author)2014-03-12


I'm thinking of ways to change the design to make the border (which contains all of the mechanics) around the hole as small as possible. If this would be the frontdoor to a house, and the diameter of the hole is 2 meters (6.56 feet), the ring would extend two meters around that, including into the ground. There has to be a way to minimise this.

NTT (author)perpetualrabbit2014-03-12

You're absolutely right. This design is limited because it does not overlap. As a result and as can be seen, everything must be spread out around the centre. To get past this you should be looking at an over-lapping iris. Something like this:

This one works well because the mechanism isn't restricted to one layer (the blades are also very thin by comparison). This would work best in thin metal and with a lot of oil.

Hope that's food for thought. And thank you for the compliment btw.

ruth.s.nyaboke (author)NTT2015-01-16

This sounds like it can work. I want to make it as a door to a 1 1/2 foot opening. Any ideas/help/suggestions would be awesome!! I have access to a laser cutter.

Alderin (author)NTT2014-03-14

Personally, I don't like the overlapping designs because they never
seem to fully close, whereas a large version of this one could be built
with tongue and grooves between the blades for a very solid closure.

Adding more blades should make the blades smaller, to lessen the width of the border. That said, I'm stuck on the math of how to make this happen beyond the 5 here. Maybe more blades could be worked out with compass and a lot of paper, but I'm not 100% sure it'll work.

That said, if you aren't minimizing the layers, and you keep 5 blades, you'd only need 1x the blade width outside of the doorway, so about 1 meter (Where the corners stop at 'open'). The actuation ring could be where the corners stop, such that the swing arms are tangent to the circle. It adds 2 layers to this design, but removes that 1m extra 'depth' around the door for you.

bquint (author)2014-09-15

Hi! For any reason I don't see the dxf and the svg files. Would you please make it available for me? I am very excited of trying to reproduce your project.

steveastrouk (author)2014-04-20

Great piece. I've been playing with it to use flexing arms from the outer ring to the petals, and having no moving joints except the outer ring.

NTT (author)steveastrouk2014-04-20

That's an interesting idea. I'd like to see some pictures of that

steveastrouk (author)NTT2014-04-20

I'm Struggling with materials....thin laser ply is useless.....I might try PET-G

siluentas (author)2014-04-03

it looks fantastic

NTT (author)siluentas2014-04-20

Thank you :-)

Manfred.Overmeen (author)2014-03-27

Hi I am cutting with visicut, DXF or SVG is welcome :-D

NTT (author)Manfred.Overmeen2014-03-27

ok. I'll see what I can do.

Nobin (author)2014-03-18

Muito Legal e engenhoso

Very nice ! I will add to my homework project


alienfap (author)2014-03-18


Nice project.

However, I cannot get the .DWG file to download. I am referring to the file Mechanical_Iris_v2.dwg. Can anybody help me to download this? I'm wondering if this is my screw-up (likely) or if the link is not working.


Mark Rehorst (author)2014-03-16

Very nice!

I spent some time searching for basic iris design information several months ago and never got anywhere except for a few that people had created and posted in various places around the web. When I couldn't find anything I tried to come up with a set of mathematical rules that would allow designs to be automated using a spreadsheet but never got very far with it. I wanted to input variables like the number of blades and maximum opening diameter and have the thing calculate blade size and shape and locations of hinge pins and actuator pins. Needless to say, its a very complex problem and I never got very far with it. I was unable to locate any old books that had any iris design info in them.

There seem to be two major types of irises, those with non overlapping blades like yours, and those with overlapping blades like those commonly used in camera lenses. Overlapping blades leads to a convex, polygonal center hole and requires multiple layers due to the overlap. They can't close completely because of the overlap though it's possible to add a shutter leaf on a final layer that will close off the remaining center hole. The blade's edges rub against each other so plastics or metals would be the best materials options for them. The non overlapping blades type can close completely and have complex hole border at all positions except fully open or fully closed, making them less useful for windows/covers where you might want a partial opening.

I was thinking it might be possible to use cloth blades with elastic cords in the edges, the ends of which are attached to the fixed and rotating rings.

If anyone knows of any technical references of the design of irises I love to know about them.

jwkooi (author)2014-03-12

Very nice project!

NTT (author)jwkooi2014-03-12

Thank you :o)

schaie (author)2014-03-11

just sayin, Carl bass didn't design this, wish he would give credit too.

NTT (author)schaie2014-03-12

Ah. I didn't know that.

Like you I do hate it when people don't reference things. Particularly when we're all in this for the same good cause.

quinn (author)2014-03-11

It's a really attractive and significant upgrade. I'm going to make one at Techshop this evening. Wonder how my landlord would feel about me installing it in my front door...

NTT (author)quinn2014-03-12

Ha ha ha! Do it :oD

Don't forget the 1mm Perspex if you're going to be flipping or holding it on its side ;o)

MercuryCrest (author)2014-03-11

Thank you for this. I had made the original design and found that somewhere, somehow, something was off and things didn't perfectly line up (though they were close).

Looking forward to giving this another shot!

NTT (author)MercuryCrest2014-03-12

You're welcome.

I know what you mean with things being ever so slightly off. I noticed a couple of things that weren't centred perfectly, so hopefully this new take will have addressed them.

If you spot an error give me a shout :o)

jamal boumaaza (author)2014-03-12


rimar2000 (author)2014-03-09

BRILLIANT, congratulations.

About This Instructable




Bio: Teacher of Science and engineer
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