How to Make a 12 Leaves Mechanical Irirs

Materials:

1 - bicycle chain......yes a bicycle chain, you'll seee what's for.
1 - copper sheet
1 - 15mm MDF board (20 x 20 cm will do)
1 - 3mm MDF board (20 x 20 cm will do) ( not on the pics)
1 CD tube case
And also some tools such as:

Bicicle chain tool
Drill
4 mm drillbit
130 mm Holesaw
75 mm Holesaw
Table saw or router table, or router, or dremel.
A blowtorch
Soldering wire and paste
scissors
A visegrip (recommended)
A Vise

You will also need a template file wich you can download from here, is a dwg (Autocad) file, you have to print it on a 1:1 scale.

Ok, so what the heck is the bicycle chain for? well, every iris leaf, has two pins, one of them is  a pivot pin, and the other is a travell pin, wich runs in a slot.
So, in this project we will use the bicycle chain pins, ;)

Now,what you need to do is to take your bicycle chain, and dissasembly it several times, in order to get 24 pins, as the images show.

I put my chain tool in the vise to have a better handling.

Every chain link is componed by two pins, two little rings, and two little flat pieces, we will only use the pins, but save the other little pieces, cause they can be very usefull, and you never know when you gonna need them.

Once you get the 24 pins, clean them up very well (i use alcohol), to get all the oil and grease out, and we are ready for the next step

Now let's make some leaves!

Ok, first print the leaf template, and glue it to the copper sheet.
Now cut the leaves!

Regular scissor will do the job (Remember, this copper sheet is 0,1 mm thick)

Once you get them all cut, remove the paper, and we are ready for the next step!

Ok, now comes the fun part, we will solder two pins in every leaf, you must be carefull of where you place the pin, you have to guide yourself using the leaf template

I had no time to make a jig to precicely position the pin in every leaf, so i did it "by eye", anyway, we dont need surgical precision for this one.

Now, in case you're wondering ¿how do i solder those little things? i'll show you how i do it.

-First, i fix my visegrip on the vise
-Then i fix the leaf with the pin in position, in the visegrip
-Then you have to apply some soldering paste (flux), be generous.
-Heat it with the torch, just enough to get the paste melted
-Then, cut a piece of soldering wire, about 15 mm long, and twist it in a "U" like shape
-Then, wrap the wire around the pin base.
-And finally, heat everything untill the solder gets melted, use a soft flame, there's no need for exesive heat.
 
Do all that, and 20 minutes later you will have your 12 copper leaves set, ready to go!

Now lets make the two rings.

First, print the rings template, and glue them in to the mdf boards.

-The ring with the runners, is for the 15 mm MDF borad, and the ring with the 12 holes, is for the 3 mm MDF.

-Then cut them with the holesaw

-Sand all the edges

-Drill the holes ( 4 mm holes)

-Cut the runners in the table saw (or router table, or with a dremmel, etc) i set the cut depth to 10 mm.

And that's all, now lets go to the assembly part!

Ok! so now we have our 12 copper leaves set, and two mdf rings, let´s put them all together.

First, take the cd tube case.
Then put the 15 mm MDF ring on it
Then put the first leaf, with the tracking pin in a slot (the tracking pin is the one tha's a little offset, the other one is the pivot pin)
Then put the second leaf under the first one
Put the 3rd leaf under the 2nd......and so, untill you get the 12 leaves set up.

the put the 3 mm mdf ring on top, make all the pins fit with their respective hole (you can use some stick, or screwdriver to help) and YOU ARE READY TO GO!

Lets see a video of the iris in action! i must said this one works like a charm, opens and close very smooth.