My experience with making a mechanical component to my thesis work was difficult but fascinating. There is something absolutely amazing about creating something that moves, especially when you combine it with electronics. The first step in making the iris was finding a way of planning each part. In order for it to work properly you must make everything as perfect as possible to ensure smooth transitions. I planned and downloaded my iris using www.iriscalculator.com. The plan, when opened with illustrator can be seen in Fig, 1: Iris plan.
When I had my plan I separated the various components into their own illustrator files, printed out paper copies and cut them out carefully before taping them to the surface of a sheet of brass. I then spent two days with a jewellery saw, carefully cutting out each blade and ring.
I was happy at this point with the way the iris looked, but I had to acknowledge the fact that the weight was too much to be attached to a mask. I made the decision to not complete this version of the iris and instead experiment with alternative materials and methods of fabrication. I began the next version by visiting the rapid prototyping centre and learning how to properly format an illustrator file to be sent to the laser cutter. I then went to the plastics studio and asked the technicians which materials they would suggest for my next version of the iris. I needed something thin but resilient for the blades and therefore settled on ABS plastic. It bends easily, is thin and does not crack or shatter unlike acrylic. For the pin ring I attempted to use acrylic, but as I began setting rivets it shattered and so I settled on co-polyester. In the future I would like to do some more research into different types of plastics so that I can find the ones that suit my needs without off gassing toxic fumes like ABS. I do not usually use plastic, but in this case I didn't have much choice if I wanted the iris to function properly. It took a few attempts to laser cut all of the pieces properly and trouble shoot small mistakes. When I finally received all of my components from the rapid prototyping centre they looked like this:
In Fig.6 you can see the different pieces that make up the iris. The clear plastics are the co-polyester, the blades are ABS and the front ring sitting on the white paper is baltic birch plywood which I used an oxy-acetylene torch to burn the surface before danish oiling it to seal the wood. The bolts I cut from a piece of 1/8" brass bar and hand threaded before using lock tite to secure nuts on one end.
When the pieces were finally assembled and it began to work I was pretty excited. It really is amazing to see your hard work come to life!