Week 3: The Portal Receptacle
Note:
Mechanical Irises have always fascinated me. I salvaged an old slide photographing rig back in Chile (when I was seven or eight), and played with the shutter for a very long time. In the past few years I've seen many projects crop up that use this particular style of iris. Instead of many thin, overlapping sheets of metal, there are several triangular vanes, each pivoting on an independent axis and manipulated by a linkage to a rotating ring around the outside. Unfortunately, the mechanism takes up a lot of space. I thought of a few ways to optimize this (a slotted plate, for example), but since the extra space fit into the design well I ended up using the inefficient design.
The tricky part here was working out a good shape for the vanes. The area behind the pivot has to be small enough to avoid hitting the next vane as they move. I made a constant radius cut around the pivot out to the minimum point of contact in the closed position to prevent collision. The curve of the vanes also recedes slightly, so they get farther from the next pivot the wider they open. The shape of the curves was also affected by the choice between fully closing, or opening into a perfect circle. The geometry prevents a curve that can both fully interlock and then open into a smooth circle (at least I convinced myself of this at 4am last night, so I could be wrong - I don't quite remember my reasoning... EDIT: I'm pretty sure it's possible after thinking it over again, oh well!). I ended up making the vanes fully interlock, then adding a bounding ring slightly smaller than the "circle" created by the edges of the opening vanes to make the open hole into a true circle, at the expense of some lost diameter.
In the end, I finished up with a nice rubbish bin that can be made with some fiberglass and a laser cutter. The portal decals in the cylinder were drawn in Inkscape by Christine! She based them off the decals on the incinerator on the last level of Portal 1, since I couldn't find any high resolution images to use.
The tricky part here was working out a good shape for the vanes. The area behind the pivot has to be small enough to avoid hitting the next vane as they move. I made a constant radius cut around the pivot out to the minimum point of contact in the closed position to prevent collision. The curve of the vanes also recedes slightly, so they get farther from the next pivot the wider they open. The shape of the curves was also affected by the choice between fully closing, or opening into a perfect circle. The geometry prevents a curve that can both fully interlock and then open into a smooth circle (at least I convinced myself of this at 4am last night, so I could be wrong - I don't quite remember my reasoning... EDIT: I'm pretty sure it's possible after thinking it over again, oh well!). I ended up making the vanes fully interlock, then adding a bounding ring slightly smaller than the "circle" created by the edges of the opening vanes to make the open hole into a true circle, at the expense of some lost diameter.
In the end, I finished up with a nice rubbish bin that can be made with some fiberglass and a laser cutter. The portal decals in the cylinder were drawn in Inkscape by Christine! She based them off the decals on the incinerator on the last level of Portal 1, since I couldn't find any high resolution images to use.